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Abstract
Central apnea syndrome is a disorder with protean manifestations and concomitant conditions. It can occur as a distinct clinical entity or as part of another clinical syndrome. The pathogenesis of central sleep apnea (CSA) varies depending on the clinical condition. Sleep-related withdrawal of the ventilatory drive to breathe is the common denominator among all cases of central apnea, whereas hypocapnia is the final common pathway leading to apnea in the majority of central apnea. Medical conditions most closely associated with CSA include heart failure, stroke, spinal cord injury, and opioid use, among others. Nocturnal polysomnography is the standard diagnostic method, including measurement of sleep and respiration. The latter includes detection of flow, measurement of oxyhemoglobin saturation and detection of respiratory effort. Management strategy incorporates clinical presentation, associated conditions, and the polysomnographic findings in an individualized manner. The pathophysiologic heterogeneity may explain the protean clinical manifestations and the lack of a single effective therapy for all patients. While research has enhanced our understanding of the pathogenesis of central apnea, treatment options are extrapolated from treatment of obstructive sleep apnea. Co-morbid conditions and concomitant obstructive sleep apnea influence therapeutic approach significantly. Therapeutic options include positive pressure therapy, pharmacologic therapy, and supplemental Oxygen. Continuous positive airway pressure (CPAP) is the initial standard of care, although the utility of other modes of positive pressure therapy, as well as pharmacotherapy and device-based therapies, are currently being investigated.
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Affiliation(s)
- Geoffrey Ginter
- Department of Internal Medicine, University Health Center and John D. Dingell VA Medical Center, Wayne State University School of Medicine, Detroit, MI, United States
| | - M Safwan Badr
- Department of Internal Medicine, University Health Center and John D. Dingell VA Medical Center, Wayne State University School of Medicine, Detroit, MI, United States.
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Orr JE, Ayappa I, Eckert DJ, Feldman JL, Jackson CL, Javaheri S, Khayat RN, Martin JL, Mehra R, Naughton MT, Randerath WJ, Sands SA, Somers VK, Badr MS. Research Priorities for Patients with Heart Failure and Central Sleep Apnea. An Official American Thoracic Society Research Statement. Am J Respir Crit Care Med 2021; 203:e11-e24. [PMID: 33719931 PMCID: PMC7958519 DOI: 10.1164/rccm.202101-0190st] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Background: Central sleep apnea (CSA) is common among patients with heart failure and has been strongly linked to adverse outcomes. However, progress toward improving outcomes for such patients has been limited. The purpose of this official statement from the American Thoracic Society is to identify key areas to prioritize for future research regarding CSA in heart failure. Methods: An international multidisciplinary group with expertise in sleep medicine, pulmonary medicine, heart failure, clinical research, and health outcomes was convened. The group met at the American Thoracic Society 2019 International Conference to determine research priority areas. A statement summarizing the findings of the group was subsequently authored using input from all members. Results: The workgroup identified 11 specific research priorities in several key areas: 1) control of breathing and pathophysiology leading to CSA, 2) variability across individuals and over time, 3) techniques to examine CSA pathogenesis and outcomes, 4) impact of device and pharmacological treatment, and 5) implementing CSA treatment for all individuals Conclusions: Advancing care for patients with CSA in the context of heart failure will require progress in the arenas of translational (basic through clinical), epidemiological, and patient-centered outcome research. Given the increasing prevalence of heart failure and its associated substantial burden to individuals, society, and the healthcare system, targeted research to improve knowledge of CSA pathogenesis and treatment is a priority.
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Zeineddine S, Badr MS. Treatment-Emergent Central Apnea: Physiologic Mechanisms Informing Clinical Practice. Chest 2021; 159:2449-2457. [PMID: 33497650 DOI: 10.1016/j.chest.2021.01.036] [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] [Received: 03/08/2020] [Revised: 12/11/2020] [Accepted: 01/14/2021] [Indexed: 11/26/2022] Open
Abstract
The purpose of this review was to describe our management approach to patients with treatment-emergent central sleep apnea (TECSA). The emergence of central sleep apnea during positive airway pressure therapy occurs in approximately 8% of titration studies for OSA, and it has been associated with several demographic, clinical, and polysomnographic factors, as well as factors related to the titration study itself. TECSA shares similar pathophysiology with central sleep apnea. In fact, central and OSA pathophysiologic mechanisms are inextricably intertwined, with ventilatory instability and upper airway narrowing occurring in both entities. TECSA is a "dynamic" process, with spontaneous resolution with ongoing positive airway pressure therapy in most patients, persistence in some, or appearing de novo in a minority of patients. Management strategy for TECSA aims to eliminate abnormal respiratory events, stabilize sleep architecture, and improve the underlying contributing medical comorbidities. CPAP therapy remains a standard therapy for TECSA. Expectant management is appropriate given its transient nature in most cases, whereas select patients would benefit from an early switch to an alternative positive airway pressure modality. Other treatment options include supplemental oxygen and pharmacologic therapy.
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Affiliation(s)
- Salam Zeineddine
- John D. Dingell VA Medical Center, Detroit, MI; Department of Medicine, Wayne State University, Detroit, MI
| | - M Safwan Badr
- John D. Dingell VA Medical Center, Detroit, MI; Department of Medicine, Wayne State University, Detroit, MI.
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Obstructive Sleep Apnea and Testosterone Therapy. Sex Med Rev 2020; 9:296-303. [PMID: 32636155 DOI: 10.1016/j.sxmr.2020.04.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 04/15/2020] [Accepted: 04/26/2020] [Indexed: 02/06/2023]
Abstract
INTRODUCTION There is persistent speculation that testosterone therapy (TTh) may induce worsening of obstructive sleep apnea (OSA). As both the incidence of OSA and the use of TTh grow more prevalent, it is important to review the current evidence that supports or refutes this relationship. OBJECTIVES To review the current literature regarding the relationship between TTh and OSA. METHODS A literature search was conducted to identify relevant studies. Search terms included "obstructive sleep apnea" and "testosterone replacement therapy." Titles and abstracts were reviewed for relevance. References from identified articles were searched and included, if appropriate. RESULTS The association between TTh and OSA was initially described in a 1978 case report of an individual with worsened nighttime apneas during testosterone administration, a trend seen again in subsequent small case series. In the 1990s, a large retrospective analysis and the first randomized controlled trial on the subject revealed no increased incidence of OSA in individuals on TTh. A randomized controlled trial conducted in 2012 provided a possible explanation to the previously reported discrepancies, describing a time-limited effect, wherein measures of OSA were elevated at seven weeks but were not significantly different at 18 weeks after initiation of TTh. A recent cohort study demonstrated an incidence of OSA in individuals on TTh of 16.5% compared with 12.7% in controls. TTh is thought to affect OSA in several ways. Theories that the anabolic effects of testosterone may decrease airway patency or that testosterone alters sleep architecture have been largely disproven. More likely, testosterone plays a role in altering neural response pathways to hypoxemia. CONCLUSIONS TTh likely plays a small role in exacerbating or inducing changes in OSA that may be time limited in nature. Clinicians may choose to exercise caution in prescribing TTh to individuals suffering from severe OSA. Payne K, Lipshultz LI, Hotaling JM, et al. Obstructive Sleep Apnea and Testosterone Therapy. J Sex Med 2021;9:296-303.
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Fields DP, Braegelmann KM, Meza AL, Mickelson CR, Gumnit MG, Baker TL. Competing mechanisms of plasticity impair compensatory responses to repetitive apnoea. J Physiol 2019; 597:3951-3967. [PMID: 31280489 DOI: 10.1113/jp277676] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 06/03/2019] [Indexed: 12/21/2022] Open
Abstract
KEY POINTS Intermittent reductions in respiratory neural activity, a characteristic of many ventilatory disorders, leads to inadequate ventilation and arterial hypoxia. Both intermittent reductions in respiratory neural activity and intermittent hypoxia trigger compensatory enhancements in inspiratory output when experienced separately, forms of plasticity called inactivity-induced inspiratory motor facilitation (iMF) and long-term facilitation (LTF), respectively. Reductions in respiratory neural activity that lead to moderate, but not mild, arterial hypoxia occludes plasticity expression, indicating that concurrent induction of iMF and LTF impairs plasticity through cross-talk inhibition of their respective signalling pathways. Moderate hypoxia undermines iMF by enhancing NR2B-containing NMDA receptor signalling, which can be rescued by exogenous retinoic acid, a molecule necessary for iMF. These data suggest that in ventilatory disorders characterized by reduced inspiratory motor output, such as sleep apnoea, endogenous mechanisms of compensatory plasticity may be impaired, and that exogenously activating respiratory plasticity may be a novel strategy to improve breathing. ABSTRACT Many forms of sleep apnoea are characterized by recurrent reductions in respiratory neural activity, which leads to inadequate ventilation and arterial hypoxia. Both recurrent reductions in respiratory neural activity and hypoxia activate mechanisms of compensatory plasticity that augment inspiratory output and lower the threshold for apnoea, inactivity-induced inspiratory motor facilitation (iMF) and long-term facilitation (LTF), respectively. However, despite frequent concurrence of reduced respiratory neural activity and hypoxia, mechanisms that induce and regulate iMF and LTF have only been studied separately. Here, we demonstrate that recurrent reductions in respiratory neural activity ('neural apnoea') accompanied by cessations in ventilation that result in moderate (but not mild) hypoxaemia do not elicit increased inspiratory output, suggesting that concurrent induction of iMF and LTF occludes plasticity. A key role for NMDA receptor activation in impairing plasticity following concurrent neural apnoea and hypoxia is indicated since recurrent hypoxic neural apnoeas triggered increased phrenic inspiratory output in rats in which spinal NR2B-containing NMDA receptors were inhibited. Spinal application of retinoic acid, a key molecule necessary for iMF, bypasses NMDA receptor-mediated constraints, thereby rescuing plasticity following hypoxic neural apnoeas. These studies raise the intriguing possibility that endogenous mechanisms of compensatory plasticity may be impaired in some individuals with sleep apnoea, and that exogenously activating pathways giving rise to respiratory plasticity may be a novel pharmacological strategy to improve breathing.
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Affiliation(s)
- Daryl P Fields
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Kendra M Braegelmann
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Armand L Meza
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Carly R Mickelson
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Maia G Gumnit
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
| | - Tracy L Baker
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI, USA
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Wang D, Wong KK, Rowsell L, Don GW, Yee BJ, Grunstein RR. Predicting response to oxygen therapy in obstructive sleep apnoea patients using a 10-minute daytime test. Eur Respir J 2018; 51:51/1/1701587. [DOI: 10.1183/13993003.01587-2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 10/07/2017] [Indexed: 11/05/2022]
Abstract
There is no satisfactory treatment for obstructive sleep apnoea (OSA). Supplemental low-flow oxygen therapy (LFO2) has been shown to reduce hypoxaemia and is well tolerated by patients with OSA. However, oxygen therapy may be beneficial only to certain subsets of patients with OSA. In this study, we evaluated a 10-min awake ventilatory chemoreflex test in predicting individual OSA response to 2 months of LFO2therapy.At baseline, patients with OSA underwent ventilatory chemoreflex testing in the afternoon, prior to the overnight polysomnography. Subjects were reassessed with polysomnography after 2 months of nocturnal oxygen treatment.20 patients with OSA completed the study. After 2 months of O2treatment, changes in the apnoea–hypopnoea index (AHI) were significantly correlated with baseline CO2ventilatory response threshold (VRT) and chemosensitivity (p<0.05). In predicting a fall in AHI, the area under the receiver operating characteristic curve (AUC) was 0.79 for VRT and 0.89 for chemosensitivity. When these two variables were combined in a logistic regression model, the prediction effect became stronger with an AUC of 0.97, sensitivity of 0.92 and specificity of 0.83.Our awake ventilatory chemoreflex test could be considered a simple potential clinical tool to predict individual OSA response to oxygen therapy. It could provide a novel personalised medicine approach to OSA treatment.
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Morselli LL, Temple KA, Leproult R, Ehrmann DA, Van Cauter E, Mokhlesi B. Determinants of Slow-Wave Activity in Overweight and Obese Adults: Roles of Sex, Obstructive Sleep Apnea and Testosterone Levels. Front Endocrinol (Lausanne) 2018; 9:377. [PMID: 30050500 PMCID: PMC6052085 DOI: 10.3389/fendo.2018.00377] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Accepted: 06/22/2018] [Indexed: 01/11/2023] Open
Abstract
Background: Slow-wave activity (SWA) in non-rapid eye movement (NREM) sleep, obtained by spectral analysis of the electroencephalogram, is a marker of the depth or intensity of NREM sleep. Higher levels of SWA are associated with lower arousability during NREM sleep and protect against sleep fragmentation. Multiple studies have documented that SWA levels are higher in lean women, compared to age-matched lean men, but whether these differences persist in obese subjects is unclear. Obstructive sleep apnea (OSA), a condition associated with obesity, is more prevalent in men than in women. Sex differences in SWA could therefore be one of the factors predisposing men to OSA. Furthermore, we hypothesized that higher levels of testosterone may be associated with lower levels of SWA. Objective: The aim of the current study was to identify sex differences in the determinants of SWA in young and middle-aged overweight and obese adults. Methods: We enrolled 101 overweight and obese but otherwise healthy participants from the community (44 men, 57 women) in this cross-sectional study. Participants underwent an overnight in-laboratory polysomnogram. The recordings were submitted to sleep staging and spectral analysis. Sex differences and the potential contribution of testosterone levels were evaluated after adjusting for age, body mass index and race/ethnicity. Results: OSA was present in 66% of men and in 44% of women. After adjustment for differences in age, race/ethnicity and BMI, the odds ratio for OSA in men vs. women was 3.17 (95% CI 1.14-9.43, p = 0.027). There was a graded inverse relationship between the apnea-hypopnea index (AHI) and SWA in men (β = -0.21, p = 0.018) but not in women (β = 0.10, p = 0.207). In a multivariate regression model, higher testosterone levels were independently associated with lower SWA in men after controlling for age, race/ethnicity and apnea-hypopnea index (β = -0.56, p = 0.025). Conclusion: Increasing severity of OSA was associated with significant decrease in sleep intensity in men but not in women. Higher testosterone levels were associated with lower sleep intensity in men. Men with higher testosterone levels may therefore have lower arousal thresholds and higher ventilatory instability in NREM sleep, and be at greater risk of OSA.
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Affiliation(s)
- Lisa L. Morselli
- Sleep, Metabolism and Health Center, University of Chicago, Chicago, IL, United States
- Division of Endocrinology and Metabolism, Department of Internal Medicine, University of Iowa Carver College of Medicine, Iowa City, IA, United States
| | - Karla A. Temple
- Sleep, Metabolism and Health Center, University of Chicago, Chicago, IL, United States
- Section of Endocrinology, Department of Medicine, University of Chicago, Chicago, IL, United States
| | - Rachel Leproult
- Sleep, Metabolism and Health Center, University of Chicago, Chicago, IL, United States
| | - David A. Ehrmann
- Sleep, Metabolism and Health Center, University of Chicago, Chicago, IL, United States
- Section of Endocrinology, Department of Medicine, University of Chicago, Chicago, IL, United States
| | - Eve Van Cauter
- Sleep, Metabolism and Health Center, University of Chicago, Chicago, IL, United States
- Section of Endocrinology, Department of Medicine, University of Chicago, Chicago, IL, United States
| | - Babak Mokhlesi
- Sleep, Metabolism and Health Center, University of Chicago, Chicago, IL, United States
- Section of Pulmonary and Critical Care, Department of Medicine, University of Chicago, Chicago, IL, United States
- *Correspondence: Babak Mokhlesi
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Abstract
Central sleep apnea and Cheyne-Stokes respiration are commonly observed breathing patterns during sleep in patients with congestive heart failure. Common risk factors are male gender, older age, presence of atrial fibrillation, and daytime hypocapnia. Proposed mechanisms include augmented peripheral and central chemoreceptor sensitivity, which increase ventilator instability during both wakefulness and sleep; diminished cerebrovascular reactivity and increased circulation time, which impair the normal buffering of Paco2 and hydrogen ions and delay the detection of changes in Paco2 during sleep; and rostral fluid shifts that predispose to hypocapnia.
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Chowdhuri S, Badr MS. Control of Ventilation in Health and Disease. Chest 2016; 151:917-929. [PMID: 28007622 DOI: 10.1016/j.chest.2016.12.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 12/02/2016] [Accepted: 12/05/2016] [Indexed: 11/29/2022] Open
Abstract
Control of ventilation occurs at different levels of the respiratory system through a negative feedback system that allows precise regulation of levels of arterial carbon dioxide and oxygen. Mechanisms for ventilatory instability leading to sleep-disordered breathing include changes in the genesis of respiratory rhythm and chemoresponsiveness to hypoxia and hypercapnia, cerebrovascular reactivity, abnormal chest wall and airway reflexes, and sleep state oscillations. One can potentially stabilize breathing during sleep and treat sleep-disordered breathing by identifying one or more of these pathophysiological mechanisms. This review describes the current concepts in ventilatory control that pertain to breathing instability during wakefulness and sleep, delineates potential avenues for alternative therapies to stabilize breathing during sleep, and proposes recommendations for future research.
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Affiliation(s)
- Susmita Chowdhuri
- John D. Dingell VA Medical Center, Wayne State University, Detroit MI; Department of Medicine, Wayne State University, Detroit MI.
| | - M Safwan Badr
- John D. Dingell VA Medical Center, Wayne State University, Detroit MI; Department of Medicine, Wayne State University, Detroit MI
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Lozo T, Komnenov D, Badr MS, Mateika JH. Sex differences in sleep disordered breathing in adults. Respir Physiol Neurobiol 2016; 245:65-75. [PMID: 27836648 DOI: 10.1016/j.resp.2016.11.001] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2016] [Revised: 10/26/2016] [Accepted: 11/02/2016] [Indexed: 02/06/2023]
Abstract
The prevalence of sleep disordered breathing is greater in men compared to women. This disparity could be due to sex differences in the diagnosis and presentation of sleep apnea, and the pathophysiological mechanisms that instigate this disorder. Women tend to report more non-typical symptoms of sleep apnea compared to men, and the presentation of apneic events are more prevalent in rapid compared to non-rapid eye movement sleep. In addition, there is evidence of sex differences in upper airway structure and mechanics and in neural mechanisms that impact on the control of breathing. The purpose of this review is to summarize the literature that addresses sex differences in sleep-disordered breathing, and to discuss the influence that upper airway mechanics, chemoreflex properties, and sex hormones have in modulating breathing during sleep in men and women.
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Affiliation(s)
- Tijana Lozo
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - Dragana Komnenov
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States
| | - M Safwan Badr
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Biomedical Engineering, Wayne State University Detroit, MI 48201, United States
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, MI 48201, United States; Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, United States; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, MI 48201, United States.
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El-Chami M, Shaheen D, Ivers B, Syed Z, Badr MS, Lin HS, Mateika JH. Time of day affects chemoreflex sensitivity and the carbon dioxide reserve during NREM sleep in participants with sleep apnea. J Appl Physiol (1985) 2014; 117:1149-56. [PMID: 25213638 DOI: 10.1152/japplphysiol.00681.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Our investigation was designed to determine whether the time of day affects the carbon dioxide reserve and chemoreflex sensitivity during non-rapid eye movement (NREM) sleep. Ten healthy men with obstructive sleep apnea completed a constant routine protocol that consisted of sleep sessions in the evening (10 PM to 1 AM), morning (6 AM to 9 AM), and afternoon (2 PM to 5 PM). Between sleep sessions, the participants were awake. During each sleep session, core body temperature, baseline levels of carbon dioxide (PET(CO2)) and minute ventilation, as well as the PET(CO2) that demarcated the apneic threshold and hypocapnic ventilatory response, were measured. The nadir of core body temperature during sleep occurred in the morning and was accompanied by reductions in minute ventilation and PetCO2 compared with the evening and afternoon (minute ventilation: 5.3 ± 0.3 vs. 6.2 ± 0.2 vs. 6.1 ± 0.2 l/min, P < 0.02; PET(CO2): 39.7 ± 0.4 vs. 41.4 ± 0.6 vs. 40.4 ± 0.6 Torr, P < 0.02). The carbon dioxide reserve was reduced, and the hypocapnic ventilatory response increased in the morning compared with the evening and afternoon (carbon dioxide reserve: 2.1 ± 0.3 vs. 3.6 ± 0.5 vs. 3.5 ± 0.3 Torr, P < 0.002; hypocapnic ventilatory response: 2.3 ± 0.3 vs. 1.6 ± 0.2 vs. 1.8 ± 0.2 l·min(-1)·mmHg(-1), P < 0.001). We conclude that time of day affects chemoreflex properties during sleep, which may contribute to increases in breathing instability in the morning compared with other periods throughout the day/night cycle in individuals with sleep apnea.
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Affiliation(s)
- Mohamad El-Chami
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - David Shaheen
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Blake Ivers
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Ziauddin Syed
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - M Safwan Badr
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Department of Biomedical Engineering, Wayne State University Detroit, Michigan
| | - Ho-Sheng Lin
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Department of Otolaryngology-Head & Neck Surgery, Wayne State University School of Medicine and Karmanos Cancer Institute, Detroit, Michigan; and
| | - Jason H Mateika
- John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan; Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan; Department of Internal Medicine, Wayne State University School of Medicine, Detroit, Michigan;
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From the Journal archives: Assessing the effect of anesthetic agents on the respiratory chemoreflex control of breathing. Can J Anaesth 2014; 61:664-70. [DOI: 10.1007/s12630-014-0110-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Accepted: 01/07/2014] [Indexed: 10/25/2022] Open
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Grayburn RL, Kaka Y, Tang WHW. Contemporary insights and novel treatment approaches to central sleep apnea syndrome in heart failure. CURRENT TREATMENT OPTIONS IN CARDIOVASCULAR MEDICINE 2014; 16:322. [PMID: 24874028 DOI: 10.1007/s11936-014-0322-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OPINION STATEMENT Central sleep apnea (CSA) is a common and under-diagnosed condition commonly associated with Cheyne-Stokes respiration. It is particularly prevalent in the heart failure population affecting up to 40 % of all patients with heart failure. The pathophysiology associated with CSA is based on the underlying effects of hypoventilation and hyperventilation, with neurologic dysregulation of respiratory control as the primary defect. However, therapeutic options are limited because of the prevailing perception that CSA is a consequence, rather than cause of morbidity and mortality. At present, the main focus remains treating the underlying problem (ie, intensifying heart failure therapeutics, decongestion), whereas additional suggestions of using acetazolamide, progesterone, nocturnal oxygen, and theophylline have not been validated with contemporary clinical trials. Positive pressure ventilation is currently the primary recommendation for all patients with sleep-disordered breathing (CSA included), and in some patients may effectively reduce the apnea-hypopnea index. However, significant research is ongoing to determine how to treat this complex patient population.
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Affiliation(s)
- Ryan L Grayburn
- Department of Cardiovascular Medicine, Heart and Vascular Institute, Cleveland Clinic, 9500 Euclid Avenue, Desk J3-4, Cleveland, OH, USA
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Abstract
There is a growing public awareness that hormones can have a significant impact on most biological systems, including the control of breathing. This review will focus on the actions of two broad classes of hormones on the neuronal control of breathing: sex hormones and stress hormones. The majority of these hormones are steroids; a striking feature is that both groups are derived from cholesterol. Stress hormones also include many peptides which are produced primarily within the paraventricular nucleus of the hypothalamus (PVN) and secreted into the brain or into the circulatory system. In this article we will first review and discuss the role of sex hormones in respiratory control throughout life, emphasizing how natural fluctuations in hormones are reflected in ventilatory metrics and how disruption of their endogenous cycle can predispose to respiratory disease. These effects may be mediated directly by sex hormone receptors or indirectly by neurotransmitter systems. Next, we will discuss the origins of hypothalamic stress hormones and their relationship with the respiratory control system. This relationship is 2-fold: (i) via direct anatomical connections to brainstem respiratory control centers, and (ii) via steroid hormones released from the adrenal gland in response to signals from the pituitary gland. Finally, the impact of stress on the development of neural circuits involved in breathing is evaluated in animal models, and the consequences of early stress on respiratory health and disease is discussed.
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Affiliation(s)
- Mary Behan
- Department of Comparative Biosciences, University of Wisconsin, Madison, Wisconsin, USA.
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Chowdhuri S, Bascom A, Mohan D, Diamond MP, Badr MS. Testosterone conversion blockade increases breathing stability in healthy men during NREM sleep. Sleep 2013; 36:1793-8. [PMID: 24293753 DOI: 10.5665/sleep.3202] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
STUDY OBJECTIVES Gender differences in the prevalence of sleep apnea/hypopnea syndrome may be mediated via male sex hormones. Our objective was to determine the exact pathway for a testosterone-mediated increased propensity for central sleep apnea via blockade of the 5α-reductase pathway of testosterone conversion by finasteride. DESIGN Randomization to oral finasteride vs. sham, single-center study. SETTING Sleep research laboratory. PARTICIPANTS Fourteen healthy young males without sleep apnea. INTERVENTION Hypocapnia was induced via brief nasal noninvasive positive pressure ventilation during stable NREM sleep. Cessation of mechanical ventilation resulted in hypocapnic central apnea or hypopnea. MEASUREMENTS AND RESULTS The apnea threshold (AT) was defined as the end-tidal CO₂(P(ET)CO₂) that demarcated the central apnea closest to the eupneic P(ET)CO₂. The CO₂ reserve was defined as the difference in P(ET)CO₂ between eupnea and AT. The apneic threshold and CO₂ reserve were measured at baseline and repeated after at a minimum of 1 month. Administration of finasteride resulted in decreased serum dihydrotestosterone. In the finasteride group, the eupneic ventilatory parameters were unchanged; however, the AT was decreased (38.9 ± 0.6 mm Hg vs.37.7 ± 0.9 mm Hg, P = 0.02) and the CO₂ reserve was increased (-2.5 ± 0.3 mm Hg vs. -3.8 ± 0.5 mm Hg, P = 0.003) at follow-up, with a significantly lower hypocapnic ventilatory response, thus indicating increased breathing stability during sleep. No significant changes were noted in the sham group on follow-up study. CONCLUSIONS Inhibition of testosterone action via the 5α-reductase pathway may be effective in alleviating breathing instability during sleep, presenting an opportunity for novel therapy for central sleep apnea in selected populations.
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Affiliation(s)
- Susmita Chowdhuri
- Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, MI ; Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, MI
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Wang D, Eckert DJ, Grunstein RR. Drug effects on ventilatory control and upper airway physiology related to sleep apnea. Respir Physiol Neurobiol 2013; 188:257-66. [PMID: 23685318 DOI: 10.1016/j.resp.2013.05.007] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Revised: 05/05/2013] [Accepted: 05/08/2013] [Indexed: 12/30/2022]
Abstract
Understanding the inter-relationship between pharmacological agents, ventilatory control, upper airway physiology and their consequent effects on sleep-disordered breathing may provide new directions for targeted drug therapy. Where available, this review focuses on human studies that contain both drug effects on sleep-disordered breathing and measures of ventilatory control or upper airway physiology. Many of the existing studies are limited in sample size or comprehensive methodology. At times, the presence of paradoxical findings highlights the complexity of drug therapy for OSA. The existing studies also highlight the importance of considering inter-individual pharmacokinetics and underlying causes of sleep apnea in interpreting drug effects on sleep-disordered breathing. Practical ways to assess an individual's ventilatory control and how it interacts with upper airway physiology is required for future targeted pharmacotherapy in sleep apnea.
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Affiliation(s)
- David Wang
- Woolcock Institute of Medical Research, University of Sydney, Glebe Point Road, Glebe, 2037 NSW, Australia; Department of Respiratory & Sleep Medicine, Royal Prince Alfred Hospital, Missenden Road, Camperdown, NSW 2050, Australia.
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The effects of a single mild dose of morphine on chemoreflexes and breathing in obstructive sleep apnea. Respir Physiol Neurobiol 2013. [DOI: 10.1016/j.resp.2012.11.014] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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Killick R, Wang D, Hoyos CM, Yee BJ, Grunstein RR, Liu PY. The effects of testosterone on ventilatory responses in men with obstructive sleep apnea: a randomised, placebo-controlled trial. J Sleep Res 2013; 22:331-6. [PMID: 23331844 DOI: 10.1111/jsr.12027] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 11/25/2012] [Indexed: 11/28/2022]
Abstract
We recently showed that testosterone therapy worsens sleep-disordered breathing at 6-7 weeks, but not after 18 weeks, in men with obstructive sleep apnea. Changes in ventilatory chemoreflexes may be responsible. The effect of testosterone on ventilatory chemoreflexes in men with obstructive sleep apnea has not been systematically studied before. Twenty-one obese men with obstructive sleep apnea, a subgroup of our recent report, were randomised in an 18-week, randomised, double-blind, placebo-controlled, parallel group trial to three intramuscular injections (0, 6, 12 weeks) of either 1000 mg testosterone undecanoate (n = 10) or placebo (n = 11). Awake ventilatory chemoreflex testing was performed before (week 0), during (week 6) and at the end of treatment (week 18) to determine the ventilatory carbon dioxide recruitment threshold and chemosensitivity. Sleep and breathing was assessed by overnight polysomnography at 0, 7 and 18 weeks. Serum hormones levels were measured at every visit. A significant increase in blood testosterone levels (5.65 nmol L(-1) , 0.51-10.8 nmol L(-1) , P = 0.03) and lean muscle mass (2.36 kg, 0.8-3.9 kg, P = 0.007) between the two groups was observed as expected. No significant differences were seen in ventilatory chemoreflexes between the two groups at 6 weeks or at 18 weeks. However, positive correlations were observed between changes in serum testosterone and hyperoxic ventilatory recruitment threshold (r = 0.55, P = 0.03), and between changes in hyperoxic ventilatory recruitment threshold and time spent with oxygen saturations during sleep <90% (r = 0.57, P = 0.03) at 6-7 weeks, but not at 18 weeks. Time-dependent alterations in ventilatory recruitment threshold may therefore mediate the time-dependent changes in sleep breathing observed with testosterone.
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Affiliation(s)
- Roo Killick
- NHMRC Centre for Integrated Research and Understanding of Sleep (CIRUS), Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia
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Hoyos CM, Killick R, Yee BJ, Grunstein RR, Liu PY. Effects of testosterone therapy on sleep and breathing in obese men with severe obstructive sleep apnoea: a randomized placebo-controlled trial. Clin Endocrinol (Oxf) 2012; 77:599-607. [PMID: 22512435 DOI: 10.1111/j.1365-2265.2012.04413.x] [Citation(s) in RCA: 80] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
STUDY OBJECTIVES High doses of short-term testosterone have been shown to acutely worsen sleep-disordered breathing in men with obstructive sleep apnoea (OSA). The effects of lower, near-conventional doses of testosterone in obese men with OSA may differ over the longer term but have not been systematically studied. We assessed sleep and breathing effects of near-conventional testosterone treatment as an adjunct to weight loss in obese men with severe OSA. DESIGN An 18-week randomized, double-blind, placebo-controlled, parallel group trial in 67 men. INTERVENTIONS All subjects were placed on a hypocaloric diet and then received intramuscular injections of 1000 mg testosterone undecanoate or placebo at 0, 6 and 12 weeks. MEASUREMENTS AND RESULTS Sleep and breathing were measured by nocturnal polysomnography at 0, 7 and 18 weeks. Testosterone, compared to placebo, worsened the oxygen desaturation index (ODI) by 10·3 events/h (95%CI, 0·8-19·8 events/h; P = 0·03) and nocturnal hypoxaemia (sleep time with oxygen saturation <90%, SpO(2) T90%) by 6·1% (95%CI, 1·5-10·6; P = 0·01) at 7 weeks. Testosterone therapy did not alter ODI (4·5, -5·4 to 14·4 events/h; P = 0·36) or SpO(2) T90% at 18 weeks (2·9, -1·9-7·7%; P = 0·23) compared to placebo. The testosterone treatment effects on ODI and SpO(2) T90% were not influenced by baseline testosterone concentrations (testosterone by treatment interactions, all P > 0·35). Blood testosterone concentrations did not correlate with ODI or SpO(2) T90% (all P > 0·19). CONCLUSIONS Testosterone therapy in obese men with severe OSA mildly worsens sleep-disordered breathing in a time-limited manner, irrespective of initial testosterone concentrations. This time-dependency was not related to testosterone concentrations. TRIAL REGISTRATION www.anzctr.org.au Identifier: ACTRN1260-6000404527.
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Affiliation(s)
- Camilla M Hoyos
- Endocrine and Cardiometabolic Research Group, NHMRC Centre for Integrated Research and Understanding of Sleep (CIRUS), Woolcock Institute of Medical Research, University of Sydney, Sydney, NSW, Australia
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Cui Z, Fisher J, Duffin J. Central-peripheral respiratory chemoreflex interaction in humans. Respir Physiol Neurobiol 2012; 180:126-31. [DOI: 10.1016/j.resp.2011.11.002] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2011] [Revised: 11/03/2011] [Accepted: 11/04/2011] [Indexed: 01/12/2023]
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21
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Yokhana SS, Gerst DG, Lee DS, Badr MS, Qureshi T, Mateika JH. Impact of repeated daily exposure to intermittent hypoxia and mild sustained hypercapnia on apnea severity. J Appl Physiol (1985) 2011; 112:367-77. [PMID: 22052874 DOI: 10.1152/japplphysiol.00702.2011] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We examined whether exposure to intermittent hypoxia (IH) during wakefulness impacted on the apnea/hypopnea index (AHI) during sleep in individuals with sleep apnea. Participants were exposed to twelve 4-min episodes of hypoxia in the presence of sustained mild hypercapnia each day for 10 days. A control group was exposed to sustained mild hypercapnia for a similar duration. The intermittent hypoxia protocol was completed in the evening on day 1 and 10 and was followed by a sleep study. During all sleep studies, the change in esophageal pressure (ΔPes) from the beginning to the end of an apnea and the tidal volume immediately following apneic events were used to measure respiratory drive. Following exposure to IH on day 1 and 10, the AHI increased above baseline measures (day 1: 1.95 ± 0.42 fraction of baseline, P ≤ 0.01, vs. day 10: 1.53 ± 0.24 fraction of baseline, P < 0.06). The indexes were correlated to the hypoxic ventilatory response (HVR) measured during the IH protocol but were not correlated to the magnitude of ventilatory long-term facilitation (vLTF). Likewise, ΔPes and tidal volume measures were greater on day 1 and 10 compared with baseline (ΔPes: -8.37 ± 0.84 vs. -5.90 ± 1.30 cmH(2)0, P ≤ 0.04; tidal volume: 1,193.36 ± 101.85 vs. 1,015.14 ± 119.83 ml, P ≤ 0.01). This was not the case in the control group. Interestingly, the AHI on day 10 (0.78 ± 0.13 fraction of baseline, P ≤ 0.01) was significantly less than measures obtained during baseline and day 1 in the mild hypercapnia control group. We conclude that enhancement of the HVR initiated by exposure to IH may lead to increases in the AHI during sleep and that initiation of vLTF did not appear to impact on breathing stability. Lastly, our results suggest that repeated daily exposure to mild sustained hypercapnia may lead to a decrease in breathing events.
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Affiliation(s)
- Sanar S Yokhana
- Department of Physiology, Wayne State University School of Medicine, Wayne State University, Detroit, Michigan, USA
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22
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Izumizaki M, Masaoka Y, Homma I. Coupling of dyspnea perception and tachypneic breathing during hypercapnia. Respir Physiol Neurobiol 2011; 179:276-86. [PMID: 21939787 DOI: 10.1016/j.resp.2011.09.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2011] [Revised: 08/19/2011] [Accepted: 09/08/2011] [Indexed: 10/17/2022]
Abstract
Respiratory rhythm is susceptible to behavioral influences including emotions. Since laboratory dyspnea induces negative emotions, we examined whether tachypneic breathing occurs in relation to perception of dyspnea during CO(2) rebreathing (n=21). Dyspnea intensity scored by a visual analog scale and respiratory frequency started to increase rapidly once the intensity of the stimuli exceeded a threshold for the end-tidal CO(2) fraction. The thresholds for dyspnea and respiratory frequency were similar (7.5±0.1% and 7.6±0.2% of the end-tidal CO(2) fraction, respectively), while the threshold for tidal volume (8.0±0.2%), when the tidal volume had stabilized, was significantly higher than the thresholds for dyspnea (p<0.01) and respiratory frequency (p<0.05). A positive correlation was found between the thresholds for dyspnea and respiratory frequency (r=0.81, p<0.001), and these thresholds showed good agreement on a Bland-Altman plot. These findings suggest that the start of tachypneic breathing is coupled with the threshold for dyspnea.
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Affiliation(s)
- Masahiko Izumizaki
- Department of Physiology, Showa University School of Medicine, Tokyo, Japan.
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23
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Measuring the respiratory chemoreflexes in humans. Respir Physiol Neurobiol 2011; 177:71-9. [DOI: 10.1016/j.resp.2011.04.009] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Accepted: 04/08/2011] [Indexed: 11/24/2022]
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24
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WANG DAVID, MARSHALL NATHANIELS, DUFFIN JAMES, YEE BRENDONJ, WONG KEITHK, NOORI NARGIS, NG SUSANNASW, GRUNSTEIN RONALDR. Phenotyping interindividual variability in obstructive sleep apnoea response to temazepam using ventilatory chemoreflexes during wakefulness. J Sleep Res 2011; 20:526-32. [DOI: 10.1111/j.1365-2869.2011.00931.x] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Nelson NR, Bird IM, Behan M. Testosterone restores respiratory long term facilitation in old male rats by an aromatase-dependent mechanism. J Physiol 2010; 589:409-21. [PMID: 21078587 DOI: 10.1113/jphysiol.2010.198200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Steroidal sex hormones play an important role in the neural control of breathing. Previous studies in our laboratory have shown that gonadectomy in young male rats (3 months) eliminates a form of respiratory plasticity induced by intermittent hypoxia, known as long term facilitation (LTF). Testosterone replenishment restores LTF in gonadectomized male rats, and this is dependent on the conversion of testosterone to oestradiol by aromatase. By middle age (12 months), male rats no longer exhibit LTF of hypoglossal motor output; phrenic LTF is significantly reduced, and this persists into old age. We tested the hypothesis that LTF can be restored in old male rats by administration of testosterone. Intact Fischer 344 rats (>20 months) were implanted with Silastic tubing containing testosterone (T), T plus an aromatase inhibitor (T+ADT), or 5α-dihydrotestosterone (DHT), a form of testosterone not converted to oestradiol. One week post-surgery, LTF of hypoglossal and phrenic motor output was measured. By comparison with control rats, hypoglossal LTF was increased in testosterone-treated rats, with levels approaching that of normal young rats. LTF was not restored in T+ADT or DHT-treated rats. Aromatase levels in hypoglossal and phrenic nuclei did not change with age. As serum testosterone levels did not decline with age, local bioavailability of testosterone in old rats may be a limiting factor in the expression of this form of respiratory plasticity. Our findings suggest that testosterone supplementation could potentially be used to enhance upper airway control in the elderly.
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Affiliation(s)
- N R Nelson
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706-1102, USA
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Van de Louw A, Médigue C, Papelier Y, Landrain M, Cottin F. Role of brainstem centers in cardiorespiratory phase difference during mechanical ventilation. Respir Physiol Neurobiol 2010; 174:119-27. [PMID: 20434593 DOI: 10.1016/j.resp.2010.04.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2010] [Revised: 04/07/2010] [Accepted: 04/14/2010] [Indexed: 01/31/2023]
Abstract
During mechanical ventilation, large inter-patient and intra-patient variations of the phase of respiratory sinus arrhythmia (RSA) were described. To determine whether these variations were neurally mediated, we compared the RSA phase between: (1) 12 control subjects, (2) 23 mechanically ventilated patients without brain injury (MV group) and (3) 12 brain dead, mechanically ventilated patients, whose central nervous functions were abolished (BD group). ECG and ventilatory flow were recorded during 15 min and the RSA phase was then continuously computed by complex demodulation. Control group exhibited RSA phases between 180° and 250° whereas an opposite pattern, between 0° and 90°, was observed in the BD group. For the two groups, the phase was stable over time. In the MV group, the RSA phases were distributed between 0° and 260°, with a greater variability over time than the other groups. Therefore, during mechanical ventilation, brainstem centers may induce large variations of the RSA phase, not synchronous with the mechanical effect of ventilation.
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Affiliation(s)
- Andry Van de Louw
- Unité de Biologie Intégrative des Adaptations à l'Exercice (INSERM 902/EA 3872, Genopole), ZAC du Bras de Fer, Evry, France.
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Van de Louw A, Médigue C, Papelier Y, Cottin F. Positive end-expiratory pressure may alter breathing cardiovascular variability and baroreflex gain in mechanically ventilated patients. Respir Res 2010; 11:38. [PMID: 20403192 PMCID: PMC2868796 DOI: 10.1186/1465-9921-11-38] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Accepted: 04/19/2010] [Indexed: 01/31/2023] Open
Abstract
Background Baroreflex allows to reduce sudden rises or falls of arterial pressure through parallel RR interval fluctuations induced by autonomic nervous system. During spontaneous breathing, the application of positive end-expiratory pressure (PEEP) may affect the autonomic nervous system, as suggested by changes in baroreflex efficiency and RR variability. During mechanical ventilation, some patients have stable cardiorespiratory phase difference and high-frequency amplitude of RR variability (HF-RR amplitude) over time and others do not. Our first hypothesis was that a steady pattern could be associated with reduced baroreflex sensitivity and HF-RR amplitude, reflecting a blunted autonomic nervous function. Our second hypothesis was that PEEP, widely used in critical care patients, could affect their autonomic function, promoting both steady pattern and reduced baroreflex sensitivity. Methods We tested the effect of increasing PEEP from 5 to 10 cm H2O on the breathing variability of arterial pressure and RR intervals, and on the baroreflex. Invasive arterial pressure, ECG and ventilatory flow were recorded in 23 mechanically ventilated patients during 15 minutes for both PEEP levels. HF amplitude of RR and systolic blood pressure (SBP) time series and HF phase differences between RR, SBP and ventilatory signals were continuously computed by complex demodulation. Cross-spectral analysis was used to assess the coherence and gain functions between RR and SBP, yielding baroreflex-sensitivity indices. Results At PEEP 10, the 12 patients with a stable pattern had lower baroreflex gain and HF-RR amplitude of variability than the 11 other patients. Increasing PEEP was generally associated with a decreased baroreflex gain and a greater stability of HF-RR amplitude and cardiorespiratory phase difference. Four patients who exhibited a variable pattern at PEEP 5 became stable at PEEP 10. At PEEP 10, a stable pattern was associated with higher organ failure score and catecholamine dosage. Conclusions During mechanical ventilation, stable HF-RR amplitude and cardiorespiratory phase difference over time reflect a blunted autonomic nervous function which might worsen as PEEP increases.
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Affiliation(s)
- Andry Van de Louw
- Unité de Biologie Intégrative des Adaptations à l'Exercice (INSERM 902/EA 3872, Genopole), ZAC du Bras de Fer, 3 bis impasse Christophe Colomb, 91000 Evry, France.
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Jensen D, Mask G, Tschakovsky ME. Variability of the ventilatory response to Duffin's modified hyperoxic and hypoxic rebreathing procedure in healthy awake humans. Respir Physiol Neurobiol 2010; 170:185-97. [DOI: 10.1016/j.resp.2009.12.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2009] [Revised: 12/16/2009] [Accepted: 12/17/2009] [Indexed: 11/27/2022]
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Sex steroidal hormones and respiratory control. Respir Physiol Neurobiol 2009; 164:213-21. [PMID: 18599386 DOI: 10.1016/j.resp.2008.06.006] [Citation(s) in RCA: 124] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2008] [Revised: 06/06/2008] [Accepted: 06/07/2008] [Indexed: 12/26/2022]
Abstract
There is a growing public awareness that sex hormones can have an impact on a variety of physiological processes. Yet, despite almost a century of research, we still do not have a clear picture as to the effects of sex hormones on the regulation of breathing. Considerable data has accumulated showing that estrogen, progesterone and testosterone can influence respiratory function in animals and humans. Several disorders of breathing such as obstructive sleep apnea (OSA) and sudden infant death syndrome (SIDS) show clear sex differences in their prevalence, lending weight to the importance of sex hormones in respiratory control. This review focuses on questions such as: how early do sex hormones influence breathing? Which is the most effective? Where do sex hormones exert their effects? What mechanisms are involved? Are there age-associated changes? A clearer understanding of how sex hormones influence the control of breathing could enable sex- and age-specific therapeutic interventions for diseases of the respiratory control system.
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Van de Louw A, Médigue C, Papelier Y, Cottin F. Breathing cardiovascular variability and baroreflex in mechanically ventilated patients. Am J Physiol Regul Integr Comp Physiol 2008; 295:R1934-40. [PMID: 18922962 DOI: 10.1152/ajpregu.90475.2008] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Heart rate and blood pressure variations during spontaneous ventilation are related to the negative airway pressure during inspiration. Inspiratory airway pressure is positive during mechanical ventilation, suggesting that reversal of the normal baroreflex-mediated pattern of variability may occur. We investigated heart rate and blood pressure variability and baroreflex sensitivity in 17 mechanically ventilated patients. ECG (RR intervals), invasive systolic blood pressure (SBP), and respiratory flow signals were recorded. High-frequency (HF) amplitude of RR and SBP time series and HF phase differences between RR, SBP, and ventilatory signals were continuously computed by Complex DeModulation (CDM). Cross-spectral analysis was used to assess the coherence and the gain functions between RR and SBP, yielding baroreflex sensitivity indices. The HF phase difference between SBP and ventilatory signals was nearly constant in all patients with inversion of SBP variability during the ventilator cycle compared with cycling with negative inspiratory pressure to replicate spontaneous breathing. In 12 patients (group 1), the phase difference between RR and ventilatory signals changed over time and the HF-RR amplitude varied. In the remaining five patients (group 2), RR-ventilatory signal phase and HF-RR amplitude showed little change; however, only one of these patients exhibited a RR-ventilatory signal phase difference mimicking the normal pattern of respiratory sinus arrhythmia. Spectral coherence between RR and SBP was lower in the group with phase difference changes. Positive pressure ventilation exerts mainly a mechanical effect on SBP, whereas its influence on HR variability seems more complex, suggesting a role for neural influences.
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Affiliation(s)
- Andry Van de Louw
- Unité de Biologie Intégrative des Adaptations à l'Exercise (INSERM 902/EA 3872, Genopole), ZAC du Bras de Fer, Evry, France.
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Abstract
Central apnea during sleep represents a manifestation of breathing instability in many clinical conditions of varied etiologies. Central apnea is the result of transient cessation of ventilatory motor output, which represents that inhibitory influences favoring instability predominate over excitatory influence favoring stable breathing. This article will review the determinants of central apnea, the specific features of CHF-related central apnea, and outline a management approach
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Repeated experiences of air hunger and ventilatory behavior in response to hypercapnia in the standardized rebreathing test: effects of anxiety. Biol Psychol 2007; 77:223-32. [PMID: 18077078 DOI: 10.1016/j.biopsycho.2007.10.013] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2006] [Revised: 10/18/2007] [Accepted: 10/29/2007] [Indexed: 11/22/2022]
Abstract
In this study, we assessed air hunger (AH) and ventilatory responses to repeated CO(2) exposures in healthy women (N=31), scoring high or low for trait anxiety. A standardized rebreathing test, implying a gradually increasing CO(2) stimulus, was administered three times with 15-min intervals. Respiratory behavior and the intensity of AH perception were measured continuously. Across repeated exposures, maximal tolerance for AH habituated and the slope of AH (increase in AH per unit increase in CO(2)) diminished. Also the dynamics of the breathing response changed across trials. The thresholds for AH and tidal volume (V(T)) moved closer to each other, whereas the threshold for the respiratory rate (RR) was generally postponed. In addition, the association between AH and V(T) was stronger than between AH and RR, and the latter association became weaker over trials, particularly in high anxious persons. This suggests that AH perception became increasingly influenced by psychological factors, especially in high anxious persons. The results suggest that habituation of perceived air hunger is depending on a complex interplay between both changes in respiratory behavior and in perceptual-cognitive processes related to trait anxiety.
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Abstract
INTRODUCTION With the recent increased recognition and treatment of hypogonadism in men, a caution has been given that testosterone replacement therapy (TRT) may cause or aggravate obstructive sleep apnea syndrome (OSA). AIM To evaluate the scientific data behind the cautionary statements about TRT and OSA. MAIN OUTCOME MEASURES Methodology and criteria for such studies and evaluation of documents and results based on methodology, duration, and outcome of treatment. METHODS A review of the literature on the subject of TRT and OSA was performed. The possible mechanisms of action of TRT, on breathing and respiration during sleep were explored. RESULT Historically, the first such caution came in 1978. Since then, a few similar incidence reports have been cited. The total number of patients in such reports was very small, very disproportional to the millions of patients treated with TRT. Also, there was a lack of consistent findings connecting TRT to OSA. In addition, different results may occur with physiologic replacement vs. supraphysiologic doses in regard to breathing and OSA. The studies showing the effect of TRT on OSA and breathing were all case studies with small numbers of subjects and showed little effect of TRT on OSA in the majority of case reports. Only one study using supraphysiologic doses was a double-blind, placebo-controlled study, which showed a development of OSA in healthy pooled subjects. The other reports were case studies with limited numbers of subjects, suggesting an inconsistent effect of supraphysiologic TRT on OSA and breathing. CONCLUSION Cautionary statements about TRT in OSA appear frequently in the TRT literature and guidelines, despite lack of convincing evidence that TRT causes and/or aggravates OSA. Also, there is a lack of consistency in the findings connecting TRT to OSA. It is evident that the link between TRT and OSA is weak, based on methodological issues in many of the studies, and most studies involved small numbers of men. Further studies in this area are needed.
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Affiliation(s)
- Han M Hanafy
- Southern Illinois University, Carbondale, IL 62946, USA.
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Nettlefold L, Jensen D, Janssen I, Wolfe LA. Ventilatory control and acid-base regulation across the menstrual cycle in oral contraceptive users. Respir Physiol Neurobiol 2007; 158:51-8. [PMID: 17543591 DOI: 10.1016/j.resp.2007.04.005] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2006] [Revised: 04/13/2007] [Accepted: 04/17/2007] [Indexed: 11/16/2022]
Abstract
We examined the effect of menstrual cycle (MC) phase on acid-base regulation and ventilatory control at rest in monophasic oral contraceptive (OC) users. Twelve healthy women (25+/-1 years; mean+/-S.E.) were tested during the inactive (IP; 5.1+/-0.2 days) and active (AP; 21.1+/-0.7 days) pill phase of the MC. Central and peripheral chemoreflex responsiveness was examined using a modified CO(2) rebreathing procedure. Minute ventilation (V E), breathing pattern and metabolic rate were measured during 10 min of quiet, resting breathing. Blood for the determination of arterial P(CO2) (Pa(CO2)) and hydrogen ion concentration ([H(+)]); plasma concentrations of the strong ion difference ([SID]) and total weak acid ([A(tot)]); serum concentrations of progesterone ([P(4)]) and 17beta-estradiol ([E(2)]) were also obtained. Although [E(2)] (p<0.05) and [A(tot)] (p=0.05) were increased in the IP versus AP, MC phase had no significant effect on resting V E, breathing pattern, metabolic rate, [H(+)], Pa(CO2), [SID], [P(4)] and central or peripheral chemoreflex characteristics. Overall, OC had no significant physiological effect on acid-base regulation or ventilatory control at rest in healthy women. This may reflect suppression of endogenous fluctuations in circulating [P(4)] typically observed across the MC in healthy, eumenorrheic non-OC users.
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Affiliation(s)
- Lindsay Nettlefold
- School of Kinesiology and Health Studies, Queen's University, Kingston, Ont., Canada K7L 3N6.
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Ahuja D, Mateika JH, Diamond MP, Badr MS. Ventilatory sensitivity to carbon dioxide before and after episodic hypoxia in women treated with testosterone. J Appl Physiol (1985) 2007; 102:1832-8. [PMID: 17272406 DOI: 10.1152/japplphysiol.01178.2006] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We hypothesized that the ventilatory threshold and sensitivity to carbon dioxide in the presence of hypoxia and hyperoxia during wakefulness would be increased following testosterone administration in premenopausal women. Additionally, we hypothesized that the sensitivity to carbon dioxide increases following episodic hypoxia and that this increase is enhanced after testosterone administration. Eleven women completed four modified carbon dioxide rebreathing trials before and after episodic hypoxia. Two rebreathing trials before and after episodic hypoxia were completed with oxygen levels sustained at 150 Torr, the remaining trials were repeated while oxygen was maintained at 50 Torr. The protocol was completed following 8-10 days of treatment with testosterone or placebo skin patches. Resting minute ventilation was greater following treatment with testosterone compared with placebo (testosterone 11.38 +/- 0.43 vs. placebo 10.07 +/- 0.36 l/min; P < 0.01). This increase was accompanied by an increase in the ventilatory sensitivity to carbon dioxide in the presence of sustained hyperoxia (VSco(2)(hyperoxia)) compared with placebo (3.6 +/- 0.5 vs. 2.9 +/- 0.3; P < 0.03). No change in the ventilatory sensitivity to carbon dioxide in the presence of sustained hypoxia (VSco(2 hypoxia)) following treatment with testosterone was observed. However, the VSco(2 hypoxia) was increased after episodic hypoxia. This increase was similar following treatment with placebo or testosterone patches. We conclude that treatment with testosterone leads to increases in the VSco(2)(hyperoxia), indicative of increased central chemoreflex responsiveness. We also conclude that exposure to episodic hypoxia enhances the VSco(2 hypoxia), but that this enhancement is unaffected by treatment with testosterone.
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Affiliation(s)
- Deepti Ahuja
- John D. Dingell VA Medical Center, Detroit, MI 48201, USA
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Khodadadeh B, Badr MS, Mateika JH. The ventilatory response to carbon dioxide and sustained hypoxia is enhanced after episodic hypoxia in OSA patients. Respir Physiol Neurobiol 2006; 150:122-34. [PMID: 15935740 DOI: 10.1016/j.resp.2005.04.019] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2005] [Revised: 04/20/2005] [Accepted: 04/25/2005] [Indexed: 11/29/2022]
Abstract
Our primary hypothesis was that the acute ventilatory response to carbon dioxide in the presence of sustained hypoxia {VRCO2 (hypoxia)} or hyperoxia {VRCO2 (hyperoxia)} would increase in subjects with obstructive sleep apnea (OSA) after exposure to episodic hypoxia. Secondarily, we hypothesized that chronic (i.e. years) exposure to episodic hypoxia, a hallmark of OSA, would facilitate persistent augmentation of respiratory activity (i.e. long-term facilitation) after acute (i.e. minutes) exposure to episodic hypoxia. Nine healthy males with OSA that were healthy otherwise completed a series of rebreathing trials before and after exposure to eight 4 min episodes of hypoxia. On a separate occasion, the rebreathing trials were repeated before and after exposure to atmospheric air for a duration equivalent to the episodic hypoxia protocol (i.e. sham episodic hypoxia). During the rebreathing trials, subjects initially hyperventilated to reduce the partial pressure of carbon dioxide (P(ET)CO2) below 25 Torr. Subjects then rebreathed from a bag containing a normocapnic (42 Torr), low (50 Torr) or high oxygen gas mixture (140 Torr). During the trials, P(ET)CO2 increased while the selected level of oxygen was maintained. The point at which ventilation began to rise in a linear fashion as P(ET)CO2 increased was the ventilatory threshold. The ventilatory response below and above the threshold was determined. The results showed that the VRCO2 (hypoxia) and the VRCO2 (hyperoxia) was increased after exposure to episodic hypoxia {VRCO2 (hypoxia): 7.9 +/- 1.3 versus 10.5 +/- 1.3, VRCO2 (hyperoxia): 5.9 +/- 1.1 versus 6.7 +/- 1.1 L/min/Torr}. However, only the increase in the VRCO2 (hypoxia) after episodic hypoxia was greater than the increase measured after exposure to sham episodic hypoxia. Long-term facilitation of ventilation, tidal volume and breathing frequency was not evident after episodic hypoxia. We conclude that the VRCO2 (hypoxia) is enhanced after exposure to acute episodic hypoxia and that enhancement of the VRCO2 (hypoxia) occurs even though long-term facilitation is not evident.
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Affiliation(s)
- Bradley Khodadadeh
- John D. Dingell Veterans Administration Medical Center, 4646 John R (11R), Room 4308, Detroit, MI 48201, USA
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Abstract
This paper uses a steady-state modeling approach to describe the effects of changes in acid-base balance on the chemoreflex control of breathing. First, a mathematical model is presented, which describes the control of breathing by the respiratory chemoreflexes; equations express the dependence of pulmonary ventilation on Pco(2) and Po(2) at the central and peripheral chemoreceptors. These equations, with Pco(2) values as inputs to the chemoreceptors, are transformed to equations with hydrogen ion concentrations [H(+)] in brain interstitial fluid and arterial blood as inputs, using the Stewart approach to acid-base balance. Examples illustrate the use of the model to explain the regulation of breathing during acid-base disturbances. They include diet-induced changes in sodium and chloride, altitude acclimatization, and respiratory disturbances of acid-base balance due to chronic hyperventilation and carbon dioxide retention. The examples demonstrate that the relationship between Pco(2) and [H(+)] should not be neglected when modeling the chemoreflex control of breathing. Because pulmonary ventilation controls Pco(2) rather than the actual stimulus to the chemoreceptors, [H(+)], changes in their relationship will alter the ventilatory recruitment threshold Pco(2), and thereby the steady-state resting ventilation and Pco(2).
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Affiliation(s)
- James Duffin
- Dept. of Anaesthesia, University of Toronto, Ontario.
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Jensen D, Wolfe LA, O'Donnell DE, Davies GAL. Chemoreflex control of breathing during wakefulness in healthy men and women. J Appl Physiol (1985) 2004; 98:822-8. [PMID: 15557008 DOI: 10.1152/japplphysiol.01208.2003] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
This study used a modified CO(2) rebreathing procedure to examine the effect of gender on the chemoreflex control of breathing during wakefulness in healthy men (n = 14) and women (n = 14). Women were tested in the follicular phase of the menstrual cycle. During rebreathing trials, subjects hyperventilated to reduce the partial pressure of end-tidal CO(2) (Pet(CO(2))) below 25 Torr and were then switched to a rebreathing bag containing a normocapnic hypoxic or hyperoxic gas mixture. During the trial, Pet(CO(2)) increased, while O(2) was maintained at a constant level. The point at which ventilation began to rise as Pet(CO(2)) increased was identified as the ventilatory recruitment threshold (VRT). Ventilation below the VRT was measured, and the slope of the ventilatory response above the VRT was determined. Gender had no effect on the hyperoxic or hypoxic VRT for CO(2). Central chemoreflex sensitivity was significantly greater in men than women but not after correction for forced vital capacity. Measures of peripheral chemoreflex sensitivity were similar between genders. However, the slope of the tidal volume (Vt) response to hyperoxic and hypoxic CO(2) rebreathing (corrected and uncorrected) was greater in men than women, respectively. We conclude that central chemoreflex sensitivity is greater in men compared with women as reflected by differences in ventilatory (uncorrected) and Vt (corrected and uncorrected) responses to CO(2). However, gender has no significant effect on the central chemoreflex VRT for CO(2). The peripheral chemoreflex control of breathing during wakefulness is similar between men and women.
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Affiliation(s)
- Dennis Jensen
- School of Physical and Health Education, Queen's University, Kingston, Ontario, Canada K7L 3N6
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Affiliation(s)
- Ralph F Fregosi
- Department of Physiology, College of Medicine, University of Arizona, Tucson 85721-0093, USA.
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