1
|
Georgopoulos D, Bolaki M, Stamatopoulou V, Akoumianaki E. Respiratory drive: a journey from health to disease. J Intensive Care 2024; 12:15. [PMID: 38650047 DOI: 10.1186/s40560-024-00731-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2024] [Accepted: 04/12/2024] [Indexed: 04/25/2024] Open
Abstract
Respiratory drive is defined as the intensity of respiratory centers output during the breath and is primarily affected by cortical and chemical feedback mechanisms. During the involuntary act of breathing, chemical feedback, primarily mediated through CO2, is the main determinant of respiratory drive. Respiratory drive travels through neural pathways to respiratory muscles, which execute the breathing process and generate inspiratory flow (inspiratory flow-generation pathway). In a healthy state, inspiratory flow-generation pathway is intact, and thus respiratory drive is satisfied by the rate of volume increase, expressed by mean inspiratory flow, which in turn determines tidal volume. In this review, we will explain the pathophysiology of altered respiratory drive by analyzing the respiratory centers response to arterial partial pressure of CO2 (PaCO2) changes. Both high and low respiratory drive have been associated with several adverse effects in critically ill patients. Hence, it is crucial to understand what alters the respiratory drive. Changes in respiratory drive can be explained by simultaneously considering the (1) ventilatory demands, as dictated by respiratory centers activity to CO2 (brain curve); (2) actual ventilatory response to CO2 (ventilation curve); and (3) metabolic hyperbola. During critical illness, multiple mechanisms affect the brain and ventilation curves, as well as metabolic hyperbola, leading to considerable alterations in respiratory drive. In critically ill patients the inspiratory flow-generation pathway is invariably compromised at various levels. Consequently, mean inspiratory flow and tidal volume do not correspond to respiratory drive, and at a given PaCO2, the actual ventilation is less than ventilatory demands, creating a dissociation between brain and ventilation curves. Since the metabolic hyperbola is one of the two variables that determine PaCO2 (the other being the ventilation curve), its upward or downward movements increase or decrease respiratory drive, respectively. Mechanical ventilation indirectly influences respiratory drive by modifying PaCO2 levels through alterations in various parameters of the ventilation curve and metabolic hyperbola. Understanding the diverse factors that modulate respiratory drive at the bedside could enhance clinical assessment and the management of both the patient and the ventilator.
Collapse
Affiliation(s)
| | - Maria Bolaki
- Department of Intensive Care Medicine, University Hospital of Heraklion, Heraklion, Crete, Greece
| | - Vaia Stamatopoulou
- Department of Pulmonary Medicine, University Hospital of Heraklion, Heraklion , Crete, Greece
| | - Evangelia Akoumianaki
- Medical School, University of Crete, Heraklion, Crete, Greece
- Department of Intensive Care Medicine, University Hospital of Heraklion, Heraklion, Crete, Greece
| |
Collapse
|
2
|
Duan G, Song C, Liu Y, Fu Z, Zhang C, Han X, Li Y, Zhou Y. Study on the dynamic effects of plateau hypoxic and cold environment on the thermal adaptation of short-term sojourners in Xizang. J Therm Biol 2024; 119:103774. [PMID: 38128423 DOI: 10.1016/j.jtherbio.2023.103774] [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: 08/08/2023] [Revised: 11/13/2023] [Accepted: 11/30/2023] [Indexed: 12/23/2023]
Abstract
The plateau hypoxic environment can affect the thermoregulation process of the human body, and due to the different acclimatization ability to the hypoxic environment, the thermal requirements among the people who enter Xizang at different times may be different. Accordingly, this study aims to clarify how plateau hypoxic environments influence the physiological and subjective responses of people entering Xizang at different times. And field experiments were conducted in Xi'an and Lhasa, respectively, to compare the thermal responses and oxygen responses of the subjects under different temperature conditions on the plain, the first day of entering Xizang and the 15th day of entering Xizang. The results showed that under the hypoxic environment, the thermal sensation of the subjects decreased. With the extension of the time entering Xizang, the influence of the hypoxic environment on thermal comfort was gradually weakened, but under the low temperature environment, the effect of hypoxia on thermal response was not significantly reduced. The results of this study can help to reveal how plateau hypoxic environments affect human thermal comfort and provide a theoretical basis for the design of indoor thermal environment parameters suitable for sojourners entering Xizang at different times.
Collapse
Affiliation(s)
- Guannan Duan
- School of Building Services Science and Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China
| | - Cong Song
- State Key Laboratory of Green Building, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China; School of Building Services Science and Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China.
| | - Yanfeng Liu
- State Key Laboratory of Green Building, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China; School of Building Services Science and Engineering, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China
| | - Zhiguo Fu
- Xizang Autonomous Region Construction Survey and Design Institute, Lhasa, Xizang, 850000, China
| | - Cong Zhang
- Xizang Autonomous Region Construction Survey and Design Institute, Lhasa, Xizang, 850000, China
| | - Xu Han
- Institute of Military Environmental Teaching & Research, Army Engineering University of PLA, Nanjing, Jiangsu, 210007, China
| | - Yong Li
- Institute of Military Environmental Teaching & Research, Army Engineering University of PLA, Nanjing, Jiangsu, 210007, China
| | - Yong Zhou
- School of Management, Xi'an University of Architecture and Technology, Xi'an, Shaanxi, 710055, China
| |
Collapse
|
3
|
Dobashi K, Ichinose M, Fujii N, Fujimoto T, Nishiyasu T. Effects of Pre-Exercise Voluntary Hyperventilation on Metabolic and Cardiovascular Responses During and After Intense Exercise. RESEARCH QUARTERLY FOR EXERCISE AND SPORT 2023; 94:1141-1152. [PMID: 36170018 DOI: 10.1080/02701367.2022.2121371] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2021] [Accepted: 08/29/2022] [Indexed: 06/16/2023]
Abstract
Purpose: We investigated the effects of pre-exercise voluntary hyperventilation and the resultant hypocapnia on metabolic and cardiovascular responses during and after high-intensity exercise. Methods: Ten healthy participants performed a 60-s cycling exercise at a workload of 120% peak oxygen uptake in control (spontaneous breathing), hypocapnia and normocapnia trials. Hypocapnia was induced through 20-min pre-exercise voluntary hyperventilation. In the normocapnia trial, voluntary hyperpnea was performed with CO2 inhalation to prevent hypocapnia. Results: Pre-exercise end-tidal CO2 partial pressure was lower in the hypocapnia trial than the control or normocapnia trial, with similar levels in the control and normocapnia trials. Average V ˙ O 2 during the entire exercise was lower in both the hypocapnia and normocapnia trials than in the control trial (1491 ± 252vs.1662 ± 169vs.1806 ± 149 mL min-1), with the hypocapnia trial exhibiting a greater reduction than the normocapnia trial. Minute ventilation during exercise was lower in the hypocapnia trial than the normocapnia trial. In addition, minute ventilation during the first 10s of the exercise was lower in the normocapnia than the control trial. Pre-exercise hypocapnia also reduced heart rates and arterial blood pressures during the exercise relative to the normocapnia trial, a response that lasted through the subsequent early recovery periods, though end-tidal CO2 partial pressure was similar in the two trials. Conclusions: Our results suggest that pre-exercise hyperpnea and the resultant hypocapnia reduce V ˙ O 2 during high-intensity exercise. Moreover, hypocapnia may contribute to voluntary hyperventilation-mediated cardiovascular responses during the exercise, and this response can persist into the subsequent recovery period, despite the return of arterial CO2 pressure to the normocapnic level.
Collapse
Affiliation(s)
- Kohei Dobashi
- University of Tsukuba
- Japan Society for the Promotion of Science
- Hokkaido University of Education
| | | | | | - Tomomi Fujimoto
- University of Tsukuba
- Niigata University of Health and Welfare
| | | |
Collapse
|
4
|
Guluzade NA, Huggard JD, Duffin J, Keir DA. A test of the interaction between central and peripheral respiratory chemoreflexes in humans. J Physiol 2023; 601:4591-4609. [PMID: 37566804 DOI: 10.1113/jp284772] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2023] [Accepted: 07/25/2023] [Indexed: 08/13/2023] Open
Abstract
How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured the peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic CO2 tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Twenty participants (10F) completed three repetitions of modified rebreathing tests with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) clamped at 150, 70, 60 and 45 mmHg. End-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ),P ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , ventilation (V ̇ $\dot{V}$ E ) and calculated oxygen saturation (SC O2 ) were measured breath-by-breath by gas-analyser and pneumotach. TheV ̇ $\dot{V}$ E -P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship of repeat-trials were linear-interpolated, combined, averaged into 1 mmHg bins, and fitted with a double-linear function (V ̇ $\dot{V}$ E S, L min-1 mmHg-1 ). PChS was computed at intervals of 1 mmHg ofP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding SC O2 ; and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). These processing steps were repeated at eachP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ to produce the PChS vs. isocapnicP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ relationship. These were fitted with linear and polynomial functions, and Akaike information criterion identified the best-fit model. One-way repeated measures analysis of variance assessed between-condition differences.V ̇ $\dot{V}$ E S increased (P < 0.0001) with isoxicP ET O 2 ${P_{{\mathrm{ET}}{{\mathrm{O}}_{\mathrm{2}}}}}$ from 3.7 ± 1.5 L min-1 mmHg-1 at 150 mmHg to 4.4 ± 1.8, 5.0 ± 1.6 and 6.0 ± 2.2 Lmin-1 mmHg-1 at 70, 60 and 45 mmHg, respectively. Mean SC O2 fell progressively (99.3 ± 0%, 93.7 ± 0.1%, 90.4 ± 0.1% and 80.5 ± 0.1%; P < 0.0001). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear model in 75%. Despite increasing central chemoreflex activation, PChS increased linearly withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ indicative of an additive central-peripheral chemoreflex response. KEY POINTS: How central and peripheral chemoreceptor drives to breathe interact in humans remains contentious. We measured peripheral chemoreflex sensitivity to hypoxia (PChS) at various isocapnic carbon dioxide tensions (P C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) to determine the form of the relationship between PChS and centralP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ . Participants performed three repetitions of modified rebreathing with end-tidalP O 2 ${P_{{{\mathrm{O}}_{\mathrm{2}}}}}$ fixed at 150, 70, 60 and 45 mmHg. PChS was computed at intervals of 1 mmHg of end-tidalP C O 2 ${P_{{\mathrm{C}}{{\mathrm{O}}_{\mathrm{2}}}}}$ (P ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ ) as follows: the difference inV ̇ $\dot{V}$ E between the three hypoxic profiles and the hyperoxic profile (∆V ̇ $\dot{V}$ E ) was calculated; three ∆V ̇ $\dot{V}$ E values were plotted against corresponding calculated oxygen saturation (SC O2 ); and linear regression determined PChS (Lmin-1 mmHg-1 %SC O2 -1 ). In all individuals, PChS increased withP ETC O 2 ${P_{{\mathrm{ETC}}{{\mathrm{O}}_{\mathrm{2}}}}}$ , and this relationship was best described by a linear (rather than polynomial) model in 15 of 20. Most participants did not exhibit a hypo- or hyper-additive effect of central chemoreceptors on the peripheral chemoreflex indicating that the interaction was additive.
Collapse
Affiliation(s)
- Nasimi A Guluzade
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - Joshua D Huggard
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
| | - James Duffin
- Department of Anaesthesia and Pain Management, University of Toronto, Toronto, ON, Canada
- Department of Physiology, University of Toronto, Toronto, ON, Canada
- Thornhill Research Inc., Toronto, ON, Canada
| | - Daniel A Keir
- School of Kinesiology, The University of Western Ontario, London, ON, Canada
- Toronto General Research Institute, Toronto General Hospital, Toronto, ON, Canada
- Lawson Health Research Institute, London, ON, Canada
| |
Collapse
|
5
|
Nicolò A, Sacchetti M. Differential control of respiratory frequency and tidal volume during exercise. Eur J Appl Physiol 2023; 123:215-242. [PMID: 36326866 DOI: 10.1007/s00421-022-05077-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Accepted: 10/18/2022] [Indexed: 11/06/2022]
Abstract
The lack of a testable model explaining how ventilation is regulated in different exercise conditions has been repeatedly acknowledged in the field of exercise physiology. Yet, this issue contrasts with the abundance of insightful findings produced over the last century and calls for the adoption of new integrative perspectives. In this review, we provide a methodological approach supporting the importance of producing a set of evidence by evaluating different studies together-especially those conducted in 'real' exercise conditions-instead of single studies separately. We show how the collective assessment of findings from three domains and three levels of observation support the development of a simple model of ventilatory control which proves to be effective in different exercise protocols, populations and experimental interventions. The main feature of the model is the differential control of respiratory frequency (fR) and tidal volume (VT); fR is primarily modulated by central command (especially during high-intensity exercise) and muscle afferent feedback (especially during moderate exercise) whereas VT by metabolic inputs. Furthermore, VT appears to be fine-tuned based on fR levels to match alveolar ventilation with metabolic requirements in different intensity domains, and even at a breath-by-breath level. This model reconciles the classical neuro-humoral theory with apparently contrasting findings by leveraging on the emerging control properties of the behavioural (i.e. fR) and metabolic (i.e. VT) components of minute ventilation. The integrative approach presented is expected to help in the design and interpretation of future studies on the control of fR and VT during exercise.
Collapse
Affiliation(s)
- Andrea Nicolò
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 6, 00135, Rome, Italy.
| | - Massimo Sacchetti
- Department of Movement, Human and Health Sciences, University of Rome "Foro Italico", Piazza Lauro De Bosis 6, 00135, Rome, Italy
| |
Collapse
|
6
|
Guluzade NA, Huggard JD, Keltz RR, Duffin J, Keir DA. Strategies to improve respiratory chemoreflex characterization by Duffin's rebreathing. Exp Physiol 2022; 107:1507-1520. [PMID: 36177675 DOI: 10.1113/ep090668] [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: 06/29/2022] [Accepted: 09/21/2022] [Indexed: 12/14/2022]
Abstract
NEW FINDINGS What is the central question of this study? We assessed the test-retest variability of respiratory chemoreflex characterization by Duffin's modified rebreathing method and explored whether signal averaging of repeated trials improves confidence in parameter estimation. What is the main finding and its importance? Modified rebreathing is a reproducible method to characterize responses of central and peripheral respiratory chemoreflexes. Signal averaging of multiple repeated tests minimizes within- and between-test variability, improves the confidence of chemoreflex characterization and reduces the minimal change in parameters required to establish an effect. Future experiments that apply this method might benefit from signal averaging to improve its discriminatory effect. ABSTRACT We assessed the test-retest variability of central and peripheral respiratory chemoreflex characterization by Duffin's modified rebreathing method and explored whether signal averaging of repeated trials improves confidence in parameter estimation. Over four laboratory visits, 13 participants (mean ± SD age, 25 ± 5 years) performed six repetitions of modified rebreathing in isoxic-hypoxic conditions [end-tidal P O 2 ${P_{{{\rm{O}}_{\rm{2}}}}}$ ( P ET , O 2 ${P_{{\rm{ET,}}{{\rm{O}}_{\rm{2}}}}}$ ) = 50 mmHg] and isoxic-hyperoxic conditions ( P ET , O 2 ${P_{{\rm{ET,}}{{\rm{O}}_{\rm{2}}}}}$ = 150 mmHg). End-tidal P C O 2 ${P_{{\rm{C}}{{\rm{O}}_{\rm{2}}}}}$ ( P ET , C O 2 ${P_{{\rm{ET,C}}{{\rm{O}}_{\rm{2}}}}}$ ), P ET , O 2 ${P_{{\rm{ET,}}{{\rm{O}}_{\rm{2}}}}}$ and minute ventilation ( V ̇ $\dot {\rm V}$ E ) were measured breath-by-breath, by gas analyser and pneumotachograph. The V ̇ $\dot {\rm V}$ E versus P ET , C O 2 ${P_{{\rm{ET,C}}{{\rm{O}}_{\rm{2}}}}}$ relationships were fitted with a piecewise model to estimate the ventilatory recruitment threshold (VRT) and the slope above the VRT ( V ̇ $\dot {\rm V}$ E S). Breath-by-breath data from the three within- and between-day trials were averaged using two approaches [simple average (fit then average) and ensemble average (average then fit)] and compared with a single-trial fit. Variability was assessed by intraclass correlation (ICC) and coefficient of variance (CV), and the minimal detectable change was computed for each approach using two independent sets of three trials. Within days, the VRT and V ̇ $\dot {\rm V}$ E S exhibited excellent test-retest variability in both hyperoxic conditions (VRT: ICC = 0.965, CV = 2.3%; V ̇ $\dot {\rm V}$ E S: ICC = 0.932, CV = 15.5%) and hypoxic conditions (VRT: ICC = 0.970, CV = 2.9%; V ̇ $\dot {\rm V}$ E S: ICC = 0.891, CV = 17.2%). Between-day reproducibility was also excellent (hyperoxia, VRT: ICC = 0.930, CV = 2.2%; V ̇ $\dot {\rm V}$ E S: ICC = 0.918, CV = 14.2%; and hypoxia, VRT: ICC = 0.940, CV = 3.0%; V ̇ $\dot {\rm V}$ E S: ICC = 0.880, CV = 18.1%). Compared with a single-trial fit, there were no differences in VRT or V ̇ $\dot {\rm V}$ E S using the simple average or ensemble average approaches; however, ensemble averaging reduced the minimal detectable change for V ̇ $\dot {\rm V}$ E S from 2.95 to 1.39 L min-1 mmHg-1 (hyperoxia) and from 3.64 to 1.82 L min-1 mmHg-1 (hypoxia). Single trials of modified rebreathing are reproducible; however, signal averaging of repeated trials improves confidence in parameter estimation.
Collapse
Affiliation(s)
- Nasimi A Guluzade
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Joshua D Huggard
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - Randi R Keltz
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada
| | - James Duffin
- Department of Anesthesiology and Pain Medicine, University of Toronto, Toronto, Ontario, Canada.,Department of Physiology, University of Toronto, Toronto, Ontario, Canada.,Thornhill Research Inc., Toronto, Ontario, Canada
| | - Daniel A Keir
- School of Kinesiology, The University of Western Ontario, London, Ontario, Canada.,Toronto General Research Institute, Toronto General Hospital, Toronto, Ontario, Canada.,Lawson Health Research Institute, London, Ontario, Canada
| |
Collapse
|
7
|
Jeton F, Perrin-Terrin AS, Yegen CH, Marchant D, Richalet JP, Pichon A, Boncoeur E, Bodineau L, Voituron N. In Transgenic Erythropoietin Deficient Mice, an Increase in Respiratory Response to Hypercapnia Parallels Abnormal Distribution of CO 2/H +-Activated Cells in the Medulla Oblongata. Front Physiol 2022; 13:850418. [PMID: 35514353 PMCID: PMC9061944 DOI: 10.3389/fphys.2022.850418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2022] [Accepted: 03/21/2022] [Indexed: 12/03/2022] Open
Abstract
Erythropoietin (Epo) and its receptor are expressed in central respiratory areas. We hypothesized that chronic Epo deficiency alters functioning of central respiratory areas and thus the respiratory adaptation to hypercapnia. The hypercapnic ventilatory response (HcVR) was evaluated by whole body plethysmography in wild type (WT) and Epo deficient (Epo-TAgh) adult male mice under 4%CO2. Epo-TAgh mice showed a larger HcVR than WT mice because of an increase in both respiratory frequency and tidal volume, whereas WT mice only increased their tidal volume. A functional histological approach revealed changes in CO2/H+-activated cells between Epo-TAgh and WT mice. First, Epo-TAgh mice showed a smaller increase under hypercapnia in c-FOS-positive number of cells in the retrotrapezoid nucleus/parafacial respiratory group than WT, and this, independently of changes in the number of PHOX2B-expressing cells. Second, we did not observe in Epo-TAgh mice the hypercapnic increase in c-FOS-positive number of cells in the nucleus of the solitary tract present in WT mice. Finally, whereas hypercapnia did not induce an increase in the c-FOS-positive number of cells in medullary raphe nuclei in WT mice, chronic Epo deficiency leads to raphe pallidus and magnus nuclei activation by hyperacpnia, with a significant part of c-FOS positive cells displaying an immunoreactivity for serotonin in the raphe pallidus nucleus. All of these results suggest that chronic Epo-deficiency affects both the pattern of ventilatory response to hypercapnia and associated medullary respiratory network at adult stage with an increase in the sensitivity of 5-HT and non-5-HT neurons of the raphe medullary nuclei leading to stimulation of fR for moderate level of CO2.
Collapse
Affiliation(s)
- Florine Jeton
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Anne-Sophie Perrin-Terrin
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Celine-Hivda Yegen
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France
| | - Dominique Marchant
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France
| | - Jean-Paul Richalet
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Aurélien Pichon
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| | - Emilie Boncoeur
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France
| | - Laurence Bodineau
- Inserm, UMR_S1158 Neurophysiologie Respiratoire Expérimentale et Clinique, Sorbonne Université, Paris, France
| | - Nicolas Voituron
- Laboratoire "Hypoxie et Poumons", UMR INSERM U1272, Université Paris 13, UFR SMBH, Bobigny, France.,Laboratory of Excellence (Labex) GR-Ex, PRES Sorbonne Paris Cité, Paris, France
| |
Collapse
|
8
|
Caffeine alters the breathing pattern during high-intensity whole-body exercise in healthy men. Eur J Appl Physiol 2022; 122:1497-1507. [PMID: 35396967 DOI: 10.1007/s00421-022-04934-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Accepted: 03/14/2022] [Indexed: 11/03/2022]
Abstract
PURPOSE The current study investigated the effect of caffeine on the breathing pattern during a high-intensity whole-body exercise. METHODS Using a randomized, crossover, counterbalanced, and double-blind design, twelve healthy men ingested either 5 mg.kg-1 of caffeine or cellulose (placebo) one hour before performing a high-intensity whole-body exercise (i.e., work rate corresponding to 80% of the difference between the gas exchange threshold and maximal oxygen uptake) until the limit of tolerance. Ventilatory and metabolic responses were recorded throughout the trial and at task failure. RESULTS Caffeine ingestion increased time to task failure in relation to the placebo (368.1 ± 49.6 s vs. 328.5 ± 56.6 s, p = 0.005). Caffeine also increased tidal volume and inspiratory time throughout the exercise (p < 0.05). Compared to task failure with placebo, task failure with caffeine intake was marked by higher (p < 0.05) minute ventilation (134.8 ± 16.4 vs. 147.6 ± 18.2 L.min-1), the ventilatory equivalent of oxygen consumption (37.8 ± 4.2 vs. 41.7 ± 5.5 units), and respiratory exchange ratio (1.12 ± 0.10 vs. 1.19 ± 0.11 units). CONCLUSION In conclusion, ingestion of caffeine alters the breathing pattern by increasing tidal volume and lengthening the inspiratory phase of the respiratory cycle. These findings suggest that caffeine affects the ventilatory system, which may account, in part, for its ergogenic effects during high-intensity whole-body exercises.
Collapse
|
9
|
Bishop M, Weinhold M, Turk AZ, Adeck A, SheikhBahaei S. An open-source tool for automated analysis of breathing behaviors in common marmosets and rodents. eLife 2022; 11:e71647. [PMID: 35049499 PMCID: PMC8856653 DOI: 10.7554/elife.71647] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2021] [Accepted: 01/19/2022] [Indexed: 11/13/2022] Open
Abstract
The respiratory system maintains homeostatic levels of oxygen (O2) and carbon dioxide (CO2) in the body through rapid and efficient regulation of breathing frequency and depth (tidal volume). The commonly used methods of analyzing breathing data in behaving experimental animals are usually subjective, laborious, and time-consuming. To overcome these hurdles, we optimized an analysis toolkit for the unsupervised study of respiratory activities in animal subjects. Using this tool, we analyzed breathing behaviors of the common marmoset (Callithrix jacchus), a New World non-human primate model. Using whole-body plethysmography in room air as well as acute hypoxic (10% O2) and hypercapnic (6% CO2) conditions, we describe breathing behaviors in awake, freely behaving marmosets. Our data indicate that marmosets' exposure to acute hypoxia decreased metabolic rate and increased sigh rate. However, the hypoxic condition did not augment ventilation. Hypercapnia, on the other hand, increased both the frequency and depth (i.e., tidal volume) of breathing.
Collapse
Affiliation(s)
- Mitchell Bishop
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, United States
| | - Maximilian Weinhold
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, United States
| | - Ariana Z Turk
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, United States
| | - Afuh Adeck
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, United States
| | - Shahriar SheikhBahaei
- Neuron-Glia Signaling and Circuits Unit, National Institute of Neurological Disorders and Stroke (NINDS), National Institutes of Health (NIH), Bethesda, United States
| |
Collapse
|
10
|
Schaeffer MR, Guenette JA, Jensen D. Impact of ageing and pregnancy on the minute ventilation/carbon dioxide production response to exercise. Eur Respir Rev 2021; 30:30/161/200225. [PMID: 34289982 PMCID: PMC9488679 DOI: 10.1183/16000617.0225-2020] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 09/27/2020] [Indexed: 11/28/2022] Open
Abstract
Ventilatory efficiency can be evaluated using the relationship between minute ventilation (V′E) and the rate of CO2 production (V′CO2). In accordance with the modified alveolar ventilation equation, this relationship is determined by changes in dead space volume (VD) and/or the arterial CO2 tension (PaCO2) equilibrium point. In this review, we summarise the physiological factors that may account for normative ageing and pregnancy induced increases in V′E/V′CO2 during exercise. Evidence suggests that age-related increases in VD and pregnancy-related decreases in the PaCO2 equilibrium point are mechanistically linked to the increased V′E/V′CO2 during exercise. Importantly, the resultant increase in V′E/V′CO2 (ratio or slope), with normal ageing or pregnancy, remains below the critical threshold for prognostic indication in cardiopulmonary disease, is not associated with increased risk of adverse health outcomes, and does not affect the respiratory system's ability to fulfil its primary role of eliminating CO2 and maintaining arterial oxygen saturation during exercise. The minute ventilation/carbon dioxide production response to exercise is elevated with advancing age and in healthy pregnancy due to increased dead space and lowering of the arterial partial pressure of carbon dioxide equilibrium point, respectively.https://bit.ly/2GJXm0o
Collapse
Affiliation(s)
- Michele R Schaeffer
- Centre for Heart Lung Innovation, Providence Health Care Research Institute, The University of British Columbia, St. Paul's Hospital, Vancouver, Canada.,Dept of Physical Therapy, The University of British Columbia, Vancouver, Canada
| | - Jordan A Guenette
- Centre for Heart Lung Innovation, Providence Health Care Research Institute, The University of British Columbia, St. Paul's Hospital, Vancouver, Canada .,Dept of Physical Therapy, The University of British Columbia, Vancouver, Canada.,School of Kinesiology, The University of British Columbia, Vancouver, Canada
| | - Dennis Jensen
- Dept of Kinesiology and Physical Education, McGill University, Montréal, Canada.,Research Institute of the McGill University Health Centre, Translational Research in Respiratory Diseases Program, Montréal, Canada.,Research Centre for Physical Activity and Health, Faculty of Education, McGill University, Montréal, Canada
| |
Collapse
|
11
|
Floras JS. The 2021 Carl Ludwig Lecture. Unsympathetic autonomic regulation in heart failure: patient-inspired insights. Am J Physiol Regul Integr Comp Physiol 2021; 321:R338-R351. [PMID: 34259047 DOI: 10.1152/ajpregu.00143.2021] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Defined as a structural or functional cardiac abnormality accompanied by symptoms, signs, or biomarkers of altered ventricular pressures or volumes, heart failure also is a state of autonomic disequilibrium. A large body of evidence affirms that autonomic disturbances are intrinsic to heart failure; basal or stimulated sympathetic nerve firing or neural norepinephrine (NE) release more often than not exceed homeostatic need, such that an initially adaptive adrenergic or vagal reflex response becomes maladaptive. The magnitude of such maladaptation predicts prognosis. This Ludwig lecture develops two theses: the elucidation and judiciously targeted amelioration of maladaptive autonomic disturbances offers opportunities to complement contemporary guideline-based heart failure therapy, and serendipitous single-participant insights, acquired in the course of experimental protocols with entirely different intent, can generate novel insight, inform mechanisms, and launch entirely new research directions. I précis six elements of our current synthesis of the causes and consequences of maladaptive sympathetic disequilibrium in heart failure, shaped by patient-inspired epiphanies: arterial baroreceptor reflex modulation, excitation stimulated by increased cardiac filling pressure, paradoxical muscle sympathetic activation as a peripheral neurogenic constraint on exercise capacity, renal sympathetic restraint of natriuresis, coexisting sleep apnea, and augmented chemoreceptor reflex sensitivity and then conclude by envisaging translational therapeutic opportunities.
Collapse
Affiliation(s)
- John S Floras
- University Health Network and Sinai Health Division of Cardiology, Toronto General Hospital Research Institute and Department of Medicine, University of Toronto, Toronto, Ontario, Canada
| |
Collapse
|
12
|
Labrecque L, Drapeau A, Rahimaly K, Imhoff S, Brassard P. Dynamic cerebral autoregulation and cerebrovascular carbon dioxide reactivity in middle and posterior cerebral arteries in young endurance-trained women. J Appl Physiol (1985) 2021; 130:1724-1735. [PMID: 33955257 DOI: 10.1152/japplphysiol.00963.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
The integrated responses regulating cerebral blood flow are understudied in women, particularly in relation to potential regional differences. In this study, we compared dynamic cerebral autoregulation (dCA) and cerebrovascular reactivity to carbon dioxide (CVRco2) in the middle (MCA) and posterior cerebral arteries (PCA) in 11 young endurance-trained women (age, 25 ± 4 yr; maximal oxygen uptake, 48.1 ± 4.1 mL·kg-1·min-1). dCA was characterized using a multimodal approach including a sit-to-stand and a transfer function analysis (TFA) of forced blood pressure oscillations (repeated squat-stands executed at 0.05 Hz and 0.10 Hz). The hyperoxic rebreathing test was utilized to characterize CVRco2. Upon standing, the percent reduction in blood velocity per percent reduction in mean arterial pressure during initial orthostatic stress (0-15 s after sit-to-stand), the onset of the regulatory response, and the rate of regulation did not differ between MCA and PCA (all P > 0.05). There was an ANOVA effect of anatomical location for TFA gain (P < 0.001) and a frequency effect for TFA phase (P < 0.001). However, normalized gain was not different between arteries (P = 0.18). Absolute CVRco2 was not different between MCA and PCA (1.55 ± 0.81 vs. 1.30 ± 0.49 cm·s-1/Torr, P = 0.26). Relative CVRco2 was 39% lower in the MCA (2.16 ± 1.02 vs. 3.00 ± 1.09%/Torr, P < 0.01). These findings indicate that the cerebral pressure-flow relationship appears to be similar between the MCA and the PCA in young endurance-trained women. The absence of regional differences in absolute CVRco2 could be women specific, although a direct comparison with a group of men will be necessary to address that issue.NEW & NOTEWORTHY Herein, we describe responses from two major mechanisms regulating cerebral blood flow with a special attention on regional differences in young endurance-trained women. The novel findings are that dynamic cerebral autoregulation and absolute cerebrovascular reactivity to carbon dioxide appear similar between the middle and posterior cerebral arteries of these young women.
Collapse
Affiliation(s)
- Lawrence Labrecque
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Audrey Drapeau
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Kevan Rahimaly
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Sarah Imhoff
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| | - Patrice Brassard
- Department of Kinesiology, Faculty of Medicine, Université Laval, Quebec City, Québec, Canada.,Research Center of the Institut Universitaire de Cardiologie et de Pneumologie de Québec, Quebec City, Québec, Canada
| |
Collapse
|
13
|
Phillips DB, Domnik NJ, Elbehairy AF, Preston ME, Milne KM, James MD, Vincent SG, Ibrahim-Masthan M, Neder JA, O’Donnell DE. Elevated exercise ventilation in mild COPD is not linked to enhanced central chemosensitivity. Respir Physiol Neurobiol 2021; 284:103571. [DOI: 10.1016/j.resp.2020.103571] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 10/27/2020] [Accepted: 11/01/2020] [Indexed: 11/25/2022]
|
14
|
Abstract
PURPOSE OF REVIEW Complications of mechanical ventilation, such as ventilator-induced lung injury (VILI) and ventilator-induced diaphragmatic dysfunction (VIDD), adversely affect the outcome of critically ill patients. Although mostly studied during control ventilation, it is increasingly appreciated that VILI and VIDD also occur during assisted ventilation. Hence, current research focuses on identifying ways to monitor and deliver protective ventilation in assisted modes. This review describes the operating principles of proportional modes of assist, their implications for lung and diaphragm protective ventilation, and the supporting clinical data. RECENT FINDINGS Proportional modes of assist, proportional assist ventilation, PAV, and neurally adjusted ventilatory assist, NAVA, deliver a pressure assist that is proportional to the patient's effort, enabling ventilation to be better controlled by the patient's brain. This control underlies the potential of proportional modes to avoid over-assist and under-assist, improve patient--ventilator interaction, and provide protective ventilation. Indeed, in clinical studies, proportional modes have been associated with reduced asynchronies, enhanced diaphragmatic recovery, and limitation of excessive tidal volume. Additionally, proportional modes facilitate better monitoring of the delivery of protective assisted ventilation. SUMMARY Physiological rationale and clinical data suggest a potential role for proportional modes of assist in providing and monitoring lung and diaphragm protective ventilation.
Collapse
|
15
|
Differences in the point of optimal ventilatory efficiency and the anaerobic threshold in untrained adults aged 50 to 60 years. Respir Physiol Neurobiol 2020; 282:103516. [DOI: 10.1016/j.resp.2020.103516] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 07/06/2020] [Accepted: 08/02/2020] [Indexed: 11/18/2022]
|
16
|
Dobashi K, Fujii N, Ichinose M, Fujimoto T, Nishiyasu T. Voluntary hypocapnic hyperventilation lasting 5 min and 20 min similarly reduce aerobic metabolism without affecting power outputs during Wingate anaerobic test. Eur J Sport Sci 2020; 21:1148-1155. [PMID: 32814502 DOI: 10.1080/17461391.2020.1812728] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
AbstractTwenty minutes of voluntary hypocapnic hyperventilation prior to exercise reduces the aerobic metabolic rate with a compensatory increase in the anaerobic metabolic rate without affecting exercise performance during the Wingate anaerobic test (WAnT). Thus, pre-exercise hypocapnic hyperventilation may be a useful means of stressing the anaerobic energy system during training, ultimately improving anaerobic exercise performance. However, it remains unclear whether a shorter (e.g., 5 min) pre-exercise hypocapnic hyperventilation is sufficient to reduce the aerobic metabolic rate during high-intensity exercise. We therefore compared the effects of 5-min and 20-min pre-exercise hypocapnic hyperventilation on aerobic metabolism during the 30-s WAnT. Ten healthy young males and one female performed the WAnT following 20 min of spontaneous breathing (control trial) or 5 or 20 min of voluntary hypocapnic hyperventilation. Both the 5-min and 20-min hyperventilation reduced end-tidal CO2 partial pressure (an index of arterial CO2 partial pressure) to ∼23 mmHg, whereas it remained unchanged during the spontaneous breathing. The peak, mean and minimum power outputs during the WAnT did not differ among the three trials. Oxygen uptake during the WAnT was lower in both the 5-min (1493 ± 257 mL min-1) and 20-min (1397 ± 447 mL min-1) hyperventilation trials than during the control trial (1847 ± 286 mL min-1), and was similar in the two hyperventilation trials. These results suggest that 5 min of pre-exercise hypocapnic hyperventilation reduces aerobic metabolism during the 30-s WAnT to a level similar to that seen with the 20-min hyperventilation. Moreover, exercise performance was unaffected, which implies anaerobic metabolism was enhanced.
Collapse
Affiliation(s)
- Kohei Dobashi
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.,Research Fellow of the Japan Society for the Promotion of Science, Tokyo, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| | - Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
| | - Tomomi Fujimoto
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan.,Department of Health and Sports, Niigata University of Health and Welfare, Niigata, Japan.,Institute for Human Movement and Medical Sciences, Niigata University of Health and Welfare, Niigata, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba, Japan
| |
Collapse
|
17
|
Giannoni A, Borrelli C, Gentile F, Mirizzi G, Coceani M, Paradossi U, Vergaro G, Bramanti F, Iudice G, Emdin M, Passino C. Central apnoeas and ticagrelor-related dyspnoea in patients with acute coronary syndrome. EUROPEAN HEART JOURNAL. CARDIOVASCULAR PHARMACOTHERAPY 2020; 7:180-188. [PMID: 32667975 DOI: 10.1093/ehjcvp/pvaa089] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 06/16/2020] [Accepted: 07/08/2020] [Indexed: 12/16/2022]
Abstract
AIMS Dyspnoea often occurs in patients with acute coronary syndrome (ACS) treated with ticagrelor compared with other anti-platelet agents and is a cause of drug discontinuation. We aimed to explore the contribution of central apnoeas (CA) and chemoreflex sensitization to ticagrelor-related dyspnoea in patients with ACS. METHODS AND RESULTS Sixty consecutive patients with ACS, preserved left ventricular ejection fraction, and no history of obstructive sleep apnoea, treated either with ticagrelor 90 mg b.i.d. (n = 30) or prasugrel 10 mg o.d. (n = 30) were consecutively enrolled. One week after ACS, all patients underwent two-dimensional Doppler echocardiography, pulmonary static/dynamic testing, carbon monoxide diffusion capacity assessment, 24-h cardiorespiratory monitoring for hypopnoea-apnoea detection, and evaluation of the chemosensitivity to hypercapnia by rebreathing technique. No differences were found in baseline demographic and clinical characteristics, echocardiographic, and pulmonary data between the two groups. Patients on ticagrelor, when compared with those on prasugrel, reported more frequently dyspnoea (43.3% vs. 6.7%, P = 0.001; severe dyspnoea 23.3% vs. 0%, P = 0.005), and showed higher apnoea-hypopnoea index (AHI) and central apnoea index (CAI) during the day, the night and the entire 24-h period (all P < 0.001). Similarly, they showed a higher chemosensitivity to hypercapnia (P = 0.001). Among patients treated with ticagrelor, those referring dyspnoea had the highest AHI, CAI, and chemosensitivity to hypercapnia (all P < 0.05). CONCLUSION Central apnoeas are a likely mechanism of dyspnoea and should be screened for in patients treated with ticagrelor. A drug-related sensitization of the chemoreflex may be the cause of ventilatory instability and breathlessness in this setting.
Collapse
Affiliation(s)
- Alberto Giannoni
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy.,Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Chiara Borrelli
- Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Francesco Gentile
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy
| | - Gianluca Mirizzi
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy.,Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Michele Coceani
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy
| | - Umberto Paradossi
- Cardiology and Cardiac Surgery Department, Fondazione Toscana G. Monasterio, Massa, Italy
| | - Giuseppe Vergaro
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy.,Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Francesca Bramanti
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy
| | - Giovanni Iudice
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy
| | - Michele Emdin
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy.,Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Claudio Passino
- Cardiology and Cardiovascular Medicine Department, Fondazione Toscana G. Monasterio, via Giuseppe Moruzzi 1, 56124 Pisa, Italy.,Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| |
Collapse
|
18
|
Lilitsis E, Stamatopoulou V, Andrianakis E, Petraki A, Antonogiannaki EM, Georgopoulos D, Vaporidi K, Kondili E. Inspiratory effort and breathing pattern change in response to varying the assist level: A physiological study. Respir Physiol Neurobiol 2020; 280:103474. [PMID: 32531441 PMCID: PMC7283104 DOI: 10.1016/j.resp.2020.103474] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Revised: 06/01/2020] [Accepted: 06/02/2020] [Indexed: 10/25/2022]
Abstract
AIM To describe the response of breathing pattern and inspiratory effort upon changes in assist level and to assesss if changes in respiratory rate may indicate changes in respiratory muscle effort. METHODS Prospective study of 82 patients ventilated on proportional assist ventilation (PAV+). At three levels of assist (20 %-50 %-80 %), patients' inspiratory effort and breathing pattern were evaluated using a validated prototype monitor. RESULTS Independent of the assist level, a wide range of respiratory rates (16-35br/min) was observed when patients' effort was within the accepted range. Changing the assist level resulted in paired changes in inspiratory effort and rate of the same tendency (increase or decrease) in all but four patients. Increasing the level in assist resulted in a 31 % (8-44 %) decrease in inspiratory effort and a 10 % (0-18 %) decrease in respiratory rate. The change in respiratory rate upon the change in assist correlated modestly with the change in the effort (R = 0.5). CONCLUSION Changing assist level results in changes in both respiratory rate and effort in the same direction, with change in effort being greater than that of respiratory rate. Yet, neither the magnitude of respiratory rate change nor the resulting absolute value may reliably predict the level of effort after a change in assist.
Collapse
Affiliation(s)
- Emmanouil Lilitsis
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece
| | - Vaia Stamatopoulou
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece
| | - Eleftherios Andrianakis
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece
| | - Adamantia Petraki
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece
| | - Elvira-Markela Antonogiannaki
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece
| | - Dimitrios Georgopoulos
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece
| | - Katerina Vaporidi
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece
| | - Eumorfia Kondili
- Department of Intensive Care Medicine, University Hospital of Heraklion and School of Medicine, University of Crete, Voutes, 71110, Heraklion, Crete, Greece.
| |
Collapse
|
19
|
Laurie SS, Christian K, Kysar J, Lee SMC, Lovering AT, Macias BR, Moestl S, Sies W, Mulder E, Young M, Stenger MB. Unchanged cerebrovascular CO 2 reactivity and hypercapnic ventilatory response during strict head-down tilt bed rest in a mild hypercapnic environment. J Physiol 2020; 598:2491-2505. [PMID: 32196672 DOI: 10.1113/jp279383] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2019] [Accepted: 03/16/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Carbon dioxide levels are mildly elevated on the International Space Station and it is unknown whether this chronic exposure causes physiological changes to astronauts. We combined ∼4 mmHg ambient P C O 2 with the strict head-down tilt bed rest model of spaceflight and this led to the development of optic disc oedema in one-half of the subjects. We demonstrate no change in arterialized P C O 2 , cerebrovascular reactivity to CO2 or the hypercapnic ventilatory response. Our data suggest that the mild hypercapnic environment does not contribute to the development of spaceflight associated neuro-ocular syndrome. ABSTRACT Chronically elevated carbon dioxide (CO2 ) levels can occur in confined spaces such as the International Space Station. Using the spaceflight analogue 30 days of strict 6° head-down tilt bed rest (HDTBR) in a mild hypercapnic environment ( P C O 2 = ∼4 mmHg), we investigated arterialized P C O 2 , cerebrovascular reactivity and the hypercapnic ventilatory response in 11 healthy subjects (five females) before, on days 1, 9, 15 and 30 of bed rest (BR), and 6 and 13 days after HDTBR. During all HDTBR time points, arterialized P C O 2 was not significantly different from the pre-HDTBR measured in the 6° HDT posture, with a mean (95% confidence interval) increase of 1.2 mmHg (-0.2 to 2.5 mmHg, P = 0.122) on day 30 of HDTBR. Respiratory acidosis was never detected, although a mild metabolic alkalosis developed on day 30 of HDTBR by a mean (95% confidence interval) pH change of 0.032 (0.022-0.043; P < 0.001), which remained elevated by 0.021 (0.011-0.031; P < 0.001) 6 days after HDTBR. Arterialized pH returned to pre-HDTBR levels 13 days after BR with a change of -0.001 (-0.009 to 0.007; P = 0.991). Compared to pre-HDTBR, cerebrovascular reactivity during and after HDTBR did not change. Baseline ventilation, ventilatory recruitment threshold and the slope of the ventilatory response were similar between pre-HDTBR and all other time points. Taken together, these data suggest that the mildly increased ambient P C O 2 combined with 30 days of strict 6° HDTBR did not change arterialized P C O 2 levels. Therefore, the experimental conditions were not sufficient to elicit a detectable physiological response.
Collapse
Affiliation(s)
| | - Kate Christian
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | - Jacob Kysar
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | | | - Andrew T Lovering
- Department of Human Physiology, University of Oregon, Eugene, OR, USA
| | | | | | | | | | | | | |
Collapse
|
20
|
Vaporidi K, Akoumianaki E, Telias I, Goligher EC, Brochard L, Georgopoulos D. Respiratory Drive in Critically Ill Patients. Pathophysiology and Clinical Implications. Am J Respir Crit Care Med 2020; 201:20-32. [DOI: 10.1164/rccm.201903-0596so] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Katerina Vaporidi
- Department of Intensive Care Medicine, University Hospital of Heraklion, Medical School University of Crete, Heraklion, Greece
| | - Evangelia Akoumianaki
- Department of Intensive Care Medicine, University Hospital of Heraklion, Medical School University of Crete, Heraklion, Greece
| | - Irene Telias
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Center and Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - Ewan C. Goligher
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, University Health Network, Toronto, Ontario, Canada; and
- Toronto General Hospital Research Institute, Toronto, Ontario, Canada
| | - Laurent Brochard
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Center and Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - Dimitris Georgopoulos
- Department of Intensive Care Medicine, University Hospital of Heraklion, Medical School University of Crete, Heraklion, Greece
| |
Collapse
|
21
|
Targeting Endotypic Traits with Medications for the Pharmacological Treatment of Obstructive Sleep Apnea. A Review of the Current Literature. J Clin Med 2019; 8:jcm8111846. [PMID: 31684047 PMCID: PMC6912255 DOI: 10.3390/jcm8111846] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2019] [Revised: 10/29/2019] [Accepted: 10/30/2019] [Indexed: 12/28/2022] Open
Abstract
Obstructive sleep apnea (OSA) is a highly prevalent condition with few therapeutic options. To date there is no approved pharmacotherapy for this disorder, but several attempts have been made in the past and are currently ongoing to find one. The recent identification of multiple endotypes underlying this disorder has oriented the pharmacological research towards tailored therapies targeting specific pathophysiological traits that contribute differently to cause OSA in each patient. In this review we retrospectively analyze the literature on OSA pharmacotherapy dividing the medications tested on the basis of the four main endotypes: anatomy, upper airway muscle activity, arousal threshold and ventilatory instability (loop gain). We show how recently introduced drugs for weight loss that modify upper airway anatomy may play an important role in the management of OSA in the near future, and promising results have been obtained with drugs that increase upper airway muscle activity during sleep and reduce loop gain. The lack of a medication that can effectively increase the arousal threshold makes this strategy less encouraging, although recent studies have shown that the use of certain sedatives do not worsen OSA severity and could actually improve patients' sleep quality.
Collapse
|
22
|
Keir DA, Duffin J, Millar PJ, Floras JS. Simultaneous assessment of central and peripheral chemoreflex regulation of muscle sympathetic nerve activity and ventilation in healthy young men. J Physiol 2019; 597:3281-3296. [DOI: 10.1113/jp277691] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 05/13/2019] [Indexed: 12/20/2022] Open
Affiliation(s)
- Daniel A. Keir
- University Health Network and Mount Sinai Hospital Division of CardiologyDepartment of Medicine, University of Toronto Toronto Ontario Canada
| | - James Duffin
- Departments of Anaesthesia and PhysiologyUniversity of Toronto Toronto Ontario Canada
- Thornhill Research Inc. Toronto Ontario Canada
| | - Philip J. Millar
- University Health Network and Mount Sinai Hospital Division of CardiologyDepartment of Medicine, University of Toronto Toronto Ontario Canada
- Human Health and Nutritional ScienceUniversity of Guelph Guelph Ontario Canada
| | - John S. Floras
- University Health Network and Mount Sinai Hospital Division of CardiologyDepartment of Medicine, University of Toronto Toronto Ontario Canada
| |
Collapse
|
23
|
Nicolò A, Girardi M, Bazzucchi I, Felici F, Sacchetti M. Respiratory frequency and tidal volume during exercise: differential control and unbalanced interdependence. Physiol Rep 2018; 6:e13908. [PMID: 30393984 PMCID: PMC6215760 DOI: 10.14814/phy2.13908] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2018] [Revised: 10/02/2018] [Accepted: 10/03/2018] [Indexed: 01/14/2023] Open
Abstract
Differentiating between respiratory frequency (fR ) and tidal volume (VT ) may improve our understanding of exercise hyperpnoea because fR and VT seem to be regulated by different inputs. We designed a series of exercise manipulations to improve our understanding of how fR and VT are regulated during exercise. Twelve cyclists performed an incremental test and three randomized experimental sessions in separate visits. In two of the three experimental visits, participants performed a moderate-intensity sinusoidal test followed, after recovery, by a moderate-to-severe-intensity sinusoidal test. These two visits differed in the period of the sinusoid (2 min vs. 8 min). In the third experimental visit, participants performed a trapezoidal test where the workload was self-paced in order to match a predefined trapezoidal template of rating of perceived exertion (RPE). The results collectively reveal that fR changes more with RPE than with workload, gas exchange, VT or the amount of muscle activation. However, fR dissociates from RPE during moderate exercise. Both VT and minute ventilation ( V ˙ E ) showed a similar time course and a large correlation with V ˙ CO 2 in all the tests. Nevertheless, V ˙ CO 2 was associated more with V ˙ E than with VT because VT seems to adjust continuously on the basis of fR levels to match V ˙ E with V ˙ CO 2 . The present findings provide novel insight into the differential control of fR and VT - and their unbalanced interdependence - during exercise. The emerging conceptual framework is expected to guide future research on the mechanisms underlying the long-debated issue of exercise hyperpnoea.
Collapse
Affiliation(s)
- Andrea Nicolò
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Michele Girardi
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Ilenia Bazzucchi
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Francesco Felici
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| | - Massimo Sacchetti
- Department of Movement, Human and Health SciencesUniversity of Rome “Foro Italico”RomeItaly
| |
Collapse
|
24
|
Rowsell L, Wong KKH, Yee BJ, Eckert DJ, Somogyi AA, Duffin J, Grunstein RR, Wang D. The effect of acute morphine on obstructive sleep apnoea: a randomised double-blind placebo-controlled crossover trial. Thorax 2018; 74:177-184. [DOI: 10.1136/thoraxjnl-2018-211675] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 06/26/2018] [Accepted: 07/23/2018] [Indexed: 01/18/2023]
Abstract
ObjectiveAnaesthesiology guidelines suggest that opioids worsen obstructive sleep apnoea (OSA) despite no randomised controlled trial evidence. We therefore conducted a randomised controlled trial to evaluate the effects of a common clinical dose of morphine on OSA, and to identify clinical phenotype and genotype vulnerability to opioid-respiratory depression.MethodsUnder a double-blind, randomised, crossover design, 60 male patients with OSA attended two visits to the hospital sleep laboratory, at least 1 week apart. Either 40 mg controlled-release oral morphine or placebo was administered. Awake ventilatory chemoreflex tests were performed post dose and prior to overnight polysomnography monitoring. Blood was sampled before sleep and the next morning for toxicology and genotype analyses. Sleep time with oxygen saturation (SpO2) <90% (T90) was the primary outcome.ResultsDespite a large inter-individual variability, 40 mg morphine did not worsen T90 and apnoea–hypopnoea index, and only decreased the SpO2 nadir by 1.3%. In patients with severe OSA, a lower baseline CO2ventilatory response threshold correlated with the worsening of T90, apnoea–hypopnoea index and oxygen desaturation index with morphine use. Patients with OSA and the A118G OPRM1 polymorphism of A/A and A/G had a significantly different morphine effect on awake ventilatory chemosensitivity and T90 during sleep.Conclusions40 mg oral controlled-release morphine did not worsen OSA in men, challenging traditional thinking that OSA will be worsened by opioids. Individual opioid response in patients with OSA may relate to baseline CO2 response threshold and OPRM1 genotype. Our study findings may pave the way for a precision medicine approach to avoid opioid-related risks.Trial registration numberThe Australian and New Zealand Clinical Trial Registry, ACTRN12613000858796.
Collapse
|
25
|
Hayashi K, Ito N, Ichikawa Y, Suzuki Y. Effect of food intake on the ventilatory response to increasing core temperature during exercise. Appl Physiol Nutr Metab 2018; 44:22-30. [PMID: 29944847 DOI: 10.1139/apnm-2018-0069] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Food intake increases metabolism and body temperature, which may in turn influence ventilatory responses. Our aim was to assess the effect of food intake on ventilatory sensitivity to rising core temperature during exercise. Nine healthy male subjects exercised on a cycle ergometer at 50% of peak oxygen uptake in sessions with and without prior food intake. Ventilatory sensitivity to rising core temperature was defined by the slopes of regression lines relating ventilatory parameters to core temperature. Mean skin temperature, mean body temperature (calculated from esophageal temperature and mean skin temperature), oxygen uptake, carbon dioxide elimination, minute ventilation, alveolar ventilation, and tidal volume (VT) were all significantly higher at baseline in sessions with food intake than without food intake. During exercise, esophageal temperature, mean skin temperature, mean body temperature, carbon dioxide elimination, and end-tidal CO2 pressure were all significantly higher in sessions with food intake than without it. By contrast, ventilatory parameters did not differ between sessions with and without food intake, with the exception of VT during the first 5 min of exercise. The ventilatory sensitivities to rising core temperature also did not differ, with the exception of an early transient effect on VT. Food intake increases body temperature before and during exercise. Other than during the first 5 min of exercise, food intake does not affect ventilatory parameters during exercise, despite elevation of both body temperature and metabolism. Thus, with the exception of an early transient effect on VT, ventilatory sensitivity to rising core temperature is not affected by food intake.
Collapse
Affiliation(s)
- Keiji Hayashi
- a Department of Liberal Arts, Junior College, University of Shizuoka, Shizuoka, 422-8021 Japan
| | - Nozomi Ito
- b School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, 422-8526 Japan
| | - Yoko Ichikawa
- b School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, 422-8526 Japan
| | - Yuichi Suzuki
- b School of Food and Nutritional Sciences, University of Shizuoka, Shizuoka, 422-8526 Japan
| |
Collapse
|
26
|
Lee SY, Chien DK, Huang CH, Shih SC, Lee WC, Chang WH. Dyspnea in pregnancy. Taiwan J Obstet Gynecol 2018; 56:432-436. [PMID: 28805596 DOI: 10.1016/j.tjog.2017.04.035] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2017] [Indexed: 10/19/2022] Open
Abstract
Dyspnea in pregnancy is common. It can result from adaption to body changes in pregnancy and also from complications therein. Understanding the mechanisms of change in the respiratory system during pregnancy helps with the differential diagnosis of dyspnea in normal pregnancy as opposed to pathological dyspnea.
Collapse
Affiliation(s)
- Shih-Yi Lee
- Division of Pulmonary and Critical Care Medicine, Mackay Memorial Hospital, Taiwan; Department of Nursing, Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan; Department of Medicine, Mackay Medical College, Taipei, Taiwan; Department of Internal Medicine, Mackay Memorial Hospital, Taiwan
| | - Ding-Kuo Chien
- Department of Emergency Medicine, Mackay Memorial Hospital, Taiwan; Institute of Mechatronic Engineering, National Taipei University of Technology, Taiwan; Department of Nursing, Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan; Graduate Institute of Injury Prevention and Control, Taipei Medical University, Taipei, Taiwan; School of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Medicine, Mackay Medical College, Taipei, Taiwan
| | | | - Shou-Chuan Shih
- Department of Nursing, Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan; Department of Medicine, Mackay Medical College, Taipei, Taiwan; Department of Internal Medicine, Mackay Memorial Hospital, Taiwan
| | - Wei-Cheng Lee
- Department of Nursing, Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan; Department of Medicine, Mackay Medical College, Taipei, Taiwan
| | - Wen-Han Chang
- Department of Emergency Medicine, Mackay Memorial Hospital, Taiwan; Institute of Mechatronic Engineering, National Taipei University of Technology, Taiwan; Department of Nursing, Mackay Junior College of Medicine, Nursing, and Management, Taipei, Taiwan; Graduate Institute of Injury Prevention and Control, Taipei Medical University, Taipei, Taiwan; School of Medicine, Taipei Medical University, Taipei, Taiwan; Department of Medicine, Mackay Medical College, Taipei, Taiwan.
| |
Collapse
|
27
|
Serna LY, Mañanas MA, Hernández AM, Rabinovich RA. An Improved Dynamic Model for the Respiratory Response to Exercise. Front Physiol 2018; 9:69. [PMID: 29467674 PMCID: PMC5808356 DOI: 10.3389/fphys.2018.00069] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2017] [Accepted: 01/19/2018] [Indexed: 11/30/2022] Open
Abstract
Respiratory system modeling has been extensively studied in steady-state conditions to simulate sleep disorders, to predict its behavior under ventilatory diseases or stimuli and to simulate its interaction with mechanical ventilation. Nevertheless, the studies focused on the instantaneous response are limited, which restricts its application in clinical practice. The aim of this study is double: firstly, to analyze both dynamic and static responses of two known respiratory models under exercise stimuli by using an incremental exercise stimulus sequence (to analyze the model responses when step inputs are applied) and experimental data (to assess prediction capability of each model). Secondly, to propose changes in the models' structures to improve their transient and stationary responses. The versatility of the resulting model vs. the other two is shown according to the ability to simulate ventilatory stimuli, like exercise, with a proper regulation of the arterial blood gases, suitable constant times and a better adjustment to experimental data. The proposed model adjusts the breathing pattern every respiratory cycle using an optimization criterion based on minimization of work of breathing through regulation of respiratory frequency.
Collapse
Affiliation(s)
- Leidy Y Serna
- Biomedical Engineering Research Centre (CREB), Automatic Control Department, ESAII, Universitat Politècnica de Catalunya, Barcelona, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain
| | - Miguel A Mañanas
- Biomedical Engineering Research Centre (CREB), Automatic Control Department, ESAII, Universitat Politècnica de Catalunya, Barcelona, Spain.,Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Madrid, Spain
| | - Alher M Hernández
- Bioinstrumentation and Clinical Engineering Research Group - GIBIC, Bioengineering Department, Engineering Faculty, Universidad de Antioquia (UdeA), Medellín, Colombia
| | - Roberto A Rabinovich
- ELEGI and COLT Laboratories, Centre for Inflammation Research, Queen's Medical Research Institute, University of Edinburgh, Edinburgh, United Kingdom.,Department of Respiratory Medicine, Royal Infirmary of Edinburgh, Edinburgh, United Kingdom
| |
Collapse
|
28
|
Wang D, Wong KK, Rowsell L, Don GW, Yee BJ, Grunstein RR. Predicting response to oxygen therapy in obstructive sleep apnoea patients using a 10-minute daytime test. Eur Respir J 2018; 51:51/1/1701587. [DOI: 10.1183/13993003.01587-2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/07/2017] [Indexed: 11/05/2022]
Abstract
There is no satisfactory treatment for obstructive sleep apnoea (OSA). Supplemental low-flow oxygen therapy (LFO2) has been shown to reduce hypoxaemia and is well tolerated by patients with OSA. However, oxygen therapy may be beneficial only to certain subsets of patients with OSA. In this study, we evaluated a 10-min awake ventilatory chemoreflex test in predicting individual OSA response to 2 months of LFO2therapy.At baseline, patients with OSA underwent ventilatory chemoreflex testing in the afternoon, prior to the overnight polysomnography. Subjects were reassessed with polysomnography after 2 months of nocturnal oxygen treatment.20 patients with OSA completed the study. After 2 months of O2treatment, changes in the apnoea–hypopnoea index (AHI) were significantly correlated with baseline CO2ventilatory response threshold (VRT) and chemosensitivity (p<0.05). In predicting a fall in AHI, the area under the receiver operating characteristic curve (AUC) was 0.79 for VRT and 0.89 for chemosensitivity. When these two variables were combined in a logistic regression model, the prediction effect became stronger with an AUC of 0.97, sensitivity of 0.92 and specificity of 0.83.Our awake ventilatory chemoreflex test could be considered a simple potential clinical tool to predict individual OSA response to oxygen therapy. It could provide a novel personalised medicine approach to OSA treatment.
Collapse
|
29
|
Tsuji B, Filingeri D, Honda Y, Eguchi T, Fujii N, Kondo N, Nishiyasu T. Effect of hypocapnia on the sensitivity of hyperthermic hyperventilation and the cerebrovascular response in resting heated humans. J Appl Physiol (1985) 2018; 124:225-233. [DOI: 10.1152/japplphysiol.00232.2017] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Elevating core temperature at rest causes increases in minute ventilation (V̇e), which lead to reductions in both arterial CO2 partial pressure (hypocapnia) and cerebral blood flow. We tested the hypothesis that in resting heated humans this hypocapnia diminishes the ventilatory sensitivity to rising core temperature but does not explain a large portion of the decrease in cerebral blood flow. Fourteen healthy men were passively heated using hot-water immersion (41°C) combined with a water-perfused suit, which caused esophageal temperature (Tes) to reach 39°C. During heating in two separate trials, end-tidal CO2 partial pressure decreased from the level before heating (39.4 ± 2.0 mmHg) to the end of heating (30.5 ± 6.3 mmHg) ( P = 0.005) in the Control trial. This decrease was prevented by breathing CO2-enriched air throughout the heating such that end-tidal CO2 partial pressure did not differ between the beginning (39.8 ± 1.5 mmHg) and end (40.9 ± 2.7 mmHg) of heating ( P = 1.00). The sensitivity to rising Tes (i.e., slope of the Tes − V̇E relation) did not differ between the Control and CO2-breathing trials (37.1 ± 43.1 vs. 16.5 ± 11.1 l·min−1·°C−1, P = 0.31). In both trials, middle cerebral artery blood velocity (MCAV) decreased early during heating (all P < 0.01), despite the absence of hyperventilation-induced hypocapnia. CO2 breathing increased MCAV relative to Control at the end of heating ( P = 0.005) and explained 36.6% of the heat-induced reduction in MCAV. These results indicate that during passive heating at rest ventilatory sensitivity to rising core temperature is not suppressed by hypocapnia and that most of the decrease in cerebral blood flow occurs independently of hypocapnia. NEW & NOTEWORTHY Hyperthermia causes hyperventilation and concomitant hypocapnia and cerebral hypoperfusion. The last may underlie central fatigue. We are the first to demonstrate that hyperthermia-induced hyperventilation is not suppressed by the resultant hypocapnia and that hypocapnia explains only 36% of cerebral hypoperfusion elicited by hyperthermia. These new findings advance our understanding of the mechanisms controlling ventilation and cerebral blood flow during heat stress, which may be useful for developing interventions aimed at preventing central fatigue during hyperthermia.
Collapse
Affiliation(s)
- Bun Tsuji
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, Japan
- Department of Health Sciences, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Davide Filingeri
- Environmental Ergonomics Research Centre, Loughborough Design School, Loughborough University, Loughborough, United Kingdom
| | - Yasushi Honda
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, Japan
| | - Tsubasa Eguchi
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, Japan
| | - Narihiko Kondo
- Faculty of Human Development, Kobe University, Kobe, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, Japan
| |
Collapse
|
30
|
Tipton MJ, Harper A, Paton JFR, Costello JT. The human ventilatory response to stress: rate or depth? J Physiol 2017. [PMID: 28650070 DOI: 10.1113/jp274596] [Citation(s) in RCA: 112] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Many stressors cause an increase in ventilation in humans. This is predominantly reported as an increase in minute ventilation (V̇E). But, the same V̇E can be achieved by a wide variety of changes in the depth (tidal volume, VT ) and number of breaths (respiratory frequency, ƒR ). This review investigates the impact of stressors including: cold, heat, hypoxia, pain and panic on the contributions of ƒR and VT to V̇E to see if they differ with different stressors. Where possible we also consider the potential mechanisms that underpin the responses identified, and propose mechanisms by which differences in ƒR and VT are mediated. Our aim being to consider if there is an overall differential control of ƒR and VT that applies in a wide range of conditions. We consider moderating factors, including exercise, sex, intensity and duration of stimuli. For the stressors reviewed, as the stress becomes extreme V̇E generally becomes increased more by ƒR than VT . We also present some tentative evidence that the pattern of ƒR and VT could provide some useful diagnostic information for a variety of clinical conditions. In The Physiological Society's year of 'Making Sense of Stress', this review has wide-ranging implications that are not limited to one discipline, but are integrative and relevant for physiology, psychophysiology, neuroscience and pathophysiology.
Collapse
Affiliation(s)
- Michael J Tipton
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK
| | - Abbi Harper
- Clinical Fellow in Intensive Care Medicine, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Julian F R Paton
- School of Physiology, Pharmacology and Neuroscience, Biomedical Sciences, University Walk, University of Bristol, Bristol, BS8 1TD, UK
| | - Joseph T Costello
- Extreme Environments Laboratory, Department of Sport and Exercise Science, University of Portsmouth, Portsmouth, PO1 2ER, UK
| |
Collapse
|
31
|
Nicolò A, Marcora SM, Bazzucchi I, Sacchetti M. Differential control of respiratory frequency and tidal volume during high-intensity interval training. Exp Physiol 2017; 102:934-949. [PMID: 28560751 DOI: 10.1113/ep086352] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 05/25/2017] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? By manipulating recovery intensity and exercise duration during high-intensity interval training (HIIT), we tested the hypothesis that fast inputs contribute more than metabolic stimuli to respiratory frequency (fR ) regulation. What is the main finding and its importance? Respiratory frequency, but not tidal volume, responded rapidly and in proportion to changes in workload during HIIT, and was dissociated from some markers of metabolic stimuli in response to both experimental manipulations, suggesting that fast inputs contribute more than metabolic stimuli to fR regulation. Differentiating between fR and tidal volume may help to unravel the mechanisms underlying exercise hyperpnoea. Given that respiratory frequency (fR ) has been proposed as a good marker of physical effort, furthering the understanding of how fR is regulated during exercise is of great importance. We manipulated recovery intensity and exercise duration during high-intensity interval training (HIIT) to test the hypothesis that fast inputs (including central command) contribute more than metabolic stimuli to fR regulation. Seven male cyclists performed an incremental test, a 10 and a 20 min continuous time trial (TT) as preliminary tests. Subsequently, recovery intensity and exercise duration were manipulated during HIIT (30 s work and 30 s active recovery) by performing four 10 min and one 20 min trial (recovery intensities of 85, 70, 55 and 30% of the 10 min TT mean workload; and 85% of the 20 min TT mean workload). The work intensity of the HIIT sessions was self-paced by participants to achieve the best performance possible. When manipulating recovery intensity, fR , but not tidal volume (VT ), showed a fast response to the alternation of the work and recovery phases, proportional to the extent of workload variations. No association between fR and gas exchange responses was observed. When manipulating exercise duration, fR and rating of perceived exertion were dissociated from VT , carbon dioxide output and oxygen uptake responses. Overall, the rating of perceived exertion was strongly correlated with fR (r = 0.87; P < 0.001) but not with VT . These findings may reveal a differential control of fR and VT during HIIT, with fast inputs appearing to contribute more than metabolic stimuli to fR regulation. Differentiating between fR and VT may help to unravel the mechanisms underlying exercise hyperpnoea.
Collapse
Affiliation(s)
- Andrea Nicolò
- Department of Movement, Human and Health Sciences, University of Rome 'Foro Italico', Rome, Italy
| | - Samuele M Marcora
- Endurance Research Group, School of Sport and Exercise Sciences, University of Kent, Chatham Maritime, Kent, UK
| | - Ilenia Bazzucchi
- Department of Movement, Human and Health Sciences, University of Rome 'Foro Italico', Rome, Italy
| | - Massimo Sacchetti
- Department of Movement, Human and Health Sciences, University of Rome 'Foro Italico', Rome, Italy
| |
Collapse
|
32
|
Dobashi K, Fujii N, Watanabe K, Tsuji B, Sasaki Y, Fujimoto T, Tanigawa S, Nishiyasu T. Effect of voluntary hypocapnic hyperventilation or moderate hypoxia on metabolic and heart rate responses during high-intensity intermittent exercise. Eur J Appl Physiol 2017; 117:1573-1583. [PMID: 28527012 DOI: 10.1007/s00421-017-3646-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2017] [Accepted: 05/12/2017] [Indexed: 11/28/2022]
Abstract
PURPOSE To investigate the effect of voluntary hypocapnic hyperventilation or moderate hypoxia on metabolic and heart rate responses during high-intensity intermittent exercise. METHODS Ten males performed three 30-s bouts of high-intensity cycling [Ex1 and Ex2: constant-workload at 80% of the power output in the Wingate anaerobic test (WAnT), Ex3: WAnT] interspaced with 4-min recovery periods under normoxic (Control), hypocapnic or hypoxic (2500 m) conditions. Hypocapnia was developed through voluntary hyperventilation for 20 min prior to Ex1 and during each recovery period. RESULTS End-tidal CO2 pressure was lower before each exercise in the hypocapnia than control trials. Oxygen uptake ([Formula: see text]) was lower in the hypocapnia than control trials (822 ± 235 vs. 1645 ± 245 mL min-1; mean ± SD) during Ex1, but not Ex2 or Ex3, without a between-trial difference in the power output during the exercises. Heart rates (HRs) during Ex1 (127 ± 8 vs. 142 ± 10 beats min-1) and subsequent post-exercise recovery periods were lower in the hypocapnia than control trials, without differences during or after Ex2, except at 4 min into the second recovery period. [Formula: see text] did not differ between the control and hypoxia trials throughout. CONCLUSIONS These results suggest that during three 30-s bouts of high-intensity intermittent cycling, (1) hypocapnia reduces the aerobic metabolic rate with a compensatory increase in the anaerobic metabolic rate during the first but not subsequent exercises; (2) HRs during the exercise and post-exercise recovery periods are lowered by hypocapnia, but this effect is diminished with repeated exercise bouts, and (3) moderate hypoxia (2500 m) does not affect the metabolic response during exercise.
Collapse
Affiliation(s)
- Kohei Dobashi
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8574, Japan
| | - Naoto Fujii
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8574, Japan
| | - Kazuhito Watanabe
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8574, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Bun Tsuji
- Faculty of Human Culture and Science, Prefectural University of Hiroshima, Hiroshima, Japan
| | - Yosuke Sasaki
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8574, Japan
| | - Tomomi Fujimoto
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8574, Japan.,Japan Society for the Promotion of Science, Tokyo, Japan
| | - Satoru Tanigawa
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8574, Japan
| | - Takeshi Nishiyasu
- Faculty of Health and Sport Sciences, University of Tsukuba, Tsukuba City, Ibaraki, 305-8574, Japan.
| |
Collapse
|
33
|
Tsukada S, Masaoka Y, Yoshikawa A, Okamoto K, Homma I, Izumizaki M. Coupling of dyspnea perception and occurrence of tachypnea during exercise. J Physiol Sci 2017; 67:173-180. [PMID: 27117877 PMCID: PMC10717682 DOI: 10.1007/s12576-016-0452-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 04/12/2016] [Indexed: 11/26/2022]
Abstract
During exercise, tidal volume initially contributes to ventilatory responses more than respiratory frequency, and respiratory frequency then increases rapidly while tidal volume stabilizes. Dyspnea intensity is also known to increase in a threshold-like manner. We tested the possibility that the threshold of tachypneic breathing is equal to that of dyspnea perception during cycle ergometer exercise (n = 27). Dyspnea intensity was scored by a visual analog scale. Thresholds were expressed as values of pulmonary O2 uptake at each breakpoint. Dyspnea intensity and respiratory frequency started increasing rapidly once the intensity of stimuli exceeded a threshold level. The thresholds for dyspnea intensity and for occurrence of tachypnea were significantly correlated. An intraclass correlation coefficient of 0.71 and narrow limits of agreement on the Bland-Altman plot indicated a good agreement between these thresholds. These results suggest that the start of tachypneic breathing coincides with the threshold for dyspnea intensity during cycle ergometer exercise.
Collapse
Affiliation(s)
- Setsuro Tsukada
- Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
- Department of Neurology, Showa University School of Medicine, Tokyo, Japan
| | - Yuri Masaoka
- Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Akira Yoshikawa
- Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Keiji Okamoto
- Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Ikuo Homma
- Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan
| | - Masahiko Izumizaki
- Department of Physiology, Showa University School of Medicine, 1-5-8 Hatanodai, Shinagawa-ku, Tokyo, 142-8555, Japan.
| |
Collapse
|
34
|
Chidambaran V, Pilipenko V, Spruance K, Venkatasubramanian R, Niu J, Fukuda T, Mizuno T, Zhang K, Kaufman K, Vinks AA, Martin LJ, Sadhasivam S. Fatty acid amide hydrolase-morphine interaction influences ventilatory response to hypercapnia and postoperative opioid outcomes in children. Pharmacogenomics 2016; 18:143-156. [PMID: 27977335 DOI: 10.2217/pgs-2016-0147] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIM Fatty acid amide hydrolase (FAAH) degrades anandamide, an endogenous cannabinoid. We hypothesized that FAAH variants will predict risk of morphine-related adverse outcomes due to opioid-endocannabinoid interactions. PATIENTS & METHODS In 101 postsurgical adolescents receiving morphine analgesia, we prospectively studied ventilatory response to 5% CO2 (HCVR), respiratory depression (RD) and vomiting. Blood was collected for genotyping and morphine pharmacokinetics. RESULTS We found significant FAAH-morphine interaction for missense (rs324420) and several regulatory variants, with HCVR (p < 0.0001) and vomiting (p = 0.0339). HCVR was more depressed in patients who developed RD compared with those who did not (p = 0.0034), thus FAAH-HCVR association predicts risk of impending RD from morphine use. CONCLUSION FAAH genotypes predict risk for morphine-related adverse outcomes.
Collapse
Affiliation(s)
- Vidya Chidambaran
- Department of Anesthesia, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA.,Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Valentina Pilipenko
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Kristie Spruance
- Department of Anesthesia, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Raja Venkatasubramanian
- Department of Anesthesia, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
| | - Jing Niu
- Department of Anesthesia, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA.,Division of Pharmacology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Tsuyoshi Fukuda
- Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA.,Division of Pharmacology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Tomoyuki Mizuno
- Division of Pharmacology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Kejian Zhang
- Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Kenneth Kaufman
- Center for Autoimmune Genomics and Etiology (CAGE), Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Alexander A Vinks
- Division of Pharmacology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Lisa J Martin
- Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA.,Division of Human Genetics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH 45229, USA
| | - Senthilkumar Sadhasivam
- Department of Anesthesia, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA.,Department of Pediatrics, College of Medicine, University of Cincinnati, Cincinnati, OH 45229, USA
| |
Collapse
|
35
|
|
36
|
McKay JAA, McCulloch CL, Querido JS, Foster GE, Koehle MS, Sheel AW. The effect of consistent practice of yogic breathing exercises on the human cardiorespiratory system. Respir Physiol Neurobiol 2016; 233:41-51. [PMID: 27453559 DOI: 10.1016/j.resp.2016.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 07/09/2016] [Accepted: 07/20/2016] [Indexed: 11/28/2022]
Abstract
The purpose of this investigation was to quantify the cardiovascular, respiratory, and cerebrovascular effects of two common yogic breathing exercises (YBE): bhastrika and chaturbhuj; and to determine the effect of their consistent practice on chemosensitivity. The first study was cross-sectional and compared experienced yogic breathers (YB) with matched controls; whereas the second was a 10-week longitudinal training study. The results support four major findings. First chaturbhuj resulted in a hypoxic stimulus in experienced YB compared to control [end-tidal oxygen tension (PETO2), YB: 77.5±5.7mmHg, P<0.05; control: 94.3±12.0mmHg]. Second, performance of chaturbhuj resulted in cyclic oscillations of mean arterial pressure (MAP), heart rate (HR), and middle cerebral artery velocity (MCAv) consistent with the phases of respiration. Third, post training, performance of bhastrika reduced PETO2 (end breath-hold: 90.8 8±12.1mmHg) compared to rest (100.1±7.4, P<0.05); it also resulted in significantly increased MAP at end breath-hold (96.7±13.0mmHg) compared to rest (83.0±6.6mmHg, P<0.05) and significantly increased mean MCAv (end breath-hold: 87.4±23.0cm/s, P<0.05; rest: 55.8±26.3cm/s). Fourth, experienced YB had lower central chemosensitivity than controls (YB: 3.4±0.4; control: 4.6±1.2L/min/mmHg; P<0.05). In conclusion, YBE significantly alter end-tidal gases, resulting in complex oscillations of cardiovascular and cerebrovascular variables, and if practiced consistently, may reduce chemosensitivity.
Collapse
Affiliation(s)
- Joshua A A McKay
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Cara L McCulloch
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.
| | - Jordan S Querido
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Glen E Foster
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Centre for Heart, Lung, and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Kelowna, BC, Canada
| | - Michael S Koehle
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada; Division of Sports Medicine, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| |
Collapse
|
37
|
Wilson RJA, Teppema LJ. Integration of Central and Peripheral Respiratory Chemoreflexes. Compr Physiol 2016; 6:1005-41. [PMID: 27065173 DOI: 10.1002/cphy.c140040] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
A debate has raged since the discovery of central and peripheral respiratory chemoreceptors as to whether the reflexes they mediate combine in an additive (i.e., no interaction), hypoadditive or hyperadditive manner. Here we critically review pertinent literature related to O2 and CO2 sensing from the perspective of system integration and summarize many of the studies on which these seemingly opposing views are based. Despite the intensity and quality of this debate, we have yet to reach consensus, either within or between species. In reviewing this literature, we are struck by the merits of the approaches and preparations that have been brought to bear on this question. This suggests that either the nature of combination is not important to system responses, contrary to what has long been supposed, or that the nature of the combination is more malleable than previously assumed, changing depending on physiological state and/or respiratory requirement.
Collapse
Affiliation(s)
- Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Luc J Teppema
- Department of Anesthesiology, Leiden University Medical Center, Leiden, The Netherlands
| |
Collapse
|
38
|
Affiliation(s)
- Tadayoshi Miyamoto
- Graduate School of Health Sciences, Morinomiya University of Medical Sciences
| |
Collapse
|
39
|
Albanese A, Cheng L, Ursino M, Chbat NW. An integrated mathematical model of the human cardiopulmonary system: model development. Am J Physiol Heart Circ Physiol 2015; 310:H899-921. [PMID: 26683899 DOI: 10.1152/ajpheart.00230.2014] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 12/03/2015] [Indexed: 11/22/2022]
Abstract
Several cardiovascular and pulmonary models have been proposed in the last few decades. However, very few have addressed the interactions between these two systems. Our group has developed an integrated cardiopulmonary model (CP Model) that mathematically describes the interactions between the cardiovascular and respiratory systems, along with their main short-term control mechanisms. The model has been compared with human and animal data taken from published literature. Due to the volume of the work, the paper is divided in two parts. The present paper is on model development and normophysiology, whereas the second is on the model's validation on hypoxic and hypercapnic conditions. The CP Model incorporates cardiovascular circulation, respiratory mechanics, tissue and alveolar gas exchange, as well as short-term neural control mechanisms acting on both the cardiovascular and the respiratory functions. The model is able to simulate physiological variables typically observed in adult humans under normal and pathological conditions and to explain the underlying mechanisms and dynamics.
Collapse
Affiliation(s)
| | - Limei Cheng
- Philips Research North America, Briarcliff Manor, New York
| | - Mauro Ursino
- Department of Electrical, Electronic, and Information Engineering, University of Bologna, Bologna, Italy; and
| | - Nicolas W Chbat
- Philips Research North America, Briarcliff Manor, New York; Departments of Biomedical Engineering and Mechanical Engineering, Columbia University, New York, New York
| |
Collapse
|
40
|
Ozcimen M, Sakarya Y, Goktas S, Sakarya R, Alpfidan I, Yener HI, Demir LS. The effect of rebreathing and hyperventilation on retinal and choroidal vessels measured by spectral domain optical coherence tomography. Cutan Ocul Toxicol 2015; 34:313-7. [PMID: 25597376 DOI: 10.3109/15569527.2014.990154] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE The purpose of this study was to examine the vasoreactivity in retina and choroid of the healthy eyes in response to experimentally altered partial arterial pressure of carbon dioxide (PaCO(2)) using a non-invasive technique, spectral domain optical coherence tomography (SD-OCT). MATERIALS AND METHODS The study included non-smoking participants between 18 and 35 years of age, having visual acuity of 20/20 and with no systemic and ocular diseases. At baseline, the participants breathed room air (normocapnia). Hypocapnia was created with the help of hyperventilation; for this, the participants were instructed to draw deep and quick breaths, resulting one breathing cycle per 2 s. To create hypercapnia subjects rebreathed from a 5 l bag at least 3 min. Choroidal thickness and retinal artery diameter were measured at baseline, and hyperventilation and rebreathing conditions by SD-OCT. RESULTS Twenty eyes of 20 healthy subjects were included in this study. Their mean age was 24.90 ± 5.32 years. Hyperventilation caused a significant reduction in choroidal thickness, compared with baseline, at all points; whereas rebreathing caused no significant change at all points. The mean diameters of the arteries were 151.80 ± 7.88 μm, with a significant decline to 148.90 ± 7.25 μm at hyperventilation condition and a significant increase to 153.50 ± 7.88 μm at rebreathing condition (p = 0.018, p = 0.043, respectively). CONCLUSION This study demonstrated that, SD-OCT was a useful tool in measuring the ocular vascular response under hypercapnia and hypocapnia conditions. These findings may be helpful for further understanding the physiological nature of ocular blood flow and this preliminary study provides a basis for future studies.
Collapse
Affiliation(s)
- Muammer Ozcimen
- a Department of Ophthalmology , Konya Training and Research Hospital , Konya , Turkey
| | - Yasar Sakarya
- a Department of Ophthalmology , Konya Training and Research Hospital , Konya , Turkey
| | - Sertan Goktas
- a Department of Ophthalmology , Konya Training and Research Hospital , Konya , Turkey
| | - Rabia Sakarya
- a Department of Ophthalmology , Konya Training and Research Hospital , Konya , Turkey
| | - Ismail Alpfidan
- a Department of Ophthalmology , Konya Training and Research Hospital , Konya , Turkey
| | | | - Lutfi S Demir
- c Department of Public Health , Necmettin Erbakan University, Faculty of Medicine , Konya , Turkey
| |
Collapse
|
41
|
Burgess KR, Lucas SJE, Shepherd K, Dawson A, Swart M, Thomas KN, Lucas RAI, Donnelly J, Peebles KC, Basnyat R, Ainslie PN. Influence of cerebral blood flow on central sleep apnea at high altitude. Sleep 2014; 37:1679-87. [PMID: 25197804 DOI: 10.5665/sleep.4080] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2013] [Accepted: 03/14/2014] [Indexed: 11/03/2022] Open
Abstract
STUDY OBJECTIVES To further our understanding of central sleep apnea (CSA) at high altitude during acclimatization, we tested the hypothesis that pharmacologically altering cerebral blood flow (CBF) would alter the severity of CSA at high altitude. DESIGN The study was a randomized, placebo-controlled single-blind study. SETTING A field study at 5,050 m in Nepal. PATIENTS OR PARTICIPANTS We studied 12 normal volunteers. INTERVENTIONS Between days 5 to 10 at high altitude, CBF velocity (CBFv) was increased by intravenous (IV) acetazolamide (10 mg/kg) and reduced by oral indomethacin (100 mg). MEASUREMENTS AND RESULTS Arterial blood gases, hypoxic and hypercapnic ventilatory responses, and CBFv and its reactivity to carbon dioxide were measured awake. Overnight polysomnography was performed. The central apnea-hypopnea index was elevated following administration of indomethacin (89.2 ± 43.7 to 112.5 ± 32.9 events/h; mean ± standard deviation; P < 0.05) and was reduced following IV acetazolamide (89.2 ± 43.7 to 47.1 ± 48.1 events/h; P < 0.001). Intravenous acetazolamide elevated CBFv at high altitude by 28% (95% confidence interval [CI]: 22-34%) but did not affect ventilatory responses. The elevation in CBFv was partly mediated via a selective rise in partial pressure of arterial carbon dioxide (PaCO2) (28 ± 4 to 31 ± 3 mm Hg) and an associated fall in pH (P < 0.01). Oral indomethacin reduced CBFv by 23% (95% CI: 16-30%), blunted CBFv reactivity, and increased the hypercapnic ventilatory response by 66% (95% CI: 30-102%) but had no effect on PaCO2 or pH. CONCLUSION Our findings indicate an important role for cerebral blood flow regulation in the pathophysiology of central sleep apnea at high altitude.
Collapse
Affiliation(s)
- Keith R Burgess
- Peninsula Sleep Laboratory, Sydney, New South Wales, Australia and Department of Medicine, University of Sydney, Sydney, New South Wales, Australia
| | | | - Kelly Shepherd
- Peninsula Sleep Laboratory, Sydney, New South Wales, Australia
| | - Andrew Dawson
- Peninsula Sleep Laboratory, Sydney, New South Wales, Australia
| | - Marianne Swart
- Peninsula Sleep Laboratory, Sydney, New South Wales, Australia
| | | | | | | | | | - Rishi Basnyat
- Nepal International Clinic, Kathmandu, Nepal and Banner Good Samaritan Medical Center, Phoenix, Arizona
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Canada
| |
Collapse
|
42
|
Duffin J, Mateika JH. Cross-Talk opposing view: peripheral and central chemoreflexes have additive effects on ventilation in humans. J Physiol 2014; 591:4351-3. [PMID: 24037126 DOI: 10.1113/jphysiol.2013.256800] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
|
43
|
Dutschmann M, Bautista TG, Mörschel M, Dick TE. Learning to breathe: habituation of Hering-Breuer inflation reflex emerges with postnatal brainstem maturation. Respir Physiol Neurobiol 2014; 195:44-9. [PMID: 24566392 DOI: 10.1016/j.resp.2014.02.009] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2014] [Revised: 02/12/2014] [Accepted: 02/16/2014] [Indexed: 01/08/2023]
Abstract
The Hering-Breuer (HBR) reflex is considered a major regulatory feedback for the generation and patterning of respiratory activity. While HBR is important in neonates, its significance in adults is controversial. Previous experiments that investigated the plasticity of entrainment of the respiratory rhythm by vagal input demonstrated postnatal changes in HBR plasticity. Here we analyzed postnatal changes in the plasticity of HBR by mimicking the classic lung inflation tests with repetitive tonic vagal stimulation across different postnatal stages in an in situ perfused brainstem preparation of rat. The study shows that neonates stereotypically exhibit HBR stimulus-dependent prolongation of expiration while juvenile preparations (>postnatal day 16) showed significant habituation of HBR following repetitive stimulation. Subsequent experiments employing physiological lung inflation tests in situ confirmed HBR habituation in juveniles. We conclude that postnatal emergence of HBR habituation explains the weak contribution and high activation threshold of HBR in the regulation of eupnea.
Collapse
Affiliation(s)
- Mathias Dutschmann
- Florey Institute of Neuroscience and Mental Health, Melbourne, Australia; Bernstein Center for Computational Neurosciences, Göttingen, Germany.
| | - Tara G Bautista
- Florey Institute of Neuroscience and Mental Health, Melbourne, Australia
| | - Michael Mörschel
- Bernstein Center for Computational Neurosciences, Göttingen, Germany
| | - Thomas E Dick
- Department of Medicine, Case Western Reserve University, Cleveland, USA
| |
Collapse
|
44
|
Costalat G, Pichon A, Coquart J, Bauer F, Lemaître F. Cardio-ventilatory responses to poikilocapnic hypoxia and hypercapnia in trained breath-hold divers. Respir Physiol Neurobiol 2014; 192:48-54. [DOI: 10.1016/j.resp.2013.12.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/15/2013] [Accepted: 12/06/2013] [Indexed: 01/01/2023]
|
45
|
Skow RJ, Tymko MM, MacKay CM, Steinback CD, Day TA. The effects of head-up and head-down tilt on central respiratory chemoreflex loop gain tested by hyperoxic rebreathing. PROGRESS IN BRAIN RESEARCH 2014; 212:149-72. [DOI: 10.1016/b978-0-444-63488-7.00009-4] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
|
46
|
Fan JL, Subudhi AW, Evero O, Bourdillon N, Kayser B, Lovering AT, Roach RC. AltitudeOmics: enhanced cerebrovascular reactivity and ventilatory response to CO2 with high-altitude acclimatization and reexposure. J Appl Physiol (1985) 2013; 116:911-8. [PMID: 24356520 DOI: 10.1152/japplphysiol.00704.2013] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The present study is the first to examine the effect of high-altitude acclimatization and reexposure on the responses of cerebral blood flow and ventilation to CO2. We also compared the steady-state estimates of these parameters during acclimatization with the modified rebreathing method. We assessed changes in steady-state responses of middle cerebral artery velocity (MCAv), cerebrovascular conductance index (CVCi), and ventilation (V(E)) to varied levels of CO2 in 21 lowlanders (9 women; 21 ± 1 years of age) at sea level (SL), during initial exposure to 5,260 m (ALT1), after 16 days of acclimatization (ALT16), and upon reexposure to altitude following either 7 (POST7) or 21 days (POST21) at low altitude (1,525 m). In the nonacclimatized state (ALT1), MCAv and V(E) responses to CO2 were elevated compared with those at SL (by 79 ± 75% and 14.8 ± 12.3 l/min, respectively; P = 0.004 and P = 0.011). Acclimatization at ALT16 further elevated both MCAv and Ve responses to CO2 compared with ALT1 (by 89 ± 70% and 48.3 ± 32.0 l/min, respectively; P < 0.001). The acclimatization gained for V(E) responses to CO2 at ALT16 was retained by 38% upon reexposure to altitude at POST7 (P = 0.004 vs. ALT1), whereas no retention was observed for the MCAv responses (P > 0.05). We found good agreement between steady-state and modified rebreathing estimates of MCAv and V(E) responses to CO2 across all three time points (P < 0.001, pooled data). Regardless of the method of assessment, altitude acclimatization elevates both the cerebrovascular and ventilatory responsiveness to CO2. Our data further demonstrate that this enhanced ventilatory CO2 response is partly retained after 7 days at low altitude.
Collapse
Affiliation(s)
- Jui-Lin Fan
- Institute of Sports Sciences, Faculty of Biology and Medicine, University of Lausanne, Lausanne, Switzerland
| | | | | | | | | | | | | |
Collapse
|
47
|
Domnik NJ, Turcotte SE, Yuen NY, Iscoe S, Fisher JT. CO(2) rebreathing: an undergraduate laboratory to study the chemical control of breathing. ADVANCES IN PHYSIOLOGY EDUCATION 2013; 37:361-369. [PMID: 24292914 DOI: 10.1152/advan.00075.2013] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The Read CO2 rebreathing method (Read DJ. A clinical method for assessing the ventilatory response to carbon dioxide. Australas Ann Med 16: 20-32, 1967) provides a simple and reproducible approach for studying the chemical control of breathing. It has been widely used since the modifications made by Duffin and coworkers. Our use of a rebreathing laboratory to challenge undergraduate science students to investigate the control of breathing provided 8 yr of student-generated data for comparison with the literature. Students (age: 19-22 yr, Research Ethics Board approval) rebreathed from a bag containing 5% CO2 and 95% O2 (to suppress the peripheral chemoreflex to hypoxia). Rebreathing was performed, and ventilation measured, after hyperventilation to deplete tissue CO2 stores and enable the detection of the central chemoreflex threshold. We analyzed 43 data sets, of which 10 were rejected for technical reasons. The mean threshold and ventilatory sensitivity to CO2 were 43.3 ± 3.8 mmHg and 4.60 ± 3.04 l·min(-1)·mmHg(-1) (means ± SD), respectively. Threshold values were normally distributed, whereas sensitivity was skewed to the left. Both mean values agreed well with those in the literature. We conclude that the modified rebreathing protocol is a robust method for undergraduate investigation of the chemical control of breathing.
Collapse
Affiliation(s)
- N J Domnik
- Department of Biomedical and Molecular Sciences, Physiology Program, Queen's University, Kingston, Ontario, Canada; and
| | | | | | | | | |
Collapse
|
48
|
|
49
|
Ben-Tal A, Tawhai MH. Integrative approaches for modeling regulation and function of the respiratory system. WILEY INTERDISCIPLINARY REVIEWS. SYSTEMS BIOLOGY AND MEDICINE 2013; 5:687-99. [PMID: 24591490 PMCID: PMC4048368 DOI: 10.1002/wsbm.1244] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Revised: 08/02/2013] [Accepted: 08/05/2013] [Indexed: 11/08/2022]
Abstract
Mathematical models have been central to understanding the interaction between neural control and breathing. Models of the entire respiratory system-which comprises the lungs and the neural circuitry that controls their ventilation-have been derived using simplifying assumptions to compartmentalize each component of the system and to define the interactions between components. These full system models often rely-through necessity-on empirically derived relationships or parameters, in addition to physiological values. In parallel with the development of whole respiratory system models are mathematical models that focus on furthering a detailed understanding of the neural control network, or of the several functions that contribute to gas exchange within the lung. These models are biophysically based, and rely on physiological parameters. They include single-unit models for a breathing lung or neural circuit, through to spatially distributed models of ventilation and perfusion, or multicircuit models for neural control. The challenge is to bring together these more recent advances in models of neural control with models of lung function, into a full simulation for the respiratory system that builds upon the more detailed models but remains computationally tractable. This requires first understanding the mathematical models that have been developed for the respiratory system at different levels, and which could be used to study how physiological levels of O2 and CO2 in the blood are maintained.
Collapse
Affiliation(s)
- Alona Ben-Tal
- Institute of Natural and Mathematical Sciences, Massey University, Albany, Auckland, New Zealand
| | - Merryn H. Tawhai
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| |
Collapse
|
50
|
Immanuel SA, Kohler M, Pamula Y, Kabir MM, Saint DA, Baumert M. Increased variability in respiratory parameters heralds obstructive events in children with sleep disordered breathing. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2013; 2013:2024-7. [PMID: 24110115 DOI: 10.1109/embc.2013.6609928] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Sleep disordered breathing (SDB) is characterized by repeated episodes of central or obstructive apneas, disturbing respiratory patterns. The purpose of this study is to quantify respiratory variability associated with apneic/hypopneic events by computing respiratory parameters and thoraco-abdominal asynchrony (TAA) over sleep periods preceding the occurrence of obstructive events in children with SDB. One minute artifact-free epochs of ribcage (RC) and abdominal (AB) signals were extracted from the respiratory inductive plethysmograph (RIP) channel of the PSG prior to the onset of each obstruction. Breath-by-breath values of TAA were computed using a Hilbert transform based technique that measures the phase shift between the RC and AB signals. In addition, the following parameters were computed breath-by-breath from the RC signal: inspiratory time (Ti), expiratory time (Te), total time (Ttot), and the inspiratory duty cycle (DC=Ti/Ttot). Standard deviation of the parameters (SD_TAA, SD_Ti, SD_Te, SD_Ttot, SD_DC) over each 1 min epoch were calculated and averaged over each subject with respect to sleep stage. For comparison, similar measures were computed from within quiet breathing periods of each subject. We found that breaths immediately before apnea/hypopneas were associated with a high degree of variability in respiratory timing and TAA. The proposed variability analysis of RIP signals may be useful for detecting acute epochs of respiratory instability in children with SDB.
Collapse
|