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Stewart GM, Fermoyle CC, Wheatley-Guy CM, Robach P, Tiller NB, Taylor BJ, Ziegler B, Schwartz J, Gavet A, Chabridon L, Murdock RW, Constantini K, Johnson BD. Effect of Ultramarathon Trail Running at Sea Level and Altitude on Alveolar-Capillary Function and Lung Diffusion. Med Sci Sports Exerc 2024; 56:1759-1769. [PMID: 38595212 DOI: 10.1249/mss.0000000000003448] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
INTRODUCTION Endurance exercise at altitude can increase cardiac output and pulmonary vascular pressure to levels that may exceed the stress tolerability of the alveolar-capillary unit. This study examined the effect of ultramarathon trail racing at different altitudes (ranging from <1000 m to between 1500 and 2700 m) on alveolar-capillary recruitment and lung diffusion. METHODS Cardiac and lung function were examined before and after an ultramarathon in 67 runners (age: 41 ± 9 yr, body mass index: 23 ± 2 kg·m -2 , 10 females), and following 12-24 h of recovery in a subset ( n = 27). Cardiac biomarkers (cTnI and BNP) were assessed from whole blood, whereas lung fluid accumulation (comet tails), stroke volume (SV), and cardiac output ( Q ) were quantified via echocardiography. Lung diffusing capacity for carbon monoxide (DLco) and its components, alveolar membrane conductance (Dm) and capillary blood volume (Vc), were determined via a single-breath method at rest and during three stages of submaximal semirecumbent cycling (20, 30, and 40 W). RESULTS Average race time was 25 ± 12 h. From pre- to post-race, there was an increase in cardiac biomarkers (cTnI: 0.04 ± 0.02 vs 0.13 ± 0.03 ng·mL -1 , BNP: 20 ± 2 vs 112 ± 21 pg·mL -1 ; P < 0.01) and lung comet tails (2 ± 1 vs 7 ± 6, P < 0.01), a decrease in resting and exercise SV (76 ± 2 vs 69 ± 2 mL, 40 W: 93 ± 2 vs 88 ± 2 mL; P < 0.01), and an elevation in Q at rest (4.1 ± 0.1 vs 4.6 ± 0.2 L·min -1 , P < 0.01; 40 W: 7.3 ± 0.2 vs 7.4 ± 0.3 L·min -1 , P = 0.899). Resting DLco and Vc decreased after the race ( P < 0.01), whereas Dm was unchanged ( P = 0.465); however, during the three stages of exercise, DLco, Vc, and Dm were all reduced from pre- to post-race (40 W: 36.3 ± 0.9 vs 33.0 ± 0.8 mL·min -1 ·mm Hg -1 , 83 ± 3 vs 73 ± 2 mL, 186 ± 6 vs 170 ± 7 mL·min -1 ·mm Hg -1 , respectively; P < 0.01). When corrected for alveolar volume and Q , DLco decreased from pre- to post-race ( P < 0.01), and changes in DLco were similar for all ultramarathon events ( P > 0.05). CONCLUSIONS Competing in an ultramarathon leads to a transient increase in cardiac injury biomarkers, mild lung-fluid accumulation, and impairments in lung diffusion. Reductions in DLco are predominantly caused by a reduced Vc and possible pulmonary capillary de-recruitment at rest. However, impairments in alveolar-capillary recruitment and Dm both contribute to a fall in exertional DLco following an ultramarathon. Perturbations in lung diffusion were evident across a range of event distances and varying environmental exposures.
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Affiliation(s)
| | | | | | - Paul Robach
- Ecole Nationale des Sports de Montagne, Chamonix, FRANCE
| | - Nicholas B Tiller
- Institute of Respiratory Medicine and Exercise Physiology, Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center, Torrence, CA
| | - Bryan J Taylor
- Department of Cardiovascular Diseases, Mayo Clinic, Jacksonville, FL
| | - Briana Ziegler
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Jesse Schwartz
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
| | - Alice Gavet
- Ecole Nationale des Sports de Montagne, Chamonix, FRANCE
| | - Loïc Chabridon
- Ecole Nationale des Sports de Montagne, Chamonix, FRANCE
| | - Robert W Murdock
- Department of Cardiac Electrophysiology, Los Angeles Medical Center, Los Angeles, CA
| | - Keren Constantini
- School of public health, Sackler Faculty of Medicine, and Sylvan Adams Sports Institute, Tel-Aviv University, Tel Aviv, ISRAEL
| | - Bruce D Johnson
- Department of Cardiovascular Diseases, Mayo Clinic, Rochester, MN
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Kristiansen S, Jarmund AH, Hilmo J, Mollnes TE, Leth-Olsen M, Nyrnes SA, Nilsen BA, Grønli RH, Faldaas BO, Storm B, Espenes A, Nielsen EW. Femoral Nailing in a Porcine Model Causes Bone Marrow Emboli in the Lungs and Systemic Emboli in the Heart and Brain. JB JS Open Access 2024; 9:e23.00128. [PMID: 38419616 PMCID: PMC10898662 DOI: 10.2106/jbjs.oa.23.00128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 03/02/2024] Open
Abstract
Background Shaft fractures of the femur are commonly treated with intramedullary nailing, which can release bone marrow emboli into the bloodstream. Emboli can travel to the lungs, impairing gas exchange and causing inflammation. Occasionally, emboli traverse from the pulmonary to the systemic circulation, hindering perfusion and resulting in injuries such as heart and brain infarctions, known as fat embolism syndrome. We studied the extent of systemic bone marrow embolization in a pig model. Methods Twelve anesthetized pigs underwent bilateral intramedullary nailing of the femur, while 3 animals served as sham controls. Monitoring included transesophageal echocardiography (TEE), pulse oximetry, electrocardiography, arterial blood pressure measurement, and blood gas and troponin-I analysis. After surgery, animals were monitored for 240 minutes before euthanasia. Post mortem, the heart, lungs, and brain were biopsied. Results Bone marrow emboli were found in the heart and lungs of all 12 of the pigs that underwent intramedullary nailing and in the brains of 11 of them. No emboli were found in the sham group. The pigs subjected to intramedullary nailing exhibited significant hypoxia (PaO2/FiO2 ratio, 410 mm Hg [95% confidence interval (CI), 310 to 510) compared with the sham group (594 mm Hg [95% CI, 528 to 660]). The nailing group exhibited ST-segment alterations consistent with myocardial ischemia and a significant increase in the troponin-I level compared with the sham group (1,580 ng/L [95% CI, 0 to 3,456] versus 241 ng/L [95% CI, 0 to 625] at the 240-minute time point; p = 0.005). TEE detected emboli in the right ventricular outflow tract, but not systemically, in the nailing group. Conclusions Bilateral intramedullary nailing caused bone marrow emboli in the lungs and systemic emboli in the heart and brain in this pig model. The observed clinical manifestations were consistent with coronary and pulmonary emboli. TEE detected pulmonary but not systemic embolization. Clinical Relevance Femoral intramedullary nailing in humans is likely to result in embolization as described in our pig model. Focused monitoring is necessary for detection of fat embolism syndrome. Absence of visual emboli in the left ventricle on TEE does not exclude the occurrence of systemic bone marrow emboli.
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Affiliation(s)
- Steinar Kristiansen
- Department of Surgery, Nordland Hospital, Bodø, Norway
- Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway
| | - Anders Hagen Jarmund
- Department of Circulation and Medical Imaging (ISB), Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
| | - Jonas Hilmo
- Department of Surgery, Nordland Hospital, Bodø, Norway
- Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway
| | - Tom Eirik Mollnes
- Research Laboratory, Nordland Hospital, Bodø, Norway
- Department of Immunology, Oslo University Hospital, University of Oslo, Norway
| | - Martin Leth-Olsen
- Department of Circulation and Medical Imaging (ISB), Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
- Children's Clinic, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
| | - Siri Ann Nyrnes
- Department of Circulation and Medical Imaging (ISB), Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
- Children's Clinic, St. Olavs Hospital, Trondheim University Hospital, Trondheim, Norway
| | - Bent Aksel Nilsen
- Department of Surgery, Nordland Hospital, Bodø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | | | - Bjørn Ove Faldaas
- Department of Circulation and Medical Imaging (ISB), Faculty of Medicine and Health Sciences, Norwegian University of Science and Technology, Trondheim, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | - Benjamin Storm
- Department of Surgery, Nordland Hospital, Bodø, Norway
- Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | - Arild Espenes
- Department of Basic Sciences and Aquatic Medicine, Norwegian School of Veterinary Science, Oslo, Norway
| | - Erik Waage Nielsen
- Department of Surgery, Nordland Hospital, Bodø, Norway
- Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
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Connolly DM, D'Oyly TJ, Harridge SDR, Smith TG, Lee VM. Decompression Sickness Risk in Parachutist Dispatchers Exposed Repeatedly to High Altitude. Aerosp Med Hum Perform 2023; 94:666-677. [PMID: 37587625 DOI: 10.3357/amhp.6231.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/18/2023]
Abstract
INTRODUCTION: Occurrences of severe decompression sickness (DCS) in military parachutist dispatchers at 25,000 ft (7620 m) prompted revision of exposure guidelines for high altitude parachuting. This study investigated residual risks to dispatchers and explored the potential for safely conducting repeat exposures in a single duty period.METHODS: In this study, 15 healthy men, ages 20-50 yr, undertook 2 profiles of repeated hypobaric chamber decompression conducting activities representative of dispatcher duties. Phase 1 comprised two ascents to 25,000 ft (7620 m) for 60 and then 90 min. Phase 2 included three ascents first to 25,000 ft for 60 min, followed by two ascents to 22,000 ft (6706 m) for 90 min. Denitrogenation was undertaken at 15,000 ft (4572 m) with successive ascents separated by 1-h air breaks at ground level.RESULTS: At 25,000 ft (7620 m), five cases of limb (knee) pain DCS developed, the earliest at 29 min. Additionally, multiple minor knee "niggles" occurred with activity but disappeared when seated at rest. No DCS and few niggles occurred at 22,000 ft (6706 m). Early, heavy, and sustained bubble loads were common at 25,000 ft, particularly in older subjects, but lighter and later loads followed repeat exposure, especially at 22,000 ft.DISCUSSION: Parachutist dispatchers are at high risk of DCS at 25,000 ft (7620 m) commensurate with their heavy level of exertion. However, the potential exists for repeated safe ascents to 22,000 ft (6706 m), in the same duty period, if turn-around times breathing air at ground level are brief. Older dispatchers (>40 yr) with functional right-to-left (intracardiac or pulmonary) vascular shunts will be at risk of arterialization of microbubbles.Connolly DM, D'Oyly TJ, Harridge SDR, Smith TG, Lee VM. Decompression sickness risk in parachutist dispatchers exposed repeatedly to high altitude. Aerosp Med Hum Perform. 2023; 94(9):666-677.
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Davis JT, Elliott JE, Duke JW, Cristobal A, Lovering AT. Hyperoxia-induced stepwise reduction in blood flow through intrapulmonary, but not intracardiac, shunt during exercise. Am J Physiol Regul Integr Comp Physiol 2023; 325:R96-R105. [PMID: 37184225 PMCID: PMC10292968 DOI: 10.1152/ajpregu.00014.2023] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 04/25/2023] [Accepted: 05/11/2023] [Indexed: 05/16/2023]
Abstract
Blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) (QIPAVA) increases during exercise breathing air, but it has been proposed that QIPAVA is reduced during exercise while breathing a fraction of inspired oxygen ([Formula: see text]) of 1.00. It has been argued that the reduction in saline contrast bubbles through IPAVA is due to altered in vivo microbubble dynamics with hyperoxia reducing bubble stability, rather than closure of IPAVA. To definitively determine whether breathing hyperoxia decreases saline contrast bubble stability in vivo, the present study included individuals with and without patent foramen ovale (PFO) to determine if hyperoxia also eliminates left heart contrast in people with an intracardiac right-to-left shunt. Thirty-two participants consisted of 16 without a PFO; 8 females, 8 with a PFO; 4 females, and 8 with late-appearing left-sided contrast (4 females) completed five, 4-min bouts of constant-load cycle ergometer exercise (males: 250 W, females: 175 W), breathing an [Formula: see text] = 0.21, 0.40, 0.60, 0.80, and 1.00 in a balanced Latin Squares design. QIPAVA was assessed at rest and 3 min into each exercise bout via transthoracic saline contrast echocardiography and our previously used bubble scoring system. Bubble scores at [Formula: see text]= 0.21, 0.40, and 0.60 were unchanged and significantly greater than at [Formula: see text]= 0.80 and 1.00 in those without a PFO. Participants with a PFO had greater bubble scores at [Formula: see text]= 1.00 than those without a PFO. These data suggest that hyperoxia-induced decreases in QIPAVA during exercise occur when [Formula: see text] ≥ 0.80 and is not a result of altered in vivo microbubble dynamics supporting the idea that hyperoxia closes QIPAVA.
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Affiliation(s)
- James T Davis
- Indiana University School of Medicine, Department of Anatomy, Cell Biology and Physiology Bloomington, Indiana, United States
| | - Jonathan E Elliott
- Veterans Affairs Portland Health Care Systeme, Research Servic, Portland, Oregon, United States
- Department of Neurology, Oregon Health & Science University, Portland, Oregon, United States
| | - Joseph W Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, United States
| | - Alberto Cristobal
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, Oregon, United States
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Chen A, Zhu J, Zhu L, Tang Y, Li Y, Zhang Q, Zhao Y, Ma C, Liu X. Neglected intrapulmonary arteriovenous anastomoses: A comparative study of pulmonary right-to-left shunts in patients with patent foramen ovale. Front Cardiovasc Med 2023; 10:1111818. [PMID: 37089892 PMCID: PMC10117845 DOI: 10.3389/fcvm.2023.1111818] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 03/16/2023] [Indexed: 04/09/2023] Open
Abstract
ObjectivePulmonary right-to-left shunt (P-RLS) and patent foramen ovale right-to-left shunt (PFO-RLS) often appear in combination, and there are often differences and connections between them. Intrapulmonary arteriovenous anastomoses (IPAVAs), as part of P-RLS, are often overlooked because there are no technologies to detect and identify them. This study aimed to further clarify the incidence and characteristics of P-RLS with the help of contrast transesophageal echocardiography (c-TEE) and contrast transthoracic echocardiography (c-TTE), providing a reference for clinically relevant research and patent foramen ovale (PFO) management disposal decisions.MethodsWe retrospectively investigated 414 subjects who came to our hospital for c-TEE from October 2021 to July 2022, and all subjects completed c-TTE simultaneously. 7 Patients who were newly diagnosed with an atrial septal defect were excluded. Eventually, 407 patients were included in this study. Among them, 157 patients with PFO (58 patients were treated with PFO closure subsequently) and 250 patients without PFO confirmed by c-TEE were finally enrolled. In the process, we observed and analysed the presence of P-RLS.ResultsA total of 407 patients were included in the final analysis and divided into PFO group (N = 157) and non-PFO group (N = 250) according to the results of c-TEE. Whether at rest or after Valsalva maneuver, the incidence of P-RLS was significantly higher under c-TEE than under c-TTE in the two groups (P < 0.001). For both c-TTE and c-TEE, the incidence of P-RLS was slightly higher after Valsalva maneuver than at rest, but the difference was not significant (c-TTE: rest vs. Valsalva maneuver, P = 0.214; c-TEE: rest vs. Valsalva maneuver, P = 0.076). The Valsalva maneuver increased the incidence of P-RLS in the group without PFO, which was more significant in c-TEE (c-TTE: rest vs. Valsalva maneuver, P = 0.591; c-TEE: rest vs. Valsalva maneuver, P = 0.008). In both groups, the P-RLS semiquantitative grading was statistical significance under different states and examinations (P < 0.001).ConclusionThe vast majority of P-RLS are grade 1–2 and are derived from physiological IPAVAs. Even so, attention should be given to the differentiation between P-RLS and PFO-RLS. c-TEE is an effective method to detect P-RLS; however, the recruitments of c-TEE and Valsalva maneuver to P-RLS should be noted.
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Affiliation(s)
- Anni Chen
- Department of Ultrasound, The First Affiliated Hospital of Shaoxing University, Shaoxing, China
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Jianbo Zhu
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Lei Zhu
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Yunyi Tang
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Yun Li
- Department of Ultrasound, The First Affiliated Hospital of Shaoxing University, Shaoxing, China
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Qi Zhang
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Yeping Zhao
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
| | - Caiye Ma
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
- Correspondence: Xiatian Liu Caiye Ma
| | - Xiatian Liu
- Department of Ultrasound, The First Affiliated Hospital of Shaoxing University, Shaoxing, China
- Department of Ultrasound, Shaoxing People’s Hospital, Shaoxing, China
- Correspondence: Xiatian Liu Caiye Ma
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Quantification of shunt fraction using contrast ultrasound and indicator dilution in an in vitro model. Respir Physiol Neurobiol 2023; 310:104013. [PMID: 36639005 DOI: 10.1016/j.resp.2023.104013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2022] [Revised: 01/06/2023] [Accepted: 01/08/2023] [Indexed: 01/12/2023]
Abstract
Transthoracic saline contrast echocardiography is commonly used to assess intrathoracic shunt flow in vivo. Though the technique has many advantages (safe, simple, repeatable), the measurement technique lacks specificity, and the contrast agent has limited stability. This study sought to determine if the indicator dilution modeling technique could be applied to ultrasound contrast data to quantify shunt fraction and to determine if buoyant force has a significant effect on microbubble pathway determination at a "vascular" bifurcation. A model of the pulmonary circuit was perfused with blood at three distinct flow rates (low, medium and high) over shunt fractions ranging from ∼2-10 %. The buoyancy effect on contrast was quantified using a simplified in vitro model of a vascular bifurcation that had an upper and lower outflow tract where saline contrast formed from carbon monoxide (CO) gas passed through the bifurcation, was collected and quantified. The indicator dilution model was found to have a mean bias of - 3.2 % for the low flow stage, - 2.6 % for the medium flow stage and - 1.4 % for the high flow stage compared to volumetric measurements, suggesting agreement increases with increasing flow rate. Investigations of the buoyant effects revealed that at lower flow rates, contrast bubbles that encounter a bifurcation will favor the upper outflow tract over the lower. However, this effect is reduced by increasing the flow rate two-fold. These data identify that application of indicator dilution theory to contrast ultrasound data and the pathway ultrasound contrast travels in a network of tubules is flow dependent.
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Monahan K, Brittain E, Tolle JJ. Measurement of pulmonary transit time and estimation of pulmonary blood volume after exercise using contrast echocardiography. J Echocardiogr 2023; 21:16-22. [PMID: 35829996 DOI: 10.1007/s12574-022-00582-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 06/07/2022] [Accepted: 06/23/2022] [Indexed: 11/28/2022]
Abstract
BACKGROUND Pulmonary transit time (PTT) and pulmonary blood volume (PBV) derived from non-invasive imaging correlate with pulmonary artery wedge pressure. The response of PBV to exercise may be useful in the evaluation of cardiopulmonary disease but whether PBV can be obtained reliably following exercise is unknown. We therefore aimed to assess the technical feasibility of measuring PTT and PBV after exercise using contrast echocardiography. METHODS In healthy volunteers, PTT was calculated from time-intensity curves generated as contrast traversed the cardiac chambers before and immediately after participants performed sub-maximal exercise on the Standard Bruce Protocol. From the product of PTT and heart rate (HR) during contrast passage through the pulmonary circulation, PBV relative to systemic stroke volume (rPBV) was calculated. RESULTS The cohort consisted of 14 individuals (age: 46 ± 8 years; 2 female) without cardiopulmonary disease. Exercise time was 8 ¾ ± 1 ¾ minutes and participants reached 85 ± 9% of age-predicted maximal HR, which corresponded to a near-doubling of resting HR at the time of post-exercise contrast injection. Data sufficient to derive PTT and rPBV were obtained for all participants. With exercise, the change in PBV from baseline ranged from 56 to 138% of systemic stroke volume, consistent with rPBV and absolute PBV values obtained in prior studies. CONCLUSIONS Acquisition of PTT and rPBV using contrast echocardiography after exercise is achievable and the results are physiologically plausible. As the next step towards clinical implementation, validation of this technique against hemodynamic exercise studies appears reasonable.
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Affiliation(s)
- Ken Monahan
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
| | - Evan Brittain
- Division of Cardiovascular Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - James J Tolle
- Division of Allergy, Pulmonary, and Critical Care Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
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Millington SJ, Mayo-Malasky H, Koenig S. Agitated Saline Contrast Injection in Patients with Severe Hypoxemia. J Intensive Care Med 2023; 38:479-486. [PMID: 36827332 PMCID: PMC10154990 DOI: 10.1177/08850666231159019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/25/2023]
Abstract
The use of agitated saline contrast (ASC) during echocardiographic examinations is a well-established practice, most commonly performed to identify atrial septal abnormalities in the context of stroke. In the intensive care unit, this technique may be employed to identify anatomic right-to-left shunts (either intracardiac or transpulmonary) that may be contributing to hypoxemic respiratory failure. This narrative review will describe the technique of ASC injection, summarize clinical scenarios where it may be useful, and review the strengths and limitations of the tool.
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Affiliation(s)
- Scott J Millington
- Department of Critical Care, University of Ottawa/The Ottawa Hospital, Ottawa, ON Canada
| | - Henry Mayo-Malasky
- Donald and Barbara Zucker School of Medicine at Hofstra/Northwell, 25049Long Island Jewish Medical Center, New Hyde Park, NY, USA
| | - Seth Koenig
- Department of Critical Care, Kent Hospital, Warwick, RI, USA
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Doolette DJ, Mitchell SJ. Extended lifetimes of bubbles at hyperbaric pressure may contribute to inner ear decompression sickness during saturation diving. J Appl Physiol (1985) 2022; 133:517-523. [PMID: 35834629 DOI: 10.1152/japplphysiol.00121.2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Inner ear decompression sickness (IEDCS) may occur after upward or downward excursions in saturation diving. Previous studies in non-saturation diving strongly suggest IEDCS is caused by arterialization of small venous bubbles across intracardiac or intrapulmonary right-to-left shunts, and bubble growth through inward diffusion of supersaturated gas when they arrive in the inner ear. The present study used published saturation diving data, and models of inner ear inert gas kinetics and bubble dynamics in arterial conditions to assess whether IEDCS after saturation excursions could also be explained by arterialization of venous bubbles, and whether such bubbles might survive longer and be more likely to reach the inner ear under deep saturation diving conditions. Previous data show that saturation excursions produce venous bubbles. Modelling shows gas supersaturation in the inner ear persists longer than in the brain after such excursions, explaining why the inner ear would be more vulnerable to injury by arriving bubbles. Estimated survival of arterialized bubbles is significantly prolonged at high ambient pressure such that bubbles large enough to be filtered by pulmonary capillaries but able to cross right-to-left shunts are more likely to survive transit to the inner ear than at the surface. IEDCS after saturation excursions is plausibly caused by arterialization of venous bubbles whose prolonged arterial survival at deep depths suggests larger bubbles in greater numbers reach the inner ear.
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Affiliation(s)
- David J Doolette
- Department of Anaesthesiology, The University of Auckland, Auckland, New Zealand
| | - Simon J Mitchell
- Department of Anaesthesiology, The University of Auckland, Auckland, New Zealand
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Kristiansen S, Storm B, Dahle D, Domaas Josefsen T, Dybwik K, Nilsen BA, Waage-Nielsen E. Intraosseous fluid resuscitation causes systemic fat emboli in a porcine hemorrhagic shock model. Scand J Trauma Resusc Emerg Med 2021; 29:172. [PMID: 34930433 PMCID: PMC8686379 DOI: 10.1186/s13049-021-00986-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Accepted: 11/09/2021] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND Intraosseous cannulation can be life-saving when intravenous access cannot be readily achieved. However, it has been shown that the procedure may cause fat emboli to the lungs and brain. Fat embolization may cause serious respiratory failure and fat embolism syndrome. We investigated whether intraosseous fluid resuscitation in pigs in hemorrhagic shock caused pulmonary or systemic embolization to the heart, brain, or kidneys and if this was enhanced by open chest conditions. METHODS We induced hemorrhagic shock in anesthetized pigs followed by fluid-resuscitation through bilaterally placed tibial (hind leg) intraosseous cannulas. The fluid-resuscitation was limited to intraosseous or i.v. fluid therapy, and did not involve cardiopulmonary resuscitation or other interventions. A subgroup underwent median sternotomy with pericardiectomy and pleurotomy before hemorrhagic shock was induced. We used invasive hemodynamic and respiratory monitoring including Swan Ganz pulmonary artery catheter and transesophageal echocardiography and obtained biopsies from the lungs, heart, brain, and left kidney postmortem. RESULTS All pigs exposed to intraosseous infusion had pulmonary fat emboli in postmortem biopsies. Additionally, seven of twenty-one pigs had coronary fat emboli. None of the pigs with open chest had fat emboli in postmortem lung, heart, or kidney biopsies. During intraosseous fluid-resuscitation, three pigs developed significant ST-elevations on ECG; all of these animals had coronary fat emboli on postmortem biopsies. CONCLUSIONS Systemic fat embolism occurred in the form of coronary fat emboli in a third of the animals who underwent intraosseous fluid resuscitation. Open chest conditions did not increase the incidence of systemic fat embolization.
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Affiliation(s)
- Steinar Kristiansen
- Surgery and Intensive Care Unit, University Hospital of Northern Norway, Tromsø, Norway.
- Department of Surgery, Nordland Hospital Trust, Bodø, Norway.
- Department of Clinical Medicine, Faculty of Health Sciences, Arctic University of Norway, Tromsø, Norway.
| | - Benjamin Storm
- Department of Surgery, Nordland Hospital Trust, Bodø, Norway
- Department of Clinical Medicine, Faculty of Health Sciences, Arctic University of Norway, Tromsø, Norway
- Research Laboratory, Nordland Hospital Trust, Bodø, Norway
| | - Dalia Dahle
- Faculty of Biosciences and Aquaculture, Nord University, Bodø, Norway
| | | | - Knut Dybwik
- Department of Surgery, Nordland Hospital Trust, Bodø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
| | | | - Erik Waage-Nielsen
- Department of Surgery, Nordland Hospital Trust, Bodø, Norway
- Department of Clinical Medicine, Faculty of Health Sciences, Arctic University of Norway, Tromsø, Norway
- Research Laboratory, Nordland Hospital Trust, Bodø, Norway
- Faculty of Nursing and Health Sciences, Nord University, Bodø, Norway
- Department of Immunology, Oslo University Hospital, University of Oslo, Oslo, Norway
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Kohshi K, Denoble PJ, Tamaki H, Morimatsu Y, Ishitake T, Lemaître F. Decompression Illness in Repetitive Breath-Hold Diving: Why Ischemic Lesions Involve the Brain? Front Physiol 2021; 12:711850. [PMID: 34539434 PMCID: PMC8446421 DOI: 10.3389/fphys.2021.711850] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 07/28/2021] [Indexed: 12/03/2022] Open
Abstract
Nitrogen (N2) accumulation in the blood and tissues can occur due to breath-hold (BH) diving. Post-dive venous gas emboli have been documented in commercial BH divers (Ama) after repetitive dives with short surface intervals. Hence, BH diving can theoretically cause decompression illness (DCI). “Taravana,” the diving syndrome described in Polynesian pearl divers by Cross in the 1960s, is likely DCI. It manifests mainly with cerebral involvements, especially stroke-like brain attacks with the spinal cord spared. Neuroradiological studies on Ama divers showed symptomatic and asymptomatic ischemic lesions in the cerebral cortex, subcortex, basal ganglia, brainstem, and cerebellum. These lesions localized in the external watershed areas and deep perforating arteries are compatible with cerebral arterial gas embolism. The underlying mechanisms remain to be elucidated. We consider that the most plausible mechanisms are arterialized venous gas bubbles passing through the lungs, bubbles mixed with thrombi occlude cerebral arteries and then expand from N2 influx from the occluded arteries and the brain. The first aid normobaric oxygen appears beneficial. DCI prevention strategy includes avoiding long-lasting repetitive dives for more than several hours, prolonging the surface intervals. This article provides an overview of clinical manifestations of DCI following repetitive BH dives and discusses possible mechanisms based on clinical and neuroimaging studies.
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Affiliation(s)
- Kiyotaka Kohshi
- Division of Neurosurgery, Nishinihon Hospital, Kumamoto, Japan.,Department of Environmental Medicine, Kurume University School of Medicine, Kurume, Japan
| | | | - Hideki Tamaki
- Department of Environmental Medicine, Kurume University School of Medicine, Kurume, Japan.,Division of Surgery and General Medicine, Tamaki Hospital, Hagi, Japan
| | - Yoshitaka Morimatsu
- Department of Environmental Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Tatsuya Ishitake
- Department of Environmental Medicine, Kurume University School of Medicine, Kurume, Japan
| | - Frédéric Lemaître
- Faculty of Sport Sciences, University of Rouen, Mont-Saint-Aignan, France.,CRIOBE USR 3278, CNRS-EPHE-UPVD, PSL, Moorea, France
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12
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Implication of Blood Rheology and Pulmonary Hemodynamics on Exercise-Induced Hypoxemia at Sea Level and Altitude in Athletes. Int J Sport Nutr Exerc Metab 2021; 31:397-405. [PMID: 34303308 DOI: 10.1123/ijsnem.2021-0013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 05/10/2021] [Accepted: 05/11/2021] [Indexed: 11/18/2022]
Abstract
This study aimed to investigate the changes in blood viscosity, pulmonary hemodynamics, nitric oxide (NO) production, and maximal oxygen uptake (V˙O2max) during a maximal incremental test conducted in normoxia and during exposure to moderate altitude (2,400 m) in athletes exhibiting exercise-induced hypoxemia at sea level (EIH). Nine endurance athletes with EIH and eight without EIH (NEIH) performed a maximal incremental test under three conditions: sea level, 1 day after arrival in hypoxia, and 5 days after arrival in hypoxia (H5) at 2,400 m. Gas exchange and oxygen peripheral saturation (SpO2) were continuously monitored. Cardiac output, pulmonary arterial pressure, and total pulmonary vascular resistance were assessed by echocardiography. Venous blood was sampled before and 3 min after exercise cessation to analyze blood viscosity and NO end-products. At sea level, athletes with EIH exhibited an increase in blood viscosity and NO levels during exercise while NEIH athletes showed no change. Pulmonary hemodynamics and aerobic performance were not different between the two groups. No between-group differences in blood viscosity, pulmonary hemodynamics, and V˙O2max were found at 1 day after arrival in hypoxia. At H5, lower total pulmonary vascular resistance and greater NO concentration were reported in response to exercise in EIH compared with NEIH athletes. EIH athletes had greater cardiac output and lower SpO2 at maximal exercise in H5, but no between-group differences occurred regarding blood viscosity and V˙O2max. The pulmonary vascular response observed at H5 in EIH athletes may be involved in the greater cardiac output of EIH group and counterbalanced the drop in SpO2 in order to achieve similar V˙O2max than NEIH athletes.
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13
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Tetzlaff K, Lemaitre F, Burgstahler C, Luetkens JA, Eichhorn L. Going to Extremes of Lung Physiology-Deep Breath-Hold Diving. Front Physiol 2021; 12:710429. [PMID: 34305657 PMCID: PMC8299524 DOI: 10.3389/fphys.2021.710429] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2021] [Accepted: 06/16/2021] [Indexed: 01/03/2023] Open
Abstract
Breath-hold diving involves environmental challenges, such as water immersion, hydrostatic pressure, and asphyxia, that put the respiratory system under stress. While training and inherent individual factors may increase tolerance to these challenges, the limits of human respiratory physiology will be reached quickly during deep breath-hold dives. Nonetheless, world records in deep breath-hold diving of more than 214 m of seawater have considerably exceeded predictions from human physiology. Investigations of elite breath-hold divers and their achievements revised our understanding of possible physiological adaptations in humans and revealed techniques such as glossopharyngeal breathing as being essential to achieve extremes in breath-hold diving performance. These techniques allow elite athletes to increase total lung capacity and minimize residual volume, thereby reducing thoracic squeeze. However, the inability of human lungs to collapse early during descent enables respiratory gas exchange to continue at greater depths, forcing nitrogen (N2) out of the alveolar space to dissolve in body tissues. This will increase risk of N2 narcosis and decompression stress. Clinical cases of stroke-like syndromes after single deep breath-hold dives point to possible mechanisms of decompression stress, caused by N2 entering the vasculature upon ascent from these deep dives. Mechanisms of neurological injury and inert gas narcosis during deep breath-hold dives are still incompletely understood. This review addresses possible hypotheses and elucidates factors that may contribute to pathophysiology of deep freediving accidents. Awareness of the unique challenges to pulmonary physiology at depth is paramount to assess medical risks of deep breath-hold diving.
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Affiliation(s)
- Kay Tetzlaff
- Department of Sports Medicine, University Hospital of Tübingen, Tübingen, Germany
| | - Frederic Lemaitre
- Faculte des Sciences du Sport et de l'Education Physique, Universite de Rouen, Rouen, France
| | - Christof Burgstahler
- Department of Sports Medicine, University Hospital of Tübingen, Tübingen, Germany
| | | | - Lars Eichhorn
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Bonn, Bonn, Germany
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14
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Galambos C, Bush D, Abman SH. Intrapulmonary bronchopulmonary anastomoses in COVID-19 respiratory failure. Eur Respir J 2021; 58:13993003.04397-2020. [PMID: 33863743 PMCID: PMC8051184 DOI: 10.1183/13993003.04397-2020] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 04/05/2021] [Indexed: 11/22/2022]
Abstract
The spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has led to a devastating and worldwide pandemic disease known as coronavirus disease 2019 (COVID-19). COVID-19 causes acute hypoxic respiratory failure (COVID-ARF), a major cause of mortality and morbidity, with an incompletely understood pathophysiological mechanism. Gattinoniet al. [1] noted that COVID-19 patients with acute hypoxic respiratory failure have lung disease that is often characterised by a remarkable dissociation between relatively well-preserved lung mechanics, including lung compliance, and severe hypoxaemia. These findings are consistent with the concept that profound hypoxaemia occurring in ventilated patients with highly compliant lungs could be due to the loss of regulation of lung perfusion and impaired hypoxic pulmonary vasoconstriction. Early autopsy studies suggest that the lung circulation is a major target of coronavirus infection, which leads to striking pulmonary vascular disease due to variable degrees of thrombosis, apoptosis, oedema, inflammation and angiogenesis [2–4]. These changes contribute to dysregulation of the pulmonary vasculature, which induces perfusion abnormalities and contributes to the physiological phenotypes reported in COVID-19 pneumonia. Further, computed tomography suggests a unique “tree in bud” appearance of small pulmonary arteries [3] and transcranial agitated saline microbubble doppler studies of COVID-19 patients with hypoxaemia have demonstrated intrapulmonary shunting of these bubbles, and that the presence and degree of transpulmonary bubble transit correlates with the degree of hypoxaemia [5]. Despite these studies, histopathological correlates of severe hypoxaemia and shunt in the setting of relatively normal lung compliance in COVID-19 patients are largely lacking. Open intrapulmonary bronchopulmonary anastomoses (IBA) were identified in COVID-19 patients who died of respiratory failure. IBA may be the microanatomical basis of intrapulmonary right to left shunt leading to severe hypoxaemia in COVID-19.https://bit.ly/3e2GajO
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Affiliation(s)
- Csaba Galambos
- Pediatric Heart Lung Center, Aurora, CO, USA .,Children's Hospital Colorado, Aurora, CO, USA.,University of Colorado Anschutz School of Medicine, Aurora, CO, USA
| | - Douglas Bush
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - Steven H Abman
- Pediatric Heart Lung Center, Aurora, CO, USA.,Children's Hospital Colorado, Aurora, CO, USA.,University of Colorado Anschutz School of Medicine, Aurora, CO, USA
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15
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Clark AR, Burrowes KS, Tawhai MH. Integrative Computational Models of Lung Structure-Function Interactions. Compr Physiol 2021; 11:1501-1530. [PMID: 33577123 DOI: 10.1002/cphy.c200011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Anatomically based integrative models of the lung and their interaction with other key components of the respiratory system provide unique capabilities for investigating both normal and abnormal lung function. There is substantial regional variability in both structure and function within the normal lung, yet it remains capable of relatively efficient gas exchange by providing close matching of air delivery (ventilation) and blood delivery (perfusion) to regions of gas exchange tissue from the scale of the whole organ to the smallest continuous gas exchange units. This is despite remarkably different mechanisms of air and blood delivery, different fluid properties, and unique scale-dependent anatomical structures through which the blood and air are transported. This inherent heterogeneity can be exacerbated in the presence of disease or when the body is under stress. Current computational power and data availability allow for the construction of sophisticated data-driven integrative models that can mimic respiratory system structure, function, and response to intervention. Computational models do not have the same technical and ethical issues that can limit experimental studies and biomedical imaging, and if they are solidly grounded in physiology and physics they facilitate investigation of the underlying interaction between mechanisms that determine respiratory function and dysfunction, and to estimate otherwise difficult-to-access measures. © 2021 American Physiological Society. Compr Physiol 11:1501-1530, 2021.
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Affiliation(s)
- Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Kelly S Burrowes
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Merryn H Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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16
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Lee M, Oh JH. Echocardiographic diagnosis of right-to-left shunt using transoesophageal and transthoracic echocardiography. Open Heart 2020; 7:openhrt-2019-001150. [PMID: 32763965 PMCID: PMC7412608 DOI: 10.1136/openhrt-2019-001150] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 03/09/2020] [Accepted: 06/01/2020] [Indexed: 01/16/2023] Open
Abstract
Background The diagnosis and quantification of right-to-left shunt (RLS) using transthoracic echocardiography (TTE) as well as transoesophageal echocardiography (TOE) have not been well established. We aimed to diagnose RLS by TOE using direct visualisation of the shunt and to compare the diagnosis with TTE diagnosis using conventional methods. Methods and results We evaluated 141 patients with ischaemic stroke for RLS by both non-sedation TOE and TTE using saline contrast and Valsalva manoeuvre. The amount (graded as 0 to IV) and timing of RLS were demonstrated. All patients were classified into four groups by TOE based on direct visualisation of shunt through a patent foramen ovale (PFO) or either pulmonary vein: no shunt (group 1: n=11), PFO (group 2: n=47), pulmonary RLS (group 3: n=25) and indeterminate RLS (group 4: n=58). All cases in group 3 showed delayed shunt, and all cases in group 4 had small shunt. On TTE findings, all cases with early appearing large shunt (cardiac cycles ≤3 and shunt grade ≥III) were group 2. Six of the eight patients with delayed appearing large shunt on TTE were group 3. TTE diagnosis of PFO using criteria of cardiac beats ≤3 and grade ≥II had a sensitivity of 85% and a specificity of 98% compared with TOE diagnosis using shunt visualisation. Conclusions Compared with TOE using shunt visualisation, TTE accurately diagnosed large PFO using criteria of cardiac cycles ≤3 and shunt grade ≥III. TTE possibly diagnosed pulmonary shunt using criteria of cardiac cycles >3 and shunt grade ≥III. Both modalities showed limitations in diagnosing small amount of RLS.
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Affiliation(s)
- Mirae Lee
- Division of Cardiology, Department of Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Gyeongsangnam-Do, Republic of Korea
| | - Ju Hyeon Oh
- Division of Cardiology, Department of Medicine, Samsung Changwon Hospital, Sungkyunkwan University School of Medicine, Changwon, Gyeongsangnam-Do, Republic of Korea
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17
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Boulet LM, Vermeulen TD, Cotton PD, Foster GE. Influence of blood Po 2 on the stability of agitated saline contrast. J Appl Physiol (1985) 2020; 129:1341-1347. [PMID: 33054656 DOI: 10.1152/japplphysiol.00488.2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The utility of transthoracic saline contrast echocardiography (TTSCE) to assess blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) in humans is limited due to the potential destabilizing effects of the gas concentration gradients established in varied blood-gas environments. This study assessed the specific effect of a hyperoxic and mixed venous blood-gas environment on the stability of saline contrast. We hypothesized that the rate of contrast mass lost in hyperoxic blood would be similar to mixed venous due to the establishment of equal and opposing gas gradients (O2, N2, CO2) created when the partial pressure of dissolved gases is manipulated. Using an in vitro model of the pulmonary circulation perfused with defibrinated sheep blood and a membrane oxygenator to control blood gases, we assessed the percent contrast conserved (an index of contrast stability) between inflow and outflow sites at multiple flow rates (1.8, 2.8, 4.3, and 6.8 L/min) in a hyperoxic (Po2: 646 ± 16 mmHg; Pco2: 0 ± 0 mmHg) and a mixed venous blood gas condition (Po2: 35 ± 3 mmHg; Pco2: 40 ± 0 mmHg). We found significant contrast decay with time in both conditions, with slightly higher contrast conservation in the hyperoxia trials (64 ± 32%) versus the mixed venous trials (55 ± 21%). These findings suggest that contrast stability is not likely a factor affecting the interpretation of TTSCE performed in healthy humans breathing hyperoxia and lends support to the existence of a local O2-dependent mechanism contributing to the regulation of Q̇IPAVA.NEW & NOTEWORTHY Hyperoxic blood has a small stabilizing effect on agitated saline contrast compared with mixed venous blood, lending support to studies that show the reversal of exercise-induced blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) with hyperoxia. These data support the possible presence of a local O2-dependent regulatory mechanism within the pulmonary vasculature that may play a role in Q̇IPAVA regulation.
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Affiliation(s)
- Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Tyler D Vermeulen
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Paul D Cotton
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, British Columbia, Canada
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18
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Dempsey JA, La Gerche A, Hull JH. Is the healthy respiratory system built just right, overbuilt, or underbuilt to meet the demands imposed by exercise? J Appl Physiol (1985) 2020; 129:1235-1256. [PMID: 32790594 DOI: 10.1152/japplphysiol.00444.2020] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In the healthy, untrained young adult, a case is made for a respiratory system (airways, pulmonary vasculature, lung parenchyma, respiratory muscles, and neural ventilatory control system) that is near ideally designed to ensure a highly efficient, homeostatic response to exercise of varying intensities and durations. Our aim was then to consider circumstances in which the intra/extrathoracic airways, pulmonary vasculature, respiratory muscles, and/or blood-gas distribution are underbuilt or inadequately regulated relative to the demands imposed by the cardiovascular system. In these instances, the respiratory system presents a significant limitation to O2 transport and contributes to the occurrence of locomotor muscle fatigue, inhibition of central locomotor output, and exercise performance. Most prominent in these examples of an "underbuilt" respiratory system are highly trained endurance athletes, with additional influences of sex, aging, hypoxic environments, and the highly inbred equine. We summarize by evaluating the relative influences of these respiratory system limitations on exercise performance and their impact on pathophysiology and provide recommendations for future investigation.
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Affiliation(s)
- Jerome A Dempsey
- John Robert Sutton Professor of Population Health Sciences, John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, Wisconsin
| | - Andre La Gerche
- Clinical Research Domain, Baker Heart and Diabetes Institute, Melbourne, Australia.,National Center for Sports Cardiology, St. Vincent's Hospital, Melbourne, Fitzroy, Australia
| | - James H Hull
- Department of Respiratory Medicine, Royal Brompton Hospital, London, United Kingdom.,Institute of Sport, Exercise and Health (ISEH), University College London, United Kingdom
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19
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Sanz-de la Garza M, Vaquer-Seguí A, Durán K, Blanco I, Burgos F, Alsina X, Prat-González S, Bijnens B, Sitges M. Pulmonary transit of contrast during exercise is related to improved cardio-pulmonary performance in highly trained endurance athletes. Eur J Prev Cardiol 2019; 27:1504-1514. [PMID: 31801048 DOI: 10.1177/2047487319891779] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BACKGROUND The mechanisms underlying the high interindividual variability demonstrated for right-ventricular (RV) adaptation to exercise have not yet been identified, but different pulmonary vascular adaptations among individuals could be involved. Pulmonary transit of agitated saline (PTAS) during exercise has been demonstrated to be a good estimator of vascular reserve. AIM The aim of this study was to evaluate the presence of PTAS among endurance athletes (EAs) of both sexes and its influence on RV adaptation to exercise. METHODS A total of 100 highly trained EAs performed a maximal cardiopulmonary exercise test. Bi-ventricular functional and structural characteristics as well as PTAS were evaluated at baseline and at peak exercise. Athletes were distributed between two groups based on the amount of PTAS during exercise as high (HTPAS; >12 bubbles) and low (LPTAS; ≤12 bubbles). RESULTS Overall, 11 EAs exhibited an intra-cardiac shunt at rest and 1 met the criteria for chronic pulmonary disease and were excluded from the study. Among the remaining 88 EAs (51% women), 47 (53%) athletes were classified as HPTAS and 41 (47%) as LPTAS. HPTAS capability was associated with significantly larger RV contractile reserve, larger pulmonary vascular reserve and an enhanced maximal exercise capacity. On multivariate analysis, females were the only independent correlate of the HPTAS capability. CONCLUSION In highly trained endurance athletes, a HPTAS capability during exercise corresponded to an increase in pulmonary vascular and RV contractile reserves as well as an enhanced maximal exercise capacity. The long-term clinical or performance implications of the absence or presence of pulmonary shunting, and the subsequent RV afterload increase while performing exercise, remains to be determined.
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Affiliation(s)
| | | | - Karina Durán
- Cardiovascular Institute, Hospital Clínic, Barcelona, Spain
| | - Isabel Blanco
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Pulmonary Medicine Department, Hospital Clínic, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
| | - Felip Burgos
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Pulmonary Medicine Department, Hospital Clínic, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
| | - Xavier Alsina
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Pulmonary Medicine Department, Hospital Clínic, University of Barcelona, Barcelona, Spain.,Centro de Investigación en Red de Enfermedades Respiratorias (CIBERES), Barcelona, Spain
| | - Susanna Prat-González
- Cardiovascular Institute, Hospital Clínic, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain
| | - Bart Bijnens
- Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,ICREA, Barcelona, Spain
| | - Marta Sitges
- Cardiovascular Institute, Hospital Clínic, Barcelona, Spain.,Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Barcelona, Spain.,Centro de Investigación Biomèdica en Red Enfermedades Cardiovasculares (CIBERCV), Barcelona, Spain
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20
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Stickland MK, Tedjasaputra V, Fuhr DP, Wagner HE, Collins SÉ, Byers BW, Wagner PD, Hopkins SR. Precapillary pulmonary gas exchange is similar for oxygen and inert gases. J Physiol 2019; 597:5385-5397. [PMID: 31448407 PMCID: PMC6858488 DOI: 10.1113/jp277793] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 08/01/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Precapillary gas exchange for oxygen has been documented in both humans and animals. It has been suggested that, if precapillary gas exchange occurs to a greater extent for inert gases than for oxygen, shunt and its effects on arterial oxygenation may be underestimated by the multiple inert gas elimination technique (MIGET). We evaluated fractional precapillary gas exchange in canines for O2 and two inert gases, sulphur hexafluoride and ethane, by measuring these gases in the proximal pulmonary artery, distal pulmonary artery (1 cm proximal to the wedge position) and systemic artery. Some 12-19% of pulmonary gas exchange occurred within small (1.7 mm in diameter or larger) pulmonary arteries and this was quantitatively similar for oxygen, sulphur hexafluoride and ethane. Under these experimental conditions, this suggests only minor effects of precapillary gas exchange on the magnitude of calculated shunt and the associated effect on pulmonary gas exchange estimated by MIGET. ABSTRACT Some pulmonary gas exchange is known to occur proximal to the pulmonary capillary, although the magnitude of this gas exchange is uncertain, and it is unclear whether oxygen and inert gases are similarly affected. This has implications for measuring shunt and associated gas exchange consequences. By measuring respiratory and inert gas levels in the proximal pulmonary artery (P), a distal pulmonary artery 1 cm proximal to the wedge position (using a 5-F catheter) (D) and a systemic artery (A), we evaluated precapillary gas exchange in 27 paired samples from seven anaesthetized, ventilated canines. Fractional precapillary gas exchange (F) was quantified for each gas as F = (P - D)/(P - A). The lowest solubility inert gases, sulphur hexafluoride (SF6 ) and ethane were used because, with higher solubility gases, the P-A difference is sufficiently small that experimental error prevents accurate assessment of F. Distal samples (n = 12) with oxygen (O2 ) saturation values that were (within experimental error) equal to or above systemic arterial values, suggestive of retrograde capillary blood aspiration, were discarded, leaving 15 for analysis. D was significantly lower than P for SF6 (D/P = 88.6 ± 18.1%; P = 0.03) and ethane (D/P = 90.6 ± 16.0%; P = 0.04), indicating partial excretion of inert gas across small pulmonary arteries. Distal pulmonary arterial O2 saturation was significantly higher than proximal (74.1 ± 6.8% vs. 69.0 ± 4.9%; P = 0.03). Fractional precapillary gas exchange was similar for SF6 , ethane and O2 (0.12 ± 0.19, 0.12 ± 0.20 and 0.19 ± 0.26, respectively; P = 0.54). Under these experimental conditions, 12-19% of pulmonary gas exchange occurs within the small pulmonary arteries and the extent is similar between oxygen and inert gases.
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Affiliation(s)
- Michael K Stickland
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, AB, Canada
- G.F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, AB, Canada
| | - Vincent Tedjasaputra
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, AB, Canada
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Desi P Fuhr
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, AB, Canada
| | - Harrieth E Wagner
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, CA, USA
| | - Sophie É Collins
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, AB, Canada
- Faculty of Rehabilitation Medicine, University of Alberta, Edmonton, AB, Canada
| | - Bradley W Byers
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, AB, Canada
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, AB, Canada
| | - Peter D Wagner
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, CA, USA
| | - Susan R Hopkins
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, CA, USA
- Department of Radiology, University of California San Diego, San Diego, CA, USA
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21
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Stickland MK, Tedjasaputra V, Seaman C, Fuhr DP, Collins SÉ, Wagner H, van Diepen S, Byers BW, Wagner PD, Hopkins SR. Intra-pulmonary arteriovenous anastomoses and pulmonary gas exchange: evaluation by microspheres, contrast echocardiography and inert gas elimination. J Physiol 2019; 597:5365-5384. [PMID: 31429918 PMCID: PMC6858494 DOI: 10.1113/jp277695] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 08/12/2019] [Indexed: 01/23/2023] Open
Abstract
KEY POINTS Imaging techniques such as contrast echocardiography suggest that anatomical intra-pulmonary arteriovenous anastomoses (IPAVAs) are present at rest and are recruited to a greater extent in conditions such as exercise. IPAVAs have the potential to act as a shunt, although gas exchange methods have not demonstrated significant shunt in the normal lung. To evaluate this discrepancy, we compared anatomical shunt with 25-µm microspheres to contrast echocardiography, and gas exchange shunt measured by the multiple inert gas elimination technique (MIGET). Intra-pulmonary shunt measured by 25-µm microspheres was not significantly different from gas exchange shunt determined by MIGET, suggesting that MIGET does not underestimate the gas exchange consequences of anatomical shunt. A positive agitated saline contrast echocardiography score was associated with anatomical shunt measured by microspheres. Agitated saline contrast echocardiography had high sensitivity but low specificity to detect a ≥1% anatomical shunt, frequently detecting small shunts inconsequential for gas exchange. ABSTRACT The echocardiographic visualization of transpulmonary agitated saline microbubbles suggests that anatomical intra-pulmonary arteriovenous anastomoses are recruited during exercise, in hypoxia, and when cardiac output is increased pharmacologically. However, the multiple inert gas elimination technique (MIGET) shows insignificant right-to-left gas exchange shunt in normal humans and canines. To evaluate this discrepancy, we measured anatomical shunt with 25-µm microspheres and compared the results to contrast echocardiography and MIGET-determined gas exchange shunt in nine anaesthetized, ventilated canines. Data were acquired under the following conditions: (1) at baseline, (2) 2 µg kg-1 min-1 i.v. dopamine, (3) 10 µg kg-1 min-1 i.v. dobutamine, and (4) following creation of an intra-atrial shunt (in four animals). Right to left anatomical shunt was quantified by the number of 25-µm microspheres recovered in systemic arterial blood. Ventilation-perfusion mismatch and gas exchange shunt were quantified by MIGET and cardiac output by direct Fick. Left ventricular contrast scores were assessed by agitated saline bubble counts, and separately by appearance of 25-µm microspheres. Across all conditions, anatomical shunt measured by 25-µm microspheres was not different from gas exchange shunt measured by MIGET (microspheres: 2.3 ± 7.4%; MIGET: 2.6 ± 6.1%, P = 0.64). Saline contrast bubble score was associated with microsphere shunt (ρ = 0.60, P < 0.001). Agitated saline contrast score had high sensitivity (100%) to detect a ≥1% shunt, but low specificity (22-48%). Gas exchange shunt by MIGET does not underestimate anatomical shunt measured using 25-µm microspheres. Contrast echocardiography is extremely sensitive, but not specific, often detecting small anatomical shunts which are inconsequential for gas exchange.
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Affiliation(s)
- Michael K Stickland
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada
- G.F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, Alberta, Canada
| | - Vincent Tedjasaputra
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Cameron Seaman
- Division of Pediatric Cardiology, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada
| | - Desi P Fuhr
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada
| | - Sophie É Collins
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada
- Faculty of Rehabilitation Medicine, University of Alberta, Alberta, Canada
| | - Harrieth Wagner
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, USA
| | - Sean van Diepen
- Department of Critical Care and Division of Cardiology, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada
| | - Bradley W Byers
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Alberta, Canada
- Faculty of Kinesiology, Sport and Recreation, University of Alberta, Edmonton, Alberta, Canada
| | - Peter D Wagner
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, USA
| | - Susan R Hopkins
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, USA
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Carter EA, Koch S, O'Donovan JP, Sheel AW, Milsom WK, Koehle MS. Perfusion of Intrapulmonary Arteriovenous Anastomoses Is Not Related to VO 2max in Hypoxia and Is Unchanged by Oral Sildenafil. High Alt Med Biol 2019; 20:399-406. [PMID: 31618060 DOI: 10.1089/ham.2019.0051] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Background: Perfusion of intrapulmonary arteriovenous anastomoses (IPAVA) is increased during exercise and in hypoxia and is associated with variations in oxygen saturation (SPO2), resulting in blood bypassing the pulmonary microcirculation. Sildenafil is a pulmonary vasodilator that improves SPO2 and endurance performance in hypoxia. The purpose of this study was to determine if 50 mg sildenafil would reduce IPAVA perfusion (QIPAVA) and if the decrement in maximal exercise capacity (VO2max) in hypoxia is related to QIPAVA. We hypothesized that during progressive levels of hypoxia at rest (FIO2 = 0.21, 0.14, 0.12), sildenafil would increase SPO2 and reduce bubble score (estimate of QIPAVA) compared to placebo, and that the decrement in VO2max in hypoxia would be positively correlated with bubble score at rest in hypoxia. Materials and Methods: Fourteen endurance-trained men performed a graded maximal exercise test at sea level and at a simulated altitude of 3000 m, followed by two experimental visits where, after randomly ingesting sildenafil or placebo, they underwent agitated saline contrast echocardiography during progressive levels of hypoxia at rest. Results: All participants experienced a decrement in power output in hypoxia that ranged from 9% to 19% lower than sea level values. Compared to normoxia, bubble score increased significantly in hypoxia (p < 0.001) with no effect of sildenafil (p = 0.580). There was a negative correlation between SPO2 and bubble score (p < 0.001). The decrement in peak power output at VO2max in hypoxia was unrelated to IPAVA perfusion in resting hypoxia (p = 0.32). Several participants demonstrated QIPAVA greater than zero in room air, indicating that arterial hypoxemia may not be the sole mechanism for QIPAVA. Conclusion: These results indicate that the VO2max decrement caused by hypoxia is not related to QIPAVA and that sildenafil does not improve VO2max in hypoxia through modulation of QIPAVA.
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Affiliation(s)
- Eric A Carter
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - Sarah Koch
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - James P O'Donovan
- Sports Medicine Department, Sports Surgery Clinic, Santry, Ireland.,Division of Sport and Exercise Medicine, Department of Family Practice, University of British Columbia, Vancouver, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, Canada
| | - William K Milsom
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Michael S Koehle
- School of Kinesiology, University of British Columbia, Vancouver, Canada.,Division of Sport and Exercise Medicine, Department of Family Practice, University of British Columbia, Vancouver, Canada
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23
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Norvik C, Westöö CK, Peruzzi N, Lovric G, van der Have O, Mokso R, Jeremiasen I, Brunnström H, Galambos C, Bech M, Tran-Lundmark K. Synchrotron-based phase-contrast micro-CT as a tool for understanding pulmonary vascular pathobiology and the 3-D microanatomy of alveolar capillary dysplasia. Am J Physiol Lung Cell Mol Physiol 2019; 318:L65-L75. [PMID: 31596108 DOI: 10.1152/ajplung.00103.2019] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
This study aimed to explore the value of synchrotron-based phase-contrast microcomputed tomography (micro-CT) in pulmonary vascular pathobiology. The microanatomy of the lung is complex with intricate branching patterns. Tissue sections are therefore difficult to interpret. Recruited intrapulmonary bronchopulmonary anastomoses (IBAs) have been described in several forms of pulmonary hypertension, including alveolar capillary dysplasia with misaligned pulmonary veins (ACD/MPV). Here, we examine paraffin-embedded tissue using this nondestructive method for high-resolution three-dimensional imaging. Blocks of healthy and ACD/MPV lung tissue were used. Pulmonary and bronchial arteries in the ACD/MPV block had been preinjected with dye. One section per block was stained, and areas of interest were marked to allow precise beam-alignment during image acquisition at the X02DA TOMCAT beamline (Swiss Light Source). A ×4 magnifying objective coupled to a 20-µm thick scintillating material and a sCMOS detector yielded the best trade-off between spatial resolution and field-of-view. A phase retrieval algorithm was applied and virtual tomographic slices and video clips of the imaged volumes were produced. Dye injections generated a distinct attenuation difference between vessels and surrounding tissue, facilitating segmentation and three-dimensional rendering. Histology and immunohistochemistry post-imaging offered complementary information. IBAs were confirmed in ACD/MPV, and the MPVs were positioned like bronchial veins/venules. We demonstrate the advantages of using synchrotron-based phase-contrast micro-CT for three-dimensional characterization of pulmonary microvascular anatomy in paraffin-embedded tissue. Vascular dye injections add additional value. We confirm intrapulmonary shunting in ACD/MPV and provide support for the hypothesis that MPVs are dilated bronchial veins/venules.
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Affiliation(s)
- Christian Norvik
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | | | - Niccolò Peruzzi
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Goran Lovric
- Centre d'Imagerie BioMédicale, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.,Swiss Light Source, Paul Scherrer Institute, Villigen, Switzerland
| | - Oscar van der Have
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | | | - Ida Jeremiasen
- Department of Experimental Medical Science, Lund University, Lund, Sweden
| | - Hans Brunnström
- Division of Oncology and Pathology, Department of Clinical Sciences, Lund University, Lund, Sweden
| | - Csaba Galambos
- Children's Hospital Colorado, Department of Pathology and Laboratory Medicine, Aurora, Colorado
| | - Martin Bech
- Medical Radiation Physics, Department of Clinical Sciences, Lund University, Lund, Sweden
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24
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Hong B, Lee KH, Yoo HJ, Lee J, Yun S, Ahn KT, Chung W. Unexpected development of intraoperative paradoxical air embolism during hysteroscopic myomectomy. J OBSTET GYNAECOL 2019; 40:885-886. [DOI: 10.1080/01443615.2019.1636777] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Affiliation(s)
- Boohwi Hong
- Department of Anaesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon, South Korea
- Department of Anaesthesiology and Pain Medicine, School of Medicine, Chungnam National University, Daejeon, South Korea
| | - Ki Hwan Lee
- Department of Obstetrics and Gynaecology, Chungnam National University Hospital, Daejeon, South Korea
- Department of Obstetrics and Gynaecology, Chungnam National University College of Medicine, Daejeon, South Korea
| | - Heon Jong Yoo
- Department of Obstetrics and Gynaecology, Chungnam National University Hospital, Daejeon, South Korea
- Department of Obstetrics and Gynaecology, Chungnam National University College of Medicine, Daejeon, South Korea
| | - Jieun Lee
- Department of Anaesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon, South Korea
| | - Sangwon Yun
- Department of Anaesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon, South Korea
| | - Kye Taek Ahn
- Department of Internal Medicine, Division of Cardiology, Chungnam National University Hospital, Chungnam National University School of Medicine, Daejeon, South Korea
| | - Woosuk Chung
- Department of Anaesthesiology and Pain Medicine, Chungnam National University Hospital, Daejeon, South Korea
- Department of Anaesthesiology and Pain Medicine, School of Medicine, Chungnam National University, Daejeon, South Korea
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25
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Phillips DB, Stickland MK. Respiratory limitations to exercise in health: a brief review. CURRENT OPINION IN PHYSIOLOGY 2019. [DOI: 10.1016/j.cophys.2019.05.012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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26
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Nitzan I, Goldberg S, Hammerman C, Bin-Nun A, Bromiker R. Effect of rewarming in oxygenation and respiratory condition after neonatal exposure to moderate therapeutic hypothermia. Pediatr Neonatol 2019; 60:423-427. [PMID: 30459100 DOI: 10.1016/j.pedneo.2018.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/09/2018] [Revised: 08/28/2018] [Accepted: 10/25/2018] [Indexed: 11/25/2022] Open
Abstract
BACKGROUND To assess changes in clinical condition and oxygenation in neonates after rewarming following moderate therapeutic hypothermia (MTH) for neonatal encephalopathy. METHODS Retrospective study of 28 neonates receiving MTH in a tertiary neonatal intensive care unit in Israel. We compared pre-and 24 h post-rewarming arterial oxygen saturation (SaO2) as measured by the blood gases analyzer, pulse-oximetry saturation (SpO2), and cardio-respiratory condition. RESULTS The SpO2 declined from 96.9% (±2.9) before rewarming to 95.2% (±2.6) after rewarming (p < 0.001). Twelve neonates (42.9%) had clinical respiratory impairment (needing higher respiratory support or had new onset desaturations). In 16 neonates (57.1%) with no change in respiratory support after rewarming, SpO2 decreased from 98.3 ± 1.9% to 95.6 ± 3.0% (p < 0.001) and SaO2 decreased from 97.1 ± 1.7% to 96.0 ± 2.3% (p = 0.002). The mean SpO2 decrease was greater than mean SaO2 decrease (2.63 ± 1.8 and 1.1 ± 1.3 respectively, p = 0.021). CONCLUSION Neonates who underwent MTH showed reduction in oxygenation after rewarming either by decreasing SpO2 or increasing FiO2 requirements. The SpO2 decline was larger than the SaO2 decline. We suggest careful monitoring of neonates after rewarming.
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Affiliation(s)
- Itamar Nitzan
- Neonatology Department, Shaare Zedek Medical Center, Jerusalem, Israel.
| | - Shmuel Goldberg
- Pediatric Pulmonology, Shaare Zedek Medical Center, Jerusalem, Israel; Hebrew University Faculty of Medicine, Jerusalem, Israel
| | - Cathy Hammerman
- Neonatology Department, Shaare Zedek Medical Center, Jerusalem, Israel; Hebrew University Faculty of Medicine, Jerusalem, Israel
| | - Alona Bin-Nun
- Neonatology Department, Shaare Zedek Medical Center, Jerusalem, Israel; Hebrew University Faculty of Medicine, Jerusalem, Israel
| | - Ruben Bromiker
- Neonatology Department, Shaare Zedek Medical Center, Jerusalem, Israel; Hebrew University Faculty of Medicine, Jerusalem, Israel
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Abstract
The pulmonary circulation carries deoxygenated blood from the systemic veins through the pulmonary arteries to be oxygenated in the capillaries that line the walls of the pulmonary alveoli. The pulmonary circulation carries the cardiac output with a relatively low driving pressure, and so differs considerably in structure and function from the systemic circulation to maintain a low-resistance vascular system. The pulmonary circulation is often considered to be a quasi-static system in both experimental and computational studies of pulmonary perfusion and its matching to ventilation (air flow) for exchange. However, the system is highly dynamic, with cardiac output and regional perfusion changing with posture, exercise, and over time. Here we review this dynamic system, with a focus on understanding the physiology of pulmonary vascular dynamics across spatial and temporal scales, and the changes to these dynamics that are reflective of disease. © 2019 American Physiological Society. Compr Physiol 9:1081-1100, 2019.
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Affiliation(s)
- Alys Clark
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Merryn Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
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28
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Corda A, Carta S, Varcasia A, Tamponi C, Evangelisti MA, Scala A, Pinna Parpaglia ML. Pulmonary arterial response to Angiostrongylus vasorum in naturally infected dogs: echocardiographic findings in two cases. Parasit Vectors 2019; 12:286. [PMID: 31164175 PMCID: PMC6549332 DOI: 10.1186/s13071-019-3544-2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 05/29/2019] [Indexed: 12/21/2022] Open
Abstract
Background Angiostrongylus vasorum is a nematode living in the pulmonary arteries of canids. Infected dogs develop severe pulmonary lesions which can potentially lead to pulmonary hypertension (PH). However, reports of PH in natural infected dogs are scant. One of the possible causes of the low prevalence of PH in A. vasorum-infected dogs could be the establishment of large diameter intrapulmonary arteriovenous anastomoses (IPAVAs), which attenuate pulmonary vascular resistance, thus reducing the pulmonary arterial pressure. The present report describes the pulmonary arterial pressure (PAP) response to A. vasorum natural infection in two dogs, assessed by echocardiography and by the saline contrast echocardiographic test (SCE). Results Both dogs showed clinical signs of respiratory disease. At presentation, case 1 did not show echocardiographic signs of PH and the SCE test was positive proving the presence of IPAVAs. However, at the follow-up visit, despite A. vasorum infection resolution, the same dog showed PH and the SCE test resulted negative, which ruled out the presence of IPAVAs. Case 2 suffered from severe pulmonary arterial hypertension and right-side congestive heart failure since the day of presentation. Saline contrast echocardiography was negative both at the time of presentation and at the follow-up visit. Conclusions In the two cases described above, the PH was not associated with IPAVAs. During A. vasorum infection, IPAVAs recruitment mechanism is able to contrast the rise of PAP until a certain level. It probably represents an initial escape mechanism of PH that, over time, exhausts its compensatory capacities allowing PAP to rise and to be detectable on echocardiography. Electronic supplementary material The online version of this article (10.1186/s13071-019-3544-2) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Andrea Corda
- Dipartimento di Medicina Veterinaria, Università degli Studi di Sassari, Sassari, Italy
| | - Silvia Carta
- Dipartimento di Medicina Veterinaria, Università degli Studi di Sassari, Sassari, Italy
| | - Antonio Varcasia
- Dipartimento di Medicina Veterinaria, Università degli Studi di Sassari, Sassari, Italy.
| | - Claudia Tamponi
- Dipartimento di Medicina Veterinaria, Università degli Studi di Sassari, Sassari, Italy
| | | | - Antonio Scala
- Dipartimento di Medicina Veterinaria, Università degli Studi di Sassari, Sassari, Italy
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Dominelli PB, Sheel AW. Exercise-induced arterial hypoxemia; some answers, more questions. Appl Physiol Nutr Metab 2019; 44:571-579. [DOI: 10.1139/apnm-2018-0468] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Exercise-induced arterial hypoxemia (EIAH) is characterized by the decrease in arterial oxygen tension and oxyhemoglobin saturation during dynamic aerobic exercise. Since the time of the initial observations, our knowledge and understanding of EIAH has grown, but many unknowns remain. The purpose of this review is to provide an update on recent findings, highlight areas of disagreement, and identify where information is lacking. Specifically, this review will place emphasis on (i) the occurrence of EIAH during submaximal exercise, (ii) whether there are sex differences in the development and severity of EIAH, and (iii) unresolved questions and future directions.
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Affiliation(s)
- Paolo B. Dominelli
- Department of Anesthesiology, Mayo Clinic, 200 First Street SW, Rochester, MN 55905, USA
| | - A. William Sheel
- School of Kinesiology, The University of British Columbia, Vancouver, BC V6T 1Z4, Canada
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30
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Guay J, Ochroch EA, Kopp S. Intraoperative use of low volume ventilation to decrease postoperative mortality, mechanical ventilation, lengths of stay and lung injury in adults without acute lung injury. Cochrane Database Syst Rev 2018; 7:CD011151. [PMID: 29985541 PMCID: PMC6513630 DOI: 10.1002/14651858.cd011151.pub3] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
BACKGROUND Since the 2000s, there has been a trend towards decreasing tidal volumes for positive pressure ventilation during surgery. This an update of a review first published in 2015, trying to determine if lower tidal volumes are beneficial or harmful for patients. OBJECTIVES To assess the benefit of intraoperative use of low tidal volume ventilation (less than 10 mL/kg of predicted body weight) compared with high tidal volumes (10 mL/kg or greater) to decrease postoperative complications in adults without acute lung injury. SEARCH METHODS We searched the Cochrane Central Register of Controlled Trials (CENTRAL 2017, Issue 5), MEDLINE (OvidSP) (from 1946 to 19 May 2017), Embase (OvidSP) (from 1974 to 19 May 2017) and six trial registries. We screened the reference lists of all studies retained and of recent meta-analysis related to the topic during data extraction. We also screened conference proceedings of anaesthesiology societies, published in two major anaesthesiology journals. The search was rerun 3 January 2018. SELECTION CRITERIA We included all parallel randomized controlled trials (RCTs) that evaluated the effect of low tidal volumes (defined as less than 10 mL/kg) on any of our selected outcomes in adults undergoing any type of surgery. We did not retain studies with participants requiring one-lung ventilation. DATA COLLECTION AND ANALYSIS Two authors independently assessed the quality of the retained studies with the Cochrane 'Risk of bias' tool. We analysed data with both fixed-effect (I2 statistic less than 25%) or random-effects (I2 statistic greater than 25%) models based on the degree of heterogeneity. When there was an effect, we calculated a number needed to treat for an additional beneficial outcome (NNTB) using the odds ratio. When there was no effect, we calculated the optimum information size. MAIN RESULTS We included seven new RCTs (536 participants) in the update.In total, we included 19 studies in the review (776 participants in the low tidal volume group and 772 in the high volume group). There are four studies awaiting classification and three are ongoing. All included studies were at some risk of bias. Participants were scheduled for abdominal surgery, heart surgery, pulmonary thromboendarterectomy, spinal surgery and knee surgery. Low tidal volumes used in the studies varied from 6 mL/kg to 8.1 mL/kg while high tidal volumes varied from 10 mL/kg to 12 mL/kg.Based on 12 studies including 1207 participants, the effects of low volume ventilation on 0- to 30-day mortality were uncertain (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.42 to 1.53; I2 = 0%; low-quality evidence). Based on seven studies including 778 participants, lower tidal volumes probably reduced postoperative pneumonia (RR 0.45, 95% CI 0.25 to 0.82; I2 = 0%; moderate-quality evidence; NNTB 24, 95% CI 16 to 160), and it probably reduced the need for non-invasive postoperative ventilatory support based on three studies including 506 participants (RR 0.31, 95% CI 0.15 to 0.64; moderate-quality evidence; NNTB 13, 95% CI 11 to 24). Based on 11 studies including 957 participants, low tidal volumes during surgery probably decreased the need for postoperative invasive ventilatory support (RR 0.33, 95% CI 0.14 to 0.77; I2 = 0%; NNTB 39, 95% CI 30 to 166; moderate-quality evidence). Based on five studies including 898 participants, there may be little or no difference in the intensive care unit length of stay (standardized mean difference (SMD) -0.06, 95% CI -0.22 to 0.10; I2 = 33%; low-quality evidence). Based on 14 studies including 1297 participants, low tidal volumes may have reduced hospital length of stay by about 0.8 days (SMD -0.15, 95% CI -0.29 to 0.00; I2 = 27%; low-quality evidence). Based on five studies including 708 participants, the effects of low volume ventilation on barotrauma (pneumothorax) were uncertain (RR 1.77, 95% CI 0.52 to 5.99; I2 = 0%; very low-quality evidence). AUTHORS' CONCLUSIONS We found moderate-quality evidence that low tidal volumes (defined as less than 10 mL/kg) decreases pneumonia and the need for postoperative ventilatory support (invasive and non-invasive). We found no difference in the risk of barotrauma (pneumothorax), but the number of participants included does not allow us to make definitive statement on this. The four studies in 'Studies awaiting classification' may alter the conclusions of the review once assessed.
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Affiliation(s)
- Joanne Guay
- University of SherbrookeDepartment of Anesthesiology, Faculty of MedicineSherbrookeQuebecCanada
- University of Quebec in Abitibi‐TemiscamingueTeaching and Research Unit, Health SciencesRouyn‐NorandaQCCanada
- Faculty of Medicine, Laval UniversityDepartment of Anesthesiology and Critical CareQuebec CityQCCanada
| | - Edward A Ochroch
- University of PennsylvaniaDepartment of Anesthesiology3400 Spruce StreetPhiladelphiaPAUSA19104
| | - Sandra Kopp
- Mayo Clinic College of MedicineDepartment of Anesthesiology and Perioperative Medicine200 1st St SWRochesterMNUSA55901
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31
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Shah AH, Osten M, Benson L, Alnasser S, Bach Y, Vishwanath R, Van De Bruaene A, Shulman H, Navaranjan J, Khan R, Horlick E. Incidence and Outcomes of Positive Bubble Contrast Study Results After Transcatheter Closure of a Patent Foramen Ovale. JACC Cardiovasc Interv 2018; 11:1095-1104. [DOI: 10.1016/j.jcin.2018.03.008] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/26/2017] [Revised: 02/05/2018] [Accepted: 03/06/2018] [Indexed: 10/14/2022]
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Clark AR, James JL, Stevenson GN, Collins SL. Understanding abnormal uterine artery Doppler waveforms: A novel computational model to explore potential causes within the utero-placental vasculature. Placenta 2018; 66:74-81. [PMID: 29884305 PMCID: PMC6511649 DOI: 10.1016/j.placenta.2018.05.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/19/2018] [Accepted: 05/02/2018] [Indexed: 10/16/2022]
Abstract
INTRODUCTION Uterine artery (UtA) Doppler indices are one of the most commonly employed screening tests for pre-eclampsia worldwide. Abnormal indices appear to result from increased uterine vascular resistance, but anatomical complexity and lack of appropriate animal models mean that little is known about the relative contribution of each of the components of the uterine vasculature to the overall UtA Doppler waveform. Previous computational models suggested that trophoblast-mediated spiral artery remodeling has a dominant effect on the UtA Doppler waveform. However, these models did not incorporate the myometrial arterio-venous anastomoses, which have significant potential to affect utero-placental haemodynamics. METHODS We present a more anatomically complete computational model, explicitly incorporating a structural description of each component of the uterine vasculature, and crucially including myometrial arterio-venous anastomoses as parallel pathways for blood-flow away from the placental bed. Wave transmission theory was applied to the network to predict UtA waveforms. RESULTS Our model shows that high UtA resistance indices, combined with notching, reflect an abnormal remodeling of the entire uterine vasculature. Incomplete spiral artery remodeling alone is unlikely to cause abnormal UtA Doppler waveforms as increased resistance in these arteries can be 'buffered' by upstream anastomoses. Critically, our results indicate that the radial arteries, may have a more important effect on utero-placental flow dynamics, and the UtA Doppler waveform than previously thought. CONCLUSIONS This model suggests that to appropriately interpret UtA Doppler waveforms they must be considered to be reflecting changes in the entire system, rather than just the spiral arteries.
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Affiliation(s)
- Alys R Clark
- Auckland Bioengineering Institute, University of Auckland, New Zealand.
| | - Joanna L James
- Department of Obstetrics and Gynaecology, Faculty of Medical and Health Sciences, University of Auckland, New Zealand
| | - Gordon N Stevenson
- School of Women's & Children's Health, University of New South Wales, Sydney, Australia
| | - Sally L Collins
- Nuffield Department of Women's and Reproductive Health, University of Oxford, The Fetal Medicine Unit, John Radcliffe Hospital, Oxford, United Kingdom
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Petrassi FA, Davis JT, Beasley KM, Evero O, Elliott JE, Goodman RD, Futral JE, Subudhi A, Solano-Altamirano JM, Goldman S, Roach RC, Lovering AT. AltitudeOmics: effect of reduced barometric pressure on detection of intrapulmonary shunt, pulmonary gas exchange efficiency, and total pulmonary resistance. J Appl Physiol (1985) 2018; 124:1363-1376. [PMID: 29357511 PMCID: PMC6008081 DOI: 10.1152/japplphysiol.00474.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 12/06/2017] [Accepted: 12/10/2017] [Indexed: 11/22/2022] Open
Abstract
Blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA) occurs in healthy humans at rest and during exercise when breathing hypoxic gas mixtures at sea level and may be a source of right-to-left shunt. However, at high altitudes, QIPAVA is reduced compared with sea level, as detected using transthoracic saline contrast echocardiography (TTSCE). It remains unknown whether the reduction in QIPAVA (i.e., lower bubble scores) at high altitude is due to a reduction in bubble stability resulting from the lower barometric pressure (PB) or represents an actual reduction in QIPAVA. To this end, QIPAVA, pulmonary artery systolic pressure (PASP), cardiac output (QT), and the alveolar-to-arterial oxygen difference (AaDO2) were assessed at rest and during exercise (70-190 W) in the field (5,260 m) and in the laboratory (1,668 m) during four conditions: normobaric normoxia (NN; [Formula: see text] = 121 mmHg, PB = 625 mmHg; n = 8), normobaric hypoxia (NH; [Formula: see text] = 76 mmHg, PB = 625 mmHg; n = 7), hypobaric normoxia (HN; [Formula: see text] = 121 mmHg, PB = 410 mmHg; n = 8), and hypobaric hypoxia (HH; [Formula: see text] = 75 mmHg, PB = 410 mmHg; n = 7). We hypothesized QIPAVA would be reduced during exercise in isooxic hypobaria compared with normobaria and that the AaDO2 would be reduced in isooxic hypobaria compared with normobaria. Bubble scores were greater in normobaric conditions, but the AaDO2 was similar in both isooxic hypobaria and normobaria. Total pulmonary resistance (PASP/QT) was elevated in HN and HH. Using mathematical modeling, we found no effect of hypobaria on bubble dissolution time within the pulmonary transit times under consideration (<5 s). Consequently, our data suggest an effect of hypobaria alone on pulmonary blood flow. NEW & NOTEWORTHY Blood flow through intrapulmonary arteriovenous anastomoses, detected by transthoracic saline contrast echocardiography, was reduced during exercise in acute hypobaria compared with normobaria, independent of oxygen tension, whereas pulmonary gas exchange efficiency was unaffected. Modeling the effect(s) of reduced air density on contrast bubble lifetime did not result in a significantly reduced contrast stability. Interestingly, total pulmonary resistance was increased by hypobaria, independent of oxygen tension, suggesting that pulmonary blood flow may be changed by hypobaria.
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Affiliation(s)
- Frank A Petrassi
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - James T Davis
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Kara M Beasley
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Oghenero Evero
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | - Jonathan E Elliott
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Randall D Goodman
- Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon
| | - Joel E Futral
- Oregon Heart and Vascular Institute, Echocardiography, Springfield, Oregon
| | - Andrew Subudhi
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | | | - Saul Goldman
- Department of Chemistry, University of Guelph , Guelph, Ontario , Canada
| | - Robert C Roach
- Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of Colorado Anschutz Medical Campus , Denver, Colorado
| | - Andrew T Lovering
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
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Roberts TJ, Burns AT, MacIsaac RJ, MacIsaac AI, Prior DL, La Gerche A. Diagnosis and Significance of Pulmonary Microvascular Disease in Diabetes. Diabetes Care 2018; 41:854-861. [PMID: 29351959 DOI: 10.2337/dc17-1904] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/20/2017] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To determine whether pulmonary microvascular disease is detectable in subjects with diabetes and associated with diminished exercise capacity using a novel echocardiographic marker quantifying the pulmonary transit of agitated contrast bubbles (PTAC). RESEARCH DESIGN AND METHODS Sixty participants (40 with diabetes and 20 control subjects) performed cardiopulmonary (maximal oxygen consumption [VO2peak]) and semisupine bicycle echocardiography exercise tests within a 1-week period. Pulmonary microvascular disease was assessed using PTAC (the number of bubbles traversing the pulmonary circulation to reach the left ventricle, categorized as low PTAC or high PTAC). Echocardiographic measures of cardiac output, pulmonary artery pressures, and biventricular function were obtained during exercise. RESULTS Subjects with diabetes and control subjects were of similar age (44 ± 13 vs. 43 ± 13 years, P = 0.87) and sex composition (70% vs. 65% male, P = 0.7). At peak exercise, low PTAC was present in more participants with diabetes than control subjects (41% vs. 12.5%, χ2P = 0.041) and, in particular, in more subjects with diabetes with microvascular complications compared with both those without complications and control subjects (55% vs. 26% vs. 13%, χ2P = 0.02). When compared with high PTAC, low PTAC was associated with a 24% lower VO2peak (P = 0.006), reduced right ventricular function (P = 0.015), and greater pulmonary artery pressures during exercise (P = 0.02). CONCLUSIONS PTAC is reduced in diabetes, particularly in the presence of microvascular pathology in other vascular beds, suggesting that it may be a meaningful indicator of pulmonary microvascular disease with important consequences for cardiovascular function and exercise capacity.
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Affiliation(s)
- Timothy J Roberts
- Department of Cardiology, St Vincent's Hospital Melbourne, Fitzroy, Australia.,St Vincent's Department of Medicine, University of Melbourne, Fitzroy, Australia
| | - Andrew T Burns
- Department of Cardiology, St Vincent's Hospital Melbourne, Fitzroy, Australia.,St Vincent's Department of Medicine, University of Melbourne, Fitzroy, Australia
| | - Richard J MacIsaac
- St Vincent's Department of Medicine, University of Melbourne, Fitzroy, Australia.,Department of Endocrinology and Diabetes, St Vincent's Hospital Melbourne, Fitzroy, Australia
| | - Andrew I MacIsaac
- Department of Cardiology, St Vincent's Hospital Melbourne, Fitzroy, Australia.,St Vincent's Department of Medicine, University of Melbourne, Fitzroy, Australia
| | - David L Prior
- Department of Cardiology, St Vincent's Hospital Melbourne, Fitzroy, Australia.,St Vincent's Department of Medicine, University of Melbourne, Fitzroy, Australia
| | - André La Gerche
- Department of Cardiology, St Vincent's Hospital Melbourne, Fitzroy, Australia .,St Vincent's Department of Medicine, University of Melbourne, Fitzroy, Australia.,Department of Cardiovascular Medicine, University Hospitals Leuven, Leuven, Belgium.,Baker Heart and Diabetes Institute, Melbourne, Australia
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35
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Brugniaux JV, Coombs GB, Barak OF, Dujic Z, Sekhon MS, Ainslie PN. Highs and lows of hyperoxia: physiological, performance, and clinical aspects. Am J Physiol Regul Integr Comp Physiol 2018; 315:R1-R27. [PMID: 29488785 DOI: 10.1152/ajpregu.00165.2017] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Molecular oxygen (O2) is a vital element in human survival and plays a major role in a diverse range of biological and physiological processes. Although normobaric hyperoxia can increase arterial oxygen content ([Formula: see text]), it also causes vasoconstriction and hence reduces O2 delivery in various vascular beds, including the heart, skeletal muscle, and brain. Thus, a seemingly paradoxical situation exists in which the administration of oxygen may place tissues at increased risk of hypoxic stress. Nevertheless, with various degrees of effectiveness, and not without consequences, supplemental oxygen is used clinically in an attempt to correct tissue hypoxia (e.g., brain ischemia, traumatic brain injury, carbon monoxide poisoning, etc.) and chronic hypoxemia (e.g., severe COPD, etc.) and to help with wound healing, necrosis, or reperfusion injuries (e.g., compromised grafts). Hyperoxia has also been used liberally by athletes in a belief that it offers performance-enhancing benefits; such benefits also extend to hypoxemic patients both at rest and during rehabilitation. This review aims to provide a comprehensive overview of the effects of hyperoxia in humans from the "bench to bedside." The first section will focus on the basic physiological principles of partial pressure of arterial O2, [Formula: see text], and barometric pressure and how these changes lead to variation in regional O2 delivery. This review provides an overview of the evidence for and against the use of hyperoxia as an aid to enhance physical performance. The final section addresses pathophysiological concepts, clinical studies, and implications for therapy. The potential of O2 toxicity and future research directions are also considered.
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Affiliation(s)
| | - Geoff B Coombs
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
| | - Otto F Barak
- Faculty of Medicine, University of Novi Sad, Novi Sad, Serbia.,Faculty of Sport and Physical Education, University of Novi Sad, Novi Sad, Serbia
| | - Zeljko Dujic
- Department of Integrative Physiology, School of Medicine, University of Split , Split , Croatia
| | - Mypinder S Sekhon
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada.,Division of Critical Care Medicine, Department of Medicine, Vancouver General Hospital, University of British Columbia , Vancouver, British Columbia , Canada
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, University of British Columbia , Kelowna, British Columbia , Canada
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36
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Krog BL, Henry MD. Biomechanics of the Circulating Tumor Cell Microenvironment. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1092:209-233. [PMID: 30368755 DOI: 10.1007/978-3-319-95294-9_11] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Circulating tumor cells (CTCs) exist in a microenvironment quite different from the solid tumor tissue microenvironment. They are detached from matrix and exposed to the immune system and hemodynamic forces leading to the conclusion that life as a CTC is "nasty, brutish, and short." While there is much evidence to support this assertion, the mechanisms underlying this are much less clear. In this chapter we will specifically focus on biomechanical influences on CTCs in the circulation and examine in detail the question of whether CTCs are mechanically fragile, a commonly held idea that is lacking in direct evidence. We will review multiple lines of evidence indicating, perhaps counterintuitively, that viable cancer cells are mechanically robust in the face of exposures to physiologic shear stresses that would be encountered by CTCs during their passage through the circulation. Finally, we present emerging evidence that malignant epithelial cells, as opposed to their benign counterparts, possess specific mechanisms that enable them to endure these mechanical stresses.
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Affiliation(s)
- Benjamin L Krog
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA
| | - Michael D Henry
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
- Department of Pathology and Urology, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
- Holden Comprehensive Cancer Center, Carver College of Medicine, University of Iowa, Iowa City, IA, USA.
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37
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Norris HC, Mangum TS, Kern JP, Elliott JE, Beasley KM, Goodman RD, Mladinov S, Barak OF, Bakovic D, Dujic Z, Lovering AT. Intrapulmonary arteriovenous anastomoses in humans with chronic obstructive pulmonary disease: implications for cryptogenic stroke? Exp Physiol 2018; 101:1128-42. [PMID: 27339093 DOI: 10.1113/ep085811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Accepted: 06/20/2016] [Indexed: 12/13/2022]
Abstract
What is the central question of this study? Do individuals with chronic obstructive pulmonary disease have blood flow through intrapulmonary arteriovenous anastomoses at rest or during exercise? What is the main finding and its importance? Individuals with chronic obstructive pulmonary disease have a greater prevalence of blood flow through intrapulmonary arteriovenous anastomoses at rest than age-matched control subjects. Given that the intrapulmonary arteriovenous anastomoses are large enough to permit venous emboli to pass into the arterial circulation, patients with chronic obstructive pulmonary disease and an elevated risk of thrombus formation may be at risk of intrapulmonary arteriovenous anastomosis-facilitated embolic injury (e.g. stroke or transient ischaemic attack). The pulmonary capillaries prevent stroke by filtering venous emboli from the circulation. Intrapulmonary arteriovenous anastomoses are large-diameter (≥50 μm) vascular connections in the lung that may compromise the integrity of the pulmonary capillary filter and have recently been linked to cryptogenic stroke and transient ischaemic attack. Prothrombotic populations, such as individuals with chronic obstructive pulmonary disease (COPD), may be at increased risk of stroke and transient ischaemic attack facilitated by intrapulmonary arteriovenous anastomoses, but the prevalence and degree of blood flow through intrapulmonary arteriovenous anastomoses in this population has not been fully examined and compared with age-matched healthy control subjects. We used saline contrast echocardiography to assess blood flow through intrapulmonary arteriovenous anastomoses at rest (n = 29 COPD and 19 control subjects) and during exercise (n = 10 COPD and 10 control subjects) in subjects with COPD and age-matched healthy control subjects. Blood flow through intrapulmonary arteriovenous anastomoses was detected in 23% of subjects with COPD at rest and was significantly higher compared with age-matched healthy control subjects. Blood flow through intrapulmonary arteriovenous anastomoses at rest was reduced or eliminated in subjects with COPD after breathing hyperoxic gas. Sixty per cent of subjects with COPD who did not have blood flow through the intrapulmonary arteriovenous anastomoses at rest had blood flow through them during exercise. The combination of blood flow through intrapulmonary arteriovenous anastomoses and potential for thrombus formation in individuals with COPD may permit venous emboli to pass into the arterial circulation and cause stroke and transient ischaemic attack. Breathing supplemental oxygen may reduce this risk in COPD. The link between blood flow through intrapulmonary arteriovenous anastomoses, stroke and transient ischaemic attack is worthy of future investigation in COPD and other populations.
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Affiliation(s)
- H Cameron Norris
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | - Tyler S Mangum
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | - Julia P Kern
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | | | - Kara M Beasley
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
| | | | - Suzana Mladinov
- Clinical Department for Pulmonary Diseases, University Hospital Center Split, Split, Croatia
| | - Otto F Barak
- Department of Physiology, University of Novi Sad, Novi Sad, Serbia
| | - Darija Bakovic
- Division of Cardiology, Department of Internal Medicine, University Hospital Center Split, Split, Croatia.,Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Zeljko Dujic
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, UK
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38
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Jasper R, Blankenship JC. Patent foramen ovale closure to prevent secondary neurologic events. Eur J Intern Med 2017; 44:1-11. [PMID: 28684051 DOI: 10.1016/j.ejim.2017.06.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 04/16/2017] [Accepted: 06/15/2017] [Indexed: 11/15/2022]
Abstract
In October of 2016 the United States Food and Drug Administration approved the Amplatzer Patent Foramen Ovale (PFO) occluder device for use in patients with cryptogenic stroke, to reduce the risk of recurrent stroke. This event followed 15years of off-label use of atrial septal occluder devices, 3 randomized trials, and enormous controversy over the efficacy of this procedure. While none of the trials reached the primary endpoint needed to prove the efficacy of PFO closure in preventing recurrent stroke, meta-analyses and 5-year follow-up of 1 trial suggest that PFO closure decreases the risk of recurrent stroke, especially in sub-groups with large shunts and atrial septal aneurysms, and especially when the Amplatzer device (rather than other devices) is used. While the relative reduction in stroke associated with PFO closure is large (about 50%), the absolute reduction is low (1-2%) and must be balanced against complications of the procedure (about 3%). Thus, PFO closure is restricted to patients with cryptogenic stroke, and depends heavily on patients' personal preferences. Uncertainties about the etiology of stroke in patients with PFO and the efficacy of PFO closure cause a difficult problem for the internal medicine specialist. At one extreme the internist may wonder if every patient with a documented PFO should be referred to a cardiologist. At the other extreme, supported by specialty society guidelines, internists may conclude that PFO closure is rarely necessary. In this paper we review the current status of PFO closure and suggest a rational strategy for this procedure.
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Affiliation(s)
- Rosie Jasper
- Department of Internal Medicine, Geisinger Medical Center, 100 North Academy Drive, Danville, PA, United States.
| | - James C Blankenship
- Department of Cardiology, Geisinger Medical Center, 100 North Academy Drive, Danville, PA, United States
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39
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O'Halloran KD. High adventure shunts old notions of pulmonary vascular control during hypoxic exercise: contrasting views that might just burst your bubble! Exp Physiol 2017; 102:617-618. [PMID: 28393420 DOI: 10.1113/ep086376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Ken D O'Halloran
- Department of Physiology, School of Medicine, University College Cork, Cork, Ireland
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40
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Duke JW, Elliott JE, Laurie SS, Voelkel T, Gladstone IM, Fish MB, Lovering AT. Relationship between quantitative and descriptive methods of studying blood flow through intrapulmonary arteriovenous anastomoses during exercise. Respir Physiol Neurobiol 2017; 243:47-54. [PMID: 28536067 DOI: 10.1016/j.resp.2017.05.006] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2017] [Revised: 05/09/2017] [Accepted: 05/15/2017] [Indexed: 10/19/2022]
Abstract
Several methods exist to study intrapulmonary arteriovenous anastomoses (IPAVA) in humans. Transthoracic saline contrast echocardiography (TTSCE), i.e., bubble scores, is minimally-invasive, but cannot be used to quantify the magnitude of blood flow through IPAVA (QIPAVA). Radiolabeled macroaggregates of albumin (99mTc-MAA) have been used to quantify QIPAVA in humans, but this requires injection of radioactive particles. Previous work has shown agreement between 99mTc-MAA and TTSCE, but this has not been tested simultaneously in the same group of subjects. Thus, the purpose of this study was to determine if there was a relationship between QIPAVA quantified with 99mTc-MAA and bubble scores obtained with TTSCE. To test this, we used 99mTc-MAA and TTSCE to quantify and detect QIPAVA at rest and during exercise in humans. QIPAVA significantly increased from rest to exercise using 99mTc-MAA and TTSCE and there was a moderately-strong, but significant relationship between methods. Our data suggest that high bubble scores generally correspond with large QIPAVA quantified with 99mTc-MAA during exercise.
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Affiliation(s)
- Joseph W Duke
- Northern Arizona University, Department of Biological Sciences, Flagstaff, AZ, USA.
| | | | | | - Thomas Voelkel
- Sacred Heart Medical Center, Department of Nuclear Medicine, Springfield, OR, USA
| | - Igor M Gladstone
- Oregon Health and Sciences University, Department of Pediatrics, Portland, OR, USA
| | - Mathews B Fish
- Sacred Heart Medical Center, Department of Nuclear Medicine, Springfield, OR, USA
| | - Andrew T Lovering
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
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41
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Boulet LM, Lovering AT, Tymko MM, Day TA, Stembridge M, Nguyen TA, Ainslie PN, Foster GE. Reduced blood flow through intrapulmonary arteriovenous anastomoses during exercise in lowlanders acclimatizing to high altitude. Exp Physiol 2017; 102:670-683. [PMID: 28370674 DOI: 10.1113/ep086182] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Accepted: 03/27/2017] [Indexed: 12/13/2022]
Abstract
NEW FINDINGS What is the central question of this study? The aim was to determine, using the technique of agitated saline contrast echocardiography, whether exercise after 4-7 days at 5050 m would affect blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) compared with exercise at sea level. What is the main finding and its importance? Despite a significant increase in both cardiac output and pulmonary pressure during exercise at high altitude, there is very little Q̇IPAVA at rest or during exercise after 4-7 days of acclimatization. Mathematical modelling suggests that bubble instability at high altitude is an unlikely explanation for the reduced Q̇IPAVA. Blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA) is elevated during exercise at sea level (SL) and at rest in acute normobaric hypoxia. After high altitude (HA) acclimatization, resting Q̇IPAVA is similar to that at SL, but it is unknown whether this is true during exercise at HA. We reasoned that exercise at HA (5050 m) would exacerbate Q̇IPAVA as a result of heightened pulmonary arterial pressure. Using a supine cycle ergometer, seven healthy adults free from intracardiac shunts underwent an incremental exercise test at SL [25, 50 and 75% of SL peak oxygen consumption (V̇O2 peak )] and at HA (25 and 50% of SL V̇O2 peak ). Echocardiography was used to determine cardiac output (Q̇) and pulmonary artery systolic pressure (PASP), and agitated saline contrast was used to determine Q̇IPAVA (bubble score; 0-5). The principal findings were as follows: (i) Q̇ was similar at SL rest (3.9 ± 0.47 l min-1 ) compared with HA rest (4.5 ± 0.49 l min-1 ; P = 0.382), but increased from rest during both SL and HA exercise (P < 0.001); (ii) PASP increased from SL rest (19.2 ± 0.7 mmHg) to HA rest (33.7 ± 2.8 mmHg; P = 0.001) and, compared with SL, PASP was further elevated during HA exercise (P = 0.003); (iii) Q̇IPAVA was increased from SL rest (0) to HA rest (median = 1; P = 0.04) and increased from resting values during SL exercise (P < 0.05), but was unchanged during HA exercise (P = 0.91), despite significant increases in Q̇ and PASP. Theoretical modelling of microbubble dissolution suggests that the lack of Q̇IPAVA in response to exercise at HA is unlikely to be caused by saline contrast instability.
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Affiliation(s)
- Lindsey M Boulet
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Michael M Tymko
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Mike Stembridge
- Cardiff School of Sport, Cardiff Metropolitan University, Cardiff, UK
| | - Trang Anh Nguyen
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada.,Department of Biomedical Engineering, International University, Vietnam National University, Ho Chi Minh City, Vietnam
| | - Philip N Ainslie
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung & Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
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42
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Bates ML, Jacobson JE, Eldridge MW. Beta Adrenergic Regulation of Intrapulmonary Arteriovenous Anastomoses in Intact Rat and Isolated Rat Lungs. Front Physiol 2017; 8:218. [PMID: 28469578 PMCID: PMC5396286 DOI: 10.3389/fphys.2017.00218] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2017] [Accepted: 03/27/2017] [Indexed: 11/18/2022] Open
Abstract
Intrapulmonary arteriovenous anastomoses (IPAVA) allow large diameter particles of venous origin to bypass the pulmonary capillary bed and embolize the systemic arterial circulation. IPAVA have been routinely observed in healthy humans with exercise, hypoxia, and catecholamine infusion, but the mechanism by which they are recruited is not well-defined. We hypothesized that beta-adrenergic receptor stimulation recruits IPAVA and that receptor blockade would limit hypoxia-induced IPAVA recruitment. To test our hypothesis, we evaluated the transpulmonary passage of microspheres in intact rats and isolated rats lung infused with the beta-adrenergic receptor agonist isoproterenol. We also evaluated IPAVA recruitment in intact rats with hypoxia and the beta-adrenergic receptor blocker propranolol. We found that IPAVA are recruited in the intact rat by isoproterenol and their recruitment by hypoxia can be minimized by propranolol, suggesting a role for the adrenergic system in the recruitment of IPAVA by hypoxia. IPAVA recruitment is completely abolished by ventilation with 100% oxygen. Isoproterenol also recruits IPAVA in isolated rat lungs. The fact that isoproterenol can recruit IPAVA in isolated lungs, without increased pulmonary flow, suggests that elevated cardiac output is not required for IPAVA recruitment.
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Affiliation(s)
- Melissa L Bates
- Critical Care Division and the John Rankin Laboratory of Pulmonary Medicine, Department of Pediatrics, University of IowaIowa City, IA, USA.,Department of Health and Human Physiology, University of IowaIowa City, IA, USA
| | - Joseph E Jacobson
- Critical Care Division and the John Rankin Laboratory of Pulmonary Medicine, Department of Pediatrics, University of IowaIowa City, IA, USA.,Michigan State University College of Human MedicineEast Lansing, MI, USA
| | - Marlowe W Eldridge
- Critical Care Division and the John Rankin Laboratory of Pulmonary Medicine, Department of Pediatrics, University of IowaIowa City, IA, USA.,Departments of Biomedical Engineering and Kinesiology, University of WisconsinMadison, WI, USA
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43
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Romac R, Barak O, Glavas D, Susilovic Grabovac Z, Lozo P, Roje I, Caljkusic K, Drmic-Hofman I, Davis JT, Dujic Z, Lovering AT. Characterization of blood flow through intrapulmonary arteriovenous anastomoses and patent foramen ovale at rest and during exercise in stroke and transient ischemic attack patients. Echocardiography 2017; 34:676-682. [DOI: 10.1111/echo.13519] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
- Rinaldo Romac
- Department of Neurology; University Hospital Center Split; Split Croatia
| | - Otto Barak
- Department of Integrative Physiology; University of Split School of Medicine; Split Croatia
- Faculty of Medicine; University of Novi Sad; Novi Sad Serbia
| | - Duska Glavas
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Zora Susilovic Grabovac
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Petar Lozo
- Division of Cardiology; Department of Internal Medicine; University Hospital Center Split; Split Croatia
| | - Igor Roje
- Department of Neurology; University Hospital Center Split; Split Croatia
| | - Kresimir Caljkusic
- Department of Anesthesiology; University Hospital Center Split; Split Croatia
| | - Irena Drmic-Hofman
- Department of Pathology, Forensic Medicine and Cytology; University Hospital Center Split; Split Croatia
- Department of Medical Chemistry and Biochemistry; University of Split School of Medicine; Split Croatia
| | - James T. Davis
- Department of Kinesiology, Recreation and Sport; Indiana State University; Terre Haute IN USA
| | - Zeljko Dujic
- Department of Integrative Physiology; University of Split School of Medicine; Split Croatia
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44
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Tedjasaputra V, van Diepen S, Collins SÉ, Michaelchuk WM, Stickland MK. Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise. J Vis Exp 2017:54949. [PMID: 28287506 PMCID: PMC5407706 DOI: 10.3791/54949] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Exercise is a stress to the pulmonary vasculature. With incremental exercise, the pulmonary diffusing capacity (DLCO) must increase to meet the increased oxygen demand; otherwise, a diffusion limitation may occur. The increase in DLCO with exercise is due to increased capillary blood volume (Vc) and membrane diffusing capacity (Dm). Vc and Dm increase secondary to the recruitment and distension of pulmonary capillaries, increasing the surface area for gas exchange and decreasing pulmonary vascular resistance, thereby attenuating the increase in pulmonary arterial pressure. At the same time, the recruitment of intrapulmonary arteriovenous anastomoses (IPAVA) during exercise may contribute to gas exchange impairment and/or prevent large increases in pulmonary artery pressure. We describe two techniques to evaluate pulmonary diffusion and circulation at rest and during exercise. The first technique uses multiple-fraction of inspired oxygen (FIO2) DLCO breath holds to determine Vc and Dm at rest and during exercise. Additionally, echocardiography with intravenous agitated saline contrast is used to assess IPAVAs recruitment. Representative data showed that the DLCO, Vc, and Dm increased with exercise intensity. Echocardiographic data showed no IPAVA recruitment at rest, while contrast bubbles were seen in the left ventricle with exercise, suggesting exercise-induced IPAVA recruitment. The evaluation of pulmonary capillary blood volume, membrane diffusing capacity, and IPAVA recruitment using echocardiographic methods is useful to characterize the ability of the lung vasculature to adapt to the stress of exercise in health as well as in diseased groups, such as those with pulmonary arterial hypertension and chronic obstructive pulmonary disease.
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Affiliation(s)
- Vincent Tedjasaputra
- Division of Pulmonary Medicine, University of Alberta; Faculty of Physical Education and Recreation, University of Alberta
| | - Sean van Diepen
- Divisions of Critical Care and Cardiology, University of Alberta
| | - Sophie É Collins
- Division of Pulmonary Medicine, University of Alberta; Faculty of Rehabilitation Medicine, University of Alberta
| | - Wade M Michaelchuk
- Division of Pulmonary Medicine, University of Alberta; Faculty of Physical Education and Recreation, University of Alberta
| | - Michael K Stickland
- Division of Pulmonary Medicine, University of Alberta; G.F. MacDonald Centre for Lung Health;
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Conhaim RL, Segal GS, Watson KE. Arterio-venous anastomoses in isolated, perfused rat lungs. Physiol Rep 2016; 4:4/21/e13023. [PMID: 27821718 PMCID: PMC5112501 DOI: 10.14814/phy2.13023] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Revised: 10/03/2016] [Accepted: 10/09/2016] [Indexed: 11/24/2022] Open
Abstract
Several studies have suggested that large-diameter (>25 μm) arterio-venous shunt pathways exist in the lungs of rats, dogs, and humans. We investigated the nature of these pathways by infusing specific-diameter fluorescent latex particles (4, 7, 15, 30, or 50 μm) into isolated, ventilated rat lungs perfused at constant pressure. All lungs received the same mass of latex (5 mg), which resulted in infused particle numbers that ranged from 1.7 × 107 4 μm particles to 7.5 × 104 50 μm particles. Particles were infused over 2 min. We used a flow cytometer to count particle appearances in venous effluent samples collected every 0.5 min for 12 min from the start of particle infusion. Cumulative percentages of infused particles that appeared in the samples averaged 3.17 ± 2.46% for 4 μm diameter particles, but ranged from 0.01% to 0.17% for larger particles. Appearances of 4 μm particles followed a rapid upslope beginning at 30 sec followed by a more gradual downslope that lasted for up to 12 min. All other particle diameters also began to appear at 30 sec, but followed highly irregular time courses. Infusion of 7 and 15 μm particles caused transient but significant perfusate flow reductions, while infusion of all other diameters caused insignificant reductions in flow. We conclude that small numbers of bypass vessels exist that can accommodate particle diameters of 7-to-50 μm. We further conclude that our 4 μm particle data are consistent with a well-developed network of serial and parallel perfusion pathways at the acinar level.
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Affiliation(s)
- Robert L Conhaim
- The William S. Middleton Memorial Veterans Hospital, Madison, Wisconsin .,Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Gilad S Segal
- Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - Kal E Watson
- Department of Surgery, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
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Aoki T, Sugimura K, Nochioka K, Miura M, Tatebe S, Yamamoto S, Yaoita N, Suzuki H, Sato H, Kozu K, Miyata S, Satoh K, Shimokawa H. Effects of Balloon Pulmonary Angioplasty on Oxygenation in Patients With Chronic Thromboembolic Pulmonary Hypertension - Importance of Intrapulmonary Shunt. Circ J 2016; 80:2227-34. [PMID: 27581344 DOI: 10.1253/circj.cj-16-0254] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
BACKGROUND Although balloon pulmonary angioplasty (BPA) improves the hemodynamics and prognosis of patients with inoperable chronic thromboembolic pulmonary hypertension (CTEPH), the mechanisms of improvement in oxygenation remain to be elucidated. METHODS AND RESULTS From August 2013 to May 2015, we performed a total of 113 BPA procedures in 24 patients with inoperable CTEPH (mean 4.7 procedures per patient). Median age was 70 [60, 74] years and 18 were female (75%). We examined hemodynamics, respiratory functions, and intrapulmonary shunt before and after the BPA procedure. Mean pulmonary arterial pressure (37 [28, 45] to 23[19, 27] mmHg, P<0.01), pulmonary vascular resistance (517 [389, 696] to 268 [239, 345] dyne/s/cm(5)) and 6-min walk distance (390 [286, 484] to 490 [411, 617] m, P<0.01) were significantly improved after BPA therapy. Furthermore, arterial oxygen partial pressure (PaO2, 54.8 [50.0, 60.8] to 65.2 [60.6, 73.2] %, P<0.01) and intrapulmonary shunt (23.4±6.0% to 19.3±5.0%, P<0.01) were also significantly ameliorated. In the multivariate analysis, decrease in intrapulmonary shunt after BPA was significantly correlated with improvement of both PaO2(r(2)=0.26, P<0.01) and SaO2(r(2)=0.49, P<0.01) after BPA. CONCLUSIONS These results indicated that BPA improved not only pulmonary hemodynamics but also oxygenation with a resultant decrease in intrapulmonary shunt. (Circ J 2016; 80: 2227-2234).
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Affiliation(s)
- Tatsuo Aoki
- Department of Cardiovascular Medicine, Tohoku University Graduate School of Medicine
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Marinoni M, Migliaccio ML, Trapani S, Bonizzoli M, Gucci L, Cianchi G, Gallerini A, Tadini Buoninsegni L, Cramaro A, Valente S, Chiostri M, Peris A. Cerebral microemboli detected by transcranial doppler in patients treated with extracorporeal membrane oxygenation. Acta Anaesthesiol Scand 2016; 60:934-44. [PMID: 27109305 DOI: 10.1111/aas.12736] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2015] [Revised: 03/09/2016] [Accepted: 03/10/2016] [Indexed: 12/22/2022]
Abstract
INTRODUCTION Cerebrovascular complications rate in patients treated with extracorporeal membrane oxygenation (ECMO) is about 7%. Ischemic stroke may be caused by solid or gaseous microemboli due to thrombosis within the circuit or cannula. Transcranial Doppler (TCD) is the only method able to detect microembolic signals (MES) in real time. The objective of this study was to detect possible MES by TCD in patients treated with veno-venous (VV) and veno-arterial (VA) ECMO and to test for a relation between the number of MES and the 6-month clinical outcome of these patients. METHODS This is a monocentric observational prospective study in patients consecutively admitted and treated with ECMO at our regional ECMO referral center in 18 months. TCD detection of MES was performed in patients upon initiation of treatment and then repeated during treatment. RESULTS Two hundred and forty-eight TCD monitoring were performed in 42 VV and 11 VA ECMO patients. MES were detected in 26.2% of VV ECMO patients and in 81.8% of VA ECMO patients (P < 0.001). In both subgroups of patients, no correlation was found between MES detection and extracorporeal flow velocities or aPTT values. In VA ECMO patients, an inverse correlation between left ventricular ejection fraction and MES grading was found (P = 0.037). In both groups, no clinical neurological impairments correlated to MES detection were found at 6 months follow-up. CONCLUSIONS MES were found in both ECMO configurations; independently from their pathophysiology, MES do not seem to influence clinical outcome. Multicenter studies are still required with more extensive cases to confirm these results.
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Affiliation(s)
- M. Marinoni
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - M. L. Migliaccio
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - S. Trapani
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - M. Bonizzoli
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - L. Gucci
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - G. Cianchi
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - A. Gallerini
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - L. Tadini Buoninsegni
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - A. Cramaro
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
| | - S. Valente
- Intensive Care Unit of Heart and Vessels Department; Careggi Teaching Hospital; Florence Italy
| | - M. Chiostri
- Intensive Care Unit of Heart and Vessels Department; Careggi Teaching Hospital; Florence Italy
| | - A. Peris
- Neuromusculoskeletal and Sensory Organs Department; Careggi Teaching Hospital; Florence Italy
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Hackett HK, Boulet LM, Dominelli PB, Foster GE. A methodological approach for quantifying and characterizing the stability of agitated saline contrast: implications for quantifying intrapulmonary shunt. J Appl Physiol (1985) 2016; 121:568-76. [PMID: 27365283 DOI: 10.1152/japplphysiol.00422.2016] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 06/27/2016] [Indexed: 12/26/2022] Open
Abstract
Agitated saline contrast echocardiography is often used to determine blood flow through intrapulmonary arteriovenous anastomoses (Q̇IPAVA). We applied indicator dilution theory to time-acoustic intensity curves obtained from a bolus injection of hand-agitated saline contrast to acquire a quantitative index of contrast mass. Using this methodology and an in vitro model of the pulmonary circulation, the purpose of this study was to determine the effect of transit time and gas composition [air vs. sulphur hexafluoride (SF6)] on contrast conservation between two detection sites separated by a convoluted network of vessels. We hypothesized that the contrast lost between the detection sites would increase with transit times and be reduced by using contrast bubbles composed of SF6 Changing the flow and/or reducing the volume of the circulatory network manipulated transit time. Contrast conservation was measured as the ratio of outflow and inflow contrast masses. For air, 53.2 ± 3.4% (SE) of contrast was conserved at a transit time of 9.25 ± 0.02 s but dropped to 16.0 ± 1.0% at a transit time of 10.17 ± 0.06 s. Compared with air, SF6 contrast conservation was significantly greater (P < 0.05) with 114.3 ± 2.9% and 73.7 ± 3.3% of contrast conserved at a transit time of 10.39 ± 0.02 s and 13.46 ± 0.04 s, respectively. In summary, time-acoustic intensity curves can quantify agitated saline contrast, but loss of contrast due to bubble dissolution makes measuring Q̇IPAVA across varying transit time difficult. Agitated saline composed of SF6 is stabilized and may be a suitable alternative for Q̇IPAVA measurement.
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Affiliation(s)
- Heather K Hackett
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada; and
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada; and
| | - Paolo B Dominelli
- School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada; and
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Duke JW, Davis JT, Ryan BJ, Elliott JE, Beasley KM, Hawn JA, Byrnes WC, Lovering AT. Decreased arterial PO2, not O2 content, increases blood flow through intrapulmonary arteriovenous anastomoses at rest. J Physiol 2016; 594:4981-96. [PMID: 27062157 DOI: 10.1113/jp272211] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 03/23/2016] [Indexed: 12/25/2022] Open
Abstract
KEY POINTS The mechanism(s) that regulate hypoxia-induced blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA ) are currently unknown. Our previous work has demonstrated that the mechanism of hypoxia-induced QIPAVA is not simply increased cardiac output, pulmonary artery systolic pressure or sympathetic nervous system activity and, instead, it may be a result of hypoxaemia directly. To determine whether it is reduced arterial PO2 (PaO2) or O2 content (CaO2) that causes hypoxia-induced QIPAVA , individuals were instructed to breathe room air and three levels of hypoxic gas at rest before (control) and after CaO2 was reduced by 10% by lowering the haemoglobin concentration (isovolaemic haemodilution; Low [Hb]). QIPAVA , assessed by transthoracic saline contrast echocardiography, significantly increased as PaO2 decreased and, despite reduced CaO2 (via isovolaemic haemodilution), was similar at iso-PaO2. These data suggest that, with alveolar hypoxia, low PaO2 causes the hypoxia-induced increase in QIPAVA , although where and how this is detected remains unknown. ABSTRACT Alveolar hypoxia causes increased blood flow through intrapulmonary arteriovenous anastomoses (QIPAVA ) in healthy humans at rest. However, it is unknown whether the stimulus regulating hypoxia-induced QIPAVA is decreased arterial PO2 (PaO2) or O2 content (CaO2). CaO2 is known to regulate blood flow in the systemic circulation and it is suggested that IPAVA may be regulated similar to the systemic vasculature. Thus, we hypothesized that reduced CaO2 would be the stimulus for hypoxia-induced QIPAVA . Blood volume (BV) was measured using the optimized carbon monoxide rebreathing method in 10 individuals. Less than 5 days later, subjects breathed room air, as well as 18%, 14% and 12.5% O2 , for 30 min each, in a randomized order, before (CON) and after isovolaemic haemodilution (10% of BV withdrawn and replaced with an equal volume of 5% human serum albumin-saline mixture) to reduce [Hb] (Low [Hb]). PaO2 was measured at the end of each condition and QIPAVA was assessed using transthoracic saline contrast echocardiography. [Hb] was reduced from 14.2 ± 0.8 to 12.8 ± 0.7 g dl(-1) (10 ± 2% reduction) from CON to Low [Hb] conditions. PaO2 was no different between CON and Low [Hb], although CaO2 was 10.4%, 9.2% and 9.8% lower at 18%, 14% and 12.5% O2 , respectively. QIPAVA significantly increased as PaO2 decreased and, despite reduced CaO2, was similar at iso-PaO2. These data suggest that, with alveolar hypoxia, low PaO2 causes the hypoxia-induced increase in QIPAVA . Whether the low PO2 is detected at the carotid body, airway and/or the vasculature remains unknown.
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Affiliation(s)
- Joseph W Duke
- Ohio University, Division of Exercise Physiology, Athens, OH, USA
| | - James T Davis
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Benjamin J Ryan
- University of Colorado at Boulder, Department of Integrative Physiology, Boulder, CO, USA
| | | | - Kara M Beasley
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Jerold A Hawn
- Oregon Heart and Vascular Institute, Springfield, OR, USA
| | - William C Byrnes
- University of Colorado at Boulder, Department of Integrative Physiology, Boulder, CO, USA
| | - Andrew T Lovering
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
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Novo Matos J, Malbon A, Dennler M, Glaus T. Intrapulmonary arteriovenous anastomoses in dogs with severe Angiostrongylus vasorum infection: clinical, radiographic, and echocardiographic evaluation. J Vet Cardiol 2016; 18:110-24. [DOI: 10.1016/j.jvc.2015.10.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2014] [Revised: 10/08/2015] [Accepted: 10/14/2015] [Indexed: 11/25/2022]
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