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Johal A, Lenet A, Sigua NL. Blowing past the apneic threshold. J Clin Sleep Med 2022; 18:2515-2518. [PMID: 35859324 PMCID: PMC9516585 DOI: 10.5664/jcsm.10162] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 06/21/2022] [Accepted: 06/22/2022] [Indexed: 11/13/2022]
Affiliation(s)
- Arminder Johal
- Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
| | - Adam Lenet
- Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
- Section of Sleep Medicine, Richard L. Roudebush VA Medical Center, Indianapolis, Indiana
| | - Ninotchka Liban Sigua
- Division of Pulmonary, Critical Care, Sleep and Occupational Medicine, Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
- Section of Sleep Medicine, Richard L. Roudebush VA Medical Center, Indianapolis, Indiana
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2
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Gu L, Yu Q, Shen Y, Wang Y, Xu Q, Zhang H. The role of monoaminergic neurons in modulating respiration during sleep and the connection with SUDEP. Biomed Pharmacother 2022; 150:112983. [PMID: 35453009 DOI: 10.1016/j.biopha.2022.112983] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2022] [Revised: 04/04/2022] [Accepted: 04/14/2022] [Indexed: 11/25/2022] Open
Abstract
Sudden unexpected death in epilepsy (SUDEP) is the leading cause of death among epilepsy patients, occurring even more frequently in cases with anti-epileptic drug resistance. Despite some advancements in characterizing SUDEP, the underlying mechanism remains incompletely understood. This review summarizes the latest advances in our understanding of the pathogenic mechanisms of SUDEP, in order to identify possible targets for the development of new strategies to prevent SUDEP. Based on our previous research along with the current literature, we focus on the role of sleep-disordered breathing (SDB) and its related neural mechanisms to consider the possible roles of monoaminergic neurons in the modulation of respiration during sleep and the occurrence of SUDEP. Overall, this review suggests that targeting the monoaminergic neurons is a promising approach to preventing SUDEP. The proposed roles of SDB and related monoaminergic neural mechanisms in SUDEP provide new insights for explaining the pathogenesis of SUDEP.
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Affiliation(s)
- LeYuan Gu
- Department of Anesthesiology, The Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou 310006, China; Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - Qian Yu
- Department of Anesthesiology, The Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou 310006, China; Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - Yue Shen
- Department of Anesthesiology, The Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou 310006, China; Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - YuLing Wang
- Department of Anesthesiology, The Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou 310006, China; Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - Qing Xu
- Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China
| | - HongHai Zhang
- Department of Anesthesiology, The Fourth Clinical School of Medicine, Zhejiang Chinese Medical University, Hangzhou 310006, China; Department of Anesthesiology, Affiliated Hangzhou First People's Hospital, Zhejiang University School of Medicine, Hangzhou, 310006, China; Westlake Laboratory of Life Sciences and Biomedicine, Hangzhou 310006, China.
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3
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Altree TJ, Eckert DJ. Obstructive sleep apnea endotypes and their postoperative relevance. Int Anesthesiol Clin 2022; 60:1-7. [PMID: 35125480 DOI: 10.1097/aia.0000000000000357] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Thomas J Altree
- Adelaide Institute for Sleep Health, Flinders Health and Medical Research Institute, Flinders University, Bedford Park, South Australia, Australia
- Respiratory and Sleep Services, Flinders Medical Centre, Southern Adelaide Local Health Network, Bedford Park, South Australia, Australia
| | - Danny J Eckert
- Adelaide Institute for Sleep Health, Flinders Health and Medical Research Institute, Flinders University, Bedford Park, South Australia, Australia
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Evolving relationship between respiratory functions & impairment in sleep and cognition in patients with multiple sclerosis. Mult Scler Relat Disord 2020; 46:102514. [PMID: 32992131 DOI: 10.1016/j.msard.2020.102514] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2020] [Revised: 09/03/2020] [Accepted: 09/05/2020] [Indexed: 11/20/2022]
Abstract
BACKGROUND The most apparent source of disability in patients with multiple sclerosis (MS) is the physical and mental impact. The pathophysiological mechanisms of cognitive dysfunction are multifactorial although hypoventilation secondary to respiratory dysfunction may contribute to cognitive decline. METHODS This study was conducted on 146 MS patients with baseline clinical assessments including the Epworth sleepiness scale (ESS) and physical disability was assessed using the Expanded Disability Status Scale (EDSS). Cognitive testing was performed utilizing the Brief International Cognitive Assessment for Multiple Sclerosis (BICAMS) and the Perceived Deficits Questionnaire (PDQ). Respiratory functions were assessed by spirometry and the respiratory muscle functional assessment was done by maximal mouth pressure measurement. RESULTS The respiratory muscle function test had a significant negative correlation with the score of ESS and PDQ scale and a significant positive correlation with the BICAMS scale score (p < 0.001). The ESS and PDQ scores were significantly negatively correlated with forced expiratory volume in the first second (FEV1)/ forced vital capacity (FVC) (p = 0.03, 0.02), FVC supine (p = 0.03, 0.01), FVC upright- FVC supine (ΔFVC) (p < 0.001, <0.001) FEV1 (p < 0.001) and FVC (L) (p < 0.001), respectively. While the BICAMS showed a significant positive correlation with spirometry results except FVC upright. ESS scores were significantly correlated with the BICAMS and PDQ scale score (p < 0.001). CONCLUSION Among MS patients, impaired respiratory functions are significantly associated with sleep disturbance and cognitive impairment. Thus the spirometry and respiratory muscle strength assessment are necessary from the early phase of MS.
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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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Webster JG, Shokoueinejad M, Wang F. A Sleep Apnea Therapy Device Uses No Added Pressure. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2018; 2018:6030-3035. [PMID: 30441711 DOI: 10.1109/embc.2018.8513679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Sleep Apnea is a common sleeping disorder that affects over 25 million Americans. Due to the complex nature of sleep apnea, and the human body, neither an effective nor comfortable treatment option for sleep apnea has been developed. Accordingly, we describe a novel alternative to current sleep apnea therapies, including CPAP therapy. A comfortable device for treating sleep apnea incorporates a mask, a flexible hose and a chamber for collecting expired air containing CO2. A sensor detects apnea and a control system automatically adjusts the amount of rebreathed CO2 minimize apnea and also minimize arousal.
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Deacon-Diaz N, Malhotra A. Inherent vs. Induced Loop Gain Abnormalities in Obstructive Sleep Apnea. Front Neurol 2018; 9:896. [PMID: 30450076 PMCID: PMC6224344 DOI: 10.3389/fneur.2018.00896] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 10/02/2018] [Indexed: 12/11/2022] Open
Abstract
Unstable ventilatory chemoreflex control, quantified as loop gain, is recognized as one of four key pathophysiological traits that contribute to cause obstructive sleep apnea (OSA). Novel treatments aimed at reducing loop gain are being investigated, with the intention that future OSA treatment may be tailored to the individual's specific cause of apnea. However, few studies have evaluated loop gain in OSA and non-OSA controls and those that have provide little evidence to support an inherent abnormality in either overall chemical loop gain in OSA patients vs. non-OSA controls, or its components (controller and plant gain). However, intermittent hypoxia may induce high controller gain through neuroplastic changes to chemoreflex control, and may also decrease plant gain via oxidative stress induced inflammation and reduced lung function. The inherent difficulties and limitations with loop gain measurements are discussed and areas where further research are required are highlighted, as only by understanding the mechanisms underlying OSA are new therapeutic approaches likely to emerge in OSA.
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Affiliation(s)
- Naomi Deacon-Diaz
- Department of Medicine, Pulmonary and Critical Care Medicine, University of California, San Diego, San Diego, CA, United States
| | - Atul Malhotra
- Department of Medicine, Pulmonary and Critical Care Medicine, University of California, San Diego, San Diego, CA, United States
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Yang X, Xiao Y, Han B, Lin K, Niu X, Chen X. Implication of mixed sleep apnea events in adult patients with obstructive sleep apnea-hypopnea syndrome. Sleep Breath 2018; 23:559-565. [PMID: 30343435 DOI: 10.1007/s11325-018-1745-0] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Revised: 10/02/2018] [Accepted: 10/16/2018] [Indexed: 12/27/2022]
Abstract
PURPOSE Although mixed sleep apnea (MSA) is one of the three types of sleep apnea, it is not considered a separate disease entity. It is generally seen as a part of obstructive sleep apnea-hypopnea syndrome (OSAHS), but its implications are often ignored. In this study, we examined its features and the potential impact on OSAHS patients. METHODS Subjects diagnosed with OSAHS by polysomnography (PSG) were enrolled. All participants underwent physical checkups and tests of blood biochemistry. They were anthropometrically, clinically, and polysomnographically studied. RESULTS MSA events were common in patients with severe OSAHS patients. There were significant differences between the pure OSAHS group and its mixed counterpart in apnea-hypopnea indices during REM (AHIREM) and non-REM (AHINREM) and in percentages of N2 or N3 sleep. Logistic regression analysis showed that, after adjustment of other parameters, patients with MSA events were mostly male, had higher body mass index (BMI), higher scores on Epworth Sleepiness Scales (ESS), higher triglyceride (TG) levels, and higher apnea-hypopnea index (AHI). The combined predictive probability of the aforementioned variables was 0.766 (95% CI = 0.725~0.806; sensitivity 61.6%, specificity 82.1%). CONCLUSIONS Our study suggested that MSA was related to the stability of the ventilatory control in OSAHS patients. MSA events occur more frequently in patients with severe OSAHS, and male gender, obesity, daytime sleepiness, and elevated TG levels were risk factors for the mixed OSAHS.
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Affiliation(s)
- Xiuping Yang
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Ying Xiao
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Baoai Han
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Kun Lin
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Xun Niu
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China
| | - Xiong Chen
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, 430022, China.
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Cori JM, Thornton T, O'Donoghue FJ, Rochford PD, White DP, Trinder J, Jordan AS. Arousal-Induced Hypocapnia Does Not Reduce Genioglossus Activity in Obstructive Sleep Apnea. Sleep 2018; 40:3608772. [PMID: 28419356 DOI: 10.1093/sleep/zsx057] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Study Objectives To determine whether arousals that terminate obstructive events in obstructive sleep apnea (OSA) (1) induce hypocapnia and (2) subsequently reduce genioglossus muscle activity following the return to sleep. Methods Thirty-one untreated patients with OSA slept instrumented with sleep staging electrodes, nasal mask and pneumotachograph, end-tidal CO2 monitoring, and intramuscular genioglossus electrodes. End-tidal CO2 was monitored, and respiratory arousals were assigned an end-arousal CO2 change value (PETCO2 on the last arousal breath minus each individual's wakefulness PETCO2). This change value, in conjunction with the normal sleep related increase in PETCO2, was used to determine whether arousals induced hypocapnia and whether the end-arousal CO2 change was associated with genioglossus muscle activity on the breaths following the return to sleep. Results Twenty-four participants provided 1137 usable arousals. Mean ± SD end-arousal CO2 change was -0.2 ± 2.4 mm Hg (below wakefulness) indicating hypocapnia typically developed during arousal. Following the return to sleep, genioglossus muscle activity did not fall below prearousal levels and was elevated for the first two breaths. End-arousal CO2 change and genioglossus muscle activity were negatively associated such that a 1 mm Hg decrease in end-arousal CO2 was associated with an ~2% increase in peak and tonic genioglossus muscle activity on the breaths following the return to sleep. Conclusions Arousal-induced hypocapnia did not result in reduced dilator muscle activity following return to sleep, and thus hypocapnia may not contribute to further obstructions via this mechanism. Elevated dilator muscle activity postarousal is likely driven by non-CO2-related stimuli.
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Affiliation(s)
- Jennifer M Cori
- Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia.,Institute for Breathing and Sleep and Austin Health, Heidelberg, Victoria, Australia
| | - Therese Thornton
- Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia.,Institute for Breathing and Sleep and Austin Health, Heidelberg, Victoria, Australia
| | - Fergal J O'Donoghue
- Institute for Breathing and Sleep and Austin Health, Heidelberg, Victoria, Australia.,Faculty of Medicine, Dentistry and Health Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Peter D Rochford
- Institute for Breathing and Sleep and Austin Health, Heidelberg, Victoria, Australia
| | - David P White
- Division of Sleep Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA
| | - John Trinder
- Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia
| | - Amy S Jordan
- Melbourne School of Psychological Sciences, University of Melbourne, Parkville, Victoria, Australia.,Institute for Breathing and Sleep and Austin Health, Heidelberg, Victoria, Australia
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Phenotypic approaches to obstructive sleep apnoea – New pathways for targeted therapy. Sleep Med Rev 2018; 37:45-59. [DOI: 10.1016/j.smrv.2016.12.003] [Citation(s) in RCA: 225] [Impact Index Per Article: 37.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2016] [Revised: 11/30/2016] [Accepted: 12/08/2016] [Indexed: 02/01/2023]
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11
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Cori JM, Rochford PD, O’Donoghue FJ, Trinder J, Jordan AS. The Influence of CO2 on Genioglossus Muscle After-Discharge Following Arousal From Sleep. Sleep 2017; 40:4356853. [DOI: 10.1093/sleep/zsx160] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Shokoueinejad M, Fernandez C, Carroll E, Wang F, Levin J, Rusk S, Glattard N, Mulchrone A, Zhang X, Xie A, Teodorescu M, Dempsey J, Webster J. Sleep apnea: a review of diagnostic sensors, algorithms, and therapies. Physiol Meas 2017; 38:R204-R252. [PMID: 28820743 DOI: 10.1088/1361-6579/aa6ec6] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
While public awareness of sleep related disorders is growing, sleep apnea syndrome (SAS) remains a public health and economic challenge. Over the last two decades, extensive controlled epidemiologic research has clarified the incidence, risk factors including the obesity epidemic, and global prevalence of obstructive sleep apnea (OSA), as well as establishing a growing body of literature linking OSA with cardiovascular morbidity, mortality, metabolic dysregulation, and neurocognitive impairment. The US Institute of Medicine Committee on Sleep Medicine estimates that 50-70 million US adults have sleep or wakefulness disorders. Furthermore, the American Academy of Sleep Medicine (AASM) estimates that more than 29 million US adults suffer from moderate to severe OSA, with an estimated 80% of those individuals living unaware and undiagnosed, contributing to more than $149.6 billion in healthcare and other costs in 2015. Although various devices have been used to measure physiological signals, detect apneic events, and help treat sleep apnea, significant opportunities remain to improve the quality, efficiency, and affordability of sleep apnea care. As our understanding of respiratory and neurophysiological signals and sleep apnea physiological mechanisms continues to grow, and our ability to detect and process biomedical signals improves, novel diagnostic and treatment modalities emerge. OBJECTIVE This article reviews the current engineering approaches for the detection and treatment of sleep apnea. APPROACH It discusses signal acquisition and processing, highlights the current nonsurgical and nonpharmacological treatments, and discusses potential new therapeutic approaches. MAIN RESULTS This work has led to an array of validated signal and sensor modalities for acquiring, storing and viewing sleep data; a broad class of computational and signal processing approaches to detect and classify SAS disease patterns; and a set of distinctive therapeutic technologies whose use cases span the continuum of disease severity. SIGNIFICANCE This review provides a current perspective of the classes of tools at hand, along with a sense of their relative strengths and areas for further improvement.
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Affiliation(s)
- Mehdi Shokoueinejad
- Department of Biomedical Engineering, University of Wisconsin-Madison, 1550 Engineering Drive, Madison, WI 53706-1609, United States of America. Department of Population Health Sciences, University of Wisconsin-Madison, 610 Walnut St 707, Madison, WI 53726, United States of America. EnsoData Research, EnsoData Inc., 111 N Fairchild St, Suite 240, Madison, WI 53703, United States of America
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A Modeling Study on Inspired CO2 Rebreathing Device for Sleep Apnea Treatment by Means of CFD Analysis and Experiment. J Med Biol Eng 2017. [DOI: 10.1007/s40846-017-0223-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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14
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Deacon N, Malhotra A. Potential protective mechanism of arousal in obstructive sleep apnea. J Thorac Dis 2016; 8:S545-6. [PMID: 27606089 DOI: 10.21037/jtd.2016.07.43] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Naomi Deacon
- Department of Medicine, Pulmonary, Critical Care and Sleep Medicine, University of California San Diego, La Jolla, California, USA
| | - Atul Malhotra
- Department of Medicine, Pulmonary, Critical Care and Sleep Medicine, University of California San Diego, La Jolla, California, USA
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15
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The role of high loop gain induced by intermittent hypoxia in the pathophysiology of obstructive sleep apnoea. Sleep Med Rev 2015; 22:3-14. [DOI: 10.1016/j.smrv.2014.10.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2014] [Revised: 10/03/2014] [Accepted: 10/07/2014] [Indexed: 02/06/2023]
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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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Abstract
Neurophysiologically, central apnea is due to a temporary failure in the pontomedullary pacemaker generating breathing rhythm. As a polysomnographic finding, central apneas occur in many pathophysiological conditions. Depending on the cause or mechanism, central apneas may not be clinically significant, for example, those that occur normally at sleep onset. In contrast, central apneas occur in a number of disorders and result in pathophysiological consequences. Central apneas occur commonly in high-altitude sojourn, disrupt sleep, and cause desaturation. Central sleep apnea also occurs in number of disorders across all age groups and both genders. Common causes of central sleep apnea in adults are congestive heart failure and chronic use of opioids to treat pain. Under such circumstances, diagnosis and treatment of central sleep apnea may improve quality of life, morbidity, and perhaps mortality. The mechanisms of central sleep apnea have been best studied in congestive heart failure and hypoxic conditions when there is increased CO2 sensitivity below eupnea resulting in lowering eupneic PCO2 below apneic threshold causing cessation of breathing until the PCO2 rises above the apneic threshold when breathing resumes. In many other disorders, the mechanism of central sleep apnea (CSA) remains to be investigated.
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Affiliation(s)
- S Javaheri
- University of Cincinnati College of Medicine, Cincinnati, Ohio, USA.
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Dempsey JA, Xie A, Patz DS, Wang D. Physiology in medicine: obstructive sleep apnea pathogenesis and treatment--considerations beyond airway anatomy. J Appl Physiol (1985) 2013; 116:3-12. [PMID: 24201709 DOI: 10.1152/japplphysiol.01054.2013] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
We review evidence in support of significant contributions to the pathogenesis of obstructive sleep apnea (OSA) from pathophysiological factors beyond the well-accepted importance of airway anatomy. Emphasis is placed on contributions from neurochemical control of central respiratory motor output through its effects on output stability, upper airway dilator muscle activation, and arousability. In turn, we consider the evidence demonstrating effective treatment of OSA via approaches that address each of these pathophysiologic risk factors. Finally, a case is made for combining treatments aimed at both anatomical and ventilatory control system deficiencies and for individualizing treatment to address a patient's own specific risk factors.
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Affiliation(s)
- Jerome A Dempsey
- James B. Skatrud Laboratory of Pulmonary & Sleep Medicine, Middleton Veterans Administration Hospital and Department of Population Health Sciences, University of Wisconsin-Madison, Madison Wisconsin
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Ward NR, Roldao V, Cowie MR, Rosen SD, McDonagh TA, Simonds AK, Morrell MJ. The effect of respiratory scoring on the diagnosis and classification of sleep disordered breathing in chronic heart failure. Sleep 2013; 36:1341-8. [PMID: 23997367 DOI: 10.5665/sleep.2960] [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: 11/03/2022] Open
Abstract
STUDY OBJECTIVES To evaluate the effect of respiratory scoring criteria on diagnosis and classification of sleep disordered breathing (SDB) in chronic heart failure (CHF). DESIGN Cross-sectional observational study. SETTING Heart failure and general cardiology clinics at two London hospitals. PATIENTS OR PARTICIPANTS One hundred eighty stable patients with CHF and a median age of 69.6 y, 86% male. INTERVENTIONS SDB was diagnosed by polysomnography. The apnea-hypopnea index (AHI) was initially scored using a conservative hypopnea definition of a ≥ 50% decrease in nasal airflow with a ≥ 4% oxygen desaturation. The AHI was rescored with hypopnea defined according to the American Academy of Sleep Medicine (AASM) alternative scoring rule, requiring an associated ≥ 3% oxygen desaturation or arousal. SDB was defined as AHI ≥ 15/h. Diagnosis and classification of SDB as obstructive sleep apnea (OSA) or central sleep apnea (CSA) with each rule were compared. The effect of mixed apneas on classification of SDB as CSA or OSA was also investigated. MEASUREMENTS AND RESULTS Median AHI increased from 9.3/h to 13.8/h (median difference 4.6/h) when the AASM alternative rule was used to score hypopneas. SDB prevalence increased from 29% to 46% with the alternative scoring rule (P < 0.001). Classification of SDB as OSA or CSA was not significantly altered by hypopnea scoring rules or the categorization of mixed apneas. CONCLUSION Hypopnea scoring rules can significantly influence the apnea-hypopnea index and diagnosis of sleep disordered breathing in chronic heart failure but do not alter the classification as obstructive sleep apnea or central sleep apnea. Standardization of hypopnea scoring rules is important to ensure consistency in diagnosis of sleep disordered breathing in chronic heart failure patients.
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Affiliation(s)
- Neil R Ward
- Clinical and Academic Department of Sleep and Breathing, National Heart and Lung Institute, Royal Brompton Hospital and Imperial College, London, United Kingdom.
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Xie A, Teodorescu M, Pegelow DF, Teodorescu MC, Gong Y, Fedie JE, Dempsey JA. Effects of stabilizing or increasing respiratory motor outputs on obstructive sleep apnea. J Appl Physiol (1985) 2013; 115:22-33. [PMID: 23599393 DOI: 10.1152/japplphysiol.00064.2013] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023] Open
Abstract
To determine how the obstructive sleep apnea (OSA) patient's pathophysiological traits predict the success of the treatment aimed at stabilization or increase in respiratory motor outputs, we studied 26 newly diagnosed OSA patients [apnea-hypopnea index (AHI) 42 ± 5 events/h with 92% of apneas obstructive] who were treated with O2 supplementation, an isocapnic rebreathing system in which CO2 was added only during hyperpnea to prevent transient hypocapnia, and a continuous rebreathing system. We also measured each patient's controller gain below eupnea [change in minute volume/change in end-tidal Pco2 (ΔVe/ΔPetCO2)], CO2 reserve (eupnea-apnea threshold PetCO2), and plant gain (ΔPetCO2/ΔVe), as well as passive upper airway closing pressure (Pcrit). With isocapnic rebreathing, 14/26 reduced their AHI to 31 ± 6% of control (P < 0.01) (responder); 12/26 did not show significant change (nonresponder). The responders vs. nonresponders had a greater controller gain (6.5 ± 1.7 vs. 2.1 ± 0.2 l·min(-1)·mmHg(-1), P < 0.01) and a smaller CO2 reserve (1.9 ± 0.3 vs. 4.3 ± 0.4 mmHg, P < 0.01) with no differences in Pcrit (-0.1 ± 1.2 vs. 0.2 ± 0.9 cmH2O, P > 0.05). Hypercapnic rebreathing (+4.2 ± 1 mmHg PetCO2) reduced AHI to 15 ± 4% of control (P < 0.001) in 17/21 subjects with a wide range of CO2 reserve. Hyperoxia (SaO2 ∼95-98%) reduced AHI to 36 ± 11% of control in 7/19 OSA patients tested. We concluded that stabilizing central respiratory motor output via prevention of transient hypocapnia prevents most OSA in selected patients with a high chemosensitivity and a collapsible upper airway, whereas increasing respiratory motor output via moderate hypercapnia eliminates OSA in most patients with a wider range of chemosensitivity and CO2 reserve. Reducing chemosensitivity via hyperoxia had a limited and unpredictable effect on OSA.
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Affiliation(s)
- Ailiang Xie
- James B. Skatrud Laboratory of Pulmonary and Sleep Medicine, William S. Middleton Memorial Veterans Affairs Hospital, Madison, WI 53705, USA.
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Complex sleep apnea unmasked by the use of a mandibular advancement device. Sleep Breath 2010; 15:249-52. [PMID: 21190088 DOI: 10.1007/s11325-010-0459-8] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2010] [Revised: 11/20/2010] [Accepted: 12/07/2010] [Indexed: 10/18/2022]
Abstract
According to most accepted definitions, complex sleep apnea syndrome (CompSAS) is described as an emergence of central apneas in a patient with obstructive sleep apnea (OSA) upon introduction of continuous positive airway pressure therapy (CPAP). We present two patients who developed comparable central apnea activity when treated with either a CPAP device or a mandibular advancement device. As similar findings have been previously documented in patients with OSA treated with maxillofacial surgery or tracheostomy, we propose that the current definition of CompSAS should broaden to include diagnosis of CompSAS in non-PAP-treated patients, who are managed with either a dental appliance or a surgical procedure.
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Abstract
Sleep-induced apnea and disordered breathing refers to intermittent, cyclical cessations or reductions of airflow, with or without obstructions of the upper airway (OSA). In the presence of an anatomically compromised, collapsible airway, the sleep-induced loss of compensatory tonic input to the upper airway dilator muscle motor neurons leads to collapse of the pharyngeal airway. In turn, the ability of the sleeping subject to compensate for this airway obstruction will determine the degree of cycling of these events. Several of the classic neurotransmitters and a growing list of neuromodulators have now been identified that contribute to neurochemical regulation of pharyngeal motor neuron activity and airway patency. Limited progress has been made in developing pharmacotherapies with acceptable specificity for the treatment of sleep-induced airway obstruction. We review three types of major long-term sequelae to severe OSA that have been assessed in humans through use of continuous positive airway pressure (CPAP) treatment and in animal models via long-term intermittent hypoxemia (IH): 1) cardiovascular. The evidence is strongest to support daytime systemic hypertension as a consequence of severe OSA, with less conclusive effects on pulmonary hypertension, stroke, coronary artery disease, and cardiac arrhythmias. The underlying mechanisms mediating hypertension include enhanced chemoreceptor sensitivity causing excessive daytime sympathetic vasoconstrictor activity, combined with overproduction of superoxide ion and inflammatory effects on resistance vessels. 2) Insulin sensitivity and homeostasis of glucose regulation are negatively impacted by both intermittent hypoxemia and sleep disruption, but whether these influences of OSA are sufficient, independent of obesity, to contribute significantly to the "metabolic syndrome" remains unsettled. 3) Neurocognitive effects include daytime sleepiness and impaired memory and concentration. These effects reflect hypoxic-induced "neural injury." We discuss future research into understanding the pathophysiology of sleep apnea as a basis for uncovering newer forms of treatment of both the ventilatory disorder and its multiple sequelae.
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Affiliation(s)
- Jerome A Dempsey
- The John Rankin Laboratory of Pulmonary Medicine, Departments of Population Health Sciences and of Orthopedics and Rehabilitation, School of Medicine and Public Health, University of Wisconsin, Madison, Wisconsin 53706, USA.
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Abstract
To understand normal sleep pattern and physiological changes during sleep, sleep and breathing interaction, nomenclature and scales used in sleep study, discuss the effect of rapid eye movements and non-rapid eye movements while sleep and to review the effects of obstructive and restrictive lung disease on gas exchange during sleep and sleep architecture.
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Affiliation(s)
- Sumer S. Choudhary
- Department of Pulmonary Medicine, Sleep Medicine, Critical Care, Shree Ramjevan Choudhary Memorial Hospital and Research Centre, Nagpur - 02, India
| | - Sanjiw R. Choudhary
- Department of Pulmonary Medicine, Sleep Medicine, Critical Care, Shree Ramjevan Choudhary Memorial Hospital and Research Centre, Nagpur - 02, India
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Abstract
Sleep-related breathing disorders are a heterogeneous group of conditions that may be associated with alterations in the structure of sleep, in sleep quality, and in gas exchange during sleep. Obstructive sleep apnea represents the most frequent cause of sleep-related breathing disorders, which encompass a diversity of conditions that either complicate coexisting disease or present as primary disorders. Many of these disorders have consequences during both sleep and wakefulness and may produce substantial burden of symptoms and disease in untreated individuals.
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Affiliation(s)
- Conrad Iber
- University of Minnesota, Pulmonary and Critical Care, Hennepin County Medical Center, Minneapolis, MN 55415, USA.
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Dempsey JA, Smith CA, Przybylowski T, Chenuel B, Xie A, Nakayama H, Skatrud JB. The ventilatory responsiveness to CO(2) below eupnoea as a determinant of ventilatory stability in sleep. J Physiol 2004; 560:1-11. [PMID: 15284345 PMCID: PMC1665213 DOI: 10.1113/jphysiol.2004.072371] [Citation(s) in RCA: 135] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2004] [Accepted: 07/22/2004] [Indexed: 11/08/2022] Open
Abstract
Sleep unmasks a highly sensitive hypocapnia-induced apnoeic threshold, whereby apnoea is initiated by small transient reductions in arterial CO(2) pressure (P(aCO(2))) below eupnoea and respiratory rhythm is not restored until P(aCO(2)) has risen significantly above eupnoeic levels. We propose that the 'CO(2) reserve' (i.e. the difference in P(aCO(2)) between eupnoea and the apnoeic threshold (AT)), when combined with 'plant gain' (or the ventilatory increase required for a given reduction in P(aCO(2))) and 'controller gain' (ventilatory responsiveness to CO(2) above eupnoea) are the key determinants of breathing instability in sleep. The CO(2) reserve varies inversely with both plant gain and the slope of the ventilatory response to reduced CO(2) below eupnoea; it is highly labile in non-random eye movement (NREM) sleep. With many types of increases or decreases in background ventilatory drive and P(aCO(2)), the slope of the ventilatory response to reduced P(aCO(2)) below eupnoea remains unchanged from control. Thus, the CO(2) reserve varies inversely with plant gain, i.e. it is widened with hyperventilation and narrowed with hypoventilation, regardless of the stimulus and whether it acts primarily at the peripheral or central chemoreceptors. However, there are notable exceptions, such as hypoxia, heart failure, or increased pulmonary vascular pressures, which all increase the slope of the CO(2) response below eupnoea and narrow the CO(2) reserve despite an accompanying hyperventilation and reduced plant gain. Finally, we review growing evidence that chemoreceptor-induced instability in respiratory motor output during sleep contributes significantly to the major clinical problem of cyclical obstructive sleep apnoea.
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Affiliation(s)
- Jerome A Dempsey
- The John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, 53726-2368, USA.
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McGuire M, MacDermott M, Bradford A. Effects of chronic intermittent asphyxia on rat diaphragm and limb muscle contractility. Chest 2003; 123:875-81. [PMID: 12628891 DOI: 10.1378/chest.123.3.875] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
OBJECTIVE In obstructive sleep apnea (OSA), there is intermittent upper airway (UA) collapse due to an imbalance between the collapsing force generated by the diaphragm and the stabilizing force of the UA muscles. This results in chronic intermittent asphyxia (CIA). We have previously shown that CIA affects UA muscle fatigue, but little is known about the effects of chronic hypoxia on diaphragm or on limb muscle contractile properties and structure. DESIGN Rats were exposed to asphyxia and normoxia twice per minute for 8 h/d for 5 weeks to simulate the intermittent asphyxia of OSA in humans. Isometric contractile properties were determined from strips of isolated diaphragm, extensor digitorum longus (EDL), and soleus muscles in Krebs solution at 30 degrees C. EDL and soleus type 1 (slow, fatigue resistant), type 2A (fast, fatigue resistant), and type 2B (fast, fatigable) fiber distribution was determined using adenosine triphosphatase staining. RESULTS CIA caused a significant increase in diaphragm, EDL, and soleus fatigue, and reduced recovery from fatigue. Most of the other contractile properties were unaffected aside from a small reduction in diaphragm half-relaxation time and EDL twitch tension and a small shift to the left in the EDL force-frequency curve. There was no change in soleus fiber-type distribution and a small increase in EDL type 2A fibers (46.1 +/- 1.2% vs 49.9 +/- 1.4%, control vs CIA [mean +/- SD]). CONCLUSIONS CIA increases diaphragm, EDL, and soleus muscle fatigue. We speculate that if this also occurs in OSA, it would contribute to the pathophysiology of the condition.
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Affiliation(s)
- Michelle McGuire
- Department of Physiology, Royal College of Surgeons in Ireland, Dublin, Ireland
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McGuire M, MacDermott M, Bradford A. The effects of chronic episodic hypercapnic hypoxia on rat upper airway muscle contractile properties and fiber-type distribution. Chest 2002; 122:1400-6. [PMID: 12377871 DOI: 10.1378/chest.122.4.1400] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/01/2022] Open
Abstract
OBJECTIVE Obstructive sleep apnea (OSA) is caused by episodes of upper airway (UA) obstruction due to an inability of UA muscles such as the geniohyoids and sternohyoids to maintain airway patency. This results in chronic episodic hypercapnic hypoxia. Chronic continuous hypoxia and episodic hypocapnic hypoxia affect skeletal muscle structure and function, but the effects of chronic episodic hypercapnic hypoxia on UA muscle structure and function are unknown. DESIGN Rats breathed air and hypercapnic hypoxic gas twice per minute for 8 h/d for 5 weeks in order to mimic the intermittent hypercapnic hypoxia of OSA in humans. Isometric contractile properties were determined using strips of isolated geniohyoid and sternohyoid muscles in physiologic saline solution at 30 degrees C. Fiber-type distribution was determined by adenosine triphosphatase staining. RESULTS For both muscles, chronic episodic hypercapnic hypoxia had no significant effect on twitch or tetanic tension, twitch/tetanic tension ratio, and tension-frequency relationship. There was a significant (p < 0.05) increase in geniohyoid fatigue (50.5 +/- 6.6% vs 43.6 +/- 5.8% of initial tension), but sternohyoid fatigue was reduced (31.5 +/- 5.2% vs 37.8 +/- 6.0% of initial tension). Geniohyoid type 1 fibers were reduced and type 2B fibers increased, whereas sternohyoid muscle had an increase in type 1 and 2A fibers and a decrease in type 2B fibers. CONCLUSIONS Chronic episodic hypercapnic hypoxia alters UA muscle structure and function, changes that may affect the regulation of UA patency.
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Affiliation(s)
- Michelle McGuire
- Department of Physiology, Royal College of Surgeons in Ireland, St. Stephen's Green, Dublin 2, Ireland
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Smith CA, Henderson KS, Xi L, Chow C, Eastwood PR, Dempsey JA. Neural-mechanical coupling of breathing in REM sleep. J Appl Physiol (1985) 1997; 83:1923-32. [PMID: 9390964 DOI: 10.1152/jappl.1997.83.6.1923] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
During rapid-eye-movement (REM) sleep the ventilatory response to airway occlusion is reduced. Possible mechanisms are reduced chemosensitivity, mechanical impairment of the chest wall secondary to the atonia of REM sleep, or phasic REM events that interrupt or fractionate ongoing diaphragm electromyogram (EMG) activity. To differentiate between these possibilities, we studied three chronically instrumented dogs before, during, and after 15-20 s of airway occlusion during non-REM (NREM) and phasic REM sleep. We found that 1) for a given inspiratory time the integrated diaphragm EMG (Di) was similar or reduced in REM sleep relative to NREM sleep; 2) for a given Di in response to airway occlusion and the hyperpnea following occlusion, the mechanical output (flow or pressure) was similar or reduced during REM sleep relative to NREM sleep; 3) for comparable durations of airway occlusion the Di and integrated inspiratory tracheal pressure tended to be smaller and more variable in REM than in NREM sleep, and 4) significant fractionations (caused visible changes in tracheal pressure) of the diaphragm EMG during airway occlusion in REM sleep occurred in approximately 40% of breathing efforts. Thus reduced and/or erratic mechanical output during and after airway occlusion in REM sleep in terms of flow rate, tidal volume, and/or pressure generation is attributable largely to reduced neural activity of the diaphragm, which in turn is likely attributable to REM effects, causing reduced chemosensitivity at the level of the peripheral chemoreceptors or, more likely, at the central integrator. Chest wall distortion secondary to the atonia of REM sleep may contribute to the reduced mechanical output following airway occlusion when ventilatory drive is highest.
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Affiliation(s)
- C A Smith
- The John Rankin Laboratory of Pulmonary Medicine, Department of Preventive Medicine, University of Wisconsin School of Medicine, Madison, Wisconsin 53705-2368, USA
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Marrone O, Salvaggio A, Insalaco G, Bonsignore MR, Cimino M, Gallina S, Speciale R. Respiration in NREM and REM sleep after upper airway surgery for obstructive sleep apnoea. J Sleep Res 1995; 4:189-195. [PMID: 10607158 DOI: 10.1111/j.1365-2869.1995.tb00168.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
To verify whether upper airway surgery in obstructive sleep apnoea syndrome affects differently respiration in NREM and REM sleep, 22 patients were studied by polysomnography before and three months after surgical treatment. On the average, treatment improved respiration during both sleep states, but no significant interaction was found between sleep state and effect of surgical treatment. According to the response to treatment, three groups of patients were identified: the first group (N = 6), with an improvement in apnoea-hypopnoea index (AHI), percentage of sleep time spent in apnoea and hypopnoea (time in AH) and mean oxyhaemoglobin saturation (SaO2) in both NREM and REM sleep; the second group (N = 5), with an improvement in AHI only in NREM sleep, associated with improvement in mean SaO2 in both sleep states; the third group (N = 11), without any improvement in AHI and time in AH, either associated (N = 5) or not (N = 6) with an improvement in mean SaO2 in both sleep states. An increase in the percentage of hypopnoeas out of the total AHI after treatment could partly account for the apparent discrepancy between AHI and mean SaO2 behaviour in the subjects of the second group, but not in the patients of the third group who improved their mean SaO2. Mixed apnoeas occurred before surgery in six subjects; they remained numerous after surgery only in two subjects who did not show any SaO2 improvement. In conclusion, the degree of improvement in respiration after upper airway surgery was similar in every patient in NREM and REM sleep.
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Affiliation(s)
- O Marrone
- Istituto di Fisiopatologia Respiratoria del CNR
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Berry RB, Light RW. Effect of hyperoxia on the arousal response to airway occlusion during sleep in normal subjects. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1992; 146:330-4. [PMID: 1489120 DOI: 10.1164/ajrccm/146.2.330] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The effect of hyperoxia on the arousal response to airway occlusion during non-rapid eye movement (NREM) sleep was studied in six normal male subjects with a mean age (+/- SD) of 23.5 +/- 8.7 yr by testing the response to the occlusion of a face mask covering the nose and mouth. Occlusion trials while the subjects breathed room air (room air condition) were alternated with trials in which subjects breathed a mixture of room air and oxygen adjusted to maintain a sleeping baseline arterial oxygen saturation of 98% (hyperoxic condition). The time to arousal (mean +/- SEM) was significantly longer during oxygen administration (4.1 +/- 4.5 versus 28.9 +/- 4.6 s; p < 0.002). The maximal deflections in airway pressure were measured at a supraglottic location during airway occlusion to reflect the degree of inspiratory effort. The maximal airway suction pressure preceding arousal did not differ between the room air (27.4 +/- 5.4 cm H2O) and hyperoxic conditions (26.6 +/- 5.9 cm H2O). Conversely, the rate of increase in inspiratory effort (maximal pressure) during occlusion was decreased by oxygen administration. We conclude that hyperoxia prolongs the time to arousal after airway occlusion by decreasing the rate of increase in the magnitude of inspiratory efforts, but it does not change the arousal threshold.
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Affiliation(s)
- R B Berry
- Pulmonary Section, Long Beach VA Medical Center, CA 90822
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Iber C, McArthur C. Awake inspiratory airway occlusion in normal humans is followed by hyperpnea and hypocapnia. RESPIRATION PHYSIOLOGY 1989; 75:349-56. [PMID: 2497505 DOI: 10.1016/0034-5687(89)90043-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The ventilatory response following 15 seconds of inspiratory airway occlusion at functional residual capacity (FRC) was studied in nine normal supine awake subjects. Expired minute ventilation (VE), CO2 output (VCO2), tidal volume (VT), and end-tidal PCO2 (PETCO2) were measured on a breath-by-breath basis. Alveolar PCO2 rose 5.6 mm Hg during the apnea (P less than 0.001). Ventilation rose 10.8 L/min on the first breath following apnea and remained elevated above control measurements for five breaths (P less than 0.05). The persistent hyperpnea was due to an increase in tidal volume and was associated with alveolar hypocapnia for 6 breaths or 30 sec (P less than 0.05) and an increase in CO2 output for 4 breaths (P less than 0.05). Changes in end-tidal PCO2 correlated with excess CO2 output relative to control measurements immediately prior to airway occlusion (P less than 0.03). After 15 sec airway occlusion at FRC, there is alveolar hypercapnia with a 2.6-fold first breath rise in ventilation. Persistent alveolar hyperventilation lasting 30 sec following airway occlusion may be due to delays in central chemoreceptor response or an afterdischarge phenomenon. This overshoot hypercapnia following airway occlusion may have some relevance to the development of central apneas following obstructive apnea episodes.
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Affiliation(s)
- C Iber
- Department of Medicine, Hennepin County Medical Center, Minneapolis, MN 55415
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Kunitomo F, Kimura H, Tatsumi K, Okita S, Tojima H, Kuriyama T, Honda Y. Abnormal breathing during sleep and chemical control of breathing during wakefulness in patients with sleep apnea syndrome. THE AMERICAN REVIEW OF RESPIRATORY DISEASE 1989; 139:164-9. [PMID: 2492171 DOI: 10.1164/ajrccm/139.1.164] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The possible role of ventilatory control in relation to sleep apnea has not yet been clarified. We investigated the relationship between awake ventilatory drives to hypoxia and hypercapnia and sleep-disordered breathing in 21 subjects with sleep apnea syndrome. The awake hypoxic ventilatory drive, which was evaluated by occlusion pressure responses, was inversely correlated with the magnitude of maximal oxygen desaturation during sleep as well as the ratio of duration with more than 4 and 10% oxygen desaturation to total sleep time. On the other hand, the awake hypercapnic ventilatory drive was not correlated with these parameters of sleep desaturation. Apnea index and duration were not correlated with the degree of hypoxic or hypercapnic ventilatory drive, respectively. Our study concluded that sleep desaturation is better correlated with hypoxic ventilatory drive than with hypercapnic ventilatory drive in patients with sleep apnea syndrome. These results are different from the results obtained in the patients with COPD in our previous study.
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Affiliation(s)
- F Kunitomo
- Department of Chest Medicine, School of Medicine, Chiba University, Japan
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