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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; 602:3893-3907. [PMID: 38924564 DOI: 10.1113/jp286303] [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: 01/19/2024] [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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Ravellette KS, Gornbein J, Tobis JM. Incidence of Atrial Fibrillation or Arrhythmias After Patent Foramen Ovale Closure. JOURNAL OF THE SOCIETY FOR CARDIOVASCULAR ANGIOGRAPHY & INTERVENTIONS 2024; 3:101173. [PMID: 39131991 PMCID: PMC11307806 DOI: 10.1016/j.jscai.2023.101173] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 08/13/2023] [Accepted: 09/05/2023] [Indexed: 08/13/2024]
Abstract
Background Patients with a patent foramen ovale (PFO) who undergo percutaneous PFO closure are at a greater risk of developing atrial fibrillation (AF) compared with patients whose PFOs are managed medically. Postclosure AF appears to be well tolerated if treated but may increase the risk for stroke. Postclosure AF is reported to occur in 3.7% to 7.4% of patients; however, incidence across devices remains uncertain. This study aims to evaluate the frequency of postclosure AF, atrial flutter, and arrhythmias in 6 PFO closure devices. Methods Four hundred forty-five patients underwent percutaneous PFO closure with appropriate follow-up between 2001 and 2021. The procedure was performed using Abbott Amplatzer PFO, Amplatzer ASD, Amplatzer Cribriform, NMT CardioSEAL, Gore Helex, or Gore Cardioform devices. Incidence of AF, atrial flutter, and arrhythmias were assessed by electrocardiogram within 6 months from closure. Multivariate logistic regression evaluated potential predictors of postclosure AF or atrial flutter. Results Postclosure AF or atrial flutter occurred in 30 patients (6.7%) within 6 months, and its incidence was significantly different across devices. Gore Cardioform had the greatest frequency of postclosure AF or atrial flutter events (16.8%) compared with other devices. The Gore Cardioform device, larger device sizes, and male sex were associated with greater risk of postclosure AF or atrial flutter. Conclusions Postclosure AF or atrial flutter was more likely to occur in the Gore Cardioform device, in males, and in patients who underwent PFO closure with larger devices. Although it is more effective for complete closure, the Gore Cardioform device was shown to be an independent predictor of postclosure AF or atrial flutter.
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Affiliation(s)
| | - Jeff Gornbein
- Statistics Core, Department of Medicine, David Geffen School of Medicine, UCLA, Los Angeles, California
| | - Jonathan M. Tobis
- Department of Medicine, Division of Cardiology, UCLA, Los Angeles, California
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Bourdillon N, Subudhi AW, Fan JL, Evero O, Elliott JE, Lovering AT, Roach RC, Kayser B. AltitudeOmics: effects of 16 days acclimatization to hypobaric hypoxia on muscle oxygen extraction during incremental exercise. J Appl Physiol (1985) 2023; 135:823-832. [PMID: 37589059 PMCID: PMC10642515 DOI: 10.1152/japplphysiol.00100.2023] [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: 02/16/2023] [Revised: 07/11/2023] [Accepted: 08/03/2023] [Indexed: 08/18/2023] Open
Abstract
Acute altitude exposure lowers arterial oxygen content ([Formula: see text]) and cardiac output ([Formula: see text]) at peak exercise, whereas O2 extraction from blood to working muscles remains similar. Acclimatization normalizes [Formula: see text] but not peak [Formula: see text] nor peak oxygen consumption (V̇o2peak). To what extent acclimatization impacts muscle O2 extraction remains unresolved. Twenty-one sea-level residents performed an incremental cycling exercise to exhaustion near sea level (SL), in acute (ALT1) and chronic (ALT16) hypoxia (5,260 m). Arterial blood gases, gas exchange at the mouth and oxy- (O2Hb) and deoxyhemoglobin (HHb) of the vastus lateralis were recorded to assess arterial O2 content ([Formula: see text]), [Formula: see text], and V̇o2. The HHb-V̇o2 slope was taken as a surrogate for muscle O2 extraction. During moderate-intensity exercise, HHb-V̇o2 slope increased to a comparable extent at ALT1 (2.13 ± 0.94) and ALT16 (2.03 ± 0.88) compared with SL (1.27 ± 0.12), indicating increased O2 extraction. However, the HHb/[Formula: see text] ratio increased from SL to ALT1 and then tended to go back to SL values at ALT16. During high-intensity exercise, HHb-V̇o2 slope reached a break point beyond which it decreased at SL and ALT1, but not at ALT16. Increased muscle O2 extraction during submaximal exercise was associated with decreased [Formula: see text] in acute hypoxia. The significantly greater muscle O2 extraction during maximal exercise in chronic hypoxia is suggestive of an O2 reserve.NEW & NOTEWORTHY During incremental exercise muscle deoxyhemoglobin (HHb) and oxygen consumption (V̇o2) both increase linearly, and the slope of their relationship is an indirect index of local muscle O2 extraction. The latter was assessed at sea level, in acute and during chronic exposure to 5,260 m. The demonstrated presence of a muscle O2 extraction reserve during chronic exposure is coherent with previous studies indicating both limited muscle oxidative capacity and decrease in motor drive.
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Affiliation(s)
- Nicolas Bourdillon
- Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland
| | - Andrew W Subudhi
- Hybl Sports Medicine and Performance Center, Department of Human Physiology and Nutrition, University of Colorado, Colorado Springs, Colorado, United States
| | - Jui-Lin Fan
- Department of Physiology, Faculty of Medical & Health Sciences, Manaaki Manawa-The Centre for Heart Research, University of Auckland, Auckland, New Zealand
| | - Oghenero Evero
- Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Jonathan E Elliott
- 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
| | - Robert C Roach
- Altitude Research Center, Department of Medicine, University of Colorado Anschutz Medical Campus, Aurora, Colorado, United States
| | - Bengt Kayser
- Institute of Sports Sciences, University of Lausanne, Lausanne, Switzerland
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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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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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Wang S, Guo ZY, Sun XX, Yuan P, Zhao QH, Wu WH, Qiu HL, Luo CJ, Gong SG, Li HT, Zhang R, He J, Wang L, Liu JM, Guo J, Jiang R. Differences in disease severity and prognosis of exercise-induced right-to-left shunt between idiopathic pulmonary arterial hypertension and chronic thromboembolic pulmonary hypertension patients. Front Cardiovasc Med 2022; 9:976730. [PMID: 36578835 PMCID: PMC9791184 DOI: 10.3389/fcvm.2022.976730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2022] [Accepted: 11/21/2022] [Indexed: 12/14/2022] Open
Abstract
Objective Whether exercise-induced venous-to-systemic shunt (EIS) during cardiopulmonary exercise testing (CPET) has different manifestations or characteristics in idiopathic pulmonary arterial hypertension (IPAH) and chronic thromboembolic pulmonary hypertension (CTEPH) patients remains unknown. We explored the differences in hemodynamics, echocardiography, and prognosis between IPAH and CTEPH patients with and without EIS. Methods We conducted a retrospective cross-sectional cohort study and included 161 PH patients at Shanghai Pulmonary Hospital. Demographic, echocardiography, pulmonary hemodynamic, and CPET variables were compared between patients with and without EIS stratified by IPAH and CTEPH. EIS was determined by CPET. Binary logistic regression analyses were performed to explore independent influencing factors of EIS. Cox survival analysis was used to quantify the impact of EIS on the prognosis of patients. Results Exercise-induced venous-to-systemic shunt was found in approximately 17.4% of 86 IPAH patients and 20% of 75 CTEPH patients. All-cause mortality occurred in 43 (26.7%) patients during a median follow-up of 6.5 years. Compared with those without EIS, patients with EIS had higher peak end-tidal O2 and lower VO2/VE and tricuspid annular plane systolic excursion (TAPSE). Among the IPAH patients, EIS was associated with lower cardiac output, cardiac index, mixed venous oxygen saturation, VO2/VE, and TAPSE and higher VE/VCO2 and right ventricular end-diastolic transverse diameter. Logistic regression analysis indicated that VO2/VE was an independent factor influencing whether IPAH patients developed EIS during CPET. Cox logistic regression indicated that female IPAH patients or IPAH patients with higher VO2/VE and EIS had a better prognosis. Female IPAH patients had better 10-year survival. In IPAH patients without EIS, patients with higher VO2/VE had better 10-year survival. However, compared with CTEPH patients without EIS, those with EIS had similar echocardiographic, hemodynamic, CPET parameter results and 10-year survival. Conclusion Exercise-induced venous-to-systemic shunt exhibits different profiles among IPAH and CTEPH patients. Among IPAH patients, those with EIS had worse peak end-tidal O2, VO2/VE, and TAPSE than those without EIS. VO2/VE was an independent factor of EIS among IPAH patients. IPAH patients with EIS, female sex or higher VO2/VE had better survival. However, the association between EIS and PAH severity or prognosis in CTEPH patients needs to be further explored.
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Affiliation(s)
- Shang Wang
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Zi-Yan Guo
- Department of Cardiovascular Intensive Care Unit, The First Affiliated Hospital of Henan University, Kaifeng, Henan, China
| | - Xing-Xing Sun
- Department of Pulmonary Function Test, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Ping Yuan
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Qin-Hua Zhao
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Wen-Hui Wu
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Hong-Ling Qiu
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Ci-Jun Luo
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Su-Gang Gong
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Hui-Ting Li
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Rui Zhang
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Jing He
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Lan Wang
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Jin-Ming Liu
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China
| | - Jian Guo
- Department of Pulmonary Function Test, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China,Jian Guo,
| | - Rong Jiang
- Department of Cardiopulmonary Circulation, Shanghai Pulmonary Hospital, School of Medicine, Tongji University, Shanghai, China,*Correspondence: Rong Jiang,
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Kelly T, Brown C, Bryant-Ekstrand M, Lord R, Dawkins T, Drane A, Futral JE, Barak O, Dragun T, Stembridge M, Spajić B, Drviš I, Duke JW, Ainslie PN, Foster GE, Dujic Z, Lovering AT. Blunted hypoxic pulmonary vasoconstriction in apnoea divers. Exp Physiol 2022; 107:1225-1240. [PMID: 35993480 DOI: 10.1113/ep090326] [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: 01/13/2022] [Accepted: 08/11/2022] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is new and noteworthy? What is the central question of this study? Does the hyperbaric, hypercapnic, acidotic, hypoxic stress of apnoea diving lead to greater pulmonary vasoreactivity and increased right-heart work in apnoea divers? What is the main finding and its importance? Compared to sex- and age-matched controls, Divers had a significantly lower change in total pulmonary resistance in response to short duration isocapnic hypoxia. With oral sildenafil (50 mg), there were no differences in total pulmonary resistance between groups, suggesting Divers can maintain normal pulmonary artery tone in hypoxic conditions. Blunted hypoxic pulmonary vasoconstriction may be beneficial during apnoea diving. ABSTRACT Competitive apnoea divers repetitively dive to depths beyond 50 m. During the final portions of ascent, Divers experience significant hypoxaemia. Additionally, hyperbaria during diving increases thoracic blood volume while simultaneously reducing lung volume, increasing pulmonary artery pressure. We hypothesized that Divers would have exaggerated hypoxic pulmonary vasoconstriction leading to increased right-heart work due to their repetitive hypoxaemia and hyperbaria, and that the administration of sildenafil would have a greater effect in reducing pulmonary resistance in Divers. We recruited 16 Divers and 16 age and sex matched non-diving controls (Controls). Using a double-blinded, placebo-controlled, cross-over design, participants were evaluated for normal cardiac and lung function, then their cardiopulmonary responses to 20-30 minutes of isocapnic hypoxia (end-tidal PO2 = 50 mm Hg) were measured one hour following ingestion of 50 mg sildenafil or placebo. Cardiac structure and cardiopulmonary function were similar at baseline. With placebo, Divers had a significantly smaller increase in total pulmonary resistance than controls after 20-30 minutes isocapnic hypoxia (Δ -3.85 ± 72.85 vs 73.74 ± 91.06 dynes/sec/cm-5 , p = .0222). With sildenafil, Divers and Controls had similarly blunted increases in total pulmonary resistance after 20-30 minutes of hypoxia. Divers also had a significantly lower systemic vascular resistance following sildenafil in normoxia. These data indicate that repetitive apnoea diving leads to a blunted hypoxic pulmonary vasoconstriction. We suggest this is a beneficial adaption allowing for increased cardiac output with reduced right heart work and thus reducing cardiac oxygen utilization under hypoxemic conditions. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Tyler Kelly
- Department of Human Physiology, University of Oregon, Eugene, Oregon, USA
| | - Courtney Brown
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | | | - Rachel Lord
- School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK
| | - Tony Dawkins
- School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK
| | - Aimee Drane
- School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK
| | - Joel E Futral
- Department of Human Physiology, University of Oregon, Eugene, Oregon, USA
| | - Otto Barak
- Department of Physiology, University of Novi Sad, Novi Sad, Serbia
| | - Tanja Dragun
- Department of Integrative Physiology, University of Split School of Medicine, Split, Croatia
| | - Michael Stembridge
- School of Sport and Health Sciences, Cardiff Metropolitan University, Cardiff, Wales, UK
| | - Boris Spajić
- Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia
| | - Ivan Drviš
- Faculty of Kinesiology, University of Zagreb, Zagreb, Croatia
| | - Joseph W Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, Arizona, USA
| | - Philip N Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Glen E Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - 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, Oregon, USA
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High prevalence of patent foramen ovale in recreational to elite breath hold divers. J Sci Med Sport 2022; 25:553-556. [DOI: 10.1016/j.jsams.2022.03.014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/14/2022] [Accepted: 03/23/2022] [Indexed: 12/13/2022]
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Schallerer AE, Duke JW, Speros JP, Mangum TS, Norris HC, Beasley KM, Laurie SS, Elliott JE, Davis JT, Lovering AT. Lower transfer factor of the lung for carbon monoxide in women with a patent foramen ovale. Exp Physiol 2022; 107:243-252. [DOI: 10.1113/ep090176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 01/10/2022] [Indexed: 11/08/2022]
Affiliation(s)
| | - Joseph W. Duke
- Department of Biological Sciences Northern Arizona University Flagstaff AZ USA
| | - Julia P. Speros
- Department of Human Physiology University of Oregon Eugene OR USA
| | - Tyler S. Mangum
- Department of Human Physiology University of Oregon Eugene OR USA
| | | | - Kara M. Beasley
- Department of Human Physiology University of Oregon Eugene OR USA
| | - Steven S. Laurie
- KBR, Cardiovascular and Vision Laboratory NASA Johnson Space Center Houston TX USA
| | - Jonathan E. Elliott
- VA Portland Health Care System Portland OR USA
- Department of Neurology Oregon Health & Science University Portland OR USA
| | - James T. Davis
- Department of Kinesiology Recreation, and Sport Indiana State University Terre Haute IN USA
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Lovering AT, Kelly TS, DiMarco KG, Bradbury KE, Charkoudian N. Implications of a patent foramen ovale on environmental physiology and pathophysiology: Do we know the hole story? J Physiol 2022; 600:1541-1553. [PMID: 35043424 DOI: 10.1113/jp281108] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 01/14/2022] [Indexed: 11/08/2022] Open
Abstract
The foramen ovale is an essential component of the foetal circulation contributing to oxygenation and carbon dioxide elimination that remains patent under certain circumstances, in ∼ 30% of the healthy adult population, without major negative sequelae in most. Adults with a patent foramen ovale (PFO) have a greater tendency to develop symptoms of acute mountain sickness and high-altitude pulmonary oedema upon ascent to high altitude, and PFO presence is associated with worse cardiopulmonary function in chronic mountain sickness. This increase in altitude illness prevalence may be related to dysregulated cerebral blood flow associated with altered respiratory chemoreflex sensitivity; however, the mechanisms remain to be elucidated. Interestingly, men with a PFO appear to have a shift in thermoregulatory control to higher internal temperatures, both at rest and during exercise, and they have blunted thermal tachypnea. The teleological "reason" for this thermoregulatory shift is unclear, but the shift of ∼0.5°C in core body temperature does not appear to be sufficient to have any significant negative consequences in terms of risk of heat illness. Further work in this area is needed, particularly in women, to evaluate mechanisms of heat storage and dissipation in these individuals as compared to people without a PFO. Consequences of a PFO in SCUBA divers include a greater incidence of unprovoked decompression sickness, but whether PFO is beneficial or detrimental to breath hold diving remains unexplored. Whether PFO presence will explain interindividual variability in responses to, and consequences from, other environmental stressors such as spaceflight remain entirely unknown. Abstract figure legend Associations between PFO and altitude illnesses, core body temperature and diving. This article is protected by copyright. All rights reserved.
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Affiliation(s)
| | - Tyler S Kelly
- University of Oregon, Department of Human Physiology, Eugene, OR
| | | | - Karleigh E Bradbury
- University of Oregon, Department of Human Physiology, Eugene, OR.,United States Army Research Institute of Environmental Medicine, Thermal & Mountain Medicine Division, Natick, MA
| | - Nisha Charkoudian
- United States Army Research Institute of Environmental Medicine, Thermal & Mountain Medicine Division, Natick, MA
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11
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DiMarco KG, Beasley KM, Shah K, Speros JP, Elliott JE, Laurie SS, Duke JW, Goodman RD, Futral JE, Hawn JA, Roach RC, Lovering AT. No effect of patent foramen ovale on acute mountain sickness and pulmonary pressure in normobaric hypoxia. Exp Physiol 2021; 107:122-132. [PMID: 34907608 DOI: 10.1113/ep089948] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 12/08/2021] [Indexed: 11/08/2022]
Abstract
What is the central question to this study? Is there a relationship between a patent foramen ovale and the development of acute mountain sickness and an exaggerated increase in pulmonary pressure in response to 7-10 hours of normobaric hypoxia? What is the main finding and its importance? Patent foramen ovale presence did not increase susceptibility to acute mountain sickness or result in an exaggerated increase in pulmonary artery systolic pressure with normobaric hypoxia. This data suggest hypobaric hypoxia is integral to the increased susceptibility to acute mountain sickness previously reported in those with patent foramen ovale, and patent foramen ovale presence alone does not contribute to the hypoxic pulmonary pressor response. ABSTRACT: Acute mountain sickness (AMS) develops following rapid ascent to altitude, but its exact causes remain unknown. A patent foramen ovale (PFO) is a right-to-left intracardiac shunt present in ∼30% of the population that has been shown to increase AMS susceptibility with high altitude hypoxia. Additionally, high altitude pulmonary edema (HAPE), is a severe type of altitude illness characterized by an exaggerated pulmonary pressure response, and there is a greater prevalence of PFO in those with a history of HAPE. However, whether hypoxia, per se, is causing the increased incidence of AMS in those with a PFO and whether a PFO is associated with an exaggerated increase in pulmonary pressure in those without a history of HAPE is unknown. Participants (n = 36) matched for biological sex (18 female) and the presence or absence of a PFO (18 PFO+) were exposed to 7-10 hours of normobaric hypoxia equivalent to 4755 m. Presence and severity of AMS was determined using the Lake Louise AMS scoring system. Pulmonary artery systolic pressure, cardiac output, and total pulmonary resistance were measured using ultrasound. We found no significant association of PFO with incidence or severity of AMS and no association of PFO with arterial oxygen saturation. Additionally, there was no effect of a PFO on pulmonary pressure, cardiac output, or total pulmonary resistance. These data suggest that hypobaric hypoxia is necessary for those with a PFO to have increased incidence of AMS and that presence of PFO is not associated with an exaggerated pulmonary pressor response. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Kaitlyn G DiMarco
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Kara M Beasley
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Karina Shah
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Julia P Speros
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
| | - Jonathan E Elliott
- VA Portland Health Care System, Portland, OR, USA.,Oregon Health and Science University, Department of Neurology, Portland, OR, USA
| | - Steven S Laurie
- KBR, Cardiovascular and Vision Laboratory, NASA Johnson Space Center, Houston, TX, USA
| | - Joseph W Duke
- Northern Arizona University, Department of Biological Sciences, Flagstaff, AZ, USA
| | | | | | - Jerold A Hawn
- Oregon Heart and Vascular Institute, Springfield, OR, USA
| | - Robert C Roach
- University of Colorado Anschutz Medical Campus, Altitude Research Center, Division of Pulmonary and Critical Care Medicine, Department of Medicine, Aurora, CO, USA
| | - Andrew T Lovering
- University of Oregon, Department of Human Physiology, Eugene, OR, USA
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12
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Liu G, Feng Z, Feng F, Xue C, Liu F, Xie X. The correlation between patent foramen ovale and brain ischemia in plateau residents. BMC Cardiovasc Disord 2021; 21:381. [PMID: 34362308 PMCID: PMC8349053 DOI: 10.1186/s12872-021-02172-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 07/21/2021] [Indexed: 11/24/2022] Open
Abstract
Background It has been suggested that patent foramen ovale (PFO) contributes to the majority of cryptogenic stroke cases in young people, however, the direct link is still undetermined. Here we analyzed the correlation between PFO and brain ischemia lesions in a cohort of cases that were long-term residents in the plateau to provide solid evidence to support the causal relation between PFO and brain ischemia lesion or cryptogenic stroke. Methods Long-term residents with young age from Qinghai Plateau were recruited and separated by PFO positivity. Brain MRI was used to image 100 PFO positive cases and 100 healthy controls. The diameter of PFO was measured by echocardiography. The location, number and anterior/posterior circulation of ischemia lesions were also evaluated. The correlation between PFO (including positivity and diameter) and brain ischemia lesion (including positivity and other characteristics) was analyzed by chi-square test. Further, the chi-square test for the trend test was used to analyze the linear correlation between these groups. Results We found a strong correlation between the positivity of PFO and brain ischemia lesion, with 71% of PFO cases showing the presence of brain ischemia lesions, and only 19% for healthy controls (p < 0.001). The diameter of PFO is strongly and linearly correlated with the incidence rate of brain ischemia lesion (RR = 3.737 (95%CI 2.496 to 5.767). Conclusion We found a convincing correlation between the positivity of PFO and brain ischemia lesion in residents of the plateau. Our findings provide another solid evidence of the direct causal relation between PFO and brain ischemia lesion.
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Affiliation(s)
- Gang Liu
- Department of Radiological Interventionalradiology, Qinghai Red Cross Hospital, Xining, 810100, Qinghai, China.
| | - Zhao Feng
- Department of Radiological Interventionalradiology, Qinghai Red Cross Hospital, Xining, 810100, Qinghai, China
| | - Fan Feng
- Department of Radiological Interventionalradiology, Qinghai Red Cross Hospital, Xining, 810100, Qinghai, China
| | - Changju Xue
- Department of Radiological Interventionalradiology, Qinghai Red Cross Hospital, Xining, 810100, Qinghai, China
| | - Fei Liu
- Department of Radiological Interventionalradiology, Qinghai Red Cross Hospital, Xining, 810100, Qinghai, China
| | - Xiaoting Xie
- Department of Radiological Interventionalradiology, Qinghai Red Cross Hospital, Xining, 810100, Qinghai, China
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13
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Fan JL, Wu TY, Lovering AT, Nan L, Bang WL, Kayser B. Differential Brain and Muscle Tissue Oxygenation Responses to Exercise in Tibetans Compared to Han Chinese. Front Physiol 2021; 12:617954. [PMID: 33716766 PMCID: PMC7943468 DOI: 10.3389/fphys.2021.617954] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2020] [Accepted: 01/18/2021] [Indexed: 11/13/2022] Open
Abstract
The Tibetans’ better aerobic exercise capacity at altitude remains ill-understood. We tested the hypothesis that Tibetans display better muscle and brain tissue oxygenation during exercise in hypoxia. Using near-infrared spectrometry (NIRS) to provide indices of tissue oxygenation, we measured oxy- and deoxy-hemoglobin ([O2Hb] and [HHb], respectively) responses of the vastus lateralis muscle and the right prefrontal cortex in ten Han Chinese and ten Tibetans during incremental cycling to exhaustion in a pressure-regulated chamber at simulated sea-level (air at 1 atm: normobaric normoxia) and 5,000 m (air at 0.5 atm: hypobaric hypoxia). Hypoxia reduced aerobic capacity by ∼22% in both groups (d = 0.8, p < 0.001 vs. normoxia), while Tibetans consistently outperformed their Han Chinese counterpart by ∼32% in normoxia and hypoxia (d = 1.0, p = 0.008). We found cerebral [O2Hb] was higher in Tibetans at normoxic maximal effort compared Han (p = 0.001), while muscle [O2Hb] was not different (p = 0.240). Hypoxic exercise lowered muscle [O2Hb] in Tibetans by a greater extent than in Han (interaction effect: p < 0.001 vs. normoxic exercise). Muscle [O2Hb] was lower in Tibetans when compared to Han during hypoxic exercise (d = 0.9, p = 0.003), but not during normoxic exercise (d = 0.4, p = 0.240). Muscle [HHb] was not different between the two groups during normoxic and hypoxic exercise (p = 0.778). Compared to Han, our findings revealed a higher brain tissue oxygenation in Tibetans during maximal exercise in normoxia, but lower muscle tissue oxygenation during exercise in hypoxia. This would suggest that the Tibetans privileged oxygenation of the brain at the expense of that of the muscle.
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Affiliation(s)
- Jui-Lin Fan
- Department of Physiology, Faculty of Medical and Health Sciences, University of Auckland, Auckland, New Zealand
| | - Tian Yi Wu
- Research Center for High Altitude Medicine, Tibet University Medical College, Lhasa, China.,National Key Laboratory of High Altitude Medicine, Xining, China
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, United States
| | - Liya Nan
- National Key Laboratory of High Altitude Medicine, Xining, China
| | - Wang Liang Bang
- National Key Laboratory of High Altitude Medicine, Xining, China
| | - Bengt Kayser
- Institute of Sport Sciences, University of Lausanne, Lausanne, Switzerland
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Duke JW, Beasley KM, Speros JP, Elliott JE, Laurie SS, Goodman RD, Futral E, Hawn JA, Lovering AT. Impaired pulmonary gas exchange efficiency, but normal pulmonary artery pressure increases, with hypoxia in men and women with a patent foramen ovale. Exp Physiol 2020; 105:1648-1659. [PMID: 32627890 DOI: 10.1113/ep088750] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 06/30/2020] [Indexed: 01/07/2023]
Abstract
NEW FINDINGS What is the central question of this study? Do individuals with a patent foramen ovale (PFO+ ) have a larger alveolar-to-arterial difference in P O 2 ( A - a D O 2 ) than those without (PFO- ) and/or an exaggerated increase in pulmonary artery systolic pressure (PASP) in response to hypoxia? What is the main finding and its importance? PFO+ had a greater A - a D O 2 while breathing air, 16% and 14% O2 , but not 12% or 10% O2 . PASP increased equally in hypoxia between PFO+ and PFO- . These data suggest that PFO+ may not have an exaggerated acute increase in PASP in response to hypoxia. ABSTRACT Patent foramen ovale (PFO) is present in 30-40% of the population and is a potential source of right-to-left shunt. Accordingly, those with a PFO (PFO+ ) may have a larger alveolar-to-arterial difference in P O 2 ( A - a D O 2 ) than those without (PFO- ) in normoxia and with mild hypoxia. Likewise, PFO is associated with high-altitude pulmonary oedema, a condition known to have an exaggerated pulmonary pressure response to hypoxia. Thus, PFO+ may also have exaggerated pulmonary pressure increases in response to hypoxia. Therefore, the purposes of the present study were to systematically determine whether or not: (1) the A - a D O 2 was greater in PFO+ than in PFO- in normoxia and mild to severe hypoxia and (2) the increase in pulmonary artery systolic pressure (PASP) in response to hypoxia was greater in PFO+ than in PFO- . We measured arterial blood gases and PASP via ultrasound in healthy PFO+ (n = 15) and PFO- (n = 15) humans breathing air and 30 min after breathing four levels of hypoxia (16%, 14%, 12%, 10% O2 , randomized and balanced order) at rest. The A - a D O 2 was significantly greater in PFO+ compared to PFO- while breathing air (2.1 ± 0.7 vs. 0.4 ± 0.3 Torr), 16% O2 (1.8 ± 1.2 vs. 0.7 ± 0.8 Torr) and 14% O2 (2.3 ± 1.2 vs. 0.7 ± 0.6 Torr), but not 12% or 10% O2 . We found no effect of PFO on PASP at any level of hypoxia. We conclude that PFO influences pulmonary gas exchange efficiency with mild hypoxia, but not the acute increase in PASP in response to hypoxia.
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Affiliation(s)
- Joseph W Duke
- Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ, USA
| | - Kara M Beasley
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Julia P Speros
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Jonathan E Elliott
- VA Portland Health Care System, Portland, OR, USA.,Department of Neurology, Oregon Health and Science University, Portland, OR, USA
| | - Steven S Laurie
- KBR, Cardiovascular and Vision Laboratory, NASA Johnson Space Center, Houston, TX, USA
| | | | - Eben Futral
- Oregon Heart and Vascular Institute, Springfield, OR, USA
| | - Jerold A Hawn
- Oregon Heart and Vascular Institute, Springfield, OR, USA
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
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15
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Sweeney LM. Impact of stressors in the aviation environment on xenobiotic dosimetry in humans: physiologically based prediction of the effect of barometric pressure or altitude. JOURNAL OF TOXICOLOGY AND ENVIRONMENTAL HEALTH. PART A 2020; 83:302-312. [PMID: 32366185 DOI: 10.1080/15287394.2020.1755403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Standard health risks from volatile organic compounds (VOCs) are generally interpreted at ambient environmental conditions. The aim of this study was to develop a strategy for using physiologically based pharmacokinetic (PBPK) modeling to compare known risks in the general population to calculated risks in pilots experiencing pressure-based stressors. PBPK models facilitate these comparisons by prediction of how target-tissue specific doses are altered when a stressor, such as high altitude, produces changes in physiological parameters. Cardiac output, regional blood flow, and alveolar ventilation rate following acute exposure to altitude ranging from moderate to extremely high were estimated from published data from 52 groups of human subjects. Scenarios where pilots might inhale toluene, 1,2,4-trimethylbenzene (1,2,4-TMB), or cyclohexane during routine military flight training were simulated. At the recommended Threshold Limit Values (TLV), arterial blood concentrations were predicted to be higher for exposure at 15000 ft (4572 m) than at sea level. The differences were greater for toluene and TMB, which have higher blood: air and fat: blood partition coefficients than less lipophilic cyclohexane. In summary, quantitative approaches to internal dosimetry prediction that take advantage of existing knowledge of physiological changes induced by occupational stressors possess potential as tools in performing a human health risk assessment.
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Affiliation(s)
- Lisa M Sweeney
- UES, Inc., Assigned to US Air Force Research Laboratory, 711th Human Performance Wing , Dayton, OH, USA
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16
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Kumar P, Rusheen J, Tobis JM. A comparison of methods to determine patent foramen ovale size. Catheter Cardiovasc Interv 2019; 96:E621-E629. [DOI: 10.1002/ccd.28665] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 12/07/2019] [Indexed: 11/10/2022]
Affiliation(s)
- Preetham Kumar
- Division of Cardiology, Department of Medicine University of California Los Angeles California
| | - Joshua Rusheen
- Division of Cardiology, Department of Medicine University of California Los Angeles California
| | - Jonathan M. Tobis
- Division of Cardiology, Department of Medicine University of California Los Angeles California
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17
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Davis JT, Boulet LM, Hardin AM, Chang AJ, Lovering AT, Foster GE. Ventilatory responses to acute hypoxia and hypercapnia in humans with a patent foramen ovale. J Appl Physiol (1985) 2018; 126:730-738. [PMID: 30521423 DOI: 10.1152/japplphysiol.00741.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Subjects with a patent foramen ovale (PFO) have blunted ventilatory acclimatization to high altitude compared with subjects without PFO. The blunted response observed could be because of differences in central and/or peripheral respiratory chemoreflexes. We hypothesized that compared with subjects without a PFO (PFO-), subjects with a PFO (PFO+) would have blunted ventilatory responses to acute hypoxia and hypercapnia. Sixteen PFO+ subjects (9 female) and 15 PFO- subjects (8 female) completed four 20-min trials on the same day: 1) normoxic hypercapnia (NH), 2) hyperoxic hypercapnia (HH), 3) isocapnic hypoxia (IH), and 4) poikilocapnic hypoxia (PH). Hypercapnic trials were completed before the hypoxic trials, the order of the hypercapnic (NH & HH) and hypoxic (IH & PH) trials were randomized, and trials were separated by ≥40 min. During the NH trials but not the HH trials subjects who were PFO+ had a blunted hypercapnic ventilatory response compared with subjects who were PFO- (1.41 ± 0.46 l·min-1·mmHg-1 vs. 1.98 ± 0.71 l·min-1·mmHg-1, P = 0.02). There were no differences between the PFO+ and PFO- subjects with respect to the acute hypoxic ventilatory response during IH and PH trials. Hypoxic ventilatory depression was similar between subjects who were PFO+ and PFO- during IH. These data suggest that compared with subjects who were PFO-, subjects who were PFO+ have normal ventilatory chemosensitivity to acute hypoxia but blunted ventilatory chemosensitivity to carbon dioxide, possibly because of reduced carbon dioxide sensitivity of either the central and/or the peripheral chemoreceptors. NEW & NOTEWORTHY Patent foramen ovale (PFO) is found in ~25%-40% of the population. The presence of a PFO appears to be associated with blunted ventilatory responses during acute exposure to normoxic hypercapnia. The reason for this blunted ventilatory response during acute exposure to normoxic hypercapnia is unknown but may suggest differences in either central and/or peripheral chemoreflex contribution to hypercapnia.
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Affiliation(s)
- James T Davis
- Indiana State University, Department of Kinesiology, Recreation, and Sport, Terre Haute, Indiana
| | - Lindsey M Boulet
- University of British Columbia, Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science , Kelowna, BC , Canada
| | - Alyssa M Hardin
- University of Oregon, Department of Human Physiology , Eugene, Oregon
| | - Alex J Chang
- University of Oregon, Department of Human Physiology , Eugene, Oregon
| | - Andrew T Lovering
- University of Oregon, Department of Human Physiology , Eugene, Oregon
| | - Glen E Foster
- University of British Columbia, Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science , Kelowna, BC , Canada
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18
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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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19
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Muza SR. Wearable physiological sensors and real-time algorithms for detection of acute mountain sickness. J Appl Physiol (1985) 2018; 124:557-563. [DOI: 10.1152/japplphysiol.00367.2017] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
This is a minireview of potential wearable physiological sensors and algorithms (process and equations) for detection of acute mountain sickness (AMS). Given the emerging status of this effort, the focus of the review is on the current clinical assessment of AMS, known risk factors (environmental, demographic, and physiological), and current understanding of AMS pathophysiology. Studies that have examined a range of physiological variables to develop AMS prediction and/or detection algorithms are reviewed to provide insight and potential technological roadmaps for future development of real-time physiological sensors and algorithms to detect AMS. Given the lack of signs and nonspecific symptoms associated with AMS, development of wearable physiological sensors and embedded algorithms to predict in the near term or detect established AMS will be challenging. Prior work using [Formula: see text], HR, or HRv has not provided the sensitivity and specificity for useful application to predict or detect AMS. Rather than using spot checks as most prior studies have, wearable systems that continuously measure SpO2 and HR are commercially available. Employing other statistical modeling approaches such as general linear and logistic mixed models or time series analysis to these continuously measured variables is the most promising approach for developing algorithms that are sensitive and specific for physiological prediction or detection of AMS.
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Affiliation(s)
- Stephen R. Muza
- Strategic Science Management Office, US Army Research Institute of Environmental Medicine, Natick, Massachusetts
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20
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Davis JT, Hay MW, Hardin AM, White MD, Lovering AT. Effect of a patent foramen ovale in humans on thermal responses to passive cooling and heating. J Appl Physiol (1985) 2017; 123:1423-1432. [PMID: 28819008 DOI: 10.1152/japplphysiol.01032.2016] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 08/11/2017] [Accepted: 08/11/2017] [Indexed: 11/22/2022] Open
Abstract
Humans with a patent foramen ovale (PFO) have a higher esophageal temperature (Tesoph) than humans without a PFO (PFO-). Thus the presence of a PFO might also be associated with differences in thermal responsiveness to passive cooling and heating such as shivering and hyperpnea, respectively. The purpose of this study was to determine whether thermal responses to passive cooling and heating are different between PFO- subjects and subjects with a PFO (PFO+). We hypothesized that compared with PFO- subjects PFO+ subjects would cool down more rapidly and heat up slower and that PFO+ subjects who experienced thermal hyperpnea would have a blunted increase in ventilation. Twenty-seven men (13 PFO+) completed two trials separated by >48 h: 1) 60 min of cold water immersion (19.5 ± 0.9°C) and 2) 30 min of hot water immersion (40.5 ± 0.2°C). PFO+ subjects had a higher Tesoph before and during cold water and hot water immersion (P < 0.05). However, the rate of temperature change was similar between groups for each condition. Within a subset of 18 subjects (8 PFO+) who experienced thermal hyperpnea, PFO+ subjects experienced thermal hyperpnea at a higher absolute Tesoph but with a blunted magnitude compared with PFO- subjects. These data suggest that PFO+ subjects have a higher Tesoph at rest and have blunted thermal hyperpnea during passive heating.NEW & NOTEWORTHY Patent foramen ovale (PFO) is found in ~25-40% of the population. The presence of a PFO appears to be associated with a greater core body temperature and blunted ventilatory responses during passive heating. The reason for this blunted ventilatory response to passive heating is unknown but may suggest differences in thermal sensitivity in PFO+ subjects compared with PFO- subjects.
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Affiliation(s)
- James T Davis
- Department of Kinesiology, Recreation, and Sport, Indiana State University, Terre Haute, Indiana
| | - Madeline W Hay
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
| | - Alyssa M Hardin
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
| | - Matthew D White
- Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Vancouver, British Columbia, Canada
| | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, Oregon; and
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21
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Beidleman BA, Fulco CS, Cadarette BS, Cymerman A, Buller MJ, Salgado RM, Posch AM, Staab JE, Sils IV, Yurkevicius BR, Luippold AJ, Welles AP, Muza SR. Is normobaric hypoxia an effective treatment for sustaining previously acquired altitude acclimatization? J Appl Physiol (1985) 2017; 123:1214-1227. [PMID: 28705998 DOI: 10.1152/japplphysiol.00344.2017] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2017] [Revised: 07/06/2017] [Accepted: 07/06/2017] [Indexed: 12/25/2022] Open
Abstract
This study examined whether normobaric hypoxia (NH) treatment is more efficacious for sustaining high-altitude (HA) acclimatization-induced improvements in ventilatory and hematologic responses, acute mountain sickness (AMS), and cognitive function during reintroduction to altitude (RA) than no treatment at all. Seventeen sea-level (SL) residents (age = 23 ± 6 yr; means ± SE) completed in the following order: 1) 4 days of SL testing; 2) 12 days of HA acclimatization at 4,300 m; 3) 12 days at SL post-HA acclimatization (Post) where each received either NH (n = 9, [Formula: see text] = 0.122) or Sham (n = 8; [Formula: see text] = 0.207) treatment; and 4) 24-h reintroduction to 4,300-m altitude (RA) in a hypobaric chamber (460 Torr). End-tidal carbon dioxide pressure ([Formula: see text]), hematocrit (Hct), and AMS cerebral factor score were assessed at SL, on HA2 and HA11, and after 20 h of RA. Cognitive function was assessed using the SynWin multitask performance test at SL, on HA1 and HA11, and after 4 h of RA. There was no difference between NH and Sham treatment, so data were combined. [Formula: see text] (mmHg) decreased from SL (37.2 ± 0.5) to HA2 (32.2 ± 0.6), decreased further by HA11 (27.1 ± 0.4), and then increased from HA11 during RA (29.3 ± 0.6). Hct (%) increased from SL (42.3 ± 1.1) to HA2 (45.9 ± 1.0), increased again from HA2 to HA11 (48.5 ± 0.8), and then decreased from HA11 during RA (46.4 ± 1.2). AMS prevalence (%) increased from SL (0 ± 0) to HA2 (76 ± 11) and then decreased at HA11 (0 ± 0) and remained depressed during RA (17 ± 10). SynWin scores decreased from SL (1,615 ± 62) to HA1 (1,306 ± 94), improved from HA1 to HA11 (1,770 ± 82), and remained increased during RA (1,707 ± 75). These results demonstrate that HA acclimatization-induced improvements in ventilatory and hematologic responses, AMS, and cognitive function are partially retained during RA after 12 days at SL whether or not NH treatment is utilized.NEW & NOTEWORTHY This study demonstrates that normobaric hypoxia treatment over a 12-day period at sea level was not more effective for sustaining high-altitude (HA) acclimatization during reintroduction to HA than no treatment at all. The noteworthy aspect is that athletes, mountaineers, and military personnel do not have to go to extraordinary means to retain HA acclimatization to an easily accessible and relevant altitude if reexposure occurs within a 2-wk time period.
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Affiliation(s)
- Beth A Beidleman
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts;
| | - Charles S Fulco
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Bruce S Cadarette
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Allen Cymerman
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Mark J Buller
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Roy M Salgado
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Alexander M Posch
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Janet E Staab
- Military Performance Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts; and
| | - Ingrid V Sils
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Beau R Yurkevicius
- Thermal and Mountain Medicine Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | | | - Alexander P Welles
- Biophysics and Biomedical Modeling Division, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
| | - Stephen R Muza
- Scientifc Strategic Management Office, U.S. Army Research Institute of Environmental Medicine, Natick, Massachusetts
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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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23
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Loeppky JA, Sheard AC, Salgado RM, Mermier CM. V ESTPD as a measure of ventilatory acclimatization to hypobaric hypoxia. Physiol Int 2017; 103:377-391. [PMID: 28229643 DOI: 10.1556/2060.103.2016.3.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
This study compared the ventilation response to an incremental ergometer exercise at two altitudes: 633 mmHg (resident altitude = 1,600 m) and following acute decompression to 455 mmHg (≈4,350 m altitude) in eight male cyclists and runners. At 455 mmHg, the VESTPD at RER <1.0 was significantly lower and the VEBTPS was higher because of higher breathing frequency; at VO2max, both VESTPD and VEBTPS were not significantly different. As percent of VO2max, the VEBTPS was nearly identical and VESTPD was 30% lower throughout the exercise at 455 mmHg. The lower VESTPD at lower pressure differs from two classical studies of acclimatized subjects (Silver Hut and OEII), where VESTPD at submaximal workloads was maintained or increased above that at sea level. The lower VESTPD at 455 mmHg in unacclimatized subjects at submaximal workloads results from acute respiratory alkalosis due to the initial fall in HbO2 (≈0.17 pHa units), reduction in PACO2 (≈5 mmHg) and higher PAO2 throughout the exercise, which are partially pre-established during acclimatization. Regression equations from these studies predict VESTPD from VO2 and PB in unacclimatized and acclimatized subjects. The attainment of ventilatory acclimatization to altitude can be estimated from the measured vs. predicted difference in VESTPD at low workloads after arrival at altitude.
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Affiliation(s)
- J A Loeppky
- 1 Research Section: VA Medical Center , Albuquerque, NM, USA (retired) and Adjunct Faculty: Department of Health, Exercise and Sports Sciences, The University of New Mexico , Albuquerque, NM, USA
| | - A C Sheard
- 2 School of Kinesiology and Nutritional Science, California State University , Los Angeles, CA, USA
| | - R M Salgado
- 3 Thermal and Mountain Medicine Division, United States Army Research Institute of Environmental Medicine , Natick, MA, USA
| | - C M Mermier
- 4 Department of Health, Exercise and Sports Sciences, The University of New Mexico , Albuquerque, NM, USA
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Lovering AT, Elliott JE, Davis JT. Physiological impact of patent foramen ovale on pulmonary gas exchange, ventilatory acclimatization, and thermoregulation. J Appl Physiol (1985) 2016; 121:512-7. [PMID: 27418686 DOI: 10.1152/japplphysiol.00192.2015] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The foramen ovale, which is part of the normal fetal cardiopulmonary circulation, fails to close after birth in ∼35% of the population and represents a potential source of right-to-left shunt. Despite the prevalence of patent foramen ovale (PFO) in the general population, cardiopulmonary, exercise, thermoregulatory, and altitude physiologists may have underestimated the potential effect of this shunted blood flow on normal physiological processes in otherwise healthy humans. Because this shunted blood bypasses the respiratory system, it would not participate in either gas exchange or respiratory system cooling and may have impacts on other physiological processes that remain undetermined. The consequences of this shunted blood flow in PFO-positive (PFO+) subjects can potentially have a significant, and negative, impact on the alveolar-to-arterial oxygen difference (AaDO2), ventilatory acclimatization to high altitude and respiratory system cooling with PFO+ subjects having a wider AaDO2 at rest, during exercise after acclimatization, blunted ventilatory acclimatization, and a higher core body temperature (∼0.4(°)C) at rest and during exercise. There is also an association of PFO with high-altitude pulmonary edema and acute mountain sickness. These effects on physiological processes are likely dependent on both the presence and size of the PFO, with small PFOs not likely to have significant/measureable effects. The PFO can be an important determinant of normal physiological processes and should be considered a potential confounder to the interpretation of former and future data, particularly in small data sets where a significant number of PFO+ subjects could be present and significantly impact the measured outcomes.
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Affiliation(s)
- Andrew T Lovering
- University of Oregon, Department of Human Physiology, Eugene, Oregon;
| | - Jonathan E Elliott
- Oregon Health & Science University, Department of Neurology and VA Portland Health Care System, Portland, Oregon; and
| | - James T Davis
- Indiana State University, Department of Kinesiology, Recreation, and Sport, Terre Haute, Indiana
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25
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Lovering AT, Lozo M, Barak O, Davis JT, Lojpur M, Lozo P, Čaljkušić K, Dujić Ž. Resting arterial hypoxaemia in subjects with chronic heart failure, pulmonary hypertension and patent foramen ovale. Exp Physiol 2016; 101:657-70. [DOI: 10.1113/ep085657] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 03/14/2016] [Indexed: 01/09/2023]
Affiliation(s)
| | - Mislav Lozo
- Department of Cardiology; University Hospital Centre Split; Split Croatia
| | - Otto Barak
- Department of Integrative Physiology; University of Split, School of Medicine; Split Croatia
- Department of Physiology; University of Novi Sad; Novi Sad Serbia
| | - James T. Davis
- Department of Human Physiology; University of Oregon; Eugene OR USA
| | - Mihajlo Lojpur
- Department of Anesthesiology; University Hospital Centre Split; Split Croatia
| | - Petar Lozo
- Department of Cardiology; University Hospital Centre Split; Split Croatia
| | - Krešimir Čaljkušić
- Department of Neurology; University Hospital Centre Split; Split Croatia
| | - Željko Dujić
- Department of Integrative Physiology; University of Split, School of Medicine; Split Croatia
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26
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Tymko MM, Hoiland RL, Kuca T, Boulet LM, Tremblay JC, Pinske BK, Williams AM, Foster GE. Measuring the human ventilatory and cerebral blood flow response to CO2: a technical consideration for the end-tidal-to-arterial gas gradient. J Appl Physiol (1985) 2016; 120:282-96. [DOI: 10.1152/japplphysiol.00787.2015] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2015] [Accepted: 10/19/2015] [Indexed: 11/22/2022] Open
Abstract
Our aim was to quantify the end-tidal-to-arterial gas gradients for O2 (PET-PaO2) and CO2 (Pa-PETCO2) during a CO2 reactivity test to determine their influence on the cerebrovascular (CVR) and ventilatory (HCVR) response in subjects with (PFO+, n = 8) and without (PFO−, n = 7) a patent foramen ovale (PFO). We hypothesized that 1) the Pa-PETCO2 would be greater in hypoxia compared with normoxia, 2) the Pa-PETCO2 would be similar, whereas the PET-PaO2 gradient would be greater in those with a PFO, 3) the HCVR and CVR would be underestimated when plotted against PETCO2 compared with PaCO2, and 4) previously derived prediction algorithms will accurately target PaCO2. PETCO2 was controlled by dynamic end-tidal forcing in steady-state steps of −8, −4, 0, +4, and +8 mmHg from baseline in normoxia and hypoxia. Minute ventilation (V̇E), internal carotid artery blood flow (Q̇ICA), middle cerebral artery blood velocity (MCAv), and temperature corrected end-tidal and arterial blood gases were measured throughout experimentation. HCVR and CVR were calculated using linear regression analysis by indexing V̇E and relative changes in Q̇ICA, and MCAv against PETCO2, predicted PaCO2, and measured PaCO2. The Pa-PETCO2 was similar between hypoxia and normoxia and PFO+ and PFO−. The PET-PaO2 was greater in PFO+ by 2.1 mmHg during normoxia ( P = 0.003). HCVR and CVR plotted against PETCO2 underestimated HCVR and CVR indexed against PaCO2 in normoxia and hypoxia. Our PaCO2 prediction equation modestly improved estimates of HCVR and CVR. In summary, care must be taken when indexing reactivity measures to PETCO2 compared with PaCO2.
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Affiliation(s)
- Michael M. Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Ryan L. Hoiland
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Tomas Kuca
- Department of Anesthesia, Pain and Perioperative Medicine, Department of Critical Care Medicine, Dalhousie University, Halifax, Canada
| | - Lindsey M. Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Joshua C. Tremblay
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Bryenna K. Pinske
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Alexandra M. Williams
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Glen E. Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
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Murdoch DR. Revisiting the Cause of Focal Neurological Deficits and Profound Dyspnea at High Altitude—The Potential Role of Patent Foramen Ovale. High Alt Med Biol 2015. [DOI: 10.1089/ham.2015.0064] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Affiliation(s)
- David R. Murdoch
- Department of Pathology, University of Otago, Christchurch, New Zealand
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28
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Sightings, edited by Erik Swenson and Peter Bärtsch. High Alt Med Biol 2015. [DOI: 10.1089/ham.2015.29004.stg] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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29
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Tymko MM, Ainslie PN, MacLeod DB, Willie CK, Foster GE. End tidal-to-arterial CO2 and O2 gas gradients at low- and high-altitude during dynamic end-tidal forcing. Am J Physiol Regul Integr Comp Physiol 2015; 308:R895-906. [DOI: 10.1152/ajpregu.00425.2014] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2014] [Accepted: 03/23/2015] [Indexed: 11/22/2022]
Abstract
We sought to characterize and quantify the performance of a portable dynamic end-tidal forcing (DEF) system in controlling the partial pressure of arterial CO2 (PaCO2) and O2 (PaO2) at low (LA; 344 m) and high altitude (HA; 5,050 m) during an isooxic CO2 test and an isocapnic O2 test, which is commonly used to measure ventilatory and vascular reactivity in humans ( n = 9). The isooxic CO2 tests involved step changes in the partial pressure of end-tidal CO2 (PetCO2) of −10, −5, 0, +5, and +10 mmHg from baseline. The isocapnic O2 test consisted of a 10-min hypoxic step (PetO2 = 47 mmHg) from baseline at LA and a 5-min euoxic step (PetO2 = 100 mmHg) from baseline at HA. At both altitudes, PetO2 and PetCO2 were controlled within narrow limits (<1 mmHg from target) during each protocol. During the isooxic CO2 test at LA, PetCO2 consistently overestimated PaCO2 ( P < 0.01) at both baseline (2.1 ± 0.5 mmHg) and hypercapnia (+5 mmHg: 2.1 ± 0.7 mmHg; +10 mmHg: 1.9 ± 0.5 mmHg). This Pa-PetCO2 gradient was approximately twofold greater at HA ( P < 0.05). At baseline at both altitudes, PetO2 overestimated PaO2 by a similar extent (LA: 6.9 ± 2.1 mmHg; HA: 4.5 ± 0.9 mmHg; both P < 0.001). This overestimation persisted during isocapnic hypoxia at LA (6.9 ± 0.6 mmHg) and during isocapnic euoxia at HA (3.8 ± 1.2 mmHg). Step-wise multiple regression analysis, on the basis of the collected data, revealed that it may be possible to predict an individual's arterial blood gases during DEF. Future research is needed to validate these prediction algorithms and determine the implications of end-tidal-to-arterial gradients in the assessment of ventilatory and/or vascular reactivity.
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Affiliation(s)
- Michael M. Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Philip N. Ainslie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - David B. MacLeod
- Department of Anesthesiology, Duke University Medical Center, Durham, North Carolina
| | - Chris K. Willie
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
| | - Glen E. Foster
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science, University of British Columbia, Kelowna, Canada; and
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