1
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Marullo AL, Bird JD, Ciorogariu-Ivan AM, Boulet LM, Strzalkowski NDJ, Day TA. Acute hyperglycemia does not affect central respiratory chemoreflex responsiveness to CO 2 in healthy humans. Respir Physiol Neurobiol 2021; 296:103803. [PMID: 34653661 DOI: 10.1016/j.resp.2021.103803] [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: 08/29/2021] [Revised: 10/05/2021] [Accepted: 10/10/2021] [Indexed: 11/17/2022]
Abstract
The central respiratory chemoreceptor complex (CCRC) is comprised of brainstem neurons and surrounding interoceptors, which collectively increase ventilation in response to elevated brainstem tissue CO2/[H+] (i.e., central chemoreflex; CCR). The extent that the CCRC detects/responds to other metabolically related chemostimuli is unknown. We aimed to test the effects of acute oral glucose ingestion on CCR reactivity in heathy human participants (n = 38). We instrumented participants with a pneumotachometer (minute ventilation) and a gas sample line connected to a dual gas analyzer (pressure of end-tidal CO2). Following a baseline (BL) period and capillary blood [glucose] (BG) sample, fasted (F) participants underwent a modified hyperoxic rebreathing test to assess CCR reactivity. Participants then consumed a 75 g standard glucose beverage (glucose loaded; GL). Following 30-min, they underwent a second BL, BG sample and hyperoxic rebreathing test. BG and metabolic rate were higher in GL, confirming the metabolic stimulus. However, the ventilatory recruitment threshold and the CCR responses were unchanged between F and GL states.
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Affiliation(s)
- Anthony L Marullo
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Jordan D Bird
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Anna-Maria Ciorogariu-Ivan
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Lindsey M Boulet
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Colombia Okanagan, Kelowna, BC, Canada
| | - Nicholas D J Strzalkowski
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada.
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2
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Schulz A, Back SN, Schaan VK, Bertsch K, Vögele C. On the construct validity of interoceptive accuracy based on heartbeat counting: Cardiovascular determinants of absolute and tilt-induced change scores. Biol Psychol 2021; 164:108168. [PMID: 34411619 DOI: 10.1016/j.biopsycho.2021.108168] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2021] [Revised: 08/11/2021] [Accepted: 08/11/2021] [Indexed: 12/18/2022]
Abstract
Interoceptive accuracy (IAcc) as assessed with the heartbeat counting task (IAccHBCT) may be affected by a range of factors including (1.) the ability to adequately detect cardiac signals, indicated by IAcc in a heartbeat discrimination task (IAccHBDT), (2.) cardiac signal properties, affected by sympathetic and parasympathetic tone, and (3.) non-interoceptive processes, including time estimation accuracy (TEAcc). In the current study we investigated the contribution of these factors to absolute and Δ IAccHBCT scores, induced by passive head-up and head-down tilt in 49 healthy individuals. A set of hierarchical regression models showed IAccHBDT scores as the strongest and, across different orthostatic (tilt) conditions, most stable (positive) predictor of absolute and Δ IAccHBCT scores. Neither indicators of cardiac signal properties (except for HR in head-down-tilt), nor TEAcc predicted absolute or Δ IAccHBCT scores. These findings support the convergent and discriminant validity of absolute and Δ IAccHBCT scores.
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Affiliation(s)
- André Schulz
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg.
| | - Sarah N Back
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg; Division of Clinical Psychology and Psychotherapy, Department of Psychology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Violetta K Schaan
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg
| | - Katja Bertsch
- Division of Clinical Psychology and Psychotherapy, Department of Psychology, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Claus Vögele
- Clinical Psychophysiology Laboratory, Department of Behavioural and Cognitive Sciences, University of Luxembourg, Esch-sur-Alzette, Luxembourg
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3
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Leacy JK, Linares AM, Zouboules SM, Rampuri ZH, Bird JD, Herrington BA, Mann LM, Soriano JE, Thrall SF, Kalker A, Brutsaert TD, O'Halloran KD, Sherpa MT, Day TA. Cardiorespiratory hysteresis during incremental high‐altitude ascent–descent quantifies the magnitude of ventilatory acclimatization. Exp Physiol 2020; 106:139-150. [DOI: 10.1113/ep088488] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2020] [Accepted: 05/13/2020] [Indexed: 11/08/2022]
Affiliation(s)
- Jack K. Leacy
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
- Department of Physiology School of Medicine College of Medicine & Health University College Cork Cork Ireland
| | - Andrea M. Linares
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Shaelynn M. Zouboules
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Zahrah H. Rampuri
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Jordan D. Bird
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Brittney A. Herrington
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Leah M. Mann
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Jan E. Soriano
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Scott F. Thrall
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
| | - Anne Kalker
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
- Radboud University Nijmegen The Netherlands
| | | | - Ken D. O'Halloran
- Department of Physiology School of Medicine College of Medicine & Health University College Cork Cork Ireland
| | | | - Trevor A. Day
- Department of Biology Faculty of Science and Technology Mount Royal University Calgary Alberta Canada
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4
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Kermorgant M, Nasr N, Custaud MA, Navasiolava N, Arbeille P, Guinet P, Labrunée M, Besnier F, Arvanitis DN, Czosnyka M, Senard JM, Pavy-Le Traon A. Effects of Resistance Exercise and Nutritional Supplementation on Dynamic Cerebral Autoregulation in Head-Down Bed Rest. Front Physiol 2019; 10:1114. [PMID: 31507460 PMCID: PMC6718616 DOI: 10.3389/fphys.2019.01114] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 08/12/2019] [Indexed: 11/13/2022] Open
Abstract
Head-down bed rest (HDBR) is commonly considered as ground-based analog to spaceflight and simulates the headward fluid shift and cardiovascular deconditioning associated with spaceflight. We investigated in healthy volunteers whether HDBR, with or without countermeasures, affect cerebral autoregulation (CA). Twelve men (at selection: 34 ± 7 years; 176 ± 7 cm; 70 ± 7 kg) underwent three interventions of a 21-day HDBR: a control condition without countermeasure (CON), a condition with resistance vibration exercise (RVE) comprising of squats, single leg heel, and bilateral heel raises and a condition using also RVE associated with nutritional supplementation (NeX). Cerebral blood flow velocity was assessed using transcranial Doppler ultrasonography. CA was evaluated by transfer function analysis and by the autoregulatory index (Mxa) in order to determine the relationship between mean cerebral blood flow velocity and mean arterial blood pressure. In RVE condition, coherence was increased after HDBR. In CON condition, Mxa index was significantly reduced after HDBR. In contrast, in RVE and NeX conditions, Mxa were increased after HBDR. Our results indicate that HDBR without countermeasures may improve dynamic CA, but this adaptation may be dampened with RVE. Furthermore, nutritional supplementation did not enhance or worsen the negative effects of RVE. These findings should be carefully considered and could not be applied in spaceflight. Indeed, the subjects spent their time in supine position during bed rest, unlike the astronauts who perform normal daily activities.
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Affiliation(s)
- Marc Kermorgant
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Nathalie Nasr
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
| | - Marc-Antoine Custaud
- MITOVASC Institute, UMR CNRS 6015, UMR INSERM 1083, Clinical Research Centre, University Hospital of Angers, Angers, France
| | - Nastassia Navasiolava
- MITOVASC Institute, UMR CNRS 6015, UMR INSERM 1083, Clinical Research Centre, University Hospital of Angers, Angers, France
| | | | - Patrick Guinet
- Department of Anesthesiology, Thoracic and Cardiovascular Surgery, Rennes University Hospital, Rennes, France
| | - Marc Labrunée
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Rehabilitation, Toulouse University Hospital, Toulouse, France
| | - Florent Besnier
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Dina N Arvanitis
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France
| | - Marek Czosnyka
- Brain Physics Laboratory, Division of Neurosurgery, Department of Clinical Neurosciences, Cambridge University Hospitals, Cambridge, United Kingdom.,Institute of Electronic Systems, Warsaw University of Technology, Warsaw, Poland
| | - Jean-Michel Senard
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Clinical Pharmacology, Toulouse University Hospital, Toulouse, France
| | - Anne Pavy-Le Traon
- INSERM UMR 1048, Institute of Cardiovascular and Metabolic Diseases (I2MC), Toulouse, France.,Department of Neurology, Institute for Neurosciences, Toulouse University Hospital, Toulouse, France
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5
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Intra-individual variability in cerebrovascular and respiratory chemosensitivity: Can we characterize a chemoreflex “reactivity profile”? Respir Physiol Neurobiol 2017; 242:30-39. [DOI: 10.1016/j.resp.2017.02.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2016] [Revised: 02/14/2017] [Accepted: 02/24/2017] [Indexed: 01/05/2023]
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6
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Hilz MJ, Moeller S, Buechner S, Czarkowska H, Ayappa I, Axelrod FB, Rapoport DM. Obstructive Sleep-Disordered Breathing Is More Common than Central in Mild Familial Dysautonomia. J Clin Sleep Med 2016; 12:1607-1614. [PMID: 27655467 DOI: 10.5664/jcsm.6342] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Accepted: 07/19/2016] [Indexed: 01/22/2023]
Abstract
STUDY OBJECTIVES In familial dysautonomia (FD) patients, sleep-disordered breathing (SDB) might contribute to their high risk of sleep-related sudden death. Prevalence of central versus obstructive sleep apneas is controversial but may be therapeutically relevant. We, therefore, assessed sleep structure and SDB in FD-patients with no history of SDB. METHODS 11 mildly affected FD-patients (28 ± 11 years) without clinically overt SDB and 13 controls (28 ± 10 years) underwent polysomnographic recording during one night. We assessed sleep stages, obstructive and central apneas (≥ 90% air flow reduction) and hypopneas (> 30% decrease in airflow with ≥ 4% oxygen-desaturation), and determined obstructive (oAI) and central (cAI) apnea indices and the hypopnea index (HI) as count of respective apneas/hypopneas divided by sleep time. We obtained the apnea-hypopnea index (AHI4%) from the total of apneas and hypopneas divided by sleep time. We determined differences between FD-patients and controls using the U-test and within-group differences between oAIs, cAIs, and HIs using the Friedman test and Wilcoxon test. RESULTS Sleep structure was similar in FD-patients and controls. AHI4% and HI were significantly higher in patients than controls. In patients, HIs were higher than oAIs and oAIs were higher than cAIs. In controls, there was no difference between HIs, oAIs, and cAIs. Only patients had apneas and hypopneas during slow wave sleep. CONCLUSIONS In our FD-patients, obstructive apneas were more common than central apneas. These findings may be related to FD-specific pathophysiology. The potential ramifications of SDB in FD-patients suggest the utility of polysomnography to unveil SDB and initiate treatment. COMMENTARY A commentary on this article appears in this issue on page 1583.
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Affiliation(s)
- Max J Hilz
- Department of Neurology, University of Erlangen-Nürnberg, Erlangen, Germany.,Autonomic Unit, University Colloge of London, Institute of Neurology and National Hospital for Neurology and Neurosurgery, Queen Square, London, UK
| | - Sebastian Moeller
- Department of Neurology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Susanne Buechner
- Department of Neurology, General Hospital of Bozen/Bolzano, Bozen/Bolzano, Italy
| | - Hanna Czarkowska
- Cushing Neuroscience Institute, NS-LIJ Health System, Great Neck, NY
| | - Indu Ayappa
- Division of Pulmonary, Critical Care and Sleep Medicine, New York University School of Medicine, New York, NY
| | - Felicia B Axelrod
- Dysautonomia Center, New York University Langone School of Medicine, New York, NY
| | - David M Rapoport
- Division of Pulmonary, Critical Care and Sleep Medicine, New York University School of Medicine, New York, NY
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7
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Boulet LM, Tymko MM, Jamieson AN, Ainslie PN, Skow RJ, Day TA. Influence of prior hyperventilation duration on respiratory chemosensitivity and cerebrovascular reactivity during modified hyperoxic rebreathing. Exp Physiol 2016; 101:821-35. [DOI: 10.1113/ep085706] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/16/2016] [Indexed: 12/30/2022]
Affiliation(s)
- Lindsey M. Boulet
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Michael M. Tymko
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Alenna N. Jamieson
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Philip N. Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Rachel J. Skow
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Trevor A. Day
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
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8
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Pfoh JR, Tymko MM, Abrosimova M, Boulet LM, Foster GE, Bain AR, Ainslie PN, Steinback CD, Bruce CD, Day TA. Comparing and characterizing transient and steady-state tests of the peripheral chemoreflex in humans. Exp Physiol 2016; 101:432-47. [DOI: 10.1113/ep085498] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 11/30/2015] [Indexed: 11/08/2022]
Affiliation(s)
- Jamie R. Pfoh
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Michael M. Tymko
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Maria Abrosimova
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Lindsey M. Boulet
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Glen E. Foster
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Anthony R. Bain
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Philip N. Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development; University of British Columbia Okanagan; Kelowna British Columbia Canada
| | - Craig D. Steinback
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Christina D. Bruce
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Trevor A. Day
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
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9
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MacKay CM, Skow RJ, Tymko MM, Boulet LM, Davenport MH, Steinback CD, Ainslie PN, Lemieux CCM, Day TA. Central respiratory chemosensitivity and cerebrovascular CO2 reactivity: a rebreathing demonstration illustrating integrative human physiology. ADVANCES IN PHYSIOLOGY EDUCATION 2016; 40:79-92. [PMID: 26873894 DOI: 10.1152/advan.00048.2015] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
One of the most effective ways of engaging students of physiology and medicine is through laboratory demonstrations and case studies that combine 1) the use of equipment, 2) problem solving, 3) visual representations, and 4) manipulation and interpretation of data. Depending on the measurements made and the type of test, laboratory demonstrations have the added benefit of being able to show multiple organ system integration. Many research techniques can also serve as effective demonstrations of integrative human physiology. The "Duffin" hyperoxic rebreathing test is often used in research settings as a test of central respiratory chemosensitivity and cerebrovascular reactivity to CO2. We aimed to demonstrate the utility of the hyperoxic rebreathing test for both respiratory and cerebrovascular responses to increases in CO2 and illustrate the integration of the respiratory and cerebrovascular systems. In the present article, methods such as spirometry, respiratory gas analysis, and transcranial Doppler ultrasound are described, and raw data traces can be adopted for discussion in a tutorial setting. If educators have these instruments available, instructions on how to carry out the test are provided so students can collect their own data. In either case, data analysis and quantification are discussed, including principles of linear regression, calculation of slope, the coefficient of determination (R(2)), and differences between plotting absolute versus normalized data. Using the hyperoxic rebreathing test as a demonstration of the complex interaction and integration between the respiratory and cerebrovascular systems provides senior undergraduate, graduate, and medical students with an advanced understanding of the integrative nature of human physiology.
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Affiliation(s)
- Christina M MacKay
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada; and
| | - Rachel J Skow
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada; and
| | - Michael M Tymko
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Lindsey M Boulet
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada; School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Margie H Davenport
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada; and
| | - Craig D Steinback
- Faculty of Physical Education and Recreation, University of Alberta, Edmonton, Alberta, Canada; and
| | - Philip N Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Chantelle C M Lemieux
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada
| | - Trevor A Day
- Department of Biology, Faculty of Science and Technology, Mount Royal University, Calgary, Alberta, Canada;
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10
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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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11
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Tymko MM, Skow RJ, MacKay CM, Day TA. Steady-state tilt has no effect on cerebrovascular CO2reactivity in anterior and posterior cerebral circulations. Exp Physiol 2015; 100:839-51. [DOI: 10.1113/ep085084] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2015] [Accepted: 05/11/2015] [Indexed: 01/13/2023]
Affiliation(s)
- Michael M. Tymko
- Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Science; University of British Columbia; Kelowna British Columbia Canada
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
| | - Rachel J. Skow
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Christina M. MacKay
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
- Faculty of Physical Education and Recreation; University of Alberta; Edmonton Alberta Canada
| | - Trevor A. Day
- Department of Biology, Faculty of Science and Technology; Mount Royal University; Calgary Alberta Canada
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12
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Hermand E, Lhuissier FJ, Larribaut J, Pichon A, Richalet JP. Ventilatory oscillations at exercise: effects of hyperoxia, hypercapnia, and acetazolamide. Physiol Rep 2015; 3:3/6/e12446. [PMID: 26109194 PMCID: PMC4510637 DOI: 10.14814/phy2.12446] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Periodic breathing has been found in patients with heart failure and sleep apneas, and in healthy subjects in hypoxia, during sleep and wakefulness, at rest and, recently, at exercise. To unravel the cardiorespiratory parameters liable to modulate the amplitude and period of ventilatory oscillations, 26 healthy subjects were tested under physiological (exercise) and environmental (hypoxia, hyperoxia, hyperoxic hypercapnia) stresses, and under acetazolamide (ACZ) treatment. A fast Fourier transform spectral analysis of breath-by-breath ventilation evidenced an increase in peak power under hypercapnia (vs. normoxia and hyperoxia, P < 0.001) and a decrease under ACZ (vs. placebo, P < 0.001), whereas it was not modified in hyperoxia. period was shortened by exercise in all conditions (vs. rest, P < 0.01) and by hypercapnia (vs. normoxia, P < 0.05) but remained unchanged under ACZ (vs. placebo). peak power was positively related to cardiac output () and in hyperoxia (P < 0.01), in hypercapnia (P < 0.001) and under ACZ (P < 0.001). period was negatively related to and in hyperoxia (P < 0.01 and P < 0.001, respectively), in hypercapnia (P < 0.05 and P < 0.01, respectively) and under ACZ (P < 0.05 and P < 0.01, respectively). Total respiratory cycle time was the main factor responsible for changes in period. In conclusion, exercise, hypoxia, and hypercapnia increase ventilatory oscillations by increasing and , whereas ACZ decreases ventilatory instability in part by a contrasting action on O2 and CO2 sensing. An intrinsic oscillator might modulate ventilation through a complex system where peripheral chemoreflex would play a key role.
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Affiliation(s)
- Eric Hermand
- Université Paris 13 Sorbonne Paris Cité Laboratoire "Hypoxie et poumon", Bobigny, France
| | - François J Lhuissier
- Université Paris 13 Sorbonne Paris Cité Laboratoire "Hypoxie et poumon", Bobigny, France Assistance Publique-Hôpitaux de Paris, Hôpital Avicenne Service de Physiologie explorations fonctionnelles et médecine du sport, Bobigny, France
| | - Julie Larribaut
- Université Paris 13 Sorbonne Paris Cité Laboratoire "Hypoxie et poumon", Bobigny, France
| | - Aurélien Pichon
- Université Paris 13 Sorbonne Paris Cité Laboratoire "Hypoxie et poumon", Bobigny, France
| | - Jean-Paul Richalet
- Université Paris 13 Sorbonne Paris Cité Laboratoire "Hypoxie et poumon", Bobigny, France Assistance Publique-Hôpitaux de Paris, Hôpital Avicenne Service de Physiologie explorations fonctionnelles et médecine du sport, Bobigny, France
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