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Neder JA, Santyr G, Zanette B, Kirby M, Pourafkari M, James MD, Vincent SG, Ferguson C, Wang CY, Domnik NJ, Phillips DB, Porszasz J, Stringer WW, O'Donnell DE. Beyond Spirometry: Linking Wasted Ventilation to Exertional Dyspnea in the Initial Stages of COPD. COPD 2024; 21:2301549. [PMID: 38348843 DOI: 10.1080/15412555.2023.2301549] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2023] [Accepted: 12/29/2023] [Indexed: 02/15/2024]
Abstract
Exertional dyspnea, a key complaint of patients with chronic obstructive pulmonary disease (COPD), ultimately reflects an increased inspiratory neural drive to breathe. In non-hypoxemic patients with largely preserved lung mechanics - as those in the initial stages of the disease - the heightened inspiratory neural drive is strongly associated with an exaggerated ventilatory response to metabolic demand. Several lines of evidence indicate that the so-called excess ventilation (high ventilation-CO2 output relationship) primarily reflects poor gas exchange efficiency, namely increased physiological dead space. Pulmonary function tests estimating the extension of the wasted ventilation and selected cardiopulmonary exercise testing variables can, therefore, shed unique light on the genesis of patients' out-of-proportion dyspnea. After a succinct overview of the basis of gas exchange efficiency in health and inefficiency in COPD, we discuss how wasted ventilation translates into exertional dyspnea in individual patients. We then outline what is currently known about the structural basis of wasted ventilation in "minor/trivial" COPD vis-à-vis the contribution of emphysema versus a potential impairment in lung perfusion across non-emphysematous lung. After summarizing some unanswered questions on the field, we propose that functional imaging be amalgamated with pulmonary function tests beyond spirometry to improve our understanding of this deeply neglected cause of exertional dyspnea. Advances in the field will depend on our ability to develop robust platforms for deeply phenotyping (structurally and functionally), the dyspneic patients showing unordinary high wasted ventilation despite relatively preserved FEV1.
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Affiliation(s)
- J Alberto Neder
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
| | - Giles Santyr
- Translational Medicine Department, Faculty of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Canada
| | - Brandon Zanette
- Translational Medicine Department, Faculty of Physiology and Experimental Medicine, Hospital for Sick Children, Toronto, Canada
| | - Miranda Kirby
- Department of Physics, Faculty of Science, Toronto Metropolitan University, Toronto, Canada
| | - Marina Pourafkari
- Department of Radiology and Diagnostic Imaging, Kingston Health Sciences Centre, Kingston, Canada
| | - Matthew D James
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
| | - Carrie Ferguson
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - Chu-Yi Wang
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - Nicolle J Domnik
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Canada
| | - Devin B Phillips
- School of Kinesiology and Health Science, York University, Toronto, Canada
| | - Janos Porszasz
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - William W Stringer
- The Lundquist Institute for Biomedical Innovation, Harbor U.C.L.A Medical Centre, Torrance, CA, USA
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, Canada
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Baedorf-Kassis E, Murn M, Dzierba AL, Serra AL, Garcia I, Minus E, Padilla C, Sarge T, Goodspeed VM, Matthay MA, Gong MN, Cook D, Loring SH, Talmor D, Beitler JR. Respiratory drive heterogeneity associated with systemic inflammation and vascular permeability in acute respiratory distress syndrome. Crit Care 2024; 28:136. [PMID: 38654391 PMCID: PMC11036740 DOI: 10.1186/s13054-024-04920-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2023] [Accepted: 04/17/2024] [Indexed: 04/25/2024] Open
Abstract
BACKGROUND In acute respiratory distress syndrome (ARDS), respiratory drive often differs among patients with similar clinical characteristics. Readily observable factors like acid-base state, oxygenation, mechanics, and sedation depth do not fully explain drive heterogeneity. This study evaluated the relationship of systemic inflammation and vascular permeability markers with respiratory drive and clinical outcomes in ARDS. METHODS ARDS patients enrolled in the multicenter EPVent-2 trial with requisite data and plasma biomarkers were included. Neuromuscular blockade recipients were excluded. Respiratory drive was measured as PES0.1, the change in esophageal pressure during the first 0.1 s of inspiratory effort. Plasma angiopoietin-2, interleukin-6, and interleukin-8 were measured concomitantly, and 60-day clinical outcomes evaluated. RESULTS 54.8% of 124 included patients had detectable respiratory drive (PES0.1 range of 0-5.1 cm H2O). Angiopoietin-2 and interleukin-8, but not interleukin-6, were associated with respiratory drive independently of acid-base, oxygenation, respiratory mechanics, and sedation depth. Sedation depth was not significantly associated with PES0.1 in an unadjusted model, or after adjusting for mechanics and chemoreceptor input. However, upon adding angiopoietin-2, interleukin-6, or interleukin-8 to models, lighter sedation was significantly associated with higher PES0.1. Risk of death was less with moderate drive (PES0.1 of 0.5-2.9 cm H2O) compared to either lower drive (hazard ratio 1.58, 95% CI 0.82-3.05) or higher drive (2.63, 95% CI 1.21-5.70) (p = 0.049). CONCLUSIONS Among patients with ARDS, systemic inflammatory and vascular permeability markers were independently associated with higher respiratory drive. The heterogeneous response of respiratory drive to varying sedation depth may be explained in part by differences in inflammation and vascular permeability.
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Affiliation(s)
- Elias Baedorf-Kassis
- Division of Pulmonary and Critical Care Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Michael Murn
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Amy L Dzierba
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
- Department of Pharmacy, New York-Presbyterian Hospital, New York, NY, USA
| | - Alexis L Serra
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Ivan Garcia
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Emily Minus
- Departments of Medicine and Anesthesia, University of California San Francisco, San Francisco, CA, USA
| | - Clarissa Padilla
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA
| | - Todd Sarge
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Valerie M Goodspeed
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Michael A Matthay
- Departments of Medicine and Anesthesia, University of California San Francisco, San Francisco, CA, USA
| | - Michelle N Gong
- Department of Critical Care Medicine, Montefiore Medical Center and Albert Einstein College of Medicine, Bronx, NY, USA
| | - Deborah Cook
- St. Joseph's Hospital and McMaster University, Hamilton, ON, Canada
| | - Stephen H Loring
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Daniel Talmor
- Department of Anesthesia, Critical Care, and Pain Medicine, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Jeremy R Beitler
- Columbia Respiratory Critical Care Trials Group, Columbia University College of Physicians and Surgeons, and New York-Presbyterian Hospital, 622 West 168th Street, New York, NY, 10032, USA.
- Center for Acute Respiratory Failure, New York-Presbyterian Hospital, New York, NY, USA.
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Xuan L, Wang Y, Zheng Y, Chen S, Zhu L, Zheng X, Lin S, Zhong M. Delayed lung injury on the nonsurgical side increases mortality in patients after lung cancer surgery: a retrospective cohort study. J Thorac Dis 2023; 15:5574-5584. [PMID: 37969314 PMCID: PMC10636481 DOI: 10.21037/jtd-23-822] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2023] [Accepted: 09/15/2023] [Indexed: 11/17/2023]
Abstract
Background The incidence of pulmonary complications following lung cancer surgery has declined recently; however, postoperative acute lung injury (PALI) is still common. The present study aimed to assess the prognosis of PALI after lung cancer surgery on different injury sides, describe its clinical characteristics and identify risk factors. Methods This was a monocenter retrospective study conducted in a university surgical intensive care unit (SICU). Patients requiring respiratory support with severe hypoxemia after lung cancer surgery were included. Patients were categorized based on the radiographic assessment of lung edema (RALE) score ratio, which calculates the severity of surgical/nonsurgical side of lung injury [RRALE; RALE score of the surgical side (RALES) divided by RALE score of nonsurgical side (RALENS)], into two groups: the nonsurgical-side lung injury group (RRALE <1) and others (RRALE ≥1). The primary outcome was 90-day mortality, and secondary outcomes included in-hospital 28-day mortality, total intensive care unit (ICU) length of stay (LOS), hospital LOS and 6-month survival. Results Sixteen patients were enrolled in this study. Nine patients were included in the RRALE <1 group and seven patients were included in the RRALE ≥1 group. At 90 days, six patients in the RRALE <1 group had died, whereas none died in the RRALE ≥1 group (P=0.01). No significant difference was observed in in-hospital 28-day all-cause mortality (P=0.48) or ICU or hospital LOS (P=0.34 and P=0.36, respectively) between the two groups. Survival at 6 months was significantly lower in the RRALE <1 group (33.33%) than in the RRALE ≥1 group (100.00%) (P=0.009). Conclusions Patients with severe lung injury on the nonsurgical side after lung cancer surgery had high 90-day mortality rates. Large prospective studies and accurate monitoring data are needed in the future to identify the risk factors and therapy for such lung injury.
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Affiliation(s)
- Lizhen Xuan
- Department of Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Yuxian Wang
- Department of Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Yijun Zheng
- Department of Anaesthesia, Critical Care and Pain Medicine, Fudan University Shanghai Cancer Center, Shanghai, China
| | - Song Chen
- Department of Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Ling Zhu
- Department of Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Xin Zheng
- Department of Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Shengyao Lin
- Department of Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China
| | - Ming Zhong
- Department of Critical Care Medicine, Zhongshan Hospital Fudan University, Shanghai, China
- Shanghai Institute of Infectious Disease and Biosecurity, School of Public Health, Fudan University, Shanghai, China
- Shanghai Key Laboratory of Lung Inflammation and Injury, Shanghai, China
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Neder JA. Cardiopulmonary exercise testing applied to respiratory medicine: Myths and facts. Respir Med 2023; 214:107249. [PMID: 37100256 DOI: 10.1016/j.rmed.2023.107249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 03/28/2023] [Accepted: 04/18/2023] [Indexed: 04/28/2023]
Abstract
Cardiopulmonary exercise testing (CPET) remains poorly understood and, consequently, largely underused in respiratory medicine. In addition to a widespread lack of knowledge of integrative physiology, several tenets of CPET interpretation have relevant controversies and limitations which should be appropriately recognized. With the intent to provide a roadmap for the pulmonologist to realistically calibrate their expectations towards CPET, a collection of deeply entrenched beliefs is critically discussed. They include a) the actual role of CPET in uncovering the cause(s) of dyspnoea of unknown origin, b) peak O2 uptake as the key metric of cardiorespiratory capacity, c) the value of low lactate ("anaerobic") threshold to differentiate cardiocirculatory from respiratory causes of exercise limitation, d) the challenges of interpreting heart rate-based indexes of cardiovascular performance, e) the meaning of peak breathing reserve in dyspnoeic patients, f) the merits and drawbacks of measuring operating lung volumes during exercise, g) how best interpret the metrics of gas exchange inefficiency such as the ventilation-CO2 output relationship, h) when (and why) measurements of arterial blood gases are required, and i) the advantages of recording submaximal dyspnoea "quantity" and "quality". Based on a conceptual framework that links exertional dyspnoea to "excessive" and/or "restrained" breathing, I outline the approaches to CPET performance and interpretation that proved clinically more helpful in each of these scenarios. CPET to answer clinically relevant questions in pulmonology is a largely uncharted research field: I, therefore, finalize by highlighting some lines of inquiry to improve its diagnostic and prognostic yield.
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Affiliation(s)
- J Alberto Neder
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Department of Medicine, Division of Respirology, Kingston Health Sciences Center, Queen's University, Kingston, ON, Canada.
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Respiratory patterns and baroreflex function in heart failure. Sci Rep 2023; 13:2220. [PMID: 36755066 PMCID: PMC9908869 DOI: 10.1038/s41598-023-29271-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 02/01/2023] [Indexed: 02/10/2023] Open
Abstract
Little is known on the effects of respiratory patterns on baroreflex function in heart failure (HF). Patients with HF (n = 30, age 61.6 ± 10 years, mean ± SD) and healthy controls (CNT, n = 10, age 58.9 ± 5.6 years) having their R-R interval (RRI, EKG), systolic arterial blood pressure (SBP, Finapres) and respiratory signal (RSP, Respitrace) monitored, were subjected to three recording sessions: free-breathing, fast- (≥ 12 bpm) and slow- (6 bpm) paced breathing. Baroreflex sensitivity (BRS) and power spectra of RRI, SBP, and RSP signals were calculated. During free-breathing, compared to CNT, HF patients showed a significantly greater modulation of respiratory volumes in the very-low-frequency (< 0.04 Hz) range and their BRS was not significantly different from that of CNT. During fast-paced breathing, when very-low-frequency modulations of respiration were reduced, BRS of HF patients was significantly lower than that of CNT and lower than during free breathing. During slow-paced breathing, BRS became again significantly higher than during fast breathing. In conclusion: (1) in free-breathing HF patients is present a greater modulation of respiratory volumes in the very-low-frequency range; (2) in HF patients modulation of respiration in the very-low and low frequency (around 0.1 Hz) ranges contributes to preserve baroreflex-mediated control of heart rate.
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Neder JA, Rocha A, Arbex FF, Alencar MCN, Sperandio PA, Hirai DM, Berton DC. Exertional oscillatory ventilation in subjects without heart failure reporting chronic dyspnoea. ERJ Open Res 2023; 9:00324-2022. [PMID: 36726368 PMCID: PMC9885272 DOI: 10.1183/23120541.00324-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 11/09/2022] [Indexed: 12/24/2022] Open
Abstract
Oscillatory ventilation detected on incremental cardiopulmonary exercise testing might be found in subjects without heart failure reporting exertional dyspnoea despite the best available therapy for their underlying cardiopulmonary disease https://bit.ly/3Tyl7bE.
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Affiliation(s)
- J. Alberto Neder
- Laboratory of Clinical Exercise Physiology (LACEP) and Respiratory Investigation Unit (RIU), Queen's University and Kingston General Hospital, Kingston, ON, Canada,J. Alberto Neder ()
| | - Alcides Rocha
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Flavio F. Arbex
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Maria Clara N. Alencar
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Priscila A. Sperandio
- Pulmonary Function and Clinical Exercise Physiology Unit (SEFICE), Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Daniel M. Hirai
- Department of Health and Kinesiology, Purdue University, West Lafayette, IN, USA
| | - Danilo C. Berton
- Division of Respirology, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
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Zhang J, Luo F, Ren S, Wang Y, Li W, Xu K, Zheng Z, He C, Xia J, Xiong W, Hu ZA. Spinal Cord Mapping of Respiratory Intercostal Motoneurons in Adult Mice. Neurosci Bull 2022; 38:1588-1592. [PMID: 35616883 PMCID: PMC9723038 DOI: 10.1007/s12264-022-00883-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Accepted: 03/27/2022] [Indexed: 02/07/2023] Open
Affiliation(s)
- Junhong Zhang
- Department of Geriatrics, First Affiliated Hospital, Army Medical University, Chongqing, 400038, China
| | - Fenlan Luo
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Shuancheng Ren
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Yaling Wang
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Wu Li
- Department of Geriatrics, First Affiliated Hospital, Army Medical University, Chongqing, 400038, China
| | - Kan Xu
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Ziyi Zheng
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Chao He
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Jianxia Xia
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China
| | - Wei Xiong
- Department of Geriatrics, First Affiliated Hospital, Army Medical University, Chongqing, 400038, China.
| | - Zhi-An Hu
- Department of Physiology, College of Basic Medical Sciences, Army Medical University, Chongqing, 400038, China.
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Neder JA, Phillips DB, O'Donnell DE, Dempsey JA. Excess ventilation and exertional dyspnoea in heart failure and pulmonary hypertension. Eur Respir J 2022; 60:13993003.00144-2022. [PMID: 35618273 DOI: 10.1183/13993003.00144-2022] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 05/05/2022] [Indexed: 01/11/2023]
Abstract
Increased ventilation relative to metabolic demands, indicating alveolar hyperventilation and/or increased physiological dead space (excess ventilation), is a key cause of exertional dyspnoea. Excess ventilation has assumed a prominent role in the functional assessment of patients with heart failure (HF) with reduced (HFrEF) or preserved (HFpEF) ejection fraction, pulmonary arterial hypertension (PAH) and chronic thromboembolic pulmonary hypertension (CTEPH). We herein provide the key pieces of information to the caring physician to 1) gain unique insights into the seeds of patients' shortness of breath and 2) develop a rationale for therapeutically lessening excess ventilation to mitigate this distressing symptom. Reduced bulk oxygen transfer induced by cardiac output limitation and/or right ventricle-pulmonary arterial uncoupling increase neurochemical afferent stimulation and (largely chemo-) receptor sensitivity, leading to alveolar hyperventilation in HFrEF, PAH and small-vessel, distal CTEPH. As such, interventions geared to improve central haemodynamics and/or reduce chemosensitivity have been particularly effective in lessening their excess ventilation. In contrast, 1) high filling pressures in HFpEF and 2) impaired lung perfusion leading to ventilation/perfusion mismatch in proximal CTEPH conspire to increase physiological dead space. Accordingly, 1) decreasing pulmonary capillary pressures and 2) mechanically unclogging larger pulmonary vessels (pulmonary endarterectomy and balloon pulmonary angioplasty) have been associated with larger decrements in excess ventilation. Exercise training has a strong beneficial effect across diseases. Addressing some major unanswered questions on the link of excess ventilation with exertional dyspnoea under the modulating influence of pharmacological and nonpharmacological interventions might prove instrumental to alleviate the devastating consequences of these prevalent diseases.
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Affiliation(s)
- J Alberto Neder
- Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respiratory and Critical Care Medicine, Dept of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Devin B Phillips
- Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respiratory and Critical Care Medicine, Dept of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Denis E O'Donnell
- Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respiratory and Critical Care Medicine, Dept of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Dept of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, USA
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James MD, Phillips DB, Vincent SG, Abdallah SJ, Donovan AA, de-Torres JP, Neder JA, Smith BM, Jensen D, O'Donnell DE. Exertional dyspnoea in patients with mild-to-severe chronic obstructive pulmonary disease (COPD): Neuromechanical mechanisms. J Physiol 2022; 600:4227-4245. [PMID: 35861594 DOI: 10.1113/jp283252] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2022] [Accepted: 07/11/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Dyspnoea during exercise is a common and troublesome symptom reported by patients with chronic obstructive pulmonary disease (COPD) and is linked to an elevated inspiratory neural drive (IND). The precise mechanisms of elevated IND and dyspnoea across the continuum of airflow obstruction severity in COPD remains unclear. The present study sought to determine the mechanisms of elevated IND [by diaphragm EMG, EMGdi (%max)] and dyspnoea during cardiopulmonary exercise testing (CPET) across the continuum of COPD severity. There was a strong association between increasing dyspnoea intensity and EMGdi (%max) during CPET across the COPD continuum despite significant heterogeneity in underlying pulmonary gas exchange and respiratory mechanical impairments. Critical inspiratory constraints occurred at progressively lower ventilation during exercise with worsening severity of COPD. This was associated with the progressively lower resting inspiratory capacity with worsening disease severity. Earlier critical inspiratory constraint was associated with earlier neuromechanical dissociation and greater likelihood of reporting the sensation of 'unsatisfied inspiration'. ABSTRACT In patients with COPD, exertional dyspnoea generally arises when there is imbalance between ventilatory demand and capacity, but the neurophysiological mechanisms are unclear. We therefore determined if disparity between elevated inspiratory neural drive (IND) and tidal volume (VT ) responses (neuromechanical dissociation) impacted dyspnoea intensity and quality during exercise, across the COPD severity spectrum. In this two-centre, cross-sectional observational study, 89 participants with COPD divided into tertiles of FEV1 %predicted (Tertile 1 = FEV1 = 87 ± 9%, Tertile 2 = 60 ± 9%, Tertile 3 = 32 ± 8%) and 18 non-smoking controls, completed a symptom-limited cardiopulmonary exercise tests (CPET) with measurement of IND by diaphragm electromyography [EMGdi (%max)]. The association between increasing dyspnoea intensity and EMGdi (%max) during CPET was strong (r = 0.730, P < 0.001) and not different between the four groups who showed marked heterogeneity in pulmonary gas exchange and mechanical abnormalities. Significant inspiratory constraints (tidal volume/inspiratory capacity (VT /IC) ≥ 70%) and onset of neuromechanical dissociation (EMGdi (%max):VT /IC > 0.75) occurred at progressively lower V̇E from Control to Tertile 3. Lower resting IC meant earlier onset of neuromechanical dissociation, heightened dyspnoea intensity and greater propensity (93% in Tertile 3) to select qualitative descriptors of 'unsatisfied inspiration'. We concluded that, regardless of marked variation in mechanical and pulmonary gas exchange abnormalities in our study sample, exertional dyspnoea intensity was linked to the magnitude of EMGdi (%max). Moreover, onset of critical inspiratory constraints and attendant neuromechanical dissociation amplified dyspnoea intensity at higher exercise intensities. Simple measurements of IC and breathing pattern during CPET provide useful insights into mechanisms of dyspnoea and exercise intolerance in individuals with COPD. Abstract figure legend As chronic obstructive pulmonary disease severity increases, worsening gas exchange and respiratory mechanical impairment causes increased afferent receptor stimulation, increasing inspiratory neural drive at a given ventilation. The widening disparity between progressively greater inspiratory neural drive and reduced ventilatory output causes, 'neuromechanical dissociation'. This is strongly associated with a rapid increase in the intensity of dyspnea during exercise, and the onset of the sensation of 'unsatisfied inspiration'. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Matthew D James
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Sandra G Vincent
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Sara J Abdallah
- Clinical Exercise and Respiratory Physiology Laboratory, Department of Kinesiology and Physical Education, Faculty of Education, McGill University, Montréal, Quebec, Canada.,Translational Research in Respiratory Diseases Program and Respiratory Epidemiology and Clinical Research Unit, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
| | - Adamo A Donovan
- Division of Respiratory Medicine, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Juan P de-Torres
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
| | - Benjamin M Smith
- Translational Research in Respiratory Diseases Program and Respiratory Epidemiology and Clinical Research Unit, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada.,Division of Respiratory Medicine, Department of Medicine, McGill University Health Centre, Montreal, Quebec, Canada
| | - Dennis Jensen
- Clinical Exercise and Respiratory Physiology Laboratory, Department of Kinesiology and Physical Education, Faculty of Education, McGill University, Montréal, Quebec, Canada.,Translational Research in Respiratory Diseases Program and Respiratory Epidemiology and Clinical Research Unit, Research Institute of the McGill University Health Centre, Montréal, Quebec, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
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- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
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Toledo C, Díaz-Jara E, Diaz HS, Schwarz KG, Pereyra KV, Las Heras A, Rios-Gallardo A, Andrade DC, Moreira T, Takakura A, Marcus NJ, Del Rio R. Medullary astrocytes mediate irregular breathing patterns generation in chronic heart failure through purinergic P2X7 receptor signalling. EBioMedicine 2022; 80:104044. [PMID: 35533501 PMCID: PMC9097632 DOI: 10.1016/j.ebiom.2022.104044] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Revised: 04/19/2022] [Accepted: 04/20/2022] [Indexed: 11/05/2022] Open
Abstract
Background Breathing disorders (BD) (apnoeas/hypopneas, periodic breathing) are highly prevalent in chronic heart failure (CHF) and are associated with altered central respiratory control. Ample evidence identifies the retrotrapezoid nucleus (RTN) as an important chemosensitivity region for ventilatory control and generation of BD in CHF, however little is known about the cellular mechanisms underlying the RTN/BD relationship. Within the RTN, astrocyte‐mediated purinergic signalling modulates respiration, but the potential contribution of RTN astrocytes to BD in CHF has not been explored. Methods Selective neuron and/or astrocyte-targeted interventions using either optogenetic and chemogenetic manipulations in the RTN of CHF rats were used to unveil the contribution of the RTN on the development/maintenance of BD, the role played by astrocytes in BD and the molecular mechanism underpinning these alterations. Findings We showed that episodic photo-stimulation of RTN neurons triggered BD in healthy rats, and that RTN neurons ablation in CHF animals eliminates BD. Also, we found a reduction in astrocytes activity and ATP bioavailability within the RTN of CHF rats, and that chemogenetic restoration of normal RTN astrocyte activity and ATP levels improved breathing regularity in CHF. Importantly, P"X/ P2X7 receptor (P2X7r) expression was reduced in RTN astrocytes from CHF rats and viral vector-mediated delivery of human P2X7 P2X7r into astrocytes increases ATP bioavailability and abolished BD. Interpretation Our results support that RTN astrocytes play a pivotal role on BD generation and maintenance in the setting CHF by a mechanism encompassing P2X7r signalling. Funding This study was funded by the National Research and Development Agency of Chile (ANID).
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11
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Neder JA, Kirby M, Santyr G, Pourafkari M, Smyth R, Phillips DB, Crinion S, de-Torres JP, O’Donnell DE. V̇/Q̇ Mismatch. Chest 2022; 162:1030-1047. [DOI: 10.1016/j.chest.2022.03.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2022] [Revised: 02/14/2022] [Accepted: 03/21/2022] [Indexed: 10/18/2022] Open
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12
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Harrison OK, Russell BR, Pattinson KTS. Perceptual and Ventilatory Responses to Hypercapnia in Athletes and Sedentary Individuals. Front Physiol 2022; 13:820307. [PMID: 35370804 PMCID: PMC8964958 DOI: 10.3389/fphys.2022.820307] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2021] [Accepted: 02/08/2022] [Indexed: 11/25/2022] Open
Abstract
Purpose Hypercapnic chemosensitivity traditionally captures the ventilatory response to elevated pressures of carbon dioxide in the blood. However, hypercapnia also contributes to subjective breathing perceptions, and previously we demonstrated a closer matching of perception to changes in ventilation in athletes compared to controls. Here we investigated any potential underlying hypercapnic chemosensitivity differences between groups, and explored whether these measures relate to ventilatory and perceptual responses during exercise as well as trait levels of affect. Methods A hypercapnic challenge, incremental maximal exercise test and affective questionnaires were completed by 20 endurance athletes and 20 age-/sex-matched sedentary controls. The hypercapnic challenge involved elevating end-tidal PCO2 by 0.8% (6.1 mmHg) and 1.5% (11.2 mmHg) for 3 min each (randomised), with constant end-tidal oxygen. Ventilatory and perceptual responses to hypercapnia were compared between groups, and within each group the relationships between hypercapnic chemosensitivity (slope analyses) and exercising ventilation and perceptions were calculated using Spearman’s non-parametric correlations. Results While absolute ventilation differences during hypercapnia and exercise were observed, no group differences were found across hypercapnic chemosensitivity (slope) measures. Correlation analyses revealed the anxiety hypercapnic response was related to maximal exercise anxiety, but only in sedentary individuals. Conclusion Ventilatory and perceptual hypercapnic chemosensitivity do not differ between athletes and sedentary individuals. However, ventilatory and anxiety hypercapnic chemosensitivities were related to ventilatory and anxiety responses during exercise in untrained individuals only. Athletes may employ additional strategies during exercise to reduce the influence of chemosensitivity on ventilatory and perceptual responses.
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Affiliation(s)
- Olivia K. Harrison
- Department of Psychology, University of Otago, Dunedin, New Zealand
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Wellcome Centre for Integrative NeuroImaging, University of Oxford, Oxford, United Kingdom
- *Correspondence: Olivia K. Harrison,
| | | | - Kyle T. S. Pattinson
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, United Kingdom
- Wellcome Centre for Integrative NeuroImaging, University of Oxford, Oxford, United Kingdom
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13
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do Prado DML, Silvino VO, Motta-Santos D, Dos Santos MAP. The effect of the protective face mask on cardiorespiratory response during aerobic exercise. Clin Exp Pharmacol Physiol 2022; 49:453-461. [PMID: 35090062 DOI: 10.1111/1440-1681.13624] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Revised: 11/10/2021] [Accepted: 11/20/2021] [Indexed: 11/29/2022]
Abstract
Protective face mask (PFM) has been widely used for safety purposes and, after the advent of the COVID-19 pandemic, its use is growing steadily, not only among healthcare personnel but also the general population. While PFM is important to preserve the wearer from contaminating agents present in the airflow, they are well known to increase the subjective perception of breathing difficulty. Although some studies demonstrated that PFM use worsens exercise tolerance, there are several studies stating that there is no such limitation with the use of PFM. Moreover, no serious adverse effects during physical exercise have been found in the literature. Physical exercise represents a significant challenge to the human body through a series of integrated changes in function that involve most of its physiologic systems. In this respect, cardiovascular and respiratory systems provide the capacity to sustain physical tasks over extended periods. Within this scenario, both convective oxygen (O2 ) transport (product of arterial O2 content x blood flow) to the working locomotor muscles and O2 diffusive transport from muscle capillaries to mitochondria are of paramount importance to endurance performance. Interestingly, the effects of PFM on cardiorespiratory response during aerobic exercise depends on the type of mask and exercise (i.e., walking, running, or cycling), including decrease in ventilatory demands, arterial oxygen levels, maximal oxygen consumption, and endurance performance. The purpose of this review was to elucidate the effect of protective face mask-wearing on 1) cardiorespiratory responses during aerobic exercise and 2) endurance performance.
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Affiliation(s)
| | - Valmir Oliveira Silvino
- Department of Biophysics and Physiology, Nucleus of Study in Physiology Applied to Performance and Health, Federal University of Piaui, PI, Brazil
| | - Daisy Motta-Santos
- School of Physical Education, Physiotherapy, and Occupational Therapy, Federal University Minas Gerais, MG, Brazil
| | - Marcos Antônio Pereira Dos Santos
- Department of Biophysics and Physiology, Nucleus of Study in Physiology Applied to Performance and Health, Federal University of Piaui, PI, Brazil
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14
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Rastogi R, Morgan BJ, Badr MS, Chowdhuri S. Hypercapnia-induced vasodilation in the cerebral circulation is reduced in older adults with sleep-disordered breathing. J Appl Physiol (1985) 2022; 132:14-23. [PMID: 34709067 PMCID: PMC8721948 DOI: 10.1152/japplphysiol.00347.2021] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023] Open
Abstract
The prevalence of sleep-disordered breathing (SDB) is higher in older adults compared with younger individuals. The increased propensity for ventilatory control instability in older adults may contribute to the increased prevalence of central apneas. Reductions in the cerebral vascular response to CO2 may exacerbate ventilatory overshoots and undershoots during sleep. Thus, we hypothesized that hypercapnia-induced cerebral vasodilation (HCVD) will be reduced in older compared with younger adults. In 11 older and 10 younger adults with SDB, blood flow velocity in the middle cerebral artery (MCAV) was measured using Doppler transcranial ultrasonography during multiple steady-state hyperoxic hypercapnic breathing trials while awake, interspersed with room air breathing. Changes in ventilation, MCAV, and mean arterial pressure (MAP) via finger plethysmography during the trials were compared with baseline eupneic values. For each hyperoxic hypercapnic trial, the change (Δ) in MCAV for a corresponding change in end-tidal CO2 and the HCVD or the change in cerebral vascular conductance (MCAV divided by MAP) for a corresponding change in end-tidal CO2 was determined. The hypercapnic ventilatory response was similar between the age groups, as was ΔMCAV/Δ[Formula: see text]. However, compared with young, older adults had a significantly smaller HCVD (1.3 ± 0.7 vs. 2.1 ± 0.6 units/mmHg, P = 0.004). Multivariable analyses demonstrated that age and nadir oxygen saturation during nocturnal polysomnography were significant predictors of HCVD. Thus, our data indicate that older age and SDB-related hypoxia are associated with diminished HCVD. We hypothesize that this impairment in vascular function may contribute to breathing instability during sleep in these individuals.NEW & NOTEWORTHY This study demonstrates, for the first time, in individuals with sleep-disordered breathing (SDB) that aging is associated with decreased hypercapnia-induced cerebral vasodilation (HCVD). In addition to advanced age, the magnitude of nocturnal oxygen desaturation due to SDB is an equal independent predictor of HCVD.
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Affiliation(s)
- R. Rastogi
- 1Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan,2Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - B. J. Morgan
- 3Department of Orthopedics and Rehabilitation, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin
| | - M. S. Badr
- 1Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan,2Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
| | - S. Chowdhuri
- 1Medical Service, Sleep Medicine Section, John D. Dingell Veterans Affairs Medical Center, Detroit, Michigan,2Division of Pulmonary/Critical Care and Sleep Medicine, Department of Medicine, Wayne State University School of Medicine, Detroit, Michigan
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15
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Dempsey JA, Neder JA, Phillips DB, O'Donnell DE. The physiology and pathophysiology of exercise hyperpnea. HANDBOOK OF CLINICAL NEUROLOGY 2022; 188:201-232. [PMID: 35965027 DOI: 10.1016/b978-0-323-91534-2.00001-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
In health, the near-eucapnic, highly efficient hyperpnea during mild-to-moderate intensity exercise is driven by three obligatory contributions, namely, feedforward central command from supra-medullary locomotor centers, feedback from limb muscle afferents, and respiratory CO2 exchange (V̇CO2). Inhibiting each of these stimuli during exercise elicits a reduction in hyperpnea even in the continuing presence of the other major stimuli. However, the relative contribution of each stimulus to the hyperpnea remains unknown as does the means by which V̇CO2 is sensed. Mediation of the hyperventilatory response to exercise in health is attributed to the multiple feedback and feedforward stimuli resulting from muscle fatigue. In patients with COPD, diaphragm EMG amplitude and its relation to ventilatory output are used to decipher mechanisms underlying the patients' abnormal ventilatory responses, dynamic lung hyperinflation and dyspnea during exercise. Key contributions to these exercise-limiting responses across the spectrum of COPD severity include high dead space ventilation, an excessive neural drive to breathe and highly fatigable limb muscles, together with mechanical constraints on ventilation. Major controversies concerning control of exercise hyperpnea are discussed along with the need for innovative research to uncover the link of metabolism to breathing in health and disease.
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Affiliation(s)
- Jerome A Dempsey
- John Rankin Laboratory of Pulmonary Medicine, Department of Population Health Sciences, University of Wisconsin-Madison, Madison, WI, United States.
| | - J Alberto Neder
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Devin B Phillips
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre Kingston General Hospital Campus, Kingston, ON, Canada
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16
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Hu WH, Khoo MCK. Treatment of Cheyne-Stokes Respiration in Heart Failure with Adaptive Servo-Ventilation: An Integrative Model. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2022; 1384:79-103. [PMID: 36217080 DOI: 10.1007/978-3-031-06413-5_6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The SERVE-HF (Treatment of Predominant Central Sleep Apnea by Adaptive Servo Ventilation in Patients with Heart Failure) multicenter trial found a small but significant increase in all-cause and cardiovascular mortality in patients assigned to adaptive servo-ventilation (ASV) versus guideline-based medical treatment. To better understand the physiological underpinnings of this clinical outcome, we employ an integrative computer model to simulate congestive heart failure with Cheyne-Stokes respiration (CHF-CSR) in subjects with a broad spectrum of underlying pathogenetic mechanisms, as well as to determine the in silico changes in cardiopulmonary and autonomic physiology resulting from ASV. Our simulation results demonstrate that while the elimination of CSR through ASV can partially restore cardiorespiratory and autonomic physiology toward normality in the vast majority of CHF phenotypes, the degree of restoration can be highly variable, depending on the combination of CHF mechanisms in play. The group with the lowest left ventricular ejection fraction (LVEF) appears to be most vulnerable to the potentially adverse effects of ASV, but the level of pulmonary capillary wedge pressure (PCWP) plays an important role in determining the nature of these effects.
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17
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LoMauro A, Aliverti A. Sex and gender in respiratory physiology. Eur Respir Rev 2021; 30:30/162/210038. [PMID: 34750114 DOI: 10.1183/16000617.0038-2021] [Citation(s) in RCA: 21] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 06/08/2021] [Indexed: 11/05/2022] Open
Abstract
Sex is a biological concept determined at conception. Gender is a social concept. Medicine recognises sex as a biological variable and recommends including sex as a factor in clinical practice norms and as a topic of bench and clinical research. Sex plays a role in respiratory physiology according to two pathways: hormones and anatomy, with females characterised by smaller dimensions at every level of the respiratory system. Sex hormones also play specific roles in lung inflammatory processes, breathing control and in response to diseases. The literature is extremely controversial because many factors need to be considered to avoid erroneous comparisons. The main difficulty lies in creating homogeneous groups of subjects according to age, body weight, lung/airway size, fluctuations in circulating hormone levels, and exercise protocol. Because almost all of the knowledge available in physiology is based on research in males, medicine for women is therefore less evidence-based than that being applied to men. Finally, the number of transsexual people is increasing and they represent new challenges for clinicians, due to the anatomical and physiological changes that they undergo.
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Affiliation(s)
- Antonella LoMauro
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
| | - Andrea Aliverti
- Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milan, Italy
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18
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Stewart JM, Pianosi PT. Postural orthostatic tachycardia syndrome: A respiratory disorder? Curr Res Physiol 2021; 4:1-6. [PMID: 34746821 PMCID: PMC8562237 DOI: 10.1016/j.crphys.2021.01.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 01/12/2021] [Accepted: 01/13/2021] [Indexed: 11/28/2022] Open
Abstract
Postural orthostatic tachycardia syndrome (POTS) is a disorder epitomized by the story of the blind men and the elephant. Patients may see primary care internists or pediatricians due to fatigue, be referred to neurologists for “spells”, to cardiologists for evaluation of pre-syncope or chest pain, to gastroenterologists for nausea or dyspepsia, and even pulmonologists for dyspnea. Adoption of a more systematic approach to their evaluation and better characterization of patients has led to greater understanding of comorbidities, hypotheses prompting mechanistic investigations, and pharmacologic trials. Recent work has implicated disordered sympathetic nervous system activation in response to central (thoracic) hypovolemia. It is this pathway that leads one zero in on a putative focal point from which many of the clinical manifestations can be explained – specifically the carotid body. Despite heterogeneity in etiopathogenesis of a POTS phenotype, we propose that aberrant activation and response of the carotid body represents one potential common pathway in evolution. To understand this postulate, one must jettison isolationist or reductionist ideas of chemoreceptor and baroreceptor functions of the carotid body or sinus, respectively, and consider their interaction and interdependence both locally and centrally where some of its efferents merge. Doing so enables one to connect the dots and appreciate origins of diverse manifestations of POTS, including dyspnea for which the concept of neuro-mechanical uncoupling is wanting, thereby expanding our construct of this symptom. This perspective expounds our premise that POTS has a prominent respiratory component. Dyspnea affects ~⅓ patients with postural orthostatic tachycardia syndrome (POTS). POTS is characterized by thoracic hypovolemia and compromised cephalad perfusion when upright. Carotid body and adjacent carotid sinus mediate chemo- and baro- reflexes, respectively. These are not independent and stimulation of either activates sympathetic discharge. We speculate that carotid body mediates hyperventilation and dyspnea in POTS.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, NY, USA.,Department of Physiology, New York Medical College, Valhalla, NY, USA
| | - Paolo T Pianosi
- Department of Pediatrics, Division of Pulmonary & Sleep Medicine, University of Minnesota, VCRC, 401 E River Parkway Rm 413, Minneapolis, UK
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19
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Naeije R, Richter MJ, Rubin LJ. The physiologic basis of pulmonary arterial hypertension. Eur Respir J 2021; 59:13993003.02334-2021. [PMID: 34737219 PMCID: PMC9203839 DOI: 10.1183/13993003.02334-2021] [Citation(s) in RCA: 42] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2021] [Accepted: 10/18/2021] [Indexed: 11/05/2022]
Abstract
Pulmonary arterial hypertension (PAH) is a rare dyspnea-fatigue syndrome caused by a progressive increase in pulmonary vascular resistance (PVR) and eventual right ventricular (RV) failure. In spite of extensive pulmonary vascular remodeling, lung function in PAH is generally well preserved, with hyperventilation and increased physiologic dead space, but minimal changes in lung mechanics and only mild to moderate hypoxemia and hypocapnia. Hypoxemia is mainly caused by a low mixed venous PO2 from a decreased cardiac output. Hypocapnia is mainly caused by an increased chemosensitivity. Exercise limitation in PAH is cardiovascular rather than ventilatory or muscular. The extent of pulmonary vascular disease in PAH is defined by multipoint pulmonary vascular pressure-flow relationships with a correction for hematocrit. Pulsatile pulmonary vascular pressure-flow relationships in PAH allow for the assessment of RV hydraulic load. This analysis is possible either in the frequency-domain or in the time-domain. The RV in PAH adapts to increased afterload by an increased contractility to preserve its coupling to the pulmonary circulation. When this homeometric mechanism is exhausted, the RV dilates to preserve flow output by an additional heterometric mechanism. Right heart failure is then diagnosed by imaging of increased right heart dimensions and clinical systemic congestion signs and symptoms. The coupling of the RV to the pulmonary circulation is assessed by the ratio of end-systolic to arterial elastances, but these measurements are difficult. Simplified estimates of RV-PA coupling can be obtained by magnetic resonance or echocardiographic imaging of ejection fraction.
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Affiliation(s)
| | - Manuel J Richter
- Department of Internal Medicine, Justus Liebig-University, Universities of Giessen and Marburg Lung Center (UGMLC), Giessen, Germany
| | - Lewis J Rubin
- University of California, San Diego, La Jolla, CA, USA
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20
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Ulland TK, Ewald AC, Knutson AO, Marino KM, Smith SMC, Watters JJ. Alzheimer's Disease, Sleep Disordered Breathing, and Microglia: Puzzling out a Common Link. Cells 2021; 10:2907. [PMID: 34831129 PMCID: PMC8616348 DOI: 10.3390/cells10112907] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 10/22/2021] [Accepted: 10/24/2021] [Indexed: 12/14/2022] Open
Abstract
Sleep Disordered Breathing (SDB) and Alzheimer's Disease (AD) are strongly associated clinically, but it is unknown if they are mechanistically associated. Here, we review data covering both the cellular and molecular responses in SDB and AD with an emphasis on the overlapping neuroimmune responses in both diseases. We extensively discuss the use of animal models of both diseases and their relative utilities in modeling human disease. Data presented here from mice exposed to intermittent hypoxia indicate that microglia become more activated following exposure to hypoxia. This also supports the idea that intermittent hypoxia can activate the neuroimmune system in a manner like that seen in AD. Finally, we highlight similarities in the cellular and neuroimmune responses between SDB and AD and propose that these similarities may lead to a pathological synergy between SDB and AD.
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Affiliation(s)
- Tyler K. Ulland
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison, Madison, WI 53705, USA; (T.K.U.); (K.M.M.)
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI 53705, USA
| | - Andrea C. Ewald
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
| | - Andrew O. Knutson
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
| | - Kaitlyn M. Marino
- Department of Pathology and Laboratory Medicine, University of Wisconsin Madison, Madison, WI 53705, USA; (T.K.U.); (K.M.M.)
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI 53705, USA
| | - Stephanie M. C. Smith
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
| | - Jyoti J. Watters
- Neuroscience Training Program, University of Wisconsin Madison, Madison, WI 53705, USA
- Department of Comparative Biosciences, University of Wisconsin Madison, Madison, WI 53706, USA; (A.C.E.); (A.O.K.); (S.M.C.S.)
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21
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ATS Core Curriculum 2021. Adult Sleep Medicine: Sleep Apnea. ATS Sch 2021; 2:484-496. [PMID: 34667995 PMCID: PMC8518657 DOI: 10.34197/ats-scholar.2021-0027re] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2021] [Accepted: 05/19/2021] [Indexed: 11/18/2022] Open
Abstract
The American Thoracic Society Sleep Core Curriculum updates clinicians on important sleep topics, presented during the annual meeting, and appearing in summary here. This year’s sleep core theme is sleep-disordered breathing and its management. Topics range from pathophysiological mechanisms for the association of obstructive sleep apnea (OSA) and metabolic syndrome, surgical modalities of OSA treatment, comorbid insomnia and OSA, central sleep apnea, and sleep practices during a pandemic. OSA has been associated with metabolic syndrome, independent of the role of obesity, and the pathophysiology suggests a role for sleep fragmentation and intermittent hypoxia in observed metabolic outcomes. In specific patient populations, surgical treatment modalities for OSA have demonstrated large reductions in objective disease severity compared with no treatment and may facilitate adherence to positive airway pressure treatment. Patient-centered approaches to comorbid insomnia and sleep apnea include evaluating for both OSA and insomnia simultaneously and using shared-decision making to determine the order and timing of positive airway pressure therapy and cognitive behavioral therapy for insomnia. The pathophysiology of central sleep apnea is complex and may be due to the loss of drive to breathe or instability in the regulatory pathways that control ventilation. Pandemic-era sleep practices have evolved rapidly to balance safety and sustainability of care for patients with sleep-disordered breathing.
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22
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DelRosso LM, Panek D, Redding G, Mogavero MP, Ruth C, Sheldon N, Blazier H, Strong C, Samson M, Fickenscher A, Ferri R. Obstructive Apnea and Hypopnea Length in Normal Children and Adolescents. Brain Sci 2021; 11:brainsci11101343. [PMID: 34679407 PMCID: PMC8534270 DOI: 10.3390/brainsci11101343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2021] [Revised: 10/05/2021] [Accepted: 10/09/2021] [Indexed: 11/16/2022] Open
Abstract
(1) Background: Breathing is an essential function that requires both metabolic (or au-tomatic) and voluntary (behavioral) control during wakefulness but during sleep depends on metabolic control via peripheral and central chemoreceptors. Breathing during sleep disordered breathing also depends on the maturity of the neural centers and the strength of the respiratory muscles. We do not know if the response to apnea varies with age. (2) Methods: We measured the obstructive apneas and hypopneas during REM and NREM in polysomnography studies from children referred for snoring. Exclusion criteria: younger than 1 year of age, neuromuscular or syndrome comorbidity, oxygen or positive airway pressure, central apnea, and studies with loss of airflow sensors. (3) Results: Two-hundred-and-sixty-eight sleep studies were included. Mean age was 8.7 years (4.68 SD), range 1–18 years, 160 were male, and 108 were female. The 5th centile of apnea duration during NREM is above 8 s at all ages, with a tendency to increase in the oldest groups up to 10 s. During REM sleep, it shows a gradual increase from 6 s in the youngest children to 10 s in the oldest. (4) Conclusions: Apnea/hypopnea length increases with age in children and adolescents independently from sex or severity of OSA. Using adult criteria in teens seems to be accurate.
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Affiliation(s)
- Lourdes M. DelRosso
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
- Correspondence: ; Tel.: +1-206-987-2174
| | - David Panek
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Greg Redding
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Maria Paola Mogavero
- Istituti Clinici Scientifici Maugeri, IRCCS, Scientific Institute of Pavia, Via Salvatore Maugeri 4, 27100 Pavia, Italy;
| | - Chris Ruth
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Nicole Sheldon
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Holly Blazier
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Candace Strong
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Maria Samson
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Amy Fickenscher
- Division of Pulmonary and Sleep Medicine, Seattle Children’s Hospital, 4800 Sand Point Way, Seattle, WA 98105, USA; (D.P.); (G.R.); (C.R.); (N.S.); (H.B.); (C.S.); (M.S.); (A.F.)
| | - Raffaele Ferri
- Sleep Research Centre, Oasi Research Institute—IRCCS, Via C. Ruggero 73, 94018 Troina, Italy;
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23
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Neder JA, Berton DC, Phillips DB, O'Donnell DE. Exertional ventilation/carbon dioxide output relationship in COPD: from physiological mechanisms to clinical applications. Eur Respir Rev 2021; 30:30/161/200190. [PMID: 34526312 PMCID: PMC9489189 DOI: 10.1183/16000617.0190-2020] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2020] [Accepted: 09/30/2020] [Indexed: 01/09/2023] Open
Abstract
There is well established evidence that the minute ventilation (V′E)/carbon dioxide output (V′CO2) relationship is relevant to a number of patient-related outcomes in COPD. In most circumstances, an increased V′E/V′CO2 reflects an enlarged physiological dead space (“wasted” ventilation), although alveolar hyperventilation (largely due to increased chemosensitivity) may play an adjunct role, particularly in patients with coexistent cardiovascular disease. The V′E/V′CO2 nadir, in particular, has been found to be an important predictor of dyspnoea and poor exercise tolerance, even in patients with largely preserved forced expiratory volume in 1 s. As the disease progresses, a high nadir might help to unravel the cause of disproportionate breathlessness. When analysed in association with measurements of dynamic inspiratory constraints, a high V′E/V′CO2 is valuable to ascertain a role for the “lungs” in limiting dyspnoeic patients. Regardless of disease severity, cardiocirculatory (heart failure and pulmonary hypertension) and respiratory (lung fibrosis) comorbidities can further increase V′E/V′CO2. A high V′E/V′CO2 is a predictor of poor outcome in lung resection surgery, adding value to resting lung hyperinflation in predicting all-cause and respiratory mortality across the spectrum of disease severity. Considering its potential usefulness, the V′E/V′CO2 should be valued in the clinical management of patients with COPD. The minute ventilation/carbon dioxide production relationship is relevant to a number of patient-related outcomes in COPD. Minute ventilation/carbon dioxide production, therefore, should be valued in the clinical management of these patients.https://bit.ly/3df2upH
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Affiliation(s)
- J Alberto Neder
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Danilo C Berton
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada.,Division of Respiratory Medicine, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Devin B Phillips
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Denis E O'Donnell
- Respiratory Investigation Unit and Laboratory of Clinical Exercise Physiology, Queen's University and Kingston General Hospital, Kingston, ON, Canada
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24
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Caviedes I. Ventilatory inefficiency: a key physiopathological mechanism increasing dyspnea and reducing exercise capacity in chronic obstructive pulmonary disease. J Thorac Dis 2021; 13:4614-4617. [PMID: 34422386 PMCID: PMC8339755 DOI: 10.21037/jtd-21-834] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2021] [Accepted: 06/14/2021] [Indexed: 11/08/2022]
Affiliation(s)
- Iván Caviedes
- Servicio de Enfermedades Respiratorias, Clínica Alemana de Santiago, Chile.,Facultad de Medicina, Clínica Alemana - Universidad del Desarrollo, Santiago, Chile
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25
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Iturriaga R, Alcayaga J, Chapleau MW, Somers VK. Carotid body chemoreceptors: physiology, pathology, and implications for health and disease. Physiol Rev 2021; 101:1177-1235. [PMID: 33570461 PMCID: PMC8526340 DOI: 10.1152/physrev.00039.2019] [Citation(s) in RCA: 69] [Impact Index Per Article: 23.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The carotid body (CB) is the main peripheral chemoreceptor for arterial respiratory gases O2 and CO2 and pH, eliciting reflex ventilatory, cardiovascular, and humoral responses to maintain homeostasis. This review examines the fundamental biology underlying CB chemoreceptor function, its contribution to integrated physiological responses, and its role in maintaining health and potentiating disease. Emphasis is placed on 1) transduction mechanisms in chemoreceptor (type I) cells, highlighting the role played by the hypoxic inhibition of O2-dependent K+ channels and mitochondrial oxidative metabolism, and their modification by intracellular molecules and other ion channels; 2) synaptic mechanisms linking type I cells and petrosal nerve terminals, focusing on the role played by the main proposed transmitters and modulatory gases, and the participation of glial cells in regulation of the chemosensory process; 3) integrated reflex responses to CB activation, emphasizing that the responses differ dramatically depending on the nature of the physiological, pathological, or environmental challenges, and the interactions of the chemoreceptor reflex with other reflexes in optimizing oxygen delivery to the tissues; and 4) the contribution of enhanced CB chemosensory discharge to autonomic and cardiorespiratory pathophysiology in obstructive sleep apnea, congestive heart failure, resistant hypertension, and metabolic diseases and how modulation of enhanced CB reactivity in disease conditions may attenuate pathophysiology.
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Affiliation(s)
- Rodrigo Iturriaga
- Laboratorio de Neurobiología, Facultad de Ciencias Biológicas, Pontificia Universidad Católica de Chile, Santiago, Chile, and Centro de Excelencia en Biomedicina de Magallanes, Universidad de Magallanes, Punta Arenas, Chile
| | - Julio Alcayaga
- Laboratorio de Fisiología Celular, Facultad de Ciencias, Universidad de Chile, Santiago, Chile
| | - Mark W Chapleau
- Department of Internal Medicine, University of Iowa and Department of Veterans Affairs Medical Center, Iowa City, Iowa
| | - Virend K Somers
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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26
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Pavšič K, Fabjan A, Zgonc V, Šurlan Popović K, Pretnar Oblak J, Bajrović FF. Clinical and Radiological Characteristics Associated with Respiratory Failure in Unilateral Lateral Medullary Infarction. J Stroke Cerebrovasc Dis 2021; 30:105947. [PMID: 34192618 DOI: 10.1016/j.jstrokecerebrovasdis.2021.105947] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2021] [Revised: 06/01/2021] [Accepted: 06/05/2021] [Indexed: 10/21/2022] Open
Abstract
BACKGROUND The prognosis for unilateral lateral medullary infarction (ULMI) is generally good but may be aggravated by respiratory failure with fatal outcome. Respiratory failure has been reported in patients with severe bulbar dysfunction and large rostral medullary lesions, but its associated factors have not been systematically studied. We aimed to assess clinical and radiological characteristics associated with respiratory failure in patients with pure acute ULMI. MATERIALS AND METHODS Seventy-one patients (median age 55 years, 59 males) with MRI-confirmed acute pure ULMI were studied retrospectively. Clinical characteristics were assessed and bulbar symptoms were scored using a scale developed for this study. MRI lesions were classified into 4 groups based on their vertical extent (localized/extensive) and the involvement of the open and/or closed medulla. Clinical characteristics, bulbar scores and MRI lesion characteristics were compared between patients with and without respiratory failure. RESULTS Respiratory failure occurred in 8(11%) patients. All patients with respiratory failure were male (p = 0.336), had extensive lesions involving the open medulla (p = 0.061), progression of bulbar symptoms (p=0.002) and aspiration pneumonia (p < 0.001). Peak bulbar score (OR, 7.9 [95% CI, 2.3-160.0]; p < 0.001) and older age (OR, 1.2 [95%CI, 1.0-1.6]; p=0.006) were independently associated with respiratory failure. CONCLUSIONS Extensive damage involving the open/rostral medulla, clinically presenting with severe bulbar dysfunction, in conjunction with factors such as aspiration pneumonia and older age appears to be crucial for the development of respiratory failure in pure ULMI. Further prospective studies are needed to identify other potential risk factors, pathophysiology, and effective preventive measures for respiratory failure in these patients.
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Affiliation(s)
- Katja Pavšič
- Department of Vascular Neurology and Intensive Therapy, University Medical Centre Ljubljana, Slovenia; Faculty of Medicine, University of Ljubljana, Slovenia.
| | - Andrej Fabjan
- Department of Vascular Neurology and Intensive Therapy, University Medical Centre Ljubljana, Slovenia; Institute of Physiology, Faculty of Medicine, University of Ljubljana, Slovenia
| | - Vid Zgonc
- Department of Vascular Neurology and Intensive Therapy, University Medical Centre Ljubljana, Slovenia
| | | | - Janja Pretnar Oblak
- Department of Vascular Neurology and Intensive Therapy, University Medical Centre Ljubljana, Slovenia; Faculty of Medicine, University of Ljubljana, Slovenia
| | - Fajko F Bajrović
- Department of Vascular Neurology and Intensive Therapy, University Medical Centre Ljubljana, Slovenia; Institute of Pathophysiology, Faculty of Medicine, University of Ljubljana, Slovenia
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27
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Neder JA, de Torres JP, O'Donnell DE. Recent Advances in the Physiological Assessment of Dyspneic Patients with Mild COPD. COPD 2021; 18:374-384. [PMID: 33902376 DOI: 10.1080/15412555.2021.1913110] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
There is growing recognition that a sizable fraction of COPD patients with forced expiratory volume in one second (FEV1)/forced vital capacity ratio below the lower limit of normal but preserved FEV1 reports out-of-proportion dyspnea relative to the severity of airflow limitation. Most physicians, however, assume that patients' breathlessness is unlikely to reflect the negative physiological consequences of COPD vis-à-vis FEV1 normalcy. This concise review integrates the findings of recent studies which uncovered the key pathophysiological features shared by these patients: poor pulmonary gas exchange efficiency (increased "wasted" ventilation) and gas trapping. These abnormalities are associated with two well-known causes of exertional dyspnea: heightened ventilation relative to metabolic demand and critically low inspiratory reserves, respectively. From a clinical standpoint, a low diffusion capacity associated with increased residual volume (RV) and/or RV/total lung capacity ratio might uncover these disturbances, identifying the subset of patients in whom exertional dyspnea is causally related to "mild" COPD.
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Affiliation(s)
- J Alberto Neder
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada
| | - Juan P de Torres
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada
| | - Denis E O'Donnell
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Division of Respirology, Department of Medicine, Queen's University & Kingston General Hospital, Kingston, ON, Canada
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28
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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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29
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Phillips DB, Domnik NJ, Elbehairy AF, Preston ME, Milne KM, James MD, Vincent SG, Ibrahim-Masthan M, Neder JA, O’Donnell DE. Elevated exercise ventilation in mild COPD is not linked to enhanced central chemosensitivity. Respir Physiol Neurobiol 2021; 284:103571. [DOI: 10.1016/j.resp.2020.103571] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2020] [Revised: 10/27/2020] [Accepted: 11/01/2020] [Indexed: 11/25/2022]
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30
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Abstract
In cardiopulmonary medicine, residual exertional dyspnea (RED) can be defined by the persistence of limiting breathlessness in a patient who is already under the best available therapy for the underlying heart and/or lung disease. RED is a challenge to the pulmonologist because the patient (and the referring physician) assumes that the "lung doctor" should invariably provide a successful plan to fight the symptom. After presenting a simplified framework to understand the neurobiological underpinnings of dyspnea in cardiorespiratory disease, I discuss the seeds of RED associated with 1) increased metabolic cost of work, 2) increased inspiratory constraints, 3) diaphragm dysfunction, 4) impaired right ventricle preload, 5) increased central and/or peripheral chemosensitivity, 6) increased physiological dead space, 7) increased pulmonary venous and/or high left ventricle filling pressures, 8) impaired chronotropic response to exertion, and 9) increased activation of the cortical-limbic circuits. I finalize by outlining the following two common coexistence of diseases in which these multiple mechanisms interact to produce severe RED: chronic obstructive pulmonary disease-heart failure with reduced ejection fraction and chronic pulmonary fibrosis-emphysema. RED exposes the important limitations of the current reductionist approach focused only on the (over)treatment of the poorly reversible cardiopulmonary disease(s). Conversely, recognizing the existence of RED sets the stage for a more holistic approach toward one of the most devastating symptoms known to man.
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31
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Moreira TS, Sobrinho CR, Falquetto B, Oliveira LM, Lima JD, Mulkey DK, Takakura AC. The retrotrapezoid nucleus and the neuromodulation of breathing. J Neurophysiol 2020; 125:699-719. [PMID: 33427575 DOI: 10.1152/jn.00497.2020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Breathing is regulated by a host of arousal and sleep-wake state-dependent neuromodulators to maintain respiratory homeostasis. Modulators such as acetylcholine, norepinephrine, histamine, serotonin (5-HT), adenosine triphosphate (ATP), substance P, somatostatin, bombesin, orexin, and leptin can serve complementary or off-setting functions depending on the target cell type and signaling mechanisms engaged. Abnormalities in any of these modulatory mechanisms can destabilize breathing, suggesting that modulatory mechanisms are not overly redundant but rather work in concert to maintain stable respiratory output. The present review focuses on the modulation of a specific cluster of neurons located in the ventral medullary surface, named retrotrapezoid nucleus, that are activated by changes in tissue CO2/H+ and regulate several aspects of breathing, including inspiration and active expiration.
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Affiliation(s)
- Thiago S Moreira
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Cleyton R Sobrinho
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Barbara Falquetto
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Luiz M Oliveira
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Janayna D Lima
- Department of Physiology and Biophysics, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
| | - Daniel K Mulkey
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, Connecticut
| | - Ana C Takakura
- Department of Pharmacology, Instituto de Ciencias Biomedicas, Universidade de Sao Paulo (USP), São Paulo, Brazil
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32
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Iepsen UW, Ryrsø CK, Rugbjerg M, Secher NH, Barbosa TC, Lange P, Thaning P, Pedersen BK, Mortensen SP, Fadel PJ. Cardiorespiratory responses to high-intensity skeletal muscle metaboreflex activation in chronic obstructive pulmonary disease. Clin Physiol Funct Imaging 2020; 41:146-155. [PMID: 33159389 DOI: 10.1111/cpf.12678] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2020] [Revised: 10/08/2020] [Accepted: 11/04/2020] [Indexed: 11/29/2022]
Abstract
BACKGROUND Augmented skeletal muscle metaboreflex activation may accompany chronic obstructive pulmonary disease (COPD). The maintained metaboreflex control of mean arterial pressure (MAP) that has been reported may reflect limited evaluation using only one moderate bout of static handgrip (HG) and following postexercise ischaemia (PEI). OBJECTIVE We tested the hypothesis that cardiovascular and respiratory responses to high-intensity static HG and isolated metaboreflex activation during PEI are augmented in COPD patients. METHODS Ten patients with moderate to severe COPD and eight healthy age- and BMI-matched controls performed two-minute static HG at moderate (30% maximal voluntary contraction; MVC) and high (40% MVC) intensity followed by PEI. RESULTS Despite similar ratings of perceived exertion, arm muscle mass and strength, COPD patients demonstrated lower MAP responses during both HG intensities compared with controls (time × group interaction, p < .05). Indeed, during high-intensity HG at 40% MVC, peak MAP responses were significantly lower in COPD patients (ΔMAP: COPD 41 ± 9 mmHg vs. controls 56 ± 14 mmHg, p < .05). Notably, no group differences in MAP were observed during PEI (e.g. 40% MVC PEI: ΔMAP COPD 33 ± 9 mmHg vs. controls 33 ± 6 mmHg, p > .05). We found no between-group differences in heart rate, respiratory rate, or estimated minute ventilation during HG or PEI. CONCLUSION These results suggest that the pressor response to high-intensity HG is blunted in COPD patients. Moreover, despite inducing a strong cardiovascular and respiratory stimulus, skeletal muscle metaboreflex activation evoked similar responses in COPD patients and controls.
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Affiliation(s)
- Ulrik Winning Iepsen
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Camilla Koch Ryrsø
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Mette Rugbjerg
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Niels H Secher
- Department of Anaesthesiology, Institute of Clinical Medicine, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | | | - Peter Lange
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Medical Department O, Respiratory Section, Herlev and Gentofte Hospital, Herlev, Denmark.,Department of Public Health, Section of Epidemiology, University of Copenhagen, Copenhagen, Denmark
| | - Pia Thaning
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Respiratory Medicine, University Hospital Hvidovre, Hvidovre, Denmark
| | - Bente K Pedersen
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Sefan P Mortensen
- Centre of Inflammation and Metabolism and The Centre for Physical Activity Research, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark.,Department of Cardiovascular and Renal Research, University of Southern Denmark, Odense, Denmark
| | - Paul J Fadel
- Department of Kinesiology, University of Texas at Arlington, Arlington, TX, USA
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33
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Shi J, Al-Shamli N, Chiang J, Amin R. Management of Rare Causes of Pediatric Chronic Respiratory Failure. Sleep Med Clin 2020; 15:511-526. [PMID: 33131661 DOI: 10.1016/j.jsmc.2020.07.002] [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] [Indexed: 12/19/2022]
Abstract
The need for long-term noninvasive positive pressure ventilation (NiPPV) in children with chronic respiratory failure is rapidly growing. This article reviews pediatric-specific considerations of NiPPV therapy. Indications for NiPPV therapy can be categorized by the cause of the respiratory failure: (1) upper airway obstruction, (2) musculoskeletal and/or neuromuscular disease, (3) lower respiratory tract diseases, and (4) control of breathing abnormalities. The role of NiPPV therapy in select rare conditions (spinal muscular atrophy, congenital central hypoventilation syndrome, cerebral palsy, scoliosis, and Chiari malformations) is also reviewed.
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Affiliation(s)
- Jenny Shi
- The Division of Respiratory Medicine, Department of Pediatrics, The Hospital for Sick Children, 4539 Hill Wing, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; The University of Toronto, Toronto, Ontario, Canada
| | - Nawal Al-Shamli
- The Division of Respiratory Medicine, Department of Pediatrics, The Hospital for Sick Children, 4539 Hill Wing, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; The University of Toronto, Toronto, Ontario, Canada
| | - Jackie Chiang
- The Division of Respiratory Medicine, Department of Pediatrics, The Hospital for Sick Children, 4539 Hill Wing, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; The University of Toronto, Toronto, Ontario, Canada
| | - Reshma Amin
- The Division of Respiratory Medicine, Department of Pediatrics, The Hospital for Sick Children, 4539 Hill Wing, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada; The University of Toronto, Toronto, Ontario, Canada.
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34
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Wan HY, Weavil JC, Thurston TS, Georgescu VP, Bledsoe AD, Jessop JE, Buys MJ, Richardson RS, Amann M. The muscle reflex and chemoreflex interaction: ventilatory implications for the exercising human. J Appl Physiol (1985) 2020; 129:691-700. [PMID: 32816637 DOI: 10.1152/japplphysiol.00449.2020] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
We examined the interactive influence of the muscle reflex (MR) and the chemoreflex (CR) on the ventilatory response to exercise. Eleven healthy subjects (5 women/6 men) completed three bouts of constant-load single-leg knee-extension exercise in a control trial and an identical trial conducted with lumbar intrathecal fentanyl to attenuate neural feedback from lower-limb group III/IV muscle afferents. The exercise during the two trials was performed while breathing ambient air ([Formula: see text] ~97%, [Formula: see text]~84 mmHg, [Formula: see text] ~32 mmHg, pH ~7.39), or under normocapnic hypoxia ([Formula: see text] ~79%, [Formula: see text] ~43 mmHg, [Formula: see text] ~33 mmHg, pH ~7.39) or normoxic hypercapnia ([Formula: see text] ~98%, [Formula: see text] ~105 mmHg, [Formula: see text] ~50 mmHg, pH ~7.26). During coactivation of the MR and the hypoxia-induced CR (O2-CR), minute ventilation (V̇e) and tidal volume (VT) were significantly greater compared with the sum of the responses to the activation of each reflex alone; there was no difference between the observed and summated responses in terms of breathing frequency (fB; P = 0.4). During coactivation of the MR and the hypercapnia-induced CR (CO2-CR), the observed ventilatory responses were similar to the summated responses of the reflexes (P ≥ 0.1). Therefore, the interaction between the MR and the O2-CR exerts a hyperadditive effect on V̇e and VT and an additive effect on fB, whereas the interaction between the MR and the CO2-CR is simply additive for all ventilatory parameters. These findings reveal that the MR:CR interaction further augments the ventilatory response to exercise in hypoxia.NEW & NOTEWORTHY Although the muscle reflex and the chemoreflex are recognized as independent feedback mechanisms regulating breathing during exercise, the ventilatory implications resulting from their interaction remain unclear. We quantified the individual and interactive effects of these reflexes during exercise and revealed differential modes of interaction. Importantly, the reflex interaction further amplifies the ventilatory response to exercise under hypoxemic conditions, highlighting a potential mechanism for optimizing arterial oxygenation in physically active humans at high altitude.
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Affiliation(s)
- Hsuan-Yu Wan
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Joshua C Weavil
- Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Utah
| | - Taylor S Thurston
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Vincent P Georgescu
- Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah
| | - Amber D Bledsoe
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Jacob E Jessop
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Michael J Buys
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah
| | - Russell S Richardson
- Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah
| | - Markus Amann
- Department of Anesthesiology, University of Utah, Salt Lake City, Utah.,Geriatric Research, Education, and Clinical Center, Salt Lake City Veterans Affairs Medical Center, Utah.,Department of Nutrition and Integrative Physiology, University of Utah, Salt Lake City, Utah.,Department of Internal Medicine, University of Utah, Salt Lake City, Utah
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35
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Dhont S, Derom E, Van Braeckel E, Depuydt P, Lambrecht BN. The pathophysiology of 'happy' hypoxemia in COVID-19. Respir Res 2020; 21:198. [PMID: 32723327 PMCID: PMC7385717 DOI: 10.1186/s12931-020-01462-5] [Citation(s) in RCA: 282] [Impact Index Per Article: 70.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2020] [Accepted: 07/21/2020] [Indexed: 12/20/2022] Open
Abstract
The novel coronavirus disease 2019 (COVID-19) pandemic is a global crisis, challenging healthcare systems worldwide. Many patients present with a remarkable disconnect in rest between profound hypoxemia yet without proportional signs of respiratory distress (i.e. happy hypoxemia) and rapid deterioration can occur. This particular clinical presentation in COVID-19 patients contrasts with the experience of physicians usually treating critically ill patients in respiratory failure and ensuring timely referral to the intensive care unit can, therefore, be challenging. A thorough understanding of the pathophysiological determinants of respiratory drive and hypoxemia may promote a more complete comprehension of a patient's clinical presentation and management. Preserved oxygen saturation despite low partial pressure of oxygen in arterial blood samples occur, due to leftward shift of the oxyhemoglobin dissociation curve induced by hypoxemia-driven hyperventilation as well as possible direct viral interactions with hemoglobin. Ventilation-perfusion mismatch, ranging from shunts to alveolar dead space ventilation, is the central hallmark and offers various therapeutic targets.
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Affiliation(s)
- Sebastiaan Dhont
- Department of Internal Medicine and Paediatrics, Ghent University, Corneel Heymanslaan 10, 9000, Ghent, Belgium.
| | - Eric Derom
- Department of Internal Medicine and Paediatrics, Ghent University, Corneel Heymanslaan 10, 9000, Ghent, Belgium
- Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Eva Van Braeckel
- Department of Internal Medicine and Paediatrics, Ghent University, Corneel Heymanslaan 10, 9000, Ghent, Belgium
- Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
| | - Pieter Depuydt
- Department of Internal Medicine and Paediatrics, Ghent University, Corneel Heymanslaan 10, 9000, Ghent, Belgium
- Department of Intensive Care Medicine, Ghent University Hospital, Ghent, Belgium
| | - Bart N Lambrecht
- Department of Internal Medicine and Paediatrics, Ghent University, Corneel Heymanslaan 10, 9000, Ghent, Belgium
- Department of Respiratory Medicine, Ghent University Hospital, Ghent, Belgium
- VIB-UGent Center for Inflammation Research, Ghent, Belgium
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Orr JE, Wallace MS, Malhotra A. Might chronic opioid use impact sleep-disordered breathing and vice versa? J Clin Sleep Med 2020; 16:843-845. [PMID: 32317097 PMCID: PMC7849661 DOI: 10.5664/jcsm.8500] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 04/15/2020] [Accepted: 04/15/2020] [Indexed: 11/13/2022]
Abstract
Orr JE, Wallace MS, Malhotra A. Might chronic opioid use impact sleep-disordered breathing and vice versa? J Clin Sleep Med . 2020;16(6):843–845.
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Affiliation(s)
- Jeremy E. Orr
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California, San Diego, La Jolla, California
| | - Mark S. Wallace
- Division of Pain Medicine, University of California, San Diego, La Jolla, California
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, and Sleep Medicine, University of California, San Diego, La Jolla, California
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Castro RR, Sales ARK, Nóbrega AC. Lifestyle interventions reduce exercise ventilatory variability in healthy individuals: a randomized intervention study. Future Cardiol 2020; 16:439-446. [PMID: 32323560 DOI: 10.2217/fca-2019-0070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: Variation of exercise ventilation confers poor prognosis in heart failure. Sedentary men have higher exercise ventilatory variability than athletes. However, the impact of lifestyle intervention on exercise ventilatory variability in sedentary people is unknown and this is the aim of this study. Materials & methods: Prospective controlled single-blinded interventional study that randomly assigned healthy sedentary individuals to diet and exercise (intervention group, n = 12) or no intervention (control group, n = 12) for 12 weeks. Exercise ventilatory variability was accessed before and after intervention. Results: Despite similar values at baseline, there was a 15% reduction in respiratory rate variability (root mean square of the successive differences/n) in intervention group. Conclusion: Diet and exercise training reduced exercise ventilatory variability.
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Affiliation(s)
- Renata Rt Castro
- Medicine School, Iguaçu University, Nova Iguaçu, Brazil.,Hospital Naval Marcílio Dias, Marinha do Brasil, Rio de Janeiro, Brazil
| | - Allan Robson Kluser Sales
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil.,D'Or Institute for Research and Education, São Paulo, Brazil
| | - Antonio Cl Nóbrega
- Department of Physiology and Pharmacology, Fluminense Federal University, Niterói, Brazil
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Takken T, Sonbahar Ulu H, Hulzebos EHJ. Clinical recommendations for cardiopulmonary exercise testing in children with respiratory diseases. Expert Rev Respir Med 2020; 14:691-701. [PMID: 32252564 DOI: 10.1080/17476348.2020.1752195] [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] [Indexed: 10/24/2022]
Abstract
INTRODUCTION Cardiopulmonary exercise testing (CPET) quantitates and qualitates the integrated physiological response of a person to incremental exercise and provides additional information compared to static lung function tests alone. AREAS COVERED This review covers rationale for the use of CPET parameters beyond the usual parameters like peak oxygen uptake and peak minute ventilation in children with respiratory disease. EXPERT OPINION CPET provides a wealth of data from rest, submaximal and maximal exercise and data during recovery from exercise. In this review, an interpretative approach is described for analyzing CPET data in children with respiratory disease.
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Affiliation(s)
- Tim Takken
- Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht , Utrecht, The Netherlands
| | - Hazal Sonbahar Ulu
- Faculty of Physical Therapy and Rehabilitation, Hacettepe University , Samanpazari/Ankara, Turkey
| | - Erik H J Hulzebos
- Child Development & Exercise Center, Wilhelmina Children's Hospital, University Medical Center Utrecht , Utrecht, The Netherlands
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Prospective study of sleep-disordered breathing in 28 patients with acute unilateral lateral medullary infarction. Sleep Breath 2020; 24:1557-1563. [DOI: 10.1007/s11325-020-02031-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 12/22/2019] [Accepted: 02/05/2020] [Indexed: 12/14/2022]
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Hasler ED, Saxer S, Schneider SR, Furian M, Lichtblau M, Schwarz EI, Bloch KE, Ulrich S. Effect of Breathing Oxygen-Enriched Air on Exercise Performance in Patients with Chronic Obstructive Pulmonary Disease: Randomized, Placebo-Controlled, Cross-Over Trial. Respiration 2020; 99:213-224. [PMID: 32050198 DOI: 10.1159/000505819] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2019] [Accepted: 01/06/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Patients with chronic obstructive pulmonary disease (COPD) experience dyspnea and hypoxemia during exercise. OBJECTIVE The aim of this study was to evaluate the effects of breathing oxygen-enriched air on exercise performance and associated physiological changes in patients with COPD. METHODS In a randomized, placebo-controlled, single-blind, cross-over trial, 20 patients with COPD (11 women, age 65 ± 6 years, FEV1 64 ± 19% pred., resting SpO2 ≥90%) performed 4 cycle ergospirometries to exhaustion using an incremental exercise test (IET) and a constant work rate (at 75% maximal workload with air) exercise test (CWRET), each with ambient (FiO2 0.21) and oxygen-enriched (FiO2 0.5) air. The main outcomes were the change in maximal workload in the IET and the change in exercise duration in the CWRET with oxygen versus air. Electrocardiogram, pulmonary gas exchange, thoracic volumes by inductance plethysmography, arterial blood gases, and cerebral and quadriceps muscle tissue oxygenation (CTO and MTO) were additionally measured. RESULTS In the IET, maximal workload increased from 96 ± 21 to 104 ± 28 W with oxygen. In the CWRET, exercise duration increased from 605 ± 274 to 963 ± 444 s with oxygen. At end-exercise with oxygen, CTO, MTO, PaO2, and PaCO2 were increased, while V'E/V'CO2 was reduced and thoracic volumes were similar. At the corresponding time to end of exercise with ambient air, oxygen decreased heart rate, respiratory rate, minute ventilation, and V'E/V'CO2, while oxygenation was increased. CONCLUSION In COPD patients without resting hypoxemia, breathing oxygen-enriched air improves exercise performance. This relates to a higher arterial oxygen saturation promoting oxygen availability to muscle and cerebral tissue and an enhanced ventilatory efficiency. COPD patients may benefit from oxygen therapy during exercise training.
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Affiliation(s)
| | - Stéphanie Saxer
- Pulmonary Clinic, University Hospital Zurich, Zurich, Switzerland
| | | | - Michael Furian
- Pulmonary Clinic, University Hospital Zurich, Zurich, Switzerland
| | - Mona Lichtblau
- Pulmonary Clinic, University Hospital Zurich, Zurich, Switzerland
| | | | - Konrad E Bloch
- Pulmonary Clinic, University Hospital Zurich and Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland
| | - Silvia Ulrich
- Pulmonary Clinic, University Hospital Zurich and Centre for Integrative Human Physiology, University of Zurich, Zurich, Switzerland,
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Orr JE, Schmickl CN, Edwards BA, DeYoung PN, Brena R, Sun XS, Jain S, Malhotra A, Owens RL. Pathogenesis of obstructive sleep apnea in individuals with the COPD + OSA Overlap syndrome versus OSA alone. Physiol Rep 2020; 8:e14371. [PMID: 32061194 PMCID: PMC7023887 DOI: 10.14814/phy2.14371] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2020] [Accepted: 01/11/2020] [Indexed: 02/02/2023] Open
Abstract
Overlap syndrome (OVS) is the concurrence of chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), and is associated with poor outcomes. We hypothesized that physiological changes in COPD may affect the pathogenesis of OSA in important ways. We therefore sought to measure the anatomical and nonanatomical OSA traits in individuals with OVS and compare to those with OSA alone. Patients with established OVS were recruited, along with age, gender, and BMI matched OSA only controls. Smoking and relevant comorbidities or medications were excluded. Subjects underwent baseline polysomnography followed by an overnight physiological research study to measure the OSA traits (Veupnea , Varousal , Vpassive , Vactive , and loop gain). Fifteen subjects with OVS and 15 matched controls with OSA alone were studied (overall 66 ± 8 years, 20% women, BMI 31 ± 4 kg/m2 , apnea-hypopnea index 49 ± 36/hr). Mixed-modeling was used to incorporate each measurement (range 52-270 measures/trait), and account for age, gender, and BMI. There were no significant differences in the traits between OVS and OSA subjects, although OVS subjects potentially tolerated a lower ventilation before arousal (i.e., harder to wake; p = .06). Worsened lung function was significantly associated with worsened upper airway response and more unstable breathing (p < .05 for all). Consistent differences in key OSA traits were not observed between OVS and OSA alone. However, worse lung function does appear to exert an influence on several OSA traits. These findings indicate that a diagnosis of OVS should not generally influence the approach to OSA, but that lung function might be considered if utilizing OSA trait-specific treatment.
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Affiliation(s)
- Jeremy E. Orr
- Division of Pulmonary, Critical Care, and Sleep MedicineUniversity of California San DiegoLa JollaCAUSA
| | - Christopher N. Schmickl
- Division of Pulmonary, Critical Care, and Sleep MedicineUniversity of California San DiegoLa JollaCAUSA
| | - Bradley A. Edwards
- Sleep and Circadian Medicine LaboratoryDepartment of PhysiologyMonash UniversityMelbourneVICAustralia
- Turner Institute for Brain and Mental HealthMonash UniversityMelbourneVICAustralia
| | - Pamela N. DeYoung
- Division of Pulmonary, Critical Care, and Sleep MedicineUniversity of California San DiegoLa JollaCAUSA
| | - Rebbecca Brena
- Division of Pulmonary, Critical Care, and Sleep MedicineUniversity of California San DiegoLa JollaCAUSA
| | - Xiaoying S. Sun
- Division of Biostatistics and BioinformaticsDepartment of Family Medicine and Public HealthUniversity of California San DiegoLa JollaCAUSA
| | - Sonia Jain
- Division of Biostatistics and BioinformaticsDepartment of Family Medicine and Public HealthUniversity of California San DiegoLa JollaCAUSA
| | - Atul Malhotra
- Division of Pulmonary, Critical Care, and Sleep MedicineUniversity of California San DiegoLa JollaCAUSA
| | - Robert L. Owens
- Division of Pulmonary, Critical Care, and Sleep MedicineUniversity of California San DiegoLa JollaCAUSA
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Vaporidi K, Akoumianaki E, Telias I, Goligher EC, Brochard L, Georgopoulos D. Respiratory Drive in Critically Ill Patients. Pathophysiology and Clinical Implications. Am J Respir Crit Care Med 2020; 201:20-32. [DOI: 10.1164/rccm.201903-0596so] [Citation(s) in RCA: 97] [Impact Index Per Article: 24.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Affiliation(s)
- Katerina Vaporidi
- Department of Intensive Care Medicine, University Hospital of Heraklion, Medical School University of Crete, Heraklion, Greece
| | - Evangelia Akoumianaki
- Department of Intensive Care Medicine, University Hospital of Heraklion, Medical School University of Crete, Heraklion, Greece
| | - Irene Telias
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Center and Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - Ewan C. Goligher
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
- Department of Medicine, University Health Network, Toronto, Ontario, Canada; and
- Toronto General Hospital Research Institute, Toronto, Ontario, Canada
| | - Laurent Brochard
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada
- Keenan Research Center and Li Ka Shing Knowledge Institute, St. Michael’s Hospital, Toronto, Ontario, Canada
| | - Dimitris Georgopoulos
- Department of Intensive Care Medicine, University Hospital of Heraklion, Medical School University of Crete, Heraklion, Greece
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Moore PE, Boyer D, Perkins R, Katz ES, Castro-Codesal ML, MacLean JE, Akil N, Esther CR, Kaslow J, Lewis TC, Krone KA, Quizon A, Simpson R, Benscoter D, Spielberg DR, Melicoff E, Kuklinski CA, Blatter JA, Dy J, Rettig JS, Horani A, Gross J. American Thoracic Society 2019 Pediatric Core Curriculum. Pediatr Pulmonol 2019; 54:1880-1894. [PMID: 31456278 DOI: 10.1002/ppul.24482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 08/04/2019] [Indexed: 11/07/2022]
Abstract
The American Thoracic Society Pediatric Core Curriculum updates clinicians annually in pediatric pulmonary disease in a 3 to 4 year recurring cycle of topics. The 2019 course was presented in May during the Annual International Conference. An American Board of Pediatrics Maintenance of Certification module and a continuing medical education exercise covering the contents of the Core Curriculum can be accessed online at www.thoracic.org.
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Affiliation(s)
- Paul E Moore
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Debra Boyer
- Division of Respiratory Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Ryan Perkins
- Division of Respiratory Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Eliot S Katz
- Division of Respiratory Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Maria L Castro-Codesal
- Division of Pediatric Respirology, Pulmonary, and Asthma, Department of Pediatrics, University of Alberta, Alberta, Canada
| | - Joanna E MacLean
- Division of Pediatric Respirology, Pulmonary, and Asthma, Department of Pediatrics, University of Alberta, Alberta, Canada
| | - Nour Akil
- Division of Pediatric Pulmonology, Department of Pediatrics, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Charles R Esther
- Division of Pediatric Pulmonology, Department of Pediatrics, University of North Carolina School of Medicine, Chapel Hill, North Carolina
| | - Jacob Kaslow
- Department of Pediatrics, Vanderbilt University Medical Center, Nashville, Tennessee
| | - Toby C Lewis
- Department of Pediatrics, University of Michigan Medical School, Ann Harbor, Michigan
| | - Katie A Krone
- Division of Respiratory Diseases, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Annabelle Quizon
- Division of Pediatric Pulmonology, Rady Children's Hospital, University of California San Diego, San Diego, California
| | - Ryne Simpson
- Division of Pulmonary Medicine, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - Dan Benscoter
- Division of Pulmonary Medicine, Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, Ohio
| | - David R Spielberg
- Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Ernestina Melicoff
- Department of Pediatrics, Texas Children's Hospital, Baylor College of Medicine, Houston, Texas
| | - Cadence A Kuklinski
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Joshua A Blatter
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Jamie Dy
- Department of Pediatrics, UCSF, San Francisco, California
| | - Jordan S Rettig
- Department of Anesthesiology, Perioperative and Pain Medicine, Division of Critical Care Medicine, Boston Children's Hospital, Harvard Medical School, Boston, Massachusetts
| | - Amjad Horani
- Department of Pediatrics, Washington University School of Medicine, St. Louis, Missouri
| | - Jane Gross
- Division of Pediatric Pulmonary Medicine, Department of Pediatrics, National Jewish Hospital, Denver, Colorado
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Plachi F, Balzan FM, Fröhlich LF, Gass R, Mendes NB, Schroeder E, Berton DC, O'Donnell DE, Neder JA. Exertional dyspnoea–ventilation relationship to discriminate respiratory from cardiac impairment. Eur Respir J 2019; 55:13993003.01518-2019. [DOI: 10.1183/13993003.01518-2019] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/11/2019] [Indexed: 12/20/2022]
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de la Motte T, Schwab M, Schultze T, Witte OW, Rupprecht S. An 82-Year-Old Man With Sleep-Onset Insomnia, Breathing Arrest, and Heart Failure. Chest 2019; 156:e95-e98. [PMID: 31699235 DOI: 10.1016/j.chest.2019.05.044] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2019] [Revised: 05/15/2019] [Accepted: 05/27/2019] [Indexed: 11/17/2022] Open
Abstract
CASE PRESENTATION An 82-year-old man presented with 6 months of difficulties of falling asleep. He described a feeling of fading breath culminating in breathing arrest when he becomes drowsy. These recurrent events prevented him from falling asleep. Symptoms would only appear when he went to sleep but not during wakefulness. Medical history comprised several episodes of acute decompensated heart failure due to supraventricular tachyarrhythmia with need for hospitalization during the last 2 years. He additionally had two-vessel coronary artery disease with myocardial infarction, pulmonary hypertension, chronic atrial fibrillation, peripheral arterial disease, and chronic kidney disease (stage 3). Medication included diuretics, sodium bicarbonate, angiotensin II receptor antagonist, beta-blocker, statin, clopidogrel, and phenprocoumon without sedatives or analgesics.
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Affiliation(s)
- Torben de la Motte
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany; Interdisciplinary Centre for Sleep and Ventilatory Medicine, Jena University Hospital, Jena, Germany
| | - Matthias Schwab
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany; Interdisciplinary Centre for Sleep and Ventilatory Medicine, Jena University Hospital, Jena, Germany
| | - Torsten Schultze
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany; Interdisciplinary Centre for Sleep and Ventilatory Medicine, Jena University Hospital, Jena, Germany
| | - Otto W Witte
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany
| | - Sven Rupprecht
- Hans Berger Department of Neurology, Jena University Hospital, Jena, Germany; Interdisciplinary Centre for Sleep and Ventilatory Medicine, Jena University Hospital, Jena, Germany; Research Programme "Else Kröner-Forschungskolleg AntiAge", Jena University Hospital, Jena, Germany.
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Phillips DB, Collins SÉ, Bryan TL, Wong EYL, McMurtry MS, Bhutani M, Stickland MK. The effect of carotid chemoreceptor inhibition on exercise tolerance in chronic obstructive pulmonary disease: A randomized-controlled crossover trial. Respir Med 2019; 160:105815. [PMID: 31739245 DOI: 10.1016/j.rmed.2019.105815] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Revised: 10/24/2019] [Accepted: 11/05/2019] [Indexed: 11/19/2022]
Abstract
BACKGROUND Patients with chronic obstructive pulmonary disease (COPD) have an exaggerated ventilatory response to exercise, contributing to exertional dyspnea and exercise intolerance. We recently demonstrated enhanced activity and sensitivity of the carotid chemoreceptor (CC) in COPD which may alter ventilatory and cardiovascular regulation and negatively affect exercise tolerance. We sought to determine whether CC inhibition improves ventilatory and cardiovascular regulation, dyspnea and exercise tolerance in COPD. METHODS Twelve mild-moderate COPD patients (FEV1 83 ± 15 %predicted) and twelve age- and sex-matched healthy controls completed two time-to-symptom limitation (TLIM) constant load exercise tests at 75% peak power output with either intravenous saline or low-dose dopamine (2 μg·kg-1·min-1, order randomized) to inhibit the CC. Ventilatory responses were evaluated using expired gas data and dyspnea was evaluated using a modified Borg scale. Inspiratory capacity maneuvers were performed to determine operating lung volumes. Cardiac output was estimated using impedance cardiography and vascular conductance was calculated as cardiac output/mean arterial pressure (MAP). RESULTS At a standardized exercise time of 4-min and at TLIM; ventilation, operating volumes and dyspnea were unaffected by dopamine in COPD patients and controls. In COPD, dopamine decreased MAP and increased vascular conductance at all time points. In controls, dopamine increased vascular conductance at TLIM, while MAP was unaffected. CONCLUSION There was no change in time to exhaustion in either group with dopamine. These data suggest that the CC plays a role in cardiovascular regulation during exercise in COPD; however, ventilation, dyspnea and exercise tolerance were unaffected by CC inhibition in COPD patients.
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Affiliation(s)
- Devin B Phillips
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada; Faculty of Kinesiology, Sport, and Recreation, University of Alberta, Canada
| | - Sophie É Collins
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada; Faculty of Rehabilitation Medicine, University of Alberta, Canada
| | - Tracey L Bryan
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada
| | - Eric Y L Wong
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada
| | - M Sean McMurtry
- Division of Cardiology, Faculty of Medicine and Dentistry, University of Alberta, Canada
| | - Mohit Bhutani
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada
| | - Michael K Stickland
- Division of Pulmonary Medicine, Faculty of Medicine and Dentistry, University of Alberta, Canada; G.F. MacDonald Centre for Lung Health, Covenant Health, Edmonton, Alberta, Canada.
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Jung B, Martinez M, Claessens YE, Darmon M, Klouche K, Lautrette A, Levraut J, Maury E, Oberlin M, Terzi N, Viglino D, Yordanov Y, Claret PG, Bigé N. Diagnostic et Prise en Charge de l’Acidose Métabolique Recommandations formalisées d’experts communes Société de réanimation de langue française (SRLF) – Société française de médecine d’urgence (SFMU). ANNALES FRANCAISES DE MEDECINE D URGENCE 2019. [DOI: 10.3166/afmu-2019-0162] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
L’acidose métabolique est un trouble fréquemment rencontré en médecine d’urgence et en médecine intensive réanimation. La littérature s’étant enrichie de nouvelles données concernant la prise en charge de l’acidose métabolique, la Société de Réanimation de Langue Française (SRLF) et la Société Française de Médecine d’Urgence (SFMU) ont élaboré des recommandations formalisées d’experts selon la méthodologie GRADE. Les champs de la stratégie diagnostique, de l’orientation et de la prise en charge thérapeutique ont été traités et vingt-neuf recommandations ont été formulées : quatre recommandations fortes (Grade 1), dix recommandations faibles (Grade 2) et quinze avis d’experts. Toutes ont obtenu un accord fort. L’application des méthodes d’Henderson-Hasselbalch et de Stewart pour le diagnostic du mécanisme de l’acidose métabolique est discutée et un algorithme diagnostique est proposé. L’utilisation de la cétonémie et des lactatémies veineuse et capillaire est également traitée. L’intérêt du pH, de la lactatémie et de sa cinétique pour l’orientation des patients en pré-hospitalier et aux urgences est envisagé. Enfin, les modalités de l’insulinothérapie au cours de l’acidocétose diabétique, les indications de la perfusion de bicarbonate de sodium et de l’épuration extra-rénale ainsi que les modalités de la ventilation mécanique au cours des acidoses métaboliques sévères sont traitées dans la prise en charge thérapeutique.
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Costa CM, Neder JA, Verrastro CG, Paula-Ribeiro M, Ramos R, Ferreira EM, Nery LE, O'Donnell DE, Pereira CAC, Ota-Arakaki J. Uncovering the mechanisms of exertional dyspnoea in combined pulmonary fibrosis and emphysema. Eur Respir J 2019; 55:13993003.01319-2019. [PMID: 31649067 DOI: 10.1183/13993003.01319-2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2019] [Accepted: 10/12/2019] [Indexed: 01/19/2023]
Abstract
The prevailing view is that exertional dyspnoea in patients with combined idiopathic pulmonary fibrosis (IPF) and emphysema (CPFE) can be largely explained by severe hypoxaemia. However, there is little evidence to support these assumptions.We prospectively contrasted the sensory and physiological responses to exercise in 42 CPFE and 16 IPF patients matched by the severity of exertional hypoxaemia. Emphysema and pulmonary fibrosis were quantified using computed tomography. Inspiratory constraints were assessed in a constant work rate test: capillary blood gases were obtained in a subset of patients.CPFE patients had lower exercise capacity despite less extensive fibrosis compared to IPF (p=0.004 and 0.02, respectively). Exertional dyspnoea was the key limiting symptom in 24 CPFE patients who showed significantly lower transfer factor, arterial carbon dioxide tension and ventilatory efficiency (higher minute ventilation (V'E)/carbon dioxide output (V'CO2 ) ratio) compared to those with less dyspnoea. However, there were no between-group differences in the likelihood of pulmonary hypertension by echocardiography (p=0.44). High dead space/tidal volume ratio, low capillary carbon dioxide tension emphysema severity (including admixed emphysema) and traction bronchiectasis were related to a high V'E/V'CO2 ratio in the more dyspnoeic group. V'E/V'CO2 nadir >50 (OR 9.43, 95% CI 5.28-13.6; p=0.0001) and total emphysema extent >15% (2.25, 1.28-3.54; p=0.01) predicted a high dyspnoea burden associated with severely reduced exercise capacity in CPFEContrary to current understanding, hypoxaemia per se is not the main determinant of exertional dyspnoea in CPFE. Poor ventilatory efficiency due to increased "wasted" ventilation in emphysematous areas and hyperventilation holds a key mechanistic role that deserves therapeutic attention.
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Affiliation(s)
- Camila M Costa
- Pulmonary Vascular Disease and Interstitial Lung Disease Services, Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - J Alberto Neder
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | | | - Marcelle Paula-Ribeiro
- Pulmonary Vascular Disease and Interstitial Lung Disease Services, Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Roberta Ramos
- Pulmonary Vascular Disease and Interstitial Lung Disease Services, Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Eloara M Ferreira
- Pulmonary Vascular Disease and Interstitial Lung Disease Services, Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Luiz E Nery
- Pulmonary Vascular Disease and Interstitial Lung Disease Services, Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Denis E O'Donnell
- Laboratory of Clinical Exercise Physiology and Respiratory Investigation Unit, Queen's University and Kingston General Hospital, Kingston, ON, Canada
| | - Carlos A C Pereira
- Pulmonary Vascular Disease and Interstitial Lung Disease Services, Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Jaquelina Ota-Arakaki
- Pulmonary Vascular Disease and Interstitial Lung Disease Services, Division of Respirology, Federal University of Sao Paulo, Sao Paulo, Brazil
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Elbehairy AF, O'Donnell CD, Abd Elhameed A, Vincent SG, Milne KM, James MD, Webb KA, Neder JA, O’Donnell DE. Low resting diffusion capacity, dyspnea, and exercise intolerance in chronic obstructive pulmonary disease. J Appl Physiol (1985) 2019; 127:1107-1116. [DOI: 10.1152/japplphysiol.00341.2019] [Citation(s) in RCA: 29] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The mechanisms linking reduced diffusing capacity of the lung for carbon monoxide (DlCO) to dyspnea and exercise intolerance across the chronic obstructive pulmonary disease (COPD) continuum are poorly understood. COPD progression generally involves both DlCO decline and worsening respiratory mechanics, and their relative contribution to dyspnea has not been determined. In a retrospective analysis of 300 COPD patients who completed symptom-limited incremental cardiopulmonary exercise tests, we tested the association between peak oxygen-uptake (V̇o2), DlCO, and other resting physiological measures. Then, we stratified the sample into tertiles of forced expiratory volume in 1 s (FEV1) and inspiratory capacity (IC) and compared dyspnea ratings, pulmonary gas exchange, and respiratory mechanics during exercise in groups with normal and low DlCO [i.e., <lower limit of normal (LLN)] using Global Lung Function Initiative reference values. DlCO was associated with peak V̇o2 ( P = 0.006), peak work-rate ( P = 0.005), and dyspnea/V̇o2 slope ( P < 0.001) after adjustment for other independent variables (airway obstruction and hyperinflation). Within FEV1 and IC tertiles, peak V̇o2 and work rate were lower ( P < 0.05) in low versus normal DlCO groups. Across all tertiles, low DlCO groups had higher dyspnea ratings, greater ventilatory inefficiency and arterial oxygen desaturation, and showed greater mechanical volume constraints at a lower ventilation during exercise than the normal DlCO group (all P < 0.05). After accounting for baseline resting respiratory mechanical abnormalities, DlCO<LLN was consistently associated with greater dyspnea and poorer exercise performance compared with preserved DlCO. The higher dyspnea ratings and earlier exercise termination in low DlCO groups were linked to significantly greater pulmonary gas exchange abnormalities, higher ventilatory demand, and associated accelerated dynamic mechanical constraints. NEW & NOTEWORTHY Our study demonstrated that chronic obstructive pulmonary disease patients with diffusing capacity of the lung for carbon monoxide (DlCO) less than the lower limit of normal had greater pulmonary gas exchange abnormalities, which resulted in higher ventilatory demand and greater dynamic mechanical constraints at lower ventilation during exercise. This, in turn, led to greater exertional dyspnea and exercise intolerance compared with patients with normal DlCO.
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Affiliation(s)
- Amany F. Elbehairy
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Department of Chest Diseases, Faculty of Medicine, Alexandria University, Alexandria, Egypt
| | - Conor D. O'Donnell
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Asmaa Abd Elhameed
- Department of Biomedical Informatics and Medical Statistics, Medical Research Institute, Alexandria University, Alexandria, Egypt
| | - Sandra G. Vincent
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Kathryn M. Milne
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
- Clinician Investigator Program, Department of Medicine, University of British Columbia, Vancouver, Canada
| | - Matthew D. James
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Katherine A. Webb
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - J. Alberto Neder
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
| | - Denis E. O’Donnell
- Department of Medicine and Queen’s University and Kingston Health Sciences Centre, Kingston, Ontario, Canada
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Neder JA, Berton DC, O'Donnell DE. Why we should never ignore an "isolated" low lung diffusing capacity. ACTA ACUST UNITED AC 2019; 45:e20190241. [PMID: 31508675 PMCID: PMC6733732 DOI: 10.1590/1806-3713/e20190241] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Affiliation(s)
- José Alberto Neder
- . Pulmonary Function Laboratory and Respiratory Investigation Unit, Division of Respirology and Sleep Medicine, Kingston Health Science Center & Queen's University, Kingston (ON) Canada
| | - Danilo Cortozi Berton
- . Unidade de Fisiologia Pulmonar, Hospital de Clínicas de Porto Alegre, Universidade Federal do Rio Grande do Sul, Porto Alegre (RS) Brasil
| | - Denis E O'Donnell
- . Pulmonary Function Laboratory and Respiratory Investigation Unit, Division of Respirology and Sleep Medicine, Kingston Health Science Center & Queen's University, Kingston (ON) Canada
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