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Möller FN, Fan JL, Futral JE, Hodgman CF, Kayser B, Lovering AT. Cardiopulmonary haemodynamics in Tibetans and Han Chinese during rest and exercise. J Physiol 2024. [PMID: 38924564 DOI: 10.1113/jp286303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2024] [Accepted: 05/22/2024] [Indexed: 06/28/2024] Open
Abstract
During sea-level exercise, blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) in humans without a patent foramen ovale (PFO) is negatively correlated with pulmonary pressure. Yet, it is unknown whether the superior exercise capacity of Tibetans well adapted to living at high altitude is the result of lower pulmonary pressure during exercise in hypoxia, and whether their cardiopulmonary characteristics are significantly different from lowland natives of comparable ancestry (e.g. Han Chinese). We found a 47% PFO prevalence in male Tibetans (n = 19) and Han Chinese (n = 19) participants. In participants without a PFO (n = 10 each group), we measured heart structure and function at rest and peak oxygen uptake (V ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ ), peak power output (W ̇ p e a k ${{\dot{W}}_{peak}}$ ), pulmonary artery systolic pressure (PASP), blood flow through IPAVA and cardiac output (Q ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ ) at rest and during recumbent cycle ergometer exercise at 760 Torr (SL) and at 410 Torr (ALT) barometric pressure in a pressure chamber. Tibetans achieved a higherW peak ${W}_{\textit{peak}}$ than Han, and a higherV ̇ O 2 peak ${{\dot{V}}_{{{{\mathrm{O}}}_{\mathrm{2}}}{\mathrm{peak}}}}$ at ALT without differences in heart rate, stroke volume orQ ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ . Blood flow through IPAVA was generally similar between groups. Increases in PASP and total pulmonary resistance at ALT were comparable between the groups. There were no differences in the slopes of PASP plotted as a function ofQ ̇ T ${{\dot{Q}}_{\mathrm{T}}} $ during exercise. In those without PFO, our data indicate that the superior aerobic exercise capacity of Tibetans over Han Chinese is independent of cardiopulmonary features and more probably linked to differences in local muscular oxygen extraction. KEY POINTS: Patent foramen ovale (PFO) prevalence was 47% in Tibetans and Han Chinese living at 2 275 m. Subjects with PFO were excluded from exercise studies. Compared to Han Chinese, Tibetans had a higher peak workload with acute compression to sea level barometric pressure (SL) and acute decompression to 5000 m altitude (ALT). Comprehensive cardiac structure and function at rest were not significantly different between Han Chinese and Tibetans. Tibetans and Han had similar blood flow through intrapulmonary arteriovenous anastomoses (IPAVA) during exercise at SL. Peak pulmonary artery systolic pressure (PASP) and total pulmonary resistance were different between SL and ALT, with significantly increased PASP for Han compared to Tibetans at ALT. No differences were observed between groups at acute SL and ALT.
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Affiliation(s)
- Fabian N Möller
- Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Boston, MA, USA
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
- German Sport University Cologne, Institute for Professional Sport Education and Qualification, Cologne, Germany
| | - Jui-Lin Fan
- Department of Physiology, Manaaki Manawa - The Centre for Heart Research, University of Auckland, Faculty of Medical and Health Sciences, Auckland, New Zealand
| | - Joel E Futral
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
- Oregon Heart & Vascular Institute, Springfield, Oregon, USA
| | - Charles F Hodgman
- Department of Health and Human Performance, University of Houston, Houston, TX, USA
| | - Bengt Kayser
- University of Lausanne, Institute of Sports Sciences, Lausanne, Switzerland
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
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Peters CM, Dempsey JA, Hopkins SR, Sheel AW. Is the Lung Built for Exercise? Advances and Unresolved Questions. Med Sci Sports Exerc 2023; 55:2143-2159. [PMID: 37443459 PMCID: PMC11186580 DOI: 10.1249/mss.0000000000003255] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/15/2023]
Abstract
ABSTRACT Nearly 40 yr ago, Professor Dempsey delivered the 1985 ACSM Joseph B. Wolffe Memorial Lecture titled: "Is the lung built for exercise?" Since then, much experimental work has been directed at enhancing our understanding of the functional capacity of the respiratory system by applying complex methodologies to the study of exercise. This review summarizes a symposium entitled: "Revisiting 'Is the lung built for exercise?'" presented at the 2022 American College of Sports Medicine annual meeting, highlighting the progress made in the last three-plus decades and acknowledging new research questions that have arisen. We have chosen to subdivide our topic into four areas of active study: (i) the adaptability of lung structure to exercise training, (ii) the utilization of airway imaging to better understand how airway anatomy relates to exercising lung mechanics, (iii) measurement techniques of pulmonary gas exchange and their importance, and (iv) the interactions of the respiratory and cardiovascular system during exercise. Each of the four sections highlights gaps in our knowledge of the exercising lung. Addressing these areas that would benefit from further study will help us comprehend the intricacies of the lung that allow it to meet and adapt to the acute and chronic demands of exercise in health, aging, and disease.
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Affiliation(s)
| | - Jerome A Dempsey
- Population Health Science, John Rankin Laboratory of Pulmonary Medicine, University of Wisconsin-Madison, Madison, WI
| | - Susan R Hopkins
- Department of Radiology, University of California San Diego, La Jolla, CA
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Hopkins SR, Stickland MK. The Pulmonary Vasculature. Semin Respir Crit Care Med 2023; 44:538-554. [PMID: 37816344 PMCID: PMC11192587 DOI: 10.1055/s-0043-1770059] [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] [Indexed: 10/12/2023]
Abstract
The pulmonary circulation is a low-pressure, low-resistance circuit whose primary function is to deliver deoxygenated blood to, and oxygenated blood from, the pulmonary capillary bed enabling gas exchange. The distribution of pulmonary blood flow is regulated by several factors including effects of vascular branching structure, large-scale forces related to gravity, and finer scale factors related to local control. Hypoxic pulmonary vasoconstriction is one such important regulatory mechanism. In the face of local hypoxia, vascular smooth muscle constriction of precapillary arterioles increases local resistance by up to 250%. This has the effect of diverting blood toward better oxygenated regions of the lung and optimizing ventilation-perfusion matching. However, in the face of global hypoxia, the net effect is an increase in pulmonary arterial pressure and vascular resistance. Pulmonary vascular resistance describes the flow-resistive properties of the pulmonary circulation and arises from both precapillary and postcapillary resistances. The pulmonary circulation is also distensible in response to an increase in transmural pressure and this distention, in addition to recruitment, moderates pulmonary arterial pressure and vascular resistance. This article reviews the physiology of the pulmonary vasculature and briefly discusses how this physiology is altered by common circumstances.
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Affiliation(s)
- Susan R. Hopkins
- Department of Radiology, University of California, San Diego, California
| | - Michael K. Stickland
- Department of Medicine, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta
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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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Miserocchi G. Early Endothelial Signaling Transduction in Developing Lung Edema. Life (Basel) 2023; 13:1240. [PMID: 37374024 DOI: 10.3390/life13061240] [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: 04/17/2023] [Revised: 05/17/2023] [Accepted: 05/23/2023] [Indexed: 06/29/2023] Open
Abstract
The lung promptly responds to edemagenic conditions through functional adaptations that contrast the increase in microvascular filtration. This review presents evidence for early signaling transduction by endothelial lung cells in two experimental animal models of edema, hypoxia exposure, and fluid overload (hydraulic edema). The potential role of specialized sites of the plasma membranes considered mobile signaling platforms, referred to as membrane rafts, that include caveolae and lipid rafts, is presented. The hypothesis is put forward that early changes in the lipid composition of the bilayer of the plasma membrane might trigger the signal transduction process when facing changes in the pericellular microenvironment caused by edema. Evidence is provided that for an increase in the extravascular lung water volume not exceeding 10%, changes in the composition of the plasma membrane of endothelial cells are evoked in response to mechanical stimuli from the interstitial compartment as well as chemical stimuli relating with changes in the concentration of the disassembled portions of structural macromolecules. In hypoxia, thinning of endothelial cells, a decrease in caveolae and AQP-1, and an increase in lipid rafts are observed. The interpretation of this response is that it favors oxygen diffusion and hinder trans-cellular water fluxes. In hydraulic edema, which generates greater capillary water leakages, an increase in cell volume and opposite changes in membrane rafts were observed; further, the remarkable increase in caveolae suggests a potential abluminal-luminal vesicular-dependent fluid reabsorption.
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Affiliation(s)
- Giuseppe Miserocchi
- Department of Medicine and Surgery, Università di Milano Bicocca, 20900 Monza, Italy
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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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Miserocchi G, Beretta E. A century of exercise physiology: lung fluid balance during and following exercise. Eur J Appl Physiol 2023; 123:1-24. [PMID: 36264327 DOI: 10.1007/s00421-022-05066-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 10/04/2022] [Indexed: 01/17/2023]
Abstract
PURPOSE This review recalls the principles developed over a century to describe trans-capillary fluid exchanges concerning in particular the lung during exercise, a specific condition where dyspnea is a leading symptom, the question being whether this symptom simply relates to fatigue or also implies some degree of lung edema. METHOD Data from experimental models of lung edema are recalled aiming to: (1) describe how extravascular lung water is strictly controlled by "safety factors" in physiological conditions, (2) consider how waning of "safety factors" inevitably leads to development of lung edema, (3) correlate data from experimental models with data from exercising humans. RESULTS Exercise is a strong edemagenic condition as the increase in cardiac output leads to lung capillary recruitment, increase in capillary surface for fluid exchange and potential increase in capillary pressure. The physiological low microvascular permeability may be impaired by conditions causing damage to the interstitial matrix macromolecular assembly leading to alveolar edema and haemorrhage. These conditions include hypoxia, cyclic alveolar unfolding/folding during hyperventilation putting a tensile stress on septa, intensity and duration of exercise as well as inter-individual proneness to develop lung edema. CONCLUSION Data from exercising humans showed inter-individual differences in the dispersion of the lung ventilation/perfusion ratio and increase in oxygen alveolar-capillary gradient. More recent data in humans support the hypothesis that greater vasoconstriction, pulmonary hypertension and slower kinetics of alveolar-capillary O2 equilibration relate with greater proneness to develop lung edema due higher inborn microvascular permeability possibly reflecting the morpho-functional features of the air-blood barrier.
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Affiliation(s)
- Giuseppe Miserocchi
- Dipartimento di Medicina e Chirurgia, Università Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy
| | - Egidio Beretta
- Dipartimento di Medicina e Chirurgia, Università Milano-Bicocca, Via Cadore 48, 20900, Monza, Italy.
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Forsberg U, Jonsson P, Stegmayr B. Microemboli induced by air bubbles may be deposited in organs as a consequence of contamination during medical care. Clin Kidney J 2022; 16:159-166. [PMID: 36726427 PMCID: PMC9871849 DOI: 10.1093/ckj/sfac217] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Background Larger volumes of accidental air infused during medical care may end up as emboli while microbubbles of air are supposed to be absorbed and cause no harm. The aim of this autopsy study was to investigate if microbubbles of air accidently entering the bloodline may be detected as microemboli (ME) in tissue such as lungs, brain and heart. If so, do differences in prevalence exist between haemodialysis (HD) and amyotrophic lateral sclerosis (ALS) patients. Methods Included were data from 44 patients treated by medical healthcare before death. Twenty-five cases had been treated with chronic HD and 19 cases died from ALS. Since air in the bloodline activates coagulation, ME could appear. To discriminate between microbubbles caused by artificial contamination during autopsy versus microbubbles deposited in vivo, tissues were stained with a polyclonal fluorescent antibody against fibrinogen, fibrin and fragments E and D. Fluorescence staining was used to visualize ME counted within 25 microscopic fields (600×) of a tissue preparation. One tissue preparation was used if available from the lung, heart and frontal lobe of the brain and in five cases also the cerebellum. Results Microbubbles can be verified at autopsy as ME in the lung, heart and brain in tissue from patients exposed to more extensive medical care. There were significantly more ME in the lungs versus the heart or brain. Women had fewer ME than men. The HD group had a higher median of ME per section than the ALS group (lung: 6 versus 3, P = .007; heart: 2.5 versus 1, P = .013; brain: 7.5 versus 2, P = .001) and had more sections with ME findings than the ALS group (P = .002). A correlation existed between the time on HD (months) and ME in the lungs. Conclusions More ME were present in HD patients compared with those who suffered from ALS. Minimizing air contamination from syringes, infusions and bloodlines will decrease ME and subsequent tissue injury.
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Affiliation(s)
| | - Per Jonsson
- Unit of Medicine, Umeå University, Umeå, Sweden
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Hou H, Guo C, Que C, Nie L, Zhang Q, Zhao H, Nong L, Ma W, Wang Q, Liang Z, Wang B, Ma J, Wang G. Diffuse large B-cell lymphoma presenting as reversible intrapulmonary arteriovenous shunts with hypoxia, fever and progressive jaundice: a case report and literature review. BMC Pulm Med 2022; 22:89. [PMID: 35292006 PMCID: PMC8922084 DOI: 10.1186/s12890-022-01881-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Accepted: 03/07/2022] [Indexed: 11/16/2022] Open
Abstract
Background Intrapulmonary arteriovenous shunts is rare seen in a patient without lung involvement. Case presentation This is the first report of reversible intrapulmonary arteriovenous shunts secondary to extrapulmonary lymphoma as one initial symptom. The patient presented as fever of unknown origin and dyspnea, and examinations of infection were negative. Diagnosis of DLBCL was finally confirmed through bone marrow and splenic biopsies. Intrapulmonary arteriovenous shunts were diagnosed through 100% oxygen inhalation test and transthoracic contrast echocardiography (TTCE). After the treatment of lymphoma, his respiratory failure was relieved. We rechecked the 100% oxygen inhalation test and TTCE, which both indicated that his intrapulmonary arteriovenous shunts had resolved. Conclusions We speculated the prominent inflammation from active DLBCL was the most possible mechanism associated with the reversible intrapulmonary shunt in this patient. These findings will assist us to better understand the mechanism of intrapulmonary shunts.
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Affiliation(s)
- Huan Hou
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Cuiyan Guo
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Chengli Que
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Ligong Nie
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Qi Zhang
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
| | - Hong Zhao
- Department of Infectious Diseases, Center for Liver Disease, Peking University First Hospital, Beijing, China
| | - Lin Nong
- Department of Pathology, Peking University First Hospital, Beijing, China
| | - Wei Ma
- Department of Cardiology, Peking University First Hospital, Beijing, China
| | - Qian Wang
- Department of Hematology, Peking University First Hospital, Beijing, China
| | - Zeyin Liang
- Department of Hematology, Peking University First Hospital, Beijing, China
| | - Bingjie Wang
- Department of Hematology, Peking University First Hospital, Beijing, China
| | - Jing Ma
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China.
| | - Guangfa Wang
- Department of Respiratory and Critical Care Medicine, Peking University First Hospital, 8 Xishiku Street, Xicheng District, Beijing, 100034, China
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Edlinger-Stanger M, Bernardi MH, Kovacs K, Mascha M, Neugebauer T, Böhme S, Ayoubi N, Christofi N, Garry J, Fleming N, Hiesmayr M. The effect of acute ventilation-perfusion mismatch on respiratory heat exchange in a porcine model. PLoS One 2021; 16:e0254399. [PMID: 34252138 PMCID: PMC8274834 DOI: 10.1371/journal.pone.0254399] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2020] [Accepted: 06/28/2021] [Indexed: 11/18/2022] Open
Abstract
Background Respiratory heat exchange is an important physiological process occurring in the upper and lower respiratory tract and is usually completed when inspired gases reach the alveoli. Animal and human studies demonstrated that heat exchange can be modulated by altering pulmonary ventilation and perfusion. The purpose of this study was to examine the effect of acute ventilation-perfusion (V/Q) mismatch on respiratory heat exchange. In clinical practice, monitoring respiratory heat exchange might offer the possibility of real-time tracking of acute V/Q-mismatch. Methods In 11 anesthetized, mechanically ventilated pigs, V/Q-mismatch was established by means of four interventions: single lung ventilation, high cardiac output, occlusion of the left pulmonary artery and repeated whole-lung lavage. V/Q-distributions were determined by the multiple inert gas elimination technique (MIGET). Respiratory heat exchange was measured as respiratory enthalpy using the novel, pre-commercial VQm™ monitor (development stage, Rostrum Medical Innovations, Vancouver, CA). According to MIGET, shunt perfusion of low V/Q compartments increased during single lung ventilation, high cardiac output and whole-lung lavage, whereas dead space and ventilation of high V/Q compartments increased during occlusion of the left pulmonary artery and whole-lung lavage. Results Bohr dead space increased after pulmonary artery occlusion and whole-lung lavage, venous admixture increased during single lung ventilation and whole-lung lavage, PaO2/FiO2 was decreased during all interventions. MIGET confirmed acute V/Q-mismatch. Respiratory enthalpy did not change significantly despite significant acute V/Q-mismatch. Conclusion Clinically relevant V/Q-mismatch does not impair respiratory heat exchange in the absence of additional thermal stressors and may not have clinical utility in the detection of acute changes.
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Affiliation(s)
- Maximilian Edlinger-Stanger
- Department of Cardiothoracic Anaesthesia, Intensive Care Medicine, Medical University of Vienna, Vienna, Austria
- * E-mail:
| | - Martin-Hermann Bernardi
- Department of Cardiothoracic Anaesthesia, Intensive Care Medicine, Medical University of Vienna, Vienna, Austria
| | - Katharina Kovacs
- Department of Cardiothoracic Anaesthesia, Intensive Care Medicine, Medical University of Vienna, Vienna, Austria
| | - Michael Mascha
- Department of Cardiothoracic Anaesthesia, Intensive Care Medicine, Medical University of Vienna, Vienna, Austria
| | - Thomas Neugebauer
- Department of Cardiothoracic Anaesthesia, Intensive Care Medicine, Medical University of Vienna, Vienna, Austria
| | - Stefan Böhme
- Department of Anaesthesia, Intensive Care Medicine and Pain Medicine, Medical University of Vienna, Vienna, Austria
| | | | | | - James Garry
- Rostrum Medical Innovations Inc., Vancouver, Canada
| | - Neal Fleming
- University of California Davis, Davis, California, United States of America
| | - Michael Hiesmayr
- Department of Cardiothoracic Anaesthesia, Intensive Care Medicine, Medical University of Vienna, Vienna, Austria
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Swenson ER, Hopkins SR, Stickland MK. Positive Bubble Study in Severe COVID-19: Bubbles May Be Unrelated to Gas Exchange Impairment. Am J Respir Crit Care Med 2021; 203:389-390. [PMID: 33207121 PMCID: PMC7874323 DOI: 10.1164/rccm.202010-3800le] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/04/2022] Open
Affiliation(s)
- Erik R Swenson
- Veterans Affairs Puget Sound Healthcare System Seattle, Washington
| | - Susan R Hopkins
- University of California, San Diego La Jolla, California and
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12
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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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13
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Foster GE. Measuring blood flow through intrapulmonary and intracardiac shunts: a technical labyrinth. J Physiol 2019; 597:5315-5316. [PMID: 31529499 DOI: 10.1113/jp278820] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 09/16/2019] [Indexed: 11/08/2022] Open
Affiliation(s)
- Glen E Foster
- Centre for Heart, Lung, and Vascular Health. School of Health and Exercise Science, University of British Columbia, Kelowna, British Columbia, Canada
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