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Foster K, Anholm JD, Foster G, Thapamagar S, Subedi P. Effects of Naltrexone on Sleep Quality and Periodic Breathing at High Altitude. High Alt Med Biol 2024. [PMID: 38966963 DOI: 10.1089/ham.2024.0023] [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: 07/06/2024] Open
Abstract
Foster, Katharine, James D. Anholm, Gary Foster, Suman Thapamagar, and Prajan Subedi. Effects of naltrexone on sleep quality and periodic breathing at high altitude. High Alt Med Biol. 00:000-000, 2024. Objective: This study examined the effects of naltrexone on breathing and sleep at high altitude. Mu-opioid receptor (MOR) agonists have a depressive effect on respiration. Naltrexone is known to block the MOR. We hypothesized that MOR blockade with naltrexone would result in higher nocturnal oxygen saturations, fewer apneas, and improved sleep at high altitude. Methods: This double-blind, placebo-controlled, crossover study included nine healthy volunteers (four females, five males) aged 27.9 (4.6) (mean [standard deviation]) years. Two overnight trips spaced at least 2 weeks apart took participants from Loma Linda, CA (355 m) to the Barcroft Laboratory, CA (3,810 m) for each arm. Participants ingested either 50 mg naltrexone or matching placebo at bedtime. Sleep metrics were recorded using an ambulatory physiological sleep monitor (APSM). Subjective data were measured with the Groningen Sleep Quality Scale, Stanford Sleepiness Scale, and the 2018 Lake Louise Score (LLS) for acute mountain sickness (AMS). Results: Mean overnight SpO2 was lower after taking naltrexone, 81% (6) versus 83% (4) (mean difference 1.9% [2.1, 95% confidence interval or CI = 0.1-3.6, p = 0.040]). The lowest overnight SpO2 (nadir) was lower on naltrexone 70% (6) versus 74% (4) (dif. 4.6% [4.3], CI = 1.0-8.2, p = 0.020). Total sleep time and total apnea-hypopnea index were unchanged. Subjective sleep quality was significantly worse on naltrexone measured via the Groningen Sleep Quality Scale (p = 0.033) and Stanford Sleepiness Scale (p = 0.038). AMS measured via LLS was significantly worse while taking naltrexone (p = 0.025). Conclusion: Contrary to our hypothesis, this study demonstrated a significant decrease in nocturnal oxygen saturation, worse sleep quality, and AMS scores. Further characterization of the MOR's effects on sleep and AMS is needed to evaluate potential exacerbating mechanisms for AMS and poor sleep quality at altitude.
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Affiliation(s)
- Katharine Foster
- Department of Emergency Medicine, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - James D Anholm
- Pulmonary & Critical Care, VA Loma Linda Healthcare System, Loma Linda, California, USA
- Department of Medicine, Loma Linda University School of Medicine, Loma Linda, California, USA
| | - Gary Foster
- Cardiology, St. Charles Health System, Bend, Oregon, USA
| | - Suman Thapamagar
- Department of Medicine, Loma Linda University School of Medicine, Loma Linda, California, USA
- Riverside University Healthcare System Medical Center, Moreno Valley, California, USA
| | - Prajan Subedi
- Pulmonary & Critical Care, VA Loma Linda Healthcare System, Loma Linda, California, USA
- Department of Medicine, Loma Linda University School of Medicine, Loma Linda, California, USA
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Patrician A, Anholm JD, Ainslie PN. A narrative review of periodic breathing during sleep at high altitude: From acclimatizing lowlanders to adapted highlanders. J Physiol 2024. [PMID: 38534039 DOI: 10.1113/jp285427] [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: 09/03/2023] [Accepted: 02/15/2024] [Indexed: 03/28/2024] Open
Abstract
Periodic breathing during sleep at high altitude is almost universal among sojourners. Here, in the context of acclimatization and adaptation, we provide a contemporary review on periodic breathing at high altitude, and explore whether this is an adaptive or maladaptive process. The mechanism(s), prevalence and role of periodic breathing in acclimatized lowlanders at high altitude are contrasted with the available data from adapted indigenous populations (e.g. Andean and Tibetan highlanders). It is concluded that (1) periodic breathing persists with acclimatization in lowlanders and the severity is proportional to sleeping altitude; (2) periodic breathing does not seem to coalesce with poor sleep quality such that, with acclimatization, there appears to be a lengthening of cycle length and minimal impact on the average sleeping oxygen saturation; and (3) high altitude adapted highlanders appear to demonstrate a blunting of periodic breathing, compared to lowlanders, comprising a feature that withstands the negative influences of chronic mountain sickness. These observations indicate that periodic breathing persists with high altitude acclimatization with no obvious negative consequences; however, periodic breathing is attenuated with high altitude adaptation and therefore potentially reflects an adaptive trait to this environment.
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Affiliation(s)
- Alexander Patrician
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, BC, Canada
| | - James D Anholm
- Department of Medicine, Division of Pulmonary and Critical Care, Loma Linda University School of Medicine, Loma Linda, CA, USA
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia - Okanagan, Kelowna, BC, Canada
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Ibrahim A, Stefani A, Cesari M, Roche J, Gatterer H, Holzknecht E, Turner R, Vinetti G, Furian M, Heidbreder A, Högl B, Siebenmann C. Effects of periodic breathing on sleep at high altitude: a randomized, placebo-controlled, crossover study using inspiratory CO 2. J Physiol 2024. [PMID: 38408065 DOI: 10.1113/jp285397] [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: 08/23/2023] [Accepted: 01/17/2024] [Indexed: 02/28/2024] Open
Abstract
Hypoxia at high altitude facilitates changes in ventilatory control that can lead to nocturnal periodic breathing (nPB). Here, we introduce a placebo-controlled approach to prevent nPB by increasing inspiratory CO2 and used it to assess whether nPB contributes to the adverse effects of hypoxia on sleep architecture. In a randomized, single-blinded, crossover design, 12 men underwent two sojourns (three days/nights each, separated by 4 weeks) in hypobaric hypoxia corresponding to 4000 m altitude, with polysomnography during the first and third night of each sojourn. During all nights, subjects' heads were encompassed by a canopy retaining exhaled CO2 , and CO2 concentration in the canopy (i.e. inspiratory CO2 concentration) was controlled by adjustment of fresh air inflow. Throughout the placebo sojourn inspiratory CO2 was ≤0.2%, whereas throughout the other sojourn it was increased to 1.76% (IQR, 1.07%-2.44%). During the placebo sojourn, total sleep time (TST) with nPB was 54.3% (37.4%-80.8%) and 45.0% (24.5%-56.5%) during the first and the third night, respectively (P = 0.042). Increased inspiratory CO2 reduced TST with nPB by an absolute 38.1% (28.1%-48.1%), the apnoea-hypopnoea index by 58.1/h (40.1-76.1/h), and oxygen desaturation index ≥3% by 56.0/h (38.9.1-73.2/h) (all P < 0.001), whereas it increased the mean arterial oxygen saturation in TST by 2.0% (0.4%-3.5%, P = 0.035). Increased inspiratory CO2 slightly increased the percentage of N3 sleep during the third night (P = 0.045), without other effects on sleep architecture. Increasing inspiratory CO2 effectively prevented hypoxia-induced nPB without affecting sleep macro-architecture, indicating that nPB does not explain the sleep deterioration commonly observed at high altitudes. KEY POINTS: Periodic breathing is common during sleep at high altitude, and it is unclear how this affects sleep architecture. We developed a placebo-controlled approach to prevent nocturnal periodic breathing (nPB) with inspiratory CO2 administration and used it to assess the effects of nPB on sleep in hypobaric hypoxia. Nocturnal periodic breathing was effectively mitigated by an increased inspiratory CO2 fraction in a blinded manner. Prevention of nPB did not lead to relevant changes in sleep architecture in hypobaric hypoxia. We conclude that nPB does not explain the deterioration in sleep architecture commonly observed at high altitude.
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Affiliation(s)
- Abubaker Ibrahim
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Ambra Stefani
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Matteo Cesari
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Johanna Roche
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Hannes Gatterer
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Evi Holzknecht
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Rachel Turner
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Giovanni Vinetti
- Institute of Mountain Emergency Medicine, Eurac Research, Bolzano, Italy
| | - Michael Furian
- Department of Respiratory Medicine, University Hospital of Zurich, Zurich, Switzerland
| | - Anna Heidbreder
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
| | - Birgit Högl
- Department of Neurology, Medical University of Innsbruck, Innsbruck, Austria
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Niclou A, Sarma M, Levy S, Ocobock C. To the extreme! How biological anthropology can inform exercise physiology in extreme environments. Comp Biochem Physiol A Mol Integr Physiol 2023; 284:111476. [PMID: 37423419 DOI: 10.1016/j.cbpa.2023.111476] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2023] [Revised: 07/03/2023] [Accepted: 07/04/2023] [Indexed: 07/11/2023]
Abstract
The fields of biological anthropology and exercise physiology are closely related and can provide mutually beneficial insights into human performance. These fields often use similar methods and are both interested in how humans function, perform, and respond in extreme environments. However, these two fields have different perspectives, ask different questions, and work within different theoretical frameworks and timescales. Biological anthropologists and exercise physiologists can greatly benefit from working together when examining human adaptation, acclimatization, and athletic performance in the extremes of heat, cold, and high-altitude. Here we review the adaptations and acclimatizations in these three different extreme environments. We then examine how this work has informed and built upon exercise physiology research on human performance. Finally, we present an agenda for moving forward, hopefully, with these two fields working more closely together to produce innovative research that improves our holistic understanding of human performance capacities informed by evolutionary theory, modern human acclimatization, and the desire to produce immediate and direct benefits.
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Affiliation(s)
- Alexandra Niclou
- Pennington Biomedical Research Center, Baton Rouge, LA, United States of America. https://twitter.com/fiat_luxandra
| | - Mallika Sarma
- Human Space Flight Lab, Johns Hopkins School of Medicine, Baltimore, MD, United States of America. https://twitter.com/skyy_mal
| | - Stephanie Levy
- Department of Anthropology, CUNY Hunter College, New York, NY, United States of America; New York Consortium in Evolutionary Primatology, New York, NY, United States of America. https://twitter.com/slevyscience
| | - Cara Ocobock
- University of Notre Dame Department of Anthropology, Notre Dame, IN, United States of America; Eck Institute for Global Health, Institute for Educational Initiatives, University of Notre Dame, United States of America.
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Abstract
With ascent to high altitude, barometric pressure declines, leading to a reduction in the partial pressure of oxygen at every point along the oxygen transport chain from the ambient air to tissue mitochondria. This leads, in turn, to a series of changes over varying time frames across multiple organ systems that serve to maintain tissue oxygen delivery at levels sufficient to prevent acute altitude illness and preserve cognitive and locomotor function. This review focuses primarily on the physiological adjustments and acclimatization processes that occur in the lungs of healthy individuals, including alterations in control of breathing, ventilation, gas exchange, lung mechanics and dynamics, and pulmonary vascular physiology. Because other organ systems, including the cardiovascular, hematologic and renal systems, contribute to acclimatization, the responses seen in these systems, as well as changes in common activities such as sleep and exercise, are also addressed. While the pattern of the responses highlighted in this review are similar across individuals, the magnitude of such responses often demonstrates significant interindividual variability which accounts for subsequent differences in tolerance of the low oxygen conditions in this environment.
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Affiliation(s)
- Marc Moritz Berger
- Department of Anesthesiology and Intensive Care Medicine, University Hospital Essen, University Duisburg-Essen, Essen, Germany
| | - Andrew M Luks
- Division of Pulmonary, Critical Care and Sleep Medicine, University of Washington, Seattle, Washington
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Yegen CH, Marchant D, Bernaudin JF, Planes C, Boncoeur E, Voituron N. Chronic pulmonary fibrosis alters the functioning of the respiratory neural network. Front Physiol 2023; 14:1205924. [PMID: 37383147 PMCID: PMC10293840 DOI: 10.3389/fphys.2023.1205924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 06/02/2023] [Indexed: 06/30/2023] Open
Abstract
Some patients with idiopathic pulmonary fibrosis present impaired ventilatory variables characterised by low forced vital capacity values associated with an increase in respiratory rate and a decrease in tidal volume which could be related to the increased pulmonary stiffness. The lung stiffness observed in pulmonary fibrosis may also have an effect on the functioning of the brainstem respiratory neural network, which could ultimately reinforce or accentuate ventilatory alterations. To this end, we sought to uncover the consequences of pulmonary fibrosis on ventilatory variables and how the modification of pulmonary rigidity could influence the functioning of the respiratory neuronal network. In a mouse model of pulmonary fibrosis obtained by 6 repeated intratracheal instillations of bleomycin (BLM), we first observed an increase in minute ventilation characterised by an increase in respiratory rate and tidal volume, a desaturation and a decrease in lung compliance. The changes in these ventilatory variables were correlated with the severity of the lung injury. The impact of lung fibrosis was also evaluated on the functioning of the medullary areas involved in the elaboration of the central respiratory drive. Thus, BLM-induced pulmonary fibrosis led to a change in the long-term activity of the medullary neuronal respiratory network, especially at the level of the nucleus of the solitary tract, the first central relay of the peripheral afferents, and the Pre-Bötzinger complex, the inspiratory rhythm generator. Our results showed that pulmonary fibrosis induced modifications not only of pulmonary architecture but also of central control of the respiratory neural network.
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Affiliation(s)
- Céline-Hivda Yegen
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
| | - Dominique Marchant
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
| | - Jean-François Bernaudin
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
- Faculté de Médecine, Sorbonne Université, Paris, France
| | - Carole Planes
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
- Service de Physiologie et d’Explorations Fonctionnelles, Hôpital Avicenne, APHP, Bobigny, France
| | - Emilie Boncoeur
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
| | - Nicolas Voituron
- Laboratoire Hypoxie & Poumon, UMR INSERM U1272, Université Sorbonne Paris Nord, Bobigny, France
- Département STAPS, Université Sorbonne Paris Nord, Bobigny, France
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Furian M, Bitos K, Hartmann SE, Muralt L, Lichtblau M, Bader PR, Rawling JM, Ulrich S, Poulin MJ, Bloch KE. Acute high altitude exposure, acclimatization and re-exposure on nocturnal breathing. Front Physiol 2022; 13:965021. [PMID: 36134332 PMCID: PMC9483161 DOI: 10.3389/fphys.2022.965021] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2022] [Accepted: 08/11/2022] [Indexed: 12/02/2022] Open
Abstract
Background: Effects of prolonged and repeated high-altitude exposure on oxygenation and control of breathing remain uncertain. We hypothesized that prolonged and repeated high-altitude exposure will improve altitude-induced deoxygenation and breathing instability. Methods: 21 healthy lowlanders, aged 18-30y, underwent two 7-day sojourns at a high-altitude station in Chile (4–8 hrs/day at 5,050 m, nights at 2,900 m), separated by a 1-week recovery period at 520 m. Respiratory sleep studies recording mean nocturnal pulse oximetry (SpO2), oxygen desaturation index (ODI, >3% dips in SpO2), breathing patterns and subjective sleep quality by visual analog scale (SQ-VAS, 0–100% with increasing quality), were evaluated at 520 m and during nights 1 and 6 at 2,900 m in the 1st and 2nd altitude sojourn. Results: At 520 m, mean ± SD nocturnal SpO2 was 94 ± 1%, ODI 2.2 ± 1.2/h, SQ-VAS 59 ± 20%. Corresponding values at 2,900 m, 1st sojourn, night 1 were: SpO2 86 ± 2%, ODI 23.4 ± 22.8/h, SQ-VAS 39 ± 23%; 1st sojourn, night 6: SpO2 90 ± 1%, ODI 7.3 ± 4.4/h, SQ-VAS 55 ± 20% (p < 0.05, all differences within corresponding variables). Mean differences (Δ, 95%CI) in acute effects (2,900 m, night 1, vs 520 m) between 2nd vs 1st altitude sojourn were: ΔSpO2 0% (-1 to 1), ΔODI -9.2/h (-18.0 to -0.5), ΔSQ-VAS 10% (-6 to 27); differences in acclimatization (changes night 6 vs 1), between 2nd vs 1st sojourn at 2,900 m were: ΔSpO2 -1% (-2 to 0), ΔODI 11.1/h (2.5 to 19.7), ΔSQ-VAS -15% (-31 to 1). Conclusion: Acute high-altitude exposure induced nocturnal hypoxemia, cyclic deoxygenations and impaired sleep quality. Acclimatization mitigated these effects. After recovery at 520 m, repeated exposure diminished high-altitude-induced deoxygenation and breathing instability, suggesting some retention of adaptation induced by the first altitude sojourn while subjective sleep quality remained similarly impaired.
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Affiliation(s)
- Michael Furian
- University Hospital Zurich, Department of Respiratory Medicine, Zurich, Switzerland
| | - Konstantinos Bitos
- University Hospital Zurich, Department of Respiratory Medicine, Zurich, Switzerland
| | - Sara E. Hartmann
- University of Calgary, Cumming School of Medicine, Department of Physiology and Pharmacology and Hotchkiss Brain Institute, Calgary, AB, Canada
| | - Lara Muralt
- University Hospital Zurich, Department of Respiratory Medicine, Zurich, Switzerland
| | - Mona Lichtblau
- University Hospital Zurich, Department of Respiratory Medicine, Zurich, Switzerland
| | - Patrick R. Bader
- University Hospital Zurich, Department of Respiratory Medicine, Zurich, Switzerland
| | - Jean M. Rawling
- University of Calgary, Cumming School of Medicine, Department of Family Medicine, Calgary, AB, Canada
| | - Silvia Ulrich
- University Hospital Zurich, Department of Respiratory Medicine, Zurich, Switzerland
| | - Marc J. Poulin
- University of Calgary, Cumming School of Medicine, Department of Physiology and Pharmacology and Hotchkiss Brain Institute, Calgary, AB, Canada
| | - Konrad E. Bloch
- University Hospital Zurich, Department of Respiratory Medicine, Zurich, Switzerland
- *Correspondence: Konrad E. Bloch,
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Heiniger G, Walbaum S, Sartori C, Lovis A, Sazzini M, Wellman A, Heinzer R. Altitude-Induced Sleep Apnea Is Highly Dependent on Ethnic Background (Sherpa Vs. Tamang). High Alt Med Biol 2022; 23:165-172. [PMID: 35708530 DOI: 10.1089/ham.2022.0012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Heiniger, Grégory, Simon Walbaum, Claudio Sartori, Alban Lovis, Marco Sazzini, Andrew Wellman, and Raphael Heinzer. Altitude-Induced Sleep Apnea Is Highly Dependent on Ethnic Background (Sherpa Vs. Tamang). High Alt Med Biol. 23:165-172, 2022. Rationale: High altitude-induced hypocapnic alkalosis generates central sleep apnea (CSA). In Nepal, two ethnic groups live at medium-to-high altitude: Tamangs originate from low-altitude Tibeto-Burman populations, whereas Sherpas descend from high-altitude Tibetans. Objective: To compare apnea severity at low and high altitude between Sherpas and Tamangs. Methods: Polygraphy recordings, including airflow and oxygen saturation, were performed in Nepal at "low" (2,030 m) and "high" (4,380 m) altitudes. Resting ventilation (V̇E) and mixed-exhaled CO2 (FECO2) were also measured at the same altitudes. Differences in apnea-hypopnea index (AHI), oxygen desaturation index (ODI), and % of nocturnal periodic breathing (NPB) at the two altitudes were compared between ethnicities. Measurements and Main Results: Twenty Sherpas and 20 Tamangs were included (males, median [interquartile range] age: 24.5 [21.5-27.8] years vs. 26.0 [21.5-39.8] years, body mass index: 23.9 [22.1-26.1] kg/m2 vs. 25.21 [20.6-27.6] kg/m2). Compared with Tamangs, Sherpas showed a lower increase in AHI (+7.5 [2.6-17.2]/h vs. +31.5 [18.2-57.3]/h, p < 0.001), ODI (+13.8 [5.5-28.2]/h vs. +42.0 [22.6-77.6]/h, p < 0.001), and NPB proportion (+0.9 [0-3.5]% vs. +12.8 [3.1-27.4]%, p < 0.001) from low to high altitude. Resting V̇E was higher in Sherpas versus Tamangs at both low (8.45 [6.89-10.70] l/min vs. 6.3 [4.9-8.3] l/min, p = 0.005) and high (9.7 [8.5-11] l/min vs. 8.74 [7.39-9.73] l/min, p = 0.020) altitudes, whereas the mean ± standard deviation FECO2 decrease between low and high altitude was greater in Tamangs versus Sherpas (-0.50% ± 0.44% vs. -0.80% ± 0.33%, p < 0.023). Conclusion: Overall, altitude-adapted Sherpas showed a 3.2-times smaller increase in sleep-disordered breathing between low and high altitude compared with Tamangs, and higher ventilation and a smaller drop in FECO2 at high altitude. These data suggest that genetic differences in breathing control can be protective against CSA.
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Affiliation(s)
- Grégory Heiniger
- Center for Investigation and Research in Sleep, University Hospital of Lausanne, Lausanne, Switzerland
| | - Simon Walbaum
- Department of Internal Medicine and University Hospital of Lausanne, Lausanne, Switzerland
| | - Claudio Sartori
- Department of Internal Medicine and University Hospital of Lausanne, Lausanne, Switzerland
| | - Alban Lovis
- Department of Pulmonary, University Hospital of Lausanne, Lausanne, Switzerland
| | - Marco Sazzini
- Interdepartmental Centre Alma Mater Research Institute on Global Challenges and Climate Change, University of Bologna, Bologna, Italy.,Department of Biological, Geological and Environmental Sciences (BiGeA), Laboratory of Molecular Anthropology and Centre for Genome Biology, University of Bologna, Bologna, Italy
| | - Andrew Wellman
- Division of Sleep Medicine, Harvard Medical School, Boston, Massachusetts, USA
| | - Raphael Heinzer
- Center for Investigation and Research in Sleep, University Hospital of Lausanne, Lausanne, Switzerland
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Calderon-Jofre R, Moraga D, Moraga FA. The Effect of Chronic Intermittent Hypobaric Hypoxia on Sleep Quality and Melatonin Serum Levels in Chilean Miners. Front Physiol 2022; 12:809360. [PMID: 35222064 PMCID: PMC8864145 DOI: 10.3389/fphys.2021.809360] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2021] [Accepted: 12/22/2021] [Indexed: 11/13/2022] Open
Abstract
High-altitude mining is an important economic resource for Chile. These workers are exposed to chronic intermittent hypobaric hypoxia (CIHH), which reduces their sleep quality and increases the risk of accidents and long-term illnesses. Melatonin, a hormone produced by the pineal gland, is a sleep inducer that regulates the circadian cycle and may be altered in populations subjected to CIHH. This work aimed to assess the relationship between altitude, sleep quality, and plasma melatonin concentrations in miners with CIHH exposure. 288 volunteers were recruited from five altitudes (0, 1,600, 2,500, 3,500, and 4,500 m). All volunteers worked for 7 days at altitude, followed by 7 days of rest at sea level. We performed anthropometric assessments, nocturnal oximetry, sleep quality and sleepiness surveys, and serum melatonin levels upon awakening. Although oxygen saturation progressively decreased and heart rate increased at higher altitudes, subjective perception of sleep quality was not significantly different, and sleepiness increased in all groups compared to population at sea level. Similarly, melatonin levels increased at all assessed altitudes compared to the population at sea level. These data confirm that sleep disturbances associated with CIHH increase morning melatonin levels. Therefore, this hormone and could potentially serve as a biomarker of sleep quality.
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Affiliation(s)
- Rodrigo Calderon-Jofre
- Laboratorio de Fisiología, Hipoxia y Función Vascular, Departamento de Ciencias Biomédicas, Facultad de Medicina, Universidad Católica del Norte, Coquimbo, Chile
| | - Daniel Moraga
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universidad de Tarapacá, Arica, Chile
| | - Fernando A. Moraga
- Departamento de Medicina, Facultad de Ciencias de la Salud, Universidad de Tarapacá, Arica, Chile
- *Correspondence: Fernando A. Moraga,
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Bird JD, Kalker A, Rimke AN, Chan JS, Chan G, Saran G, Jendzjowsky NG, Wilson RJA, Brutsaert TD, Sherpa MT, Day TA. Severity of central sleep apnea does not affect sleeping oxygen saturation during ascent to high altitude. J Appl Physiol (1985) 2021; 131:1432-1443. [PMID: 34435507 DOI: 10.1152/japplphysiol.00363.2021] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Central sleep apnea (CSA) is characterized by periodic breathing (PB) during sleep, defined as intermittent periods of apnea/hypopnea and hyperventilation, with associated acute fluctuations in oxyhemoglobin saturation (SO2). CSA has an incidence of ∼50% in heart failure patients but is universal at high altitude (HA; ≥2,500 m), increasing in severity with further ascent and/or time at altitude. However, whether PB is adaptive, maladaptive, or neutral with respect to sleeping SO2 at altitude is unclear. We hypothesized that PB severity would improve mean sleeping SO2 during acclimatization to HA due to relative, intermittent hyperventilation subsequent to each apnea. We utilized portable sleep monitors to assess the incidence and severity of CSA via apnea-hypopnea index (AHI) and oxygen desaturation index (ODI), and peripheral oxygen saturation ([Formula: see text]) during sleep during two ascent profiles to HA in native lowlanders: 1) rapid ascent to and residence at 3,800 m for 9 days/nights (n = 21) and 2) incremental ascent to 5,160 m over 10 days/nights (n = 21). In both ascent models, severity of AHI and ODI increased and mean sleeping [Formula: see text] decreased, as expected. However, during sleep on the last night/highest altitude of both ascent profiles, neither AHI nor ODI were correlated with mean sleeping [Formula: see text]. In addition, mean sleeping [Formula: see text] was not significantly different between high and low CSA. These data suggest that CSA is neither adaptive nor maladaptive with regard to mean oxygen saturation during sleep, owing to the relative hyperventilation between apneas, likely correcting transient apnea-mediated oxygen desaturation and maintaining mean oxygenation.NEW & NOTEWORTHY Central sleep apnea (CSA) is universal during ascent to high altitude, with intermittent and transient fluctuations in oxygen saturation, but the consequences on mean sleeping blood oxygenation are unclear. We assessed indices of CSA and mean sleeping peripheral oxygen saturation ([Formula: see text]) during ascent to high altitude using two ascent profiles: rapid ascent and residence at 3,800 m and incremental ascent to 5,160 m. The severity of CSA was not correlated with mean sleeping [Formula: see text] with ascent.
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Affiliation(s)
- Jordan D Bird
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Anne Kalker
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada.,Radboud University Medical Center, Nijmegen, The Netherlands
| | - Alexander N Rimke
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Jason S Chan
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Garrick Chan
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Gurkarn Saran
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
| | - Nicholas G Jendzjowsky
- Respiratory Medicine and Exercise Physiology, The Lundquist Institute for Biomedical Innovation, Harbor UCLA Medical Center, West Carson, California
| | - Richard J A Wilson
- Department of Physiology and Pharmacology, Hotchkiss Brain Institute and Alberta Children's Hospital Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Thomas D Brutsaert
- Department of Exercise Science, School of Education, Syracuse University, Syracuse, New York
| | | | - Trevor A Day
- Faculty of Science and Technology, Department of Biology, Mount Royal University, Calgary, Alberta, Canada
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11
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Vignati C, Mapelli M, Nusca B, Bonomi A, Salvioni E, Mattavelli I, Sciomer S, Faini A, Parati G, Agostoni P. A Breathtaking Lift: Sex and Body Mass Index Differences in Cardiopulmonary Response in a Large Cohort of Unselected Subjects with Acute Exposure to High Altitude. High Alt Med Biol 2021; 22:379-385. [PMID: 34424758 PMCID: PMC8742268 DOI: 10.1089/ham.2021.0039] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Vignati, Carlo, Massimo Mapelli, Benedetta Nusca, Alice Bonomi, Elisabetta Salvioni, Irene Mattavelli, Susanna Sciomer, Andrea Faini, Gianfranco Parati, and Piergiuseppe Agostoni. A breathtaking lift: sex and body mass index differences in cardiopulmonary response in a large cohort of unselected subjects with acute exposure to high altitude. High Alt Med Biol 00:000-000, 2021. Background: Every year, thousands of people travel to high altitude and experience hypoxemia. At high altitude, the partial pressure of oxygen decreases. The aim of this observational study was to determine if there is a relationship between anthropometric features and basic cardiorespiratory variables, including oxygen saturation (SpO2), heart rate (HR), and blood pressure (BP), following acute exposure to high altitude. Materials and Methods: At the 3,466 m top of a cableway station, we installed an automated system for measuring peripheral SpO2, HR, BP, height, weight, and body mass index (BMI). Results: Between January and October 2020, out of 4,874 volunteers (age 39.9 ± 15.4 years, male 54.4%), 3,267 provided complete data (1,808 cases during winter and 1,459 during summer). SpO2 was 86.8% ± 6.8%. At multivariable analysis, SpO2 was significantly associated with age, sex, season, BMI, and HR but not with BP. We identified 391 (12%) subjects with SpO2 ≤80%: they were older, with a higher BMI and HR but without sex or BP differences. Finally, winter season was associated with greater frequency of SpO2 ≤80% (13.3% vs. 10.3%, p = 0.008). Conclusion: Our data show that high BMI, older age, and male sex were associated with greater degrees of hypoxemia following exposure to high altitude, particularly during the winter.
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Affiliation(s)
- Carlo Vignati
- Centro Cardiologico Monzino, IRCCS, Milan, Italy.,Department of Clinical Sciences and Community Health, Cardiovascular Section, University of Milan, Milan, Italy
| | - Massimo Mapelli
- Centro Cardiologico Monzino, IRCCS, Milan, Italy.,Department of Clinical Sciences and Community Health, Cardiovascular Section, University of Milan, Milan, Italy
| | | | - Alice Bonomi
- Centro Cardiologico Monzino, IRCCS, Milan, Italy
| | | | | | - Susanna Sciomer
- Dipartimento di Scienze Cardiovascolari, Respiratorie, Nefrologiche, Anestesiologiche e Geriatriche, "Sapienza" Rome University, Rome, Italy
| | - Andrea Faini
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular, Neural and Metabolic Sciences, San Luca Hospital, Milan, Italy
| | - Gianfranco Parati
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular, Neural and Metabolic Sciences, San Luca Hospital, Milan, Italy.,Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Piergiuseppe Agostoni
- Centro Cardiologico Monzino, IRCCS, Milan, Italy.,Department of Clinical Sciences and Community Health, Cardiovascular Section, University of Milan, Milan, Italy
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12
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Venkat D, Dhillon K, Rowley JA. Effects of High Altitude on Sleep and Respiratory System. CURRENT PULMONOLOGY REPORTS 2021. [DOI: 10.1007/s13665-021-00276-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
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13
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Heinrich EC, Orr JE, Gilbertson D, Anza-Ramirez C, DeYoung PN, Djokic MA, Corante N, Vizcardo-Galindo G, Macarlupu JL, Gaio E, Powell FL, Malhotra A, Villafuerte FC, Simonson TS. Relationships Between Chemoreflex Responses, Sleep Quality, and Hematocrit in Andean Men and Women. Front Physiol 2020; 11:437. [PMID: 32435207 PMCID: PMC7219107 DOI: 10.3389/fphys.2020.00437] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Accepted: 04/08/2020] [Indexed: 12/12/2022] Open
Abstract
Andean highlanders are challenged by chronic hypoxia and many exhibit elevated hematocrit (Hct) and blunted ventilation compared to other high-altitude populations. While many Andeans develop Chronic Mountain Sickness (CMS) and excessive erythrocytosis, Hct varies markedly within Andean men and women and may be driven by individual differences in ventilatory control and/or sleep events which exacerbate hypoxemia. To test this hypothesis, we quantified relationships between resting ventilation and ventilatory chemoreflexes, sleep desaturation, breathing disturbance, and Hct in Andean men and women. Ventilatory measures were made in 109 individuals (n = 63 men; n = 46 women), and sleep measures in 45 of these participants (n = 22 men; n = 23 women). In both men and women, high Hct was associated with low daytime SpO2 (p < 0.001 and p < 0.002, respectively) and decreased sleep SpO2 (mean, nadir, and time <80%; all p < 0.02). In men, high Hct was also associated with increased end-tidal PCO2 (p < 0.009). While ventilatory responses to hypoxia and hypercapnia did not predict Hct, decreased hypoxic ventilatory responses were associated with lower daytime SpO2 in men (p < 0.01) and women (p < 0.009) and with lower nadir sleep SpO2 in women (p < 0.02). Decreased ventilatory responses to CO2 were associated with more time below 80% SpO2 during sleep in men (p < 0.05). The obstructive apnea index and apnea-hypopnea index also predicted Hct and CMS scores in men after accounting for age, BMI, and SpO2 during sleep. Finally, heart rate response to hypoxia was lower in men with higher Hct (p < 0.0001). These data support the idea that hypoventilation and decreased ventilatory sensitivity to hypoxia are associated with decreased day time and nighttime SpO2 levels that may exacerbate the stimulus for erythropoiesis in Andean men and women. However, interventional and longitudinal studies are required to establish the causal relationships between these associations.
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Affiliation(s)
- Erica C. Heinrich
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Jeremy E. Orr
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Dillon Gilbertson
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Cecilia Anza-Ramirez
- Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígen, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Pamela N. DeYoung
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Matea A. Djokic
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Noemi Corante
- Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígen, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Gustavo Vizcardo-Galindo
- Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígen, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Jose L. Macarlupu
- Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígen, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Eduardo Gaio
- Faculty of Medicine, University of Brasília, Brasília, Brazil
| | - Frank L. Powell
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
| | - Francisco C. Villafuerte
- Laboratorio de Fisiología Comparada/Fisiología del Transporte de Oxígen, Facultad de Ciencias y Filosofía, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Tatum S. Simonson
- Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California, San Diego, San Diego, CA, United States
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14
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Abstract
Central sleep apnea is prevalent in patients with heart failure, healthy individuals at high altitudes, and chronic opiate users and in the initiation of "mixed" (that is, central plus obstructive apneas). This brief review focuses on (a) the causes of repetitive, cyclical central apneas as mediated primarily through enhanced sensitivities in the respiratory control system and (b) treatment of central sleep apnea through modification of key components of neurochemical control as opposed to the current universal use of positive airway pressure.
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Affiliation(s)
- Jerome A. Dempsey
- Department of Population Health Sciences, University of Wisconsin - Madison, WARF Building, 7th Floor, 614 Walnut Street, Madison, WI 53726, USA
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15
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Lebret M, Wuyam B, Bertrand D, Chaudot C, Pépin JL, Borel JC. Effectiveness of a lightweight portable auto-CPAP device for the treatment of sleep apnea during high altitude stages of the Dakar Rally: a case report. Sleep Sci 2018; 11:123-126. [PMID: 30083301 PMCID: PMC6056067 DOI: 10.5935/1984-0063.20180023] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Sleep-related breathing disturbances are exacerbated at altitude in patients with Obstructive Sleep Apnea (OSA). The objective of this case report was to determine if a portable auto-CPAP device effectively treated sleep apnea across different altitudes. We report the severity of sleep apnea from 60 to 12,000 feet high in a man with severe OSA (Apnea Hypopnea Index at diagnosis = 60 events/hour) during the 2017 Dakar rally over the Andes mountains. The man was equipped with a lightweight portable auto-CPAP device with a narrow window [6-8 cmH2O]. Pressures delivered and corresponding residual events were assessed at different altitudes. The 95th percentile pressure reached the maximal set pressure at the highest altitudes, and residual AHI increased from 5 events/hour to 45 events/hour at the highest altitudes. Potential mechanisms behind the development of central apnea, and optimal clinical management at altitude are discussed in the light of the findings.
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Affiliation(s)
- Marius Lebret
- Inserm U1042, HP2 laboratory - Grenoble - Isère - França.,Agir a dom., Agir a dom. - Meylan - Isère - França
| | - Bernard Wuyam
- Inserm U1042, HP2 laboratory - Grenoble - Isère - França.,Thorax and vessels division Grenoble Alpes University Hospital, Sleep Laboratory and Exercise Physiology - Grenoble - Isère - França
| | - Dominique Bertrand
- Pulmonary and Sleep clinic, Pulmonary and sleep clinic - St Ismier - isère - França
| | | | - Jean-Louis Pépin
- Inserm U1042, HP2 laboratory - Grenoble - Isère - França.,Thorax and vessels division Grenoble Alpes University Hospital, Sleep Laboratory and Exercise Physiology - Grenoble - Isère - França
| | - Jean-Christian Borel
- Inserm U1042, HP2 laboratory - Grenoble - Isère - França.,Agir a dom., Agir a dom. - Meylan - Isère - França.,Thorax and vessels division Grenoble Alpes University Hospital, Sleep Laboratory and Exercise Physiology - Grenoble - Isère - França
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16
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Pun M, Hartmann SE, Furian M, Dyck AM, Muralt L, Lichtblau M, Bader PR, Rawling JM, Ulrich S, Bloch KE, Poulin MJ. Effect of Acute, Subacute, and Repeated Exposure to High Altitude (5050 m) on Psychomotor Vigilance. Front Physiol 2018; 9:677. [PMID: 29915546 PMCID: PMC5994420 DOI: 10.3389/fphys.2018.00677] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 05/15/2018] [Indexed: 12/20/2022] Open
Abstract
Aim: High altitude (HA) hypoxia may affect cognitive performance and sleep quality. Further, vigilance is reduced following sleep deprivation. We investigated the effect on vigilance, actigraphic sleep indices, and their relationships with acute mountain sickness (AMS) during very HA exposure, acclimatization, and re-exposure. Methods: A total of 21 healthy altitude-naive individuals (25 ± 4 years; 13 females) completed 2 cycles of altitude exposure separated by 7 days at low altitude (LA, 520 m). Participants slept at 2900 m and spent the day at HA, (5050 m). We report acute altitude exposure on Day 1 (LA vs. HA1) and after 6 days of acclimatization (HA1 vs. HA6). Vigilance was quantified by reaction speed in the 10-min psychomotor vigilance test reaction speed (PVT-RS). AMS was evaluated using the Environmental Symptoms Questionnaire Cerebral Score (AMS-C score). Nocturnal rest/activity was recorded to estimate sleep duration using actigraphy. Results: In Cycle 1, PVT-RS was slower at HA1 compared to LA (4.1 ± 0.8 vs. 4.5 ± 0.6 s-1, respectively, p = 0.029), but not at HA6 (4.6 ± 0.7; p > 0.05). In Cycle 2, PVT-RS at HA1 (4.6 ± 0.7) and HA6 (4.8 ± 0.6) were not different from LA (4.8 ± 0.6, p > 0.05) and significantly greater than corresponding values in Cycle 1. In both cycles, AMS scores were higher at HA1 than at LA and HA6 (p < 0.05). Estimated sleep durations (TST) at LA, 1st and 5th nights were 431.3 ± 28.7, 418.1 ± 48.6, and 379.7 ± 51.4 min, respectively, in Cycle 1 and they were significantly reduced during acclimatization exposures (LA vs. 1st night, p > 0.05; LA vs. 5th night, p = 0.012; and 1st vs. 5th night, p = 0.054). LA, 1st and 5th nights TST in Cycle 2 were 477.5 ± 96.9, 430.9 ± 34, and 341.4 ± 32.2, respectively, and we observed similar deteriorations in TST as in Cycle 1 (LA vs. 1st night, p > 0.05; LA vs. 5th night, p = 0.001; and 1st vs. 5th night, p < 0.0001). At HA1, subjects who reported higher AMS-C scores exhibited slower PVT-RS (r = -0.56; p < 0.01). Subjects with higher AMS-C scores took longer time to react to the stimuli during acute exposure (r = 0.62, p < 0.01) during HA1 of Cycle 1. Conclusion: Acute exposure to HA reduces the PVT-RS. Altitude acclimatization over 6 days recovers the reaction speed and prevents impairments during subsequent altitude re-exposure after 1 week spent near sea level. However, acclimatization does not lead to improvement in total sleep time during acute and subacute exposures.
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Affiliation(s)
- Matiram Pun
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Sara E Hartmann
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Michael Furian
- Pulmonary Division, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Adrienna M Dyck
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada
| | - Lara Muralt
- Pulmonary Division, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Mona Lichtblau
- Pulmonary Division, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Patrick R Bader
- Pulmonary Division, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Jean M Rawling
- Department of Family Medicine, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Silvia Ulrich
- Pulmonary Division, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Konrad E Bloch
- Pulmonary Division, Sleep Disorders Centre and Pulmonary Hypertension Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Marc J Poulin
- Department of Physiology and Pharmacology, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Hotchkiss Brain Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Faculty of Kinesiology, University of Calgary, Calgary, AB, Canada.,Libin Cardiovascular Institute of Alberta, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,O'Brien Institute for Public Health, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada.,Department of Clinical Neurosciences, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
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17
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Orr JE, Heinrich EC, Djokic M, Gilbertson D, Deyoung PN, Anza-Ramirez C, Villafuerte FC, Powell FL, Malhotra A, Simonson T. Adaptive Servoventilation as Treatment for Central Sleep Apnea Due to High-Altitude Periodic Breathing in Nonacclimatized Healthy Individuals. High Alt Med Biol 2018; 19:178-184. [PMID: 29641294 PMCID: PMC6014053 DOI: 10.1089/ham.2017.0147] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2017] [Accepted: 01/20/2018] [Indexed: 12/17/2022] Open
Abstract
Orr, Jeremy E., Erica C. Heinrich, Matea Djokic, Dillon Gilbertson, Pamela N. Deyoung, Cecilia Anza-Ramirez, Francisco C. Villafuerte, Frank L. Powell, Atul Malhotra, and Tatum Simonson. Adaptive servoventilation as treatment for central sleep apnea due to high-altitude periodic breathing in nonacclimatized healthy individuals. High Alt Med Biol. 19:178-184, 2018. AIMS Central sleep apnea (CSA) is common at high altitude, leading to desaturation and sleep disruption. We hypothesized that noninvasive ventilation using adaptive servoventilation (ASV) would be effective at stabilizing CSA at altitude. Supplemental oxygen was evaluated for comparison. METHODS Healthy subjects were brought from sea level to 3800 m and underwent polysomnography on three consecutive nights. Subjects underwent each condition-No treatment, ASV, and supplemental oxygen-in random order. The primary outcome was the effect of ASV on oxygen desaturation index (ODI). Secondary outcomes included oxygen saturation, arousals, symptoms, and comparison to supplemental oxygen. RESULTS Eighteen subjects underwent at least two treatment conditions. There was a significant difference in ODI across the three treatments. There was no statistical difference in ODI between no treatment and ASV (17.1 ± 4.2 vs. 10.7 ± 2.9 events/hour; p > 0.17) and no difference in saturation or arousal index. Compared with no treatment, oxygen improved the ODI (16.5 ± 4.5 events/hour vs. 0.5 ± 0.2 events/hour; p < 0.003), in addition to saturation and arousal index. CONCLUSIONS We found that ASV was not clearly efficacious at controlling CSA in persons traveling to 3800 m, whereas supplemental oxygen resolved CSA. Adjustment in the ASV algorithm may improve efficacy. ASV may have utility in acclimatized persons or at more modest altitudes.
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Affiliation(s)
- Jeremy E. Orr
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California
| | - Erica C. Heinrich
- Department of Medicine, Division of Physiology, University of California San Diego, La Jolla, California
| | - Matea Djokic
- Department of Medicine, Division of Physiology, University of California San Diego, La Jolla, California
| | - Dillon Gilbertson
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California
| | - Pamela N. Deyoung
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California
| | - Cecilia Anza-Ramirez
- Departamento de Ciencias Biológicas y Fisiológicas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Francisco C. Villafuerte
- Departamento de Ciencias Biológicas y Fisiológicas, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Frank L. Powell
- Department of Medicine, Division of Physiology, University of California San Diego, La Jolla, California
| | - Atul Malhotra
- Department of Medicine, Division of Pulmonary, Critical Care, and Sleep Medicine, University of California San Diego, La Jolla, California
| | - Tatum Simonson
- Department of Medicine, Division of Physiology, University of California San Diego, La Jolla, California
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18
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Burgess KR, Lucas SJE, Burgess KME, Sprecher KE, Donnelly J, Basnet AS, Tymko MM, Day T, Smith K, Lewis N, Ainslie PN. Increasing cerebral blood flow reduces the severity of central sleep apnea at high altitude. J Appl Physiol (1985) 2018; 124:1341-1348. [PMID: 29389246 DOI: 10.1152/japplphysiol.00799.2017] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Earlier studies have indicated an important role for cerebral blood flow in the pathophysiology of central sleep apnea (CSA) at high altitude, but were not decisive. To test the hypothesis that pharmacologically altering cerebral blood flow (CBF) without altering arterial blood gas (ABGs) values would alter the severity of CSA at high altitude, we studied 11 healthy volunteers (8M, 3F; 31 ± 7 yr) in a randomized placebo-controlled single-blind study at 5,050 m in Nepal. CBF was increased by intravenous (iv) acetazolamide (Az; 10 mg/kg) plus intravenous dobutamine (Dob) infusion (2-5 μg·kg-1·min-1) and reduced by oral indomethacin (Indo; 100 mg). ABG samples were collected and ventilatory responses to hypercapnia (HCVR) and hypoxia (HVR) were measured by rebreathing and steady-state techniques before and after drug/placebo. Duplex ultrasound of blood flow in the internal carotid and vertebral arteries was used to measure global CBF. The initial 3-4 h of sleep were recorded by full polysomnography. Intravenous Az + Dob increased global CBF by 37 ± 15% compared with placebo ( P < 0.001), whereas it was reduced by 21 ± 8% by oral Indo ( P < 0.001). ABGs and HVR were unchanged in both interventions. HCVR was reduced by 28% ± 43% ( P = 0.1) during intravenous Az ± Dob administration and was elevated by 23% ± 30% ( P = 0.05) by Indo. During intravenous Az + Dob, the CSA index fell from 140 ± 45 (control night) to 48 ± 37 events/h of sleep ( P < 0.001). Oral Indo had no significant effect on CSA. We conclude that increasing cerebral blood flow reduced the severity of CSA at high altitude; the likely mechanism is via a reduction in the background stimulation of central chemoreceptors. NEW & NOTEWORTHY This work is significant because it shows convincingly for the first time in healthy volunteers that increasing cerebral blood flow will reduce the severity of central sleep apnea in a high-altitude model, without the potentially confounding effects of altering partial pressure of arterial carbon dioxide or the ventilatory response to hypoxia. The proposed mechanism of action is that of increasing the removal of locally produced CO2 from the central chemoreceptors, causing the reduction in hypercapnic ventilatory response, hence reducing loop gain.
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Affiliation(s)
- Keith R Burgess
- Peninsula Sleep Clinic , Sydney, New South Wales , Australia.,Department of Medicine, University of Sydney , Sydney, New South Wales , Australia
| | - Samuel J E Lucas
- University of Otago , Dunedin , New Zealand.,University of Birmingham , Birmingham , United Kingdom
| | - Katie M E Burgess
- Peninsula Sleep Clinic , Sydney, New South Wales , Australia.,Department of Medicine, University of Sydney , Sydney, New South Wales , Australia
| | - Kate E Sprecher
- Peninsula Sleep Clinic , Sydney, New South Wales , Australia
| | | | | | | | - Trevor Day
- Mount Royal University , Calgary , Canada
| | - Kurt Smith
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna , Canada
| | - Nia Lewis
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna , Canada
| | - Philip N Ainslie
- Centre for Heart, Lung and Vascular Health, School of Health and Exercise Sciences, University of British Columbia, Okanagan Campus, Kelowna , Canada
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19
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Ortiz-Naretto AE, Pereiro MP, Ernst G, Borsini EE. Sleep respiratory disturbances during the ascent to Mount Aconcagua. ACTA ACUST UNITED AC 2018; 11:20-24. [PMID: 29796196 PMCID: PMC5916571 DOI: 10.5935/1984-0063.20180005] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Introduction Mountaineers exposed to hypobaric hypoxia (HH) show high-altitude periodic
breathing (PB). Objective To analyze high-altitude PB during the ascent of Mount Aconcagua
(Argentina). Materials and Methods Descriptive study in healthy volunteers using respiratory polygraphy (RP) at
different altitudes. Results We studied 8 andinist, mean age: 36 years old (25-51), body mass index (BMI)
of 23.6 (20.9-28.7) and 22.77 (20.9-27.7) upon return,
p<0.01. RP without PB showed a lower Oxygen Desaturation
Index (ODI) and a lower Apnea-Hypopnea-Index (AHI); 5.43 (0 - 20) versus
45.95 (2-122) p<0.001 and 3.9 (0-15.5) versus 44.35
(4-115) p<0.001. AHI increased with altitude at the
expense of central apneas and hypopneas: p<0.05. Conclusion High-altitude PB is frequent above 2,581m.a.s.l. And it is characterized by
short cycles. None of the mountaineers showed PB at baseline; however,
high-altitude PB occurred in all subjects above 4,900 m.a.s.l
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Affiliation(s)
- Alvaro Emilio Ortiz-Naretto
- Hospital Francisco Muñiz, Medicine Respiratory Unit - Buenos Aires City - Buenos Aires - Argentina.,Asociación Andina de Medicina para la Altura, Curso Medicina para la Altura - Mendoza City - Mendoza - Argentina.,Hospital Británico de Buenos Aires, Medicine Respiratory Unit - Buenos Aires City - Buenos Aires - Argentina
| | - Miriam Patricia Pereiro
- Hospital Materno Infantil Ramón Sarda, Central Laboratory - Buenos Aires City - Buenos Aires - Argentina.,Asociación Andina de Medicina para la Altura, Curso Medicina para la Altura - Mendoza City - Mendoza - Argentina
| | - Glenda Ernst
- Hospital Británico de Buenos Aires, Medicine Respiratory Unit - Buenos Aires City - Buenos Aires - Argentina
| | - Eduardo Enrique Borsini
- Hospital Británico de Buenos Aires, Medicine Respiratory Unit - Buenos Aires City - Buenos Aires - Argentina
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20
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Impairment of pulmonary diffusion correlates with hypoxemic burden in central sleep apnea heart failure patients. Respir Physiol Neurobiol 2017; 243:7-12. [PMID: 28467884 DOI: 10.1016/j.resp.2017.04.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 04/26/2017] [Accepted: 04/27/2017] [Indexed: 11/24/2022]
Abstract
PURPOSE Central sleep apnea (CSA) and Cheyne-Stokes respiration (CSR) are highly prevalent in heart failure (HF) and are linked to increased mortality. Impaired pulmonary diffusion capacity [DLCO] and [KCO]) have been suggested to play a key role in CSA-CSR pathophysiology. This study investigated the relationship between HF, CSR, DLCO and KCO in well-characterized HF patients. METHODS This prospective study included HF patients with CSR, all patients underwent full overnight polysomnography (PSG) and lung function testing. RESULTS A total of 100 patients were included (age 70.7±9.7years, 95% male, body mass index 28.9±5.3kg/m2, left ventricular ejection fraction 33.5±7.7%, New York Heart Association class III 65%. DLCO and oxygenation were significantly correlated with hypoxemic burden (p<0.05). Mean oxygen saturation, oxygen desaturation, C-reactive protein level and pH were significantly associated with CSA-CSR severity (p<0.05). CONCLUSION The finding that lung diffusion capacity is significantly associated with hypoxemic burden in HF patients with CSA-CSR highlights the important of lung function in HF patients.
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Webb CL, Milsom WK. Effects of low temperature on breathing pattern and ventilatory responses during hibernation in the golden-mantled ground squirrel. J Comp Physiol B 2017; 187:793-802. [DOI: 10.1007/s00360-017-1079-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2016] [Revised: 11/24/2016] [Accepted: 02/26/2017] [Indexed: 10/19/2022]
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Pham LV, Meinzen C, Arias RS, Schwartz NG, Rattner A, Miele CH, Smith PL, Schneider H, Miranda JJ, Gilman RH, Polotsky VY, Checkley W, Schwartz AR. Cross-Sectional Comparison of Sleep-Disordered Breathing in Native Peruvian Highlanders and Lowlanders. High Alt Med Biol 2017; 18:11-19. [PMID: 28306414 PMCID: PMC5361758 DOI: 10.1089/ham.2016.0102] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/29/2016] [Accepted: 01/01/2017] [Indexed: 12/16/2022] Open
Abstract
Pham, Luu V., Christopher Meinzen, Rafael S. Arias, Noah G. Schwartz, Adi Rattner, Catherine H. Miele, Philip L. Smith, Hartmut Schneider, J. Jaime Miranda, Robert H. Gilman, Vsevolod Y. Polotsky, William Checkley, and Alan R. Schwartz. Cross-sectional comparison of sleep-disordered breathing in native Peruvian highlanders and lowlanders. High Alt Med Biol. 18:11-19, 2017. BACKGROUND Altitude can accentuate sleep disordered breathing (SDB), which has been linked to cardiovascular and metabolic diseases. SDB in highlanders has not been characterized in large controlled studies. The purpose of this study was to compare SDB prevalence and severity in highlanders and lowlanders. METHODS 170 age-, body-mass-index- (BMI), and sex-matched pairs (age 58.2 ± 12.4 years, BMI 27.2 ± 3.5 kg/m2, and 86 men and 84 women) of the CRONICAS Cohort Study were recruited at a sea-level (Lima) and a high-altitude (Puno, 3825 m) setting in Peru. Participants underwent simultaneous nocturnal polygraphy and actigraphy to characterize breathing patterns, movement arousals, and sleep/wake state. We compared SDB prevalence, type, and severity between highlanders and lowlanders as measured by apnea-hypopnea index (AHI) and pulse oximetry (SPO2) during sleep. RESULTS Sleep apnea prevalence was greater in highlanders than in lowlanders (77% vs. 54%, p < 0.001). Compared with lowlanders, highlanders had twofold elevations in AHI due to increases in central rather than obstructive apneas. In highlanders compared with lowlanders, SPO2 was lower during wakefulness and decreased further during sleep (p < 0.001). Hypoxemia during wakefulness predicted sleep apnea in highlanders, and it appears to mediate the effects of altitude on sleep apnea prevalence. Surprisingly, hypoxemia was also quite prevalent in lowlanders, and it was also associated with increased odds of sleep apnea. CONCLUSIONS High altitude and hypoxemia at both high and low altitude were associated with increased SDB prevalence and severity. Our findings suggest that a large proportion of highlanders remain at risk for SDB sequelae.
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Affiliation(s)
- Luu V. Pham
- Division of Pulmonary and Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Christopher Meinzen
- Program in Global Disease Epidemiology and Control, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Rafael S. Arias
- School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Noah G. Schwartz
- University of Chicago Pritzker School of Medicine, Chicago, Illinois
| | - Adi Rattner
- School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Catherine H. Miele
- Division of Pulmonary and Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Philip L. Smith
- Division of Pulmonary and Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - Hartmut Schneider
- Division of Pulmonary and Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - J. Jaime Miranda
- School of Medicine, Universidad Peruana Cayetano Heredia, Lima, Peru
- CRONICAS Center of Excellence in Chronic Diseases, Universidad Peruana Cayetano Heredia, Lima, Peru
| | - Robert H. Gilman
- Program in Global Disease Epidemiology and Control, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Vsevolod Y. Polotsky
- Division of Pulmonary and Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
| | - William Checkley
- Division of Pulmonary and Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
- Program in Global Disease Epidemiology and Control, Department of International Health, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
| | - Alan R. Schwartz
- Division of Pulmonary and Critical Care and Sleep Medicine, Department of Medicine, School of Medicine, Johns Hopkins University, Baltimore, Maryland
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Orr JE, Malhotra A, Sands SA. Pathogenesis of central and complex sleep apnoea. Respirology 2016; 22:43-52. [PMID: 27797160 DOI: 10.1111/resp.12927] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Revised: 09/22/2016] [Accepted: 10/03/2016] [Indexed: 12/01/2022]
Abstract
Central sleep apnoea (CSA) - the temporary absence or diminution of ventilatory effort during sleep - is seen in a variety of forms including periodic breathing in infancy and healthy adults at altitude and Cheyne-Stokes respiration in heart failure. In most circumstances, the cyclic absence of effort is paradoxically a consequence of hypersensitive ventilatory chemoreflex responses to oppose changes in airflow, that is elevated loop gain, leading to overshoot/undershoot ventilatory oscillations. Considerable evidence illustrates overlap between CSA and obstructive sleep apnoea (OSA), including elevated loop gain in patients with OSA and the presence of pharyngeal narrowing during central apnoeas. Indeed, treatment of OSA, whether via continuous positive airway pressure (CPAP), tracheostomy or oral appliances, can reveal CSA, an occurrence referred to as complex sleep apnoea. Factors influencing loop gain include increased chemosensitivity (increased controller gain), reduced damping of blood gas levels (increased plant gain) and increased lung to chemoreceptor circulatory delay. Sleep-wake transitions and pharyngeal dilator muscle responses effectively raise the controller gain and therefore also contribute to total loop gain and overall instability. In some circumstances, for example apnoea of infancy and central congenital hypoventilation syndrome, central apnoeas are the consequence of ventilatory depression and defective ventilatory responses, that is low loop gain. The efficacy of available treatments for CSA can be explained in terms of their effects on loop gain, for example CPAP improves lung volume (plant gain), stimulants reduce the alveolar-inspired PCO2 difference and supplemental oxygen lowers chemosensitivity. Understanding the magnitude of loop gain and the mechanisms contributing to instability may facilitate personalized interventions for CSA.
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Affiliation(s)
- Jeremy E Orr
- Division of Pulmonary and Critical Care Medicine, University of California San Diego, La Jolla, California, USA
| | - Atul Malhotra
- Division of Pulmonary and Critical Care Medicine, University of California San Diego, La Jolla, California, USA
| | - Scott A Sands
- Division of Sleep and Circadian Disorders, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA.,Department of Allergy Immunology and Respiratory Medicine and Central Clinical School, The Alfred and Monash University, Melbourne, Victoria, Australia
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Reduced respiratory neural activity elicits a long-lasting decrease in the CO 2 threshold for apnea in anesthetized rats. Exp Neurol 2016; 287:235-242. [PMID: 27474512 DOI: 10.1016/j.expneurol.2016.07.020] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Revised: 07/21/2016] [Accepted: 07/25/2016] [Indexed: 12/23/2022]
Abstract
Two critical parameters that influence breathing stability are the levels of arterial pCO2 at which breathing ceases and subsequently resumes - termed the apneic and recruitment thresholds (AT and RT, respectively). Reduced respiratory neural activity elicits a chemoreflex-independent, long-lasting increase in phrenic burst amplitude, a form of plasticity known as inactivity-induced phrenic motor facilitation (iPMF). The physiological significance of iPMF is unknown. To determine if iPMF and neural apnea have long-lasting physiological effects on breathing, we tested the hypothesis that patterns of neural apnea that induce iPMF also elicit changes in the AT and RT. Phrenic nerve activity and end-tidal CO2 were recorded in urethane-anesthetized, ventilated rats to quantify phrenic nerve burst amplitude and the AT and RT before and after three patterns of neural apnea that differed in their duration and ability to elicit iPMF: brief intermittent neural apneas, a single brief "massed" neural apnea, or a prolonged neural apnea. Consistent with our hypothesis, we found that patterns of neural apnea that elicited iPMF also resulted in changes in the AT and RT. Specifically, intermittent neural apneas progressively decreased the AT with each subsequent neural apnea, which persisted for at least 60min. Similarly, a prolonged neural apnea elicited a long-lasting decrease in the AT. In both cases, the magnitude of the AT decrease was proportional to iPMF. In contrast, the RT was transiently decreased following prolonged neural apnea, and was not proportional to iPMF. No changes in the AT or RT were observed following a single brief neural apnea. Our results indicate that the AT and RT are differentially altered by neural apnea and suggest that specific patterns of neural apnea that elicit plasticity may stabilize breathing via a decrease in the AT.
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Central Sleep Apnea at High Altitude. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2016; 903:275-83. [DOI: 10.1007/978-1-4899-7678-9_19] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/05/2022]
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Abstract
Exposure to high altitude imposes significant strain on cardiopulmonary system and the brain. As a consequence, sojourners to high altitude frequently experience sleep disturbances, often reporting restless and sleepless nights. At altitudes above 3,000 meters (9,800 ft) almost all healthy subjects develop periodic breathing especially during NREM sleep. Sleep architecture gradually improves with increased NREM and REM sleep despite persistence of periodic breathing. The primary reason for periodic breathing at high altitude is a hypoxic-induced increase in chemoreceptor sensitivity to changes in PaCO2 – both above and below eupnea, leading to periods of apnea and hyperpnea. Acetazolamide improves sleep by reducing the periodic breathing through development of metabolic acidosis and induced hyperventilation decreasing the plant gain and widening the PCO2 reserve. This widening of the PCO2 reserve impedes development of central apneas during sleep. Benzodiazepines and GABA receptor antagonist such as zolpidem improve sleep without affecting breathing pattern or cognitive functions.
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Affiliation(s)
- Vahid Mohsenin
- Department of Pulmonary, Critical Care and Sleep Medicine Yale School of Medicine, Yale University, New Haven, Connecticut, USA
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Caravita S, Faini A, Lombardi C, Valentini M, Gregorini F, Rossi J, Meriggi P, Di Rienzo M, Bilo G, Agostoni P, Parati G. Sex and acetazolamide effects on chemoreflex and periodic breathing during sleep at altitude. Chest 2015; 147:120-131. [PMID: 25188815 DOI: 10.1378/chest.14-0317] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
OBJECTIVE Nocturnal periodic breathing occurs more frequently in men than in women with various clinical and pathophysiologic conditions. The mechanisms accounting for this sex-related difference are not completely understood. Acetazolamide effectively counteracts nocturnal periodic breathing, but it has been investigated almost exclusively in men. Our aim was to explore possible determinants of nocturnal periodic breathing in a high-altitude setting both in men and in women. We hypothesized that increased hypoxic chemosensitivity in men could be associated with the development of nocturnal periodic breathing at altitude more frequently than in women, and that acetazolamide, by leftward shifting the CO2 ventilatory response, could improve nocturnal periodic breathing at altitude in a sex-independent manner. METHODS Forty-four healthy lowlanders (21 women), randomized to acetazolamide or placebo, underwent cardiorespiratory sleep studies at sea level off treatment and under treatment on the first night after arrival at a 4,559-m altitude. Hypoxic and hypercapnic chemosensitivities were assessed at sea level. RESULTS Men, more frequently than women, exhibited increased hypoxic chemosensitivity and displayed nocturnal periodic breathing at altitude. Acetazolamide leftward shifted the CO2 set point and, at altitude, improved oxygenation and reduced periodic breathing in both sexes, but to a larger extent in men. Hypoxic chemosensitivity directly correlated with the number of apneas/hypopneas at altitude in the placebo group but not in the acetazolamide group. CONCLUSIONS The greater severity of periodic breathing during sleep displayed by men at altitude could be attributed to their increased hypoxic chemosensitivity. Acetazolamide counteracted the occurrence of periodic breathing at altitude in both sexes, modifying the apneic threshold and improving oxygenation. TRIAL REGISTRY EU Clinical Trials Register, EudraCT; No.: 2010-019986-27; URL: https://www.clinicaltrialsregister.eu.
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Affiliation(s)
- Sergio Caravita
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini); Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Department of Cardiovascular, Neural and Metabolic Sciences, S. Luca Hospital; the Department of Health Sciences (Drs Caravita and Parati)
| | - Andrea Faini
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini)
| | - Carolina Lombardi
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini)
| | - Mariaconsuelo Valentini
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini)
| | - Francesca Gregorini
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini)
| | - Jessica Rossi
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini)
| | - Paolo Meriggi
- University of Milano-Bicocca; Polo Tecnologico (Dr Meriggi and Mr Di Rienzo)
| | - Marco Di Rienzo
- University of Milano-Bicocca; Polo Tecnologico (Dr Meriggi and Mr Di Rienzo)
| | - Grzegorz Bilo
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini)
| | - Piergiuseppe Agostoni
- Biomedical Technology Department, Fondazione Don Carlo Gnocchi Onlus; Centro Cardiologico Monzino (Dr Agostoni)IRCCS; and the Department of Clinical Sciences and Community Health University of Milan, Milan, Italy
| | - Gianfranco Parati
- Istituto Auxologico Italiano (Drs Caravita, Faini, Lombardi, Valentini, Rossi, Bilo, and Parati and Ms Gregorini); Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Department of Cardiovascular, Neural and Metabolic Sciences, S. Luca Hospital; the Department of Health Sciences (Drs Caravita and Parati).
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Guan W, Ga Q, Li R, Bai ZZ, Wuren T, Wang J, Yang YZ, Li YH, Ge RL. Sleep disturbances in long-term immigrants with chronic mountain sickness: A comparison with healthy immigrants at high altitude. Respir Physiol Neurobiol 2015; 206:4-10. [DOI: 10.1016/j.resp.2014.11.007] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2014] [Revised: 11/05/2014] [Accepted: 11/06/2014] [Indexed: 10/24/2022]
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Marcus NJ, Del Rio R, Schultz HD. Central role of carotid body chemoreceptors in disordered breathing and cardiorenal dysfunction in chronic heart failure. Front Physiol 2014; 5:438. [PMID: 25505417 PMCID: PMC4241833 DOI: 10.3389/fphys.2014.00438] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2014] [Accepted: 10/27/2014] [Indexed: 11/13/2022] Open
Abstract
Oscillatory breathing (OB) patterns are observed in pre-term infants, patients with cardio-renal impairment, and in otherwise healthy humans exposed to high altitude. Enhanced carotid body (CB) chemoreflex sensitivity is common to all of these populations and is thought to contribute to these abnormal patterns by destabilizing the respiratory control system. OB patterns in chronic heart failure (CHF) patients are associated with greater levels of tonic and chemoreflex-evoked sympathetic nerve activity (SNA), which is associated with greater morbidity and poor prognosis. Enhanced chemoreflex drive may contribute to tonic elevations in SNA by strengthening the relationship between respiratory and sympathetic neural outflow. Elimination of CB afferents in experimental models of CHF has been shown to reduce OB, respiratory-sympathetic coupling, and renal SNA, and to improve autonomic balance in the heart. The CB chemoreceptors may play an important role in progression of CHF by contributing to respiratory instability and OB, which in turn further exacerbates tonic and chemoreflex-evoked increases in SNA to the heart and kidney.
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Affiliation(s)
- Noah J Marcus
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center Omaha, NE, USA
| | - Rodrigo Del Rio
- Laboratory of Cardiorespiratory Control, Center of Biomedical Research, Universidad Autónoma de Chile Santiago, Chile
| | - Harold D Schultz
- Department of Cellular and Integrative Physiology, University of Nebraska Medical Center Omaha, NE, USA
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Moraga FA, Jiménez D, Richalet JP, Vargas M, Osorio J. Periodic breathing and oxygen supplementation in Chilean miners at high altitude (4200m). Respir Physiol Neurobiol 2014; 203:109-15. [DOI: 10.1016/j.resp.2014.09.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2014] [Revised: 08/28/2014] [Accepted: 09/02/2014] [Indexed: 11/28/2022]
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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.
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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
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Sargent C, Schmidt WF, Aughey RJ, Bourdon PC, Soria R, Claros JCJ, Garvican-Lewis LA, Buchheit M, Simpson BM, Hammond K, Kley M, Wachsmuth N, Gore CJ, Roach GD. The impact of altitude on the sleep of young elite soccer players (ISA3600). Br J Sports Med 2014; 47 Suppl 1:i86-92. [PMID: 24282215 PMCID: PMC3903148 DOI: 10.1136/bjsports-2013-092829] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Background Altitude training is used by elite athletes to improve sports performance, but it may also disrupt sleep. The aim of this study was to examine the effects of 2 weeks at high altitude on the sleep of young elite athletes. Methods Participants (n=10) were members of the Australian under-17 soccer team on an 18-day (19-night) training camp in Bolivia, with six nights at near sea level in Santa Cruz (430 m) and 13 nights at high altitude in La Paz (3600 m). Sleep was monitored using polysomnography during a baseline night at 430 m and three nights at 3600 m (immediately after ascent, 1 week after ascent and 2 weeks after ascent). Data were analysed using effect size statistics. Results All results are reported as comparisons with baseline. Rapid eye movement (REM) sleep was likely lower immediately upon ascent to altitude, possibly lower after 1 week and similar after 2 weeks. On all three nights at altitude, hypopneas and desaturations were almost certainly higher; oxygen saturation was almost certainly lower; and central apnoeas, respiratory arousals and periodic breathing were very likely higher. The effects on REM sleep were common to all but one participant, but the effects on breathing were specific to only half the participants. Conclusions The immediate effects of terrestrial altitude of 3600 m are to reduce the amount of REM sleep obtained by young elite athletes, and to cause 50% of them to have impaired breathing during sleep. REM sleep returns to normal after 2 weeks at altitude, but impaired breathing does not improve.
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Affiliation(s)
- Charli Sargent
- Appleton Institute for Behavioural Science, Central Queensland University, , Adelaide, Australia
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Mansukhani MP, Kolla BP, Ramar K. International Classification of Sleep Disorders 2 and American Academy of Sleep Medicine Practice Parameters for Central Sleep Apnea. Sleep Med Clin 2014. [DOI: 10.1016/j.jsmc.2013.10.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Tobin MJ, Laghi F, Jubran A. Ventilatory failure, ventilator support, and ventilator weaning. Compr Physiol 2013; 2:2871-921. [PMID: 23720268 DOI: 10.1002/cphy.c110030] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The development of acute ventilatory failure represents an inability of the respiratory control system to maintain a level of respiratory motor output to cope with the metabolic demands of the body. The level of respiratory motor output is also the main determinant of the degree of respiratory distress experienced by such patients. As ventilatory failure progresses and patient distress increases, mechanical ventilation is instituted to help the respiratory muscles cope with the heightened workload. While a patient is connected to a ventilator, a physician's ability to align the rhythm of the machine with the rhythm of the patient's respiratory centers becomes the primary determinant of the level of rest accorded to the respiratory muscles. Problems of alignment are manifested as failure to trigger, double triggering, an inflationary gas-flow that fails to match inspiratory demands, and an inflation phase that persists after a patient's respiratory centers have switched to expiration. With recovery from disorders that precipitated the initial bout of acute ventilatory failure, attempts are made to discontinue the ventilator (weaning). About 20% of weaning attempts fail, ultimately, because the respiratory controller is unable to sustain ventilation and this failure is signaled by development of rapid shallow breathing. Substantial advances in the medical management of acute ventilatory failure that requires ventilator assistance are most likely to result from research yielding novel insights into the operation of the respiratory control system.
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Affiliation(s)
- Martin J Tobin
- Division of Pulmonary and Critical Care Medicine, Edward Hines Jr. Veterans Affairs Hospital and Loyola University of Chicago Stritch School of Medicine, Hines, Illinois, USA.
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Ainslie PN, Lucas SJ, Burgess KR. Breathing and sleep at high altitude. Respir Physiol Neurobiol 2013; 188:233-56. [DOI: 10.1016/j.resp.2013.05.020] [Citation(s) in RCA: 81] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2013] [Revised: 05/04/2013] [Accepted: 05/16/2013] [Indexed: 10/26/2022]
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Plataki M, Sands SA, Malhotra A. Clinical consequences of altered chemoreflex control. Respir Physiol Neurobiol 2013; 189:354-63. [PMID: 23681082 DOI: 10.1016/j.resp.2013.04.020] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2013] [Revised: 04/19/2013] [Accepted: 04/25/2013] [Indexed: 01/28/2023]
Abstract
Control of ventilation dictates various breathing patterns. The respiratory control system consists of a central pattern generator and several feedback mechanisms that act to maintain ventilation at optimal levels. The concept of loop gain has been employed to describe its stability and variability. Synthesizing all interactions under a general model that could account for every behavior has been challenging. Recent insight into the importance of these feedback systems may unveil therapeutic strategies for common ventilatory disturbances. In this review we will address the major mechanisms that have been proposed as mediators of some of the breathing patterns in health and disease that have raised controversies and discussion on ventilatory control over the years.
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Affiliation(s)
- Maria Plataki
- Department of Internal Medicine, Bridgeport Hospital, Yale New Haven Health, Bridgeport, CT, USA
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Andrews G, Ainslie PN, Shepherd K, Dawson A, Swart M, Lucas S, Burgess KR. The effect of partial acclimatization to high altitude on loop gain and central sleep apnoea severity. Respirology 2013; 17:835-40. [PMID: 22429599 DOI: 10.1111/j.1440-1843.2012.02170.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND AND OBJECTIVE Loop gain is an engineering term that predicts the stability of a feedback control system, such as the control of breathing. Based on earlier studies at lower altitudes, it was hypothesized that acclimatization to high altitude would lead to a reduction in loop gain and thus central sleep apnoea (CSA) severity. METHODS This study used exposure to very high altitude to induce CSA in healthy subjects to investigate the effect of partial acclimatization on loop gain and CSA severity. Measurements were made on 12 subjects (age 30 ± 10 years, body mass index 22.8 ± 1.9, eight males, four females) at an altitude of 5050 m over a 2-week period upon initial arrival (days 2-4) and following partial acclimatization (days 12-14). Sleep was studied by full polysomnography, and resting arterial blood gases were measured. Loop gain was measured by the 'duty cycle' method (duration of hyperpnoea/cycle length). RESULTS Partial acclimatization to high-altitude exposure was associated with both an increase in loop gain (duty cycle fell from 0.60 ± 0.05 to 0.55 ± 0.06 (P = 0.03)) and severity of CSA (apnoea-hypopnoea index increased from 76.8 ± 48.8 to 115.9 ± 20.2 (P = 0.01)), while partial arterial carbon dioxide concentration fell from 29 ± 3 to 26 ± 2 (P = 0.01). CONCLUSIONS Contrary to the results at lower altitudes, at high-altitude loop gain and severity of CSA increased.
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Affiliation(s)
- Gareth Andrews
- Department of Medicine, University of Sydney, Sydney, New South Wales, Australia
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Lee J, Nemati S, Silva I, Edwards BA, Butler JP, Malhotra A. Transfer entropy estimation and directional coupling change detection in biomedical time series. Biomed Eng Online 2012; 11:19. [PMID: 22500692 PMCID: PMC3403001 DOI: 10.1186/1475-925x-11-19] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2011] [Accepted: 04/13/2012] [Indexed: 11/28/2022] Open
Abstract
Background The detection of change in magnitude of directional coupling between two non-linear time series is a common subject of interest in the biomedical domain, including studies involving the respiratory chemoreflex system. Although transfer entropy is a useful tool in this avenue, no study to date has investigated how different transfer entropy estimation methods perform in typical biomedical applications featuring small sample size and presence of outliers. Methods With respect to detection of increased coupling strength, we compared three transfer entropy estimation techniques using both simulated time series and respiratory recordings from lambs. The following estimation methods were analyzed: fixed-binning with ranking, kernel density estimation (KDE), and the Darbellay-Vajda (D-V) adaptive partitioning algorithm extended to three dimensions. In the simulated experiment, sample size was varied from 50 to 200, while coupling strength was increased. In order to introduce outliers, the heavy-tailed Laplace distribution was utilized. In the lamb experiment, the objective was to detect increased respiratory-related chemosensitivity to O2 and CO2 induced by a drug, domperidone. Specifically, the separate influence of end-tidal PO2 and PCO2 on minute ventilation (V˙E) before and after administration of domperidone was analyzed. Results In the simulation, KDE detected increased coupling strength at the lowest SNR among the three methods. In the lamb experiment, D-V partitioning resulted in the statistically strongest increase in transfer entropy post-domperidone for PO2→V˙E. In addition, D-V partitioning was the only method that could detect an increase in transfer entropy for PCO2→V˙E, in agreement with experimental findings. Conclusions Transfer entropy is capable of detecting directional coupling changes in non-linear biomedical time series analysis featuring a small number of observations and presence of outliers. The results of this study suggest that fixed-binning, even with ranking, is too primitive, and although there is no clear winner between KDE and D-V partitioning, the reader should note that KDE requires more computational time and extensive parameter selection than D-V partitioning. We hope this study provides a guideline for selection of an appropriate transfer entropy estimation method.
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Affiliation(s)
- Joon Lee
- Harvard-MIT Division of Health Sciences and Technology, Cambridge, MA, USA.
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Fan JL, Burgess KR, Thomas KN, Lucas SJE, Cotter JD, Kayser B, Peebles KC, Ainslie PN. Effects of acetazolamide on cerebrovascular function and breathing stability at 5050 m. J Physiol 2012; 590:1213-25. [PMID: 22219343 DOI: 10.1113/jphysiol.2011.219923] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
One of the many actions of the carbonic anhydrase inhibitor, acetazolamide (ACZ), is to accelerate acclimatisation and reduce periodic breathing during sleep. The mechanism(s) by which ACZ may improve breathing stability, especially at high altitude, remain unclear. We tested the hypothesis that acute I.V. ACZ would enhance cerebrovascular reactivity to CO₂ at altitude, and thereby lower ventilatory drive and improve breathing stability during wakefulness. We measured arterial blood gases, minute ventilation (˙VE) and middle cerebral artery blood flow velocity (MCAv) before and 30 min following ACZ administration (I.V. 10 mg kg⁻¹) in 12 healthy participants at sea level and following partial acclimatisation to altitude (5050 m).Measures were made at rest and during changes in end-tidal PCO₂ and PO₂ (isocapnic hypoxia). At sea level, ACZ increased resting MCAv and its reactivity to both hypocapnia and hypercapnia (P < 0.05), and lowered resting VE, arterial O₂ saturation (Sa,O₂ ) and arterial PO₂ (Pa,O₂) (P < 0.05); arterial PCO₂ (Pa,CO₂ ) was unaltered (P > 0.05). At altitude, ACZ also increased resting MCAv and its reactivity to both hypocapnia and hypercapnia (resting MCAv and hypocapnia reactivity to a greater extent than at sea level). Moreover, ACZ at altitude elevated Pa,CO₂ and again lowered resting Pa,O₂ and Sa,O₂ (P <0.05). Although the ˙VE sensitivity to hypercapnia or isocapnic hypoxia was unaltered following ACZ at both sea level and altitude (P > 0.05), breathing stability at altitude was improved (e.g. lower incidence of ventilatory oscillations and variability of tidal volume; P < 0.05). Our data indicate that I.V. ACZ elevates cerebrovascular reactivity and improves breathing stability at altitude, independent of changes in peripheral or central chemoreflex sensitivities. We speculate that Pa,CO₂-mediated elevations in cerebral perfusion and an enhanced cerebrovascular reactivity may partly account for the improved breathing stability following ACZ at high altitude.
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Affiliation(s)
- Jui-Lin Fan
- Department of Physiology, Otago School of Medical Science, University of Otago, Dunedin, New Zealand.
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Moore J, Haouzi P, Van de Louw A, Bell HJ. Hypocapnia-dependent facilitation of augmented breaths: observations in awake vs. anesthetized rats. Respir Physiol Neurobiol 2011; 180:105-11. [PMID: 22063924 DOI: 10.1016/j.resp.2011.10.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 10/14/2011] [Accepted: 10/24/2011] [Indexed: 12/31/2022]
Abstract
We investigated whether commonly used injectable laboratory anesthetics alter the regulation of augmented breaths (ABs) in different respiratory backgrounds. Male rats were studied on three separate experimental days, receiving one of three injections in randomized order: ethyl carbamate ('urethane'; 1.2mgkg(-1)), ketamine/xylazine (ket/xyl; 80/10mgkg(-1)), or normal saline. Following each of the three interventions, breathing was monitored during 15min exposures to normoxia (room air), hypoxia (10% O(2)) and hypoxia+CO(2) (10% O(2), 5% CO(2)). Urethane anesthesia completely eliminated ABs from the breathing rhythm in room air conditions (p<0.001), and decreased the hypocapnia-dependent component of this response (p<0.001). ket/xyl left the normal incidence of ABs in room air breathing intact but significantly suppressed the hypoxia-induced facilitation of ABs (p=0.0015). These results provide the first clear evidence that laboratory anesthesia can profoundly alter the regulation of ABs including the hypocapnia-dependent component of their facilitation.
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Affiliation(s)
- J Moore
- Division of Pulmonary and Critical Care, Department of Medicine, Penn State University College of Medicine, Hershey, PA, USA
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Rodway GW, Edsell ME, Wong B, Windsor JS. Improving sleep at altitude: a comparison of therapies. Wilderness Environ Med 2011; 22:316-20. [PMID: 21982758 DOI: 10.1016/j.wem.2011.07.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2010] [Revised: 06/27/2011] [Accepted: 07/05/2011] [Indexed: 10/16/2022]
Abstract
OBJECTIVE This study aimed to compare 3 treatment modalities during sleep at an altitude of 5300 m to identify strategies for reducing the incidence of periodic breathing at high altitude. METHODS Fifteen trekkers, with identical ascent profiles and no signs or symptoms of altitude illness, served as subjects. All study participants arrived at 5300 m after a gradual ascent from 1300 m. On their second night at 5300 m, subjects were randomly assigned (with a computer-based random assignment procedure) to 1 of 4 different treatment groups: control (n = 4); 1 L/min O(2) via a demand system during sleep (n = 3); 1 L/min O(2)/CO(2) mix (1.5% CO(2)) via a demand system during sleep (n = 4); or 125 mg acetazolamide 30 minutes before bedtime (n = 4). Heart rate, respiration rate, blood oxygen saturation, tidal volume, minute volume, and apnea hypopnea index were measured. RESULTS Upon comparing the 4 groups, there were no statistically significant differences between the variables. One-way analysis of variance indicated a trend toward statistical significance for SaO(2) between groups (F = 2.9, P = .08), and Tukey Honestly Significant Difference (HSD) post hoc tests indicated a trend in the SaO(2) difference between the 1 L/min oxygen and control groups (P = .07). While 1-way analysis of variance suggested no difference for respiratory rate between groups (F = 2.5, P = .1), Tukey HSD indicated a trend in statistical difference of the respiratory rate between 1 L/min O(2) and 1 L/min O(2)/CO(2) mixture (P = .08). CONCLUSIONS These statistical trends found between control and treatment groups indicate that further study is warranted.
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Affiliation(s)
- George W Rodway
- University of Utah College of Nursing and School of Medicine, Salt Lake City, UT 84112, USA.
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Nemati S, Edwards BA, Sands SA, Berger PJ, Wellman A, Verghese GC, Malhotra A, Butler JP. Model-based characterization of ventilatory stability using spontaneous breathing. J Appl Physiol (1985) 2011; 111:55-67. [PMID: 21474696 DOI: 10.1152/japplphysiol.01358.2010] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Cyclic ventilatory instabilities are widely attributed to an increase in the sensitivity or loop gain of the chemoreflex feedback loop controlling ventilation. A major limitation in the conventional characterization of this feedback loop is the need for labor-intensive methodologies. To overcome this limitation, we developed a method based on trivariate autoregressive modeling using ventilation, end-tidal Pco(2) and Po(2); this method provides for estimation of the overall "loop gain" of the respiratory control system and its components, chemoreflex gain and plant gain. Our method was applied to recordings of spontaneous breathing in 15 anesthetized, tracheostomized, newborn lambs before and after administration of domperidone (a dopamine D(2)-receptor antagonist that increases carotid body sensitivity). We quantified the known increase in hypoxic ventilatory sensitivity in response to domperidone; controller gain for O(2) increased from 0.06 (0.03, 0.09) l·min(-1)·mmHg(-1) to 0.09 (0.08, 0.13) l·min(-1)·mmHg(-1); median (interquartile-range). We also report that domperidone increased the loop gain of the control system more than twofold [0.14 (0.12, 0.22) to 0.40 (0.15, 0.57)]. We observed no significant changes in CO(2) controller gain, or plant gains for O(2) and CO(2). Furthermore, our estimate of the cycle duration of periodic breathing compared favorably with that observed experimentally [measured: 7.5 (7.2, 9.1) vs. predicted: 7.9 (7.0, 9.2) breaths]. Our results demonstrate that model-based analysis of spontaneous breathing can 1) characterize the dynamics of the respiratory control system, and 2) provide a simple tool for elucidating an individual's propensity for ventilatory instability, in turn allowing potential therapies to be directed at the underlying mechanisms.
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Affiliation(s)
- Shamim Nemati
- Massachusetts Institute of Technology, Cambridge, MA, USA.
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Umantsev A, Golbin A. Correlations of physiological activities in nocturnal Cheyne-Stokes respiration. Nat Sci Sleep 2011; 3:21-32. [PMID: 23620676 PMCID: PMC3630982 DOI: 10.2147/nss.s15515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
We have conducted a power-spectrum-density (PSD) analysis of the distinct sleep stages of a previously diagnosed nocturnal Cheyne-Stokes respiration patient (NCSR) and studied the correlations of different physiological activities. This is the first study where the correlations were analyzed separately for different sleep stages and the influence of arousals was completely eliminated. Mathematical analysis of the polysomnographical records revealed clear indicators of the disorder in the form of large peaks in a very-low frequency range of f ≈ 0.02 Hz. We have shown existence of the significant entrainment of the cerebral and cardiac activities with respiration during different stages of sleep in the patient. The entrainment is highly pronounced in light (stage 2) and deep (stage 3) sleep, but is significantly less pronounced in rapid eye movement sleep. A correlation functions analysis revealed that the correlations between the central activities and respiration attain maximum at negative lag times. Lagging of respiration behind the central activities favors the central hypothesis of generation of NCSR. On the basis of comparison of PSD plots of a NCSR patient and a healthy patient we speculate that the vasomotor center of a NCSR patient assumes the control function in the respiratory control system. Clinical applications of the findings of the study may lead to the development of novel low-cost methods of diagnostic of NCSR based on easy-to-obtain electrocardiogram or electroencephalogram records of patients and emergence of some forms of "substitution therapy".
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Affiliation(s)
- Alexander Umantsev
- Department of Chemistry/Physics, Fayetteville State University, Fayetteville, NC, USA
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Abstract
The primary objective of the American Medical Research Expedition to Everest was to obtain information on human physiology at the highest possible altitude, including the Everest summit. An important data point was the barometric pressure on the summit, because this determines the inspired P(O(2)). The first measurement ever taken was 253.0 mmHg. Because modeling studies had shown that extreme hyperventilation was essential to reach these great altitudes, 34 alveolar gas samples were collected above an altitude of 8000 m, including 4 on the summit. These showed that hyperventilation reduced the alveolar P(CO(2)) to between 7 and 8 mmHg in one climber. An important finding was that alveolar P(O(2)) was defended at a value of about 35 mmHg by the increasing hyperventilation as the climbers ascended higher. Venous blood samples collected on two summiters gave a mean base excess of -7.2 meq.L(-1). Using the alveolar P(CO(2)) value, this gave an arterial pH of over 7.7, indicating an extreme degree of respiratory alkalosis. While climbing at an altitude of 8300 m, one summiter showed a respiratory frequency of 86 breaths.min(-1) and tidal volume of 1.26 L, indicating very rapid shallow breathing. Maximal oxygen consumption for the summit was derived by having well-acclimatized subjects exercise maximally at an altitude of 6300 m while breathing 14% oxygen. The V(O(2)) was just over 1 L.min(-1), which is sufficient to explain how exceptional humans can reach the summit without supplementary oxygen. In addition to the measurements at altitudes over 8000 m, data were obtained at two camps at 5400- and 6300-m altitude. These gave information on the control of ventilation, periodic breathing, blood physiology, cerebral function, and metabolism.
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Affiliation(s)
- John B West
- Department of Medicine, University of California San Diego, La Jolla, 92093-0623, USA.
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The hypoxia-induced facilitation of augmented breaths is suppressed by the common effect of carbonic anhydrase inhibition. Respir Physiol Neurobiol 2010; 171:201-11. [PMID: 20382275 DOI: 10.1016/j.resp.2010.04.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2009] [Revised: 04/01/2010] [Accepted: 04/02/2010] [Indexed: 11/20/2022]
Abstract
The typical respiratory response to hypoxia includes a dramatic facilitation of augmented breaths (ABs) or 'sighs' in the breathing rhythm. We recently found that when acetazolamide treatment is used to promote CO(2) retention and counteract alkalosis during exposure to hypoxia, then the hypoxia-induced facilitation of ABs is effectively prevented. These results indicate that hyperventilation-induced hypocapnia/alkalosis is an essential factor involved in the hypoxia-induced facilitation of augmented breaths. However, acetazolamide is also known to decrease the sensitivity of the arterial chemoreceptors. Therefore, the question remains as to whether acetazolamide prevents the facilitation of ABs during hypoxia by offsetting the effects of respiratory alkalosis, or alternatively by suppressing carotid body afferent activity. In the present study, we addressed this question by studying the effects of treatment with an alternative carbonic anhydrase inhibitor, methazolamide, which has been reported to leave carotid body responsiveness to hypoxia intact. Respiratory variables were monitored before, during and after 2 days of methazolamide treatment (10 mg kg(-1) IP, bid) in unsedated and unrestrained adult male rats. Pre-treatment, the number of ABs observed in a 5 min observation window was 1.2 + or - 0.8 and 17.4 + or - 3.8 in room air and hypoxia, respectively. During methazolamide treatment, the facilitation of ABs in hypoxia was rapidly and reversibly suppressed such that ABs we no longer significantly more frequent than they were in room air. The present results demonstrate that the hypoxia-induced facilitation of ABs can be suppressed via the general effects of carbonic anhydrase inhibition, which are common to both acetazolamide and methazolamide. We discuss these results as they pertain to the mechanisms regulating augmented breath production, and the possible association between hypocapnia/alkalosis and sleep disordered breathing.
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Cheyne-Stokes Respiration in Patients with Heart Failure. Lung 2009; 188:5-14. [DOI: 10.1007/s00408-009-9200-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2009] [Accepted: 11/12/2009] [Indexed: 11/27/2022]
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Bell HJ, Haouzi P. Acetazolamide suppresses the prevalence of augmented breaths during exposure to hypoxia. Am J Physiol Regul Integr Comp Physiol 2009; 297:R370-81. [DOI: 10.1152/ajpregu.00126.2009] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Augmented breaths, or “sighs,” commonly destabilize respiratory rhythm, precipitating apneas and variability in the depth and rate of breathing, which may then exacerbate sleep-disordered breathing in vulnerable individuals. We previously demonstrated that hypocapnia is a unique condition associated with a high prevalence of augmented breaths during exposure to hypoxia; the prevalence of augmented breaths during hypoxia can be returned to normal simply by the addition of CO2to the inspired air. We hypothesized that counteracting the effect of respiratory alkalosis during hypocapnic hypoxia by blocking carbonic anhydrase would yield a similar effect. We, therefore, investigated the effect of acetazolamide on the prevalence of augmented breaths in the resting breathing cycle in five awake, adult male rats. We found a 475% increase in the prevalence of augmented breaths in animals exposed to hypocapnic hypoxia compared with room air. Acetazolamide treatment (100 mg/kg ip bid) for 3 days resulted in a rapid and potent suppression of the generation of augmented breaths during hypoxia. Within 90 min of the first dose of acetazolamide, the prevalence of augmented breaths in hypoxia fell to levels that were no greater than those observed in room air. On cessation of treatment, exposure to hypocapnic hypoxia once again caused a large increase in the prevalence of augmented breaths. These results reveal a novel means by which acetazolamide acts to stabilize breathing and may help explain the beneficial effects of the drug on breathing stability at altitude and in patients with central forms of sleep-disordered breathing.
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Beecroft JM, Duffin J, Pierratos A, Chan CT, McFarlane P, Hanly PJ. Decreased chemosensitivity and improvement of sleep apnea by nocturnal hemodialysis. Sleep Med 2009; 10:47-54. [DOI: 10.1016/j.sleep.2007.11.017] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2007] [Revised: 11/15/2007] [Accepted: 11/16/2007] [Indexed: 11/16/2022]
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Increased peripheral chemosensitivity via dopaminergic manipulation promotes respiratory instability in lambs. Respir Physiol Neurobiol 2008; 164:419-28. [DOI: 10.1016/j.resp.2008.09.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2008] [Revised: 09/03/2008] [Accepted: 09/03/2008] [Indexed: 12/20/2022]
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