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Coiffard B, Dianti J, Telias I, Brochard LJ, Slutsky AS, Beck J, Sinderby C, Ferguson ND, Goligher EC. Dyssynchronous diaphragm contractions impair diaphragm function in mechanically ventilated patients. Crit Care 2024; 28:107. [PMID: 38566126 PMCID: PMC10988824 DOI: 10.1186/s13054-024-04894-3] [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: 01/31/2024] [Accepted: 03/27/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Pre-clinical studies suggest that dyssynchronous diaphragm contractions during mechanical ventilation may cause acute diaphragm dysfunction. We aimed to describe the variability in diaphragm contractile loading conditions during mechanical ventilation and to establish whether dyssynchronous diaphragm contractions are associated with the development of impaired diaphragm dysfunction. METHODS In patients receiving invasive mechanical ventilation for pneumonia, septic shock, acute respiratory distress syndrome, or acute brain injury, airway flow and pressure and diaphragm electrical activity (Edi) were recorded hourly around the clock for up to 7 days. Dyssynchronous post-inspiratory diaphragm loading was defined based on the duration of neural inspiration after expiratory cycling of the ventilator. Diaphragm function was assessed on a daily basis by neuromuscular coupling (NMC, the ratio of transdiaphragmatic pressure to diaphragm electrical activity). RESULTS A total of 4508 hourly recordings were collected in 45 patients. Edi was low or absent (≤ 5 µV) in 51% of study hours (median 71 h per patient, interquartile range 39-101 h). Dyssynchronous post-inspiratory loading was present in 13% of study hours (median 7 h per patient, interquartile range 2-22 h). The probability of dyssynchronous post-inspiratory loading was increased with reverse triggering (odds ratio 15, 95% CI 8-35) and premature cycling (odds ratio 8, 95% CI 6-10). The duration and magnitude of dyssynchronous post-inspiratory loading were associated with a progressive decline in diaphragm NMC (p < 0.01 for interaction with time). CONCLUSIONS Dyssynchronous diaphragm contractions may impair diaphragm function during mechanical ventilation. TRIAL REGISTRATION MYOTRAUMA, ClinicalTrials.gov NCT03108118. Registered 04 April 2017 (retrospectively registered).
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Affiliation(s)
- Benjamin Coiffard
- Department of Respiratory Medicine, Aix-Marseille University, APHM, Hôpital Nord, Marseille, France
| | - Jose Dianti
- Division of Respirology, Department of Medicine, University Health Network, Toronto, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
| | - Irene Telias
- Division of Respirology, Department of Medicine, University Health Network, Toronto, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
| | - Laurent J Brochard
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
| | - Arthur S Slutsky
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
| | - Jennifer Beck
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
- University of Toronto, Toronto, Canada
| | - Christer Sinderby
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
- Keenan Centre for Biomedical Research, Li Ka Shing Knowledge Institute, St. Michael's Hospital, Toronto, Canada
- University of Toronto, Toronto, Canada
| | - Niall D Ferguson
- Division of Respirology, Department of Medicine, University Health Network, Toronto, Canada
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada
- Toronto General Hospital Research Institute, 585 University Ave., 9-MaRS-9024, Toronto, ON, M5G 2N2, Canada
- Department of Physiology, University of Toronto, Toronto, Canada
- Institute for Health Policy, Management, and Evaluation, University of Toronto, Toronto, Canada
| | - Ewan C Goligher
- Division of Respirology, Department of Medicine, University Health Network, Toronto, Canada.
- Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Canada.
- Toronto General Hospital Research Institute, 585 University Ave., 9-MaRS-9024, Toronto, ON, M5G 2N2, Canada.
- Department of Physiology, University of Toronto, Toronto, Canada.
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2
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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
| | -
- Respiratory Investigation Unit, Department of Medicine, Queen's University and Kingston Health Sciences Centre, Kingston, ON, Canada
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3
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Domnik NJ, Walsted ES, Langer D. Clinical Utility of Measuring Inspiratory Neural Drive During Cardiopulmonary Exercise Testing (CPET). Front Med (Lausanne) 2020; 7:483. [PMID: 33043023 PMCID: PMC7530180 DOI: 10.3389/fmed.2020.00483] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Accepted: 07/16/2020] [Indexed: 12/18/2022] Open
Abstract
Cardiopulmonary exercise testing (CPET) has traditionally included ventilatory and metabolic measurements alongside electrocardiographic characterization; however, research increasingly acknowledges the utility of also measuring inspiratory neural drive (IND) through its surrogate measure of diaphragmatic electromyography (EMGdi). While true IND also encompasses the activation of non-diaphragmatic respiratory muscles, the current review focuses on diaphragmatic measurements, providing information about additional inspiratory muscle groups for context where appropriate. Evaluation of IND provides mechanistic insight into the origins of dyspnea and exercise limitation across pathologies; yields valuable information reflecting the integration of diverse mechanical, chemical, locomotor, and metabolic afferent signals; and can help assess the efficacy of therapeutic interventions. Further, IND measurement during the physiologic stress of exercise is uniquely poised to reveal the underpinnings of physiologic limitations masked during resting and unloaded breathing, with important information provided not only at peak exercise, but throughout exercise protocols. As our understanding of IND presentation across varying conditions continues to grow and methods for its measurement become more accessible, the translation of these principles into clinical settings is a logical next step in facilitating appropriate and nuanced management tailored to each individual's unique physiology. This review provides an overview of the current state of understanding of IND measurement during CPET: its origins, known patterns of behavior and links with dyspnea in health and major respiratory diseases, and the possibility of expanding this approach to applications beyond exercise.
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Affiliation(s)
| | - Emil S. Walsted
- Respiratory Research Unit, Bispebjerg University Hospital, Copenhagen, Denmark
| | - Daniel Langer
- Research Group for Rehabilitation in Internal Disorders, Respiratory Rehabilitation and Respiratory Division, Department of Rehabilitation Sciences, University Hospital Leuven, KU Leuven, Leuven, Belgium
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4
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Laghi F, Shaikh H, Littleton SW, Morales D, Jubran A, Tobin MJ. Inhibition of central activation of the diaphragm: a mechanism of weaning failure. J Appl Physiol (1985) 2020; 129:366-376. [PMID: 32673161 PMCID: PMC7473953 DOI: 10.1152/japplphysiol.00856.2019] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
During a T-tube trial following disconnection of mechanical ventilation, patients failing the trial do not develop contractile diaphragmatic fatigue despite increases in inspiratory pressure output. Studies in volunteers, patients, and animals raise the possibility of spinal and supraspinal reflex mechanisms that inhibit central-neural output under loaded conditions. We hypothesized that diaphragmatic recruitment is submaximal at the end of a failed weaning trial despite concurrent respiratory distress. Tidal transdiaphragmatic pressure (ΔPdi) and electrical activity (ΔEAdi) were recorded with esophago-gastric catheters during a T-tube trial in 20 critically ill patients. During the T-tube trial, ∆EAdi was greater in weaning failure patients than in weaning success patients (P = 0.049). Despite increases in ΔPdi, from 18.1 ± 2.5 to 25.9 ± 3.7 cm H2O (P < 0.001), rate of transdiaphragmatic pressure development (from 22.6 ± 3.1 to 37.8 ± 6.7 cm H2O/s; P < 0.0004), and concurrent respiratory distress, ∆EAdi at the end of a failed T-tube trial was half of maximum, signifying inhibition of central neural output to the diaphragm. The increase in ΔPdi in the weaning failure group, while ∆EAdi remained constant, indicates unexpected improvement in diaphragmatic neuromuscular coupling (from 46.7 ± 6.5 to 57.8 ± 8.4 cm H2O/%; P = 0.006). Redistribution of neural output to the respiratory muscles characterized by a progressive increase in rib cage and accessory muscle contribution to tidal breathing and expiratory muscle recruitment contributed to enhanced coupling. In conclusion, diaphragmatic recruitment is submaximal at the end of a failed weaning trial despite concurrent respiratory distress. This finding signifies that reflex inhibition of central neural output to the diaphragm contributes to weaning failure. NEW & NOTEWORTHY Research into pathophysiology of failure to wean from mechanical ventilation has excluded several factors, including contractile fatigue, but the precise mechanism remains unknown. We recorded transdiaphragmatic pressure and diaphragmatic electrical activity in patients undergoing a T-tube trial. Diaphragmatic recruitment was submaximal at the end of a failed trial despite concurrent respiratory distress, signifying that inhibition of central neural output to the diaphragm is an important mechanism of weaning failure.
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Affiliation(s)
- Franco Laghi
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital, Hines, Illinois.,Division of Pulmonary and Critical Care Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
| | - Hameeda Shaikh
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital, Hines, Illinois.,Division of Pulmonary and Critical Care Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
| | - Stephen W Littleton
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital, Hines, Illinois.,Division of Pulmonary and Critical Care Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
| | - Daniel Morales
- Division of Pulmonary and Critical Care Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
| | - Amal Jubran
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital, Hines, Illinois.,Division of Pulmonary and Critical Care Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
| | - Martin J Tobin
- Division of Pulmonary and Critical Care Medicine, Hines Veterans Affairs Hospital, Hines, Illinois.,Division of Pulmonary and Critical Care Medicine, Loyola University Chicago Stritch School of Medicine, Maywood, Illinois
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5
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Ramsook AH, Mitchell RA, Guenette JA. Reply to: Assessment of 'neural respiratory drive' from the parasternal intercostal muscles. Respir Physiol Neurobiol 2018; 259:173-175. [PMID: 30096376 DOI: 10.1016/j.resp.2018.08.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2018] [Accepted: 08/06/2018] [Indexed: 10/28/2022]
Affiliation(s)
- Andrew H Ramsook
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, BC, Canada; Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada
| | - Reid A Mitchell
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, BC, Canada; Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada
| | - Jordan A Guenette
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, BC, Canada; Department of Physical Therapy, University of British Columbia, Vancouver, BC, Canada.
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6
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Ramsook AH, Molgat-Seon Y, Schaeffer MR, Wilkie SS, Camp PG, Reid WD, Romer LM, Guenette JA. Effects of inspiratory muscle training on respiratory muscle electromyography and dyspnea during exercise in healthy men. J Appl Physiol (1985) 2017; 122:1267-1275. [PMID: 28255085 DOI: 10.1152/japplphysiol.00046.2017] [Citation(s) in RCA: 45] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Revised: 02/13/2017] [Accepted: 02/26/2017] [Indexed: 11/22/2022] Open
Abstract
Inspiratory muscle training (IMT) has consistently been shown to reduce exertional dyspnea in health and disease; however, the physiological mechanisms remain poorly understood. A growing body of literature suggests that dyspnea intensity can be explained largely by an awareness of increased neural respiratory drive, as measured indirectly using diaphragmatic electromyography (EMGdi). Accordingly, we sought to determine whether improvements in dyspnea following IMT can be explained by decreases in inspiratory muscle electromyography (EMG) activity. Twenty-five young, healthy, recreationally active men completed a detailed familiarization visit followed by two maximal incremental cycle exercise tests separated by 5 wk of randomly assigned pressure threshold IMT or sham control (SC) training. The IMT group (n = 12) performed 30 inspiratory efforts twice daily against a 30-repetition maximum intensity. The SC group (n = 13) performed a daily bout of 60 inspiratory efforts against 10% maximal inspiratory pressure (MIP), with no weekly adjustments. Dyspnea intensity was measured throughout exercise using the modified 0-10 Borg scale. Sternocleidomastoid and scalene EMG was measured using surface electrodes, whereas EMGdi was measured using a multipair esophageal electrode catheter. IMT significantly improved MIP (pre: -138 ± 45 vs. post: -160 ± 43 cmH2O, P < 0.01), whereas the SC intervention did not. Dyspnea was significantly reduced at the highest equivalent work rate (pre: 7.6 ± 2.5 vs. post: 6.8 ± 2.9 Borg units, P < 0.05), but not in the SC group, with no between-group interaction effects. There were no significant differences in respiratory muscle EMG during exercise in either group. Improvements in dyspnea intensity ratings following IMT in healthy humans cannot be explained by changes in the electrical activity of the inspiratory muscles.NEW & NOTEWORTHY Exertional dyspnea intensity is thought to reflect an increased awareness of neural respiratory drive, which is measured indirectly using diaphragmatic electromyography (EMGdi). We examined the effects of inspiratory muscle training (IMT) on dyspnea, EMGdi, and EMG of accessory inspiratory muscles. IMT significantly reduced submaximal dyspnea intensity ratings but did not change EMG of any inspiratory muscles. Improvements in exertional dyspnea following IMT may be the result of nonphysiological factors or physiological adaptations unrelated to neural respiratory drive.
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Affiliation(s)
- Andrew H Ramsook
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada
| | - Yannick Molgat-Seon
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Michele R Schaeffer
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada
| | - Sabrina S Wilkie
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada
| | - Pat G Camp
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada
| | - W Darlene Reid
- Department of Physical Therapy, University of Toronto, Toronto, Ontario, Canada; and
| | - Lee M Romer
- Centre for Human Performance, Exercise, and Rehabilitation, Brunel University London, Uxbridge, United Kingdom
| | - Jordan A Guenette
- Centre for Heart Lung Innovation, University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada; .,Department of Physical Therapy, University of British Columbia, Vancouver, British Columbia, Canada.,School of Kinesiology, University of British Columbia, Vancouver, British Columbia, Canada
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7
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Poulsen MK, Thomsen LP, Mifsud NL, Nielsen NPB, Jørgensen RM, Kjærgaard S, Karbing DS. Electrical activity of the diaphragm during progressive cycling exercise in endurance-trained men. Respir Physiol Neurobiol 2014; 205:77-83. [PMID: 25448397 DOI: 10.1016/j.resp.2014.10.012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Revised: 10/17/2014] [Accepted: 10/20/2014] [Indexed: 11/28/2022]
Abstract
The study aimed to investigate diaphragm respiratory drive modulation through electrical activity of the diaphragm (EADi) during progressive cycling in endurance-trained men (N=7) and to test day-to-day measurement reliability. Normalized EADi increased at exercise intensities from 40% workload (WL) to 70% and 85%WL but plateaued from 70% to 85% (p<0.05). V˙O2, V˙CO2, V˙E, increased at all exercise intensities, where Vt and BF increased from 40% to 55% WL and from 70% to 85% and RER increased at 70% and 85% (p<0.05). Bland-Altman plots of normalized EADi showed bias of 0.9% and -6.4% and limits of agreement of ±36.0% and ±30.4% for absolute measurements and relative changes from 40% WL, respectively. Within-day variability appeared constant indicating that measurements within a trial are reliable. Results suggest that diaphragm respiratory drive increases at moderate exercise intensities, but plateaus at high intensities where other respiratory muscles might contribute significantly to the breathing effort, perhaps to "protect" against diaphragm fatigue.
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Affiliation(s)
- Mathias Krogh Poulsen
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark.
| | - Lars Pilegaard Thomsen
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark
| | - Nicolai Lees Mifsud
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark
| | - Niels-Peter Brøchner Nielsen
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark
| | - René Melvad Jørgensen
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark
| | - Søren Kjærgaard
- Department of Anesthesiology, Aalborg University Hospital, 9000 Aalborg, Denmark
| | - Dan Stieper Karbing
- Respiratory and Critical Care Group, Department of Health Science and Technology, Aalborg University, Fredrik Bajers vej 7, E4, Aalborg East, 9220 Aalborg, Denmark
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8
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Mendonca CT, Schaeffer MR, Riley P, Jensen D. Physiological mechanisms of dyspnea during exercise with external thoracic restriction: role of increased neural respiratory drive. J Appl Physiol (1985) 2013; 116:570-81. [PMID: 24356524 DOI: 10.1152/japplphysiol.00950.2013] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We tested the hypothesis that neuromechanical uncoupling of the respiratory system forms the mechanistic basis of dyspnea during exercise in the setting of "abnormal" restrictive constraints on ventilation (VE). To this end, we examined the effect of chest wall strapping (CWS) sufficient to mimic a "mild" restrictive lung deficit on the interrelationships between VE, breathing pattern, dynamic operating lung volumes, esophageal electrode-balloon catheter-derived measures of the diaphragm electromyogram (EMGdi) and the transdiaphragmatic pressure time product (PTPdi), and sensory intensity and unpleasantness ratings of dyspnea during exercise. Twenty healthy men aged 25.7 ± 1.1 years (means ± SE) completed symptom-limited incremental cycle exercise tests under two randomized conditions: unrestricted control and CWS to reduce vital capacity (VC) by 21.6 ± 0.5%. Compared with control, exercise with CWS was associated with 1) an exaggerated EMGdi and PTPdi response; 2) no change in the relationship between EMGdi and each of tidal volume (expressed as a percentage of VC), inspiratory reserve volume, and PTPdi, thus indicating relative preservation of neuromechanical coupling; 3) increased sensory intensity and unpleasantness ratings of dyspnea; and 4) no change in the relationship between increasing EMGdi and each of the intensity and unpleasantness of dyspnea. In conclusion, the increased intensity and unpleasantness of dyspnea during exercise with CWS could not be readily explained by increased neuromechanical uncoupling but likely reflected the awareness of increased neural respiratory drive (EMGdi) needed to achieve any given VE during exercise in the setting of "abnormal" restrictive constraints on tidal volume expansion.
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Affiliation(s)
- Cassandra T Mendonca
- Clinical Exercise and Respiratory Physiology Laboratory, Department of Kinesiology and Physical Education, McGill University, Montréal, Québec, Canada
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9
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Schaeffer MR, Mendonca CT, Levangie MC, Andersen RE, Taivassalo T, Jensen D. Physiological mechanisms of sex differences in exertional dyspnoea: role of neural respiratory motor drive. Exp Physiol 2013; 99:427-41. [DOI: 10.1113/expphysiol.2013.074880] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Michele R. Schaeffer
- Clinical Exercise & Respiratory Physiology Laboratory; Department of Kinesiology & Physical Education; McGill University; Montreal Quebec Canada
| | - Cassandra T. Mendonca
- Clinical Exercise & Respiratory Physiology Laboratory; Department of Kinesiology & Physical Education; McGill University; Montreal Quebec Canada
| | - Marc C. Levangie
- Clinical Exercise & Respiratory Physiology Laboratory; Department of Kinesiology & Physical Education; McGill University; Montreal Quebec Canada
| | - Ross E. Andersen
- Clinical Exercise & Respiratory Physiology Laboratory; Department of Kinesiology & Physical Education; McGill University; Montreal Quebec Canada
| | - Tanja Taivassalo
- Clinical Exercise & Respiratory Physiology Laboratory; Department of Kinesiology & Physical Education; McGill University; Montreal Quebec Canada
| | - Dennis Jensen
- Clinical Exercise & Respiratory Physiology Laboratory; Department of Kinesiology & Physical Education; McGill University; Montreal Quebec Canada
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10
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Finucane KE, Singh B. Diaphragm efficiency estimated as power output relative to activation in chronic obstructive pulmonary disease. J Appl Physiol (1985) 2012; 113:1567-75. [PMID: 22995393 DOI: 10.1152/japplphysiol.01453.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Muscle efficiency increases with fiber length and decreases with load. Diaphragm efficiency (Eff(di)) in healthy humans, measured as power output (Wdi) relative to the root mean square of diaphragm electromyogram (RMS(di)), increases with hyperpnea due to phasic activity of abdominal muscles acting to increase diaphragm length at end expiration (L(di ee)) and decrease inspiratory load. In chronic obstructive pulmonary disease (COPD), hyperpnea may decrease Eff(di) if L(di ee) decreases and load increases due to airflow obstruction and dynamic hyperinflation. To examine this hypothesis, we measured Eff(di) in six COPD subjects (mean forced expiratory volume in 1 s: 54% predicted) when breathing air and at intervals during progressive hypercapnic hyperpnea. Wdi was measured as the product of mean inspiratory transdiaphragmatic pressure (ΔPdi(mean)), diaphragm tidal volume measured fluoroscopically, and 1/inspiratory duration. Results were compared with those of six healthy subjects reported previously. In COPD, L(di ee) was normal when breathing air. ΔPdi(mean) and Wdi increased normally, and RMS(di) increased disproportionately (P = 0.01) with hyperpnea, and, unlike health, inspiratory capacity (IC), L(di ee), and Eff(di) did not increase. IC and L(di ee) were constant with hyperpnea because mean expiratory flow increased as expiratory duration decreased (r(2) = 0.65), and because expiratory flow was terminated actively by the balance between expiratory and inspiratory muscle forces near end expiration, and these forces increased proportionately with hyperpnea (r(2) = 0.49). At maximum ventilation, diaphragm radius of curvature at end inspiration increased in COPD (P = 0.04) but not controls; diaphragm radius of curvature at end inspiration and ln(Eff(di)) were negatively correlated (P = 0.01). Thus in COPD with modest airflow obstruction, Eff(di) did not increase normally with hyperpnea due to a constant L(di ee) and inspiratory flattening of the diaphragm.
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Affiliation(s)
- Kevin E Finucane
- Department of Pulmonary Physiology and Sleep Medicine, Sir Charles Gairdner Hospital, Nedlands, WA 6009, Australia.
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Liu L, Liu H, Yang Y, Huang Y, Liu S, Beck J, Slutsky AS, Sinderby C, Qiu H. Neuroventilatory efficiency and extubation readiness in critically ill patients. CRITICAL CARE : THE OFFICIAL JOURNAL OF THE CRITICAL CARE FORUM 2012; 16:R143. [PMID: 22849707 PMCID: PMC3580730 DOI: 10.1186/cc11451] [Citation(s) in RCA: 71] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/12/2012] [Accepted: 07/31/2012] [Indexed: 12/28/2022]
Abstract
Introduction Based on the hypothesis that failure of weaning from mechanical ventilation is caused by respiratory demand exceeding the capacity of the respiratory muscles, we evaluated whether extubation failure could be characterized by increased respiratory drive and impaired efficiency to generate inspiratory pressure and ventilation. Methods Airway pressure, flow, volume, breathing frequency, and diaphragm electrical activity were measured in a heterogeneous group of patients deemed ready for a spontaneous breathing trial. Efficiency to convert neuromuscular activity into inspiratory pressure was calculated as the ratio of negative airway pressure and diaphragm electrical activity during an inspiratory occlusion. Efficiency to convert neuromuscular activity into volume was calculated as the ratio of the tidal volume to diaphragm electrical activity. All variables were obtained during a 30-minute spontaneous breathing trial on continuous positive airway pressure (CPAP) of 5 cm H2O and compared between patients for whom extubation succeeded with those for whom either the spontaneous breathing trial failed or for those who passed, but then the extubation failed. Results Of 52 patients enrolled in the study, 35 (67.3%) were successfully extubated, and 17 (32.7%) were not. Patients for whom it failed had higher diaphragm electrical activity (48%; P < 0.001) and a lower efficiency to convert neuromuscular activity into inspiratory pressure and tidal volume (40% (P < 0.001) and 53% (P < 0.001)), respectively. Neuroventilatory efficiency demonstrated the greatest predictability for weaning success. Conclusions This study shows that a mixed group of critically ill patients for whom weaning fails have increased neural respiratory drive and impaired ability to convert neuromuscular activity into tidal ventilation, in part because of diaphragm weakness. Trial Registration Clinicaltrials.gov identifier NCT01065428. ©2012 Liu et al.; licensee BioMed Central Ltd. This is an open access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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Finucane KE, Singh B. Human diaphragm efficiency estimated as power output relative to activation increases with hypercapnic hyperpnea. J Appl Physiol (1985) 2009; 107:1397-405. [PMID: 19696355 DOI: 10.1152/japplphysiol.91465.2008] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Hyperpnea with exercise or hypercapnia causes phasic contraction of abdominal muscles, potentially lengthening the diaphragm at end expiration and unloading it during inspiration. Muscle efficiency in vitro varies with load, fiber length, and precontraction stretch. To examine whether these properties of muscle contractility determine diaphragm efficiency (Effdi) in vivo, we measured Effdi in six healthy adults breathing air and during progressive hypercapnia at three levels of end-tidal Pco2 with mean values of 48 (SD 2), 55 (SD 2), and 61 (SD 1) Torr. Effdi was estimated as the ratio of diaphragm power (W˙di) [the product of mean inspiratory transdiaphragmatic pressure, diaphragm volume change (ΔVdi) measured fluoroscopically, and 1/inspiratory duration (Ti−1)] to activation [root mean square values of inspiratory diaphragm electromyogram (RMSdi) measured from esophageal electrodes]. At maximum hypercapnea relative to breathing air, 1) gastric pressure and diaphragm length at end expiration (Pgee and Ldiee, respectively) increased 1.4 (SD 0.2) and 1.13 (SD 0.08) times, ( P < 0.01 for both); 2) inspiratory change (Δ) in Pg decreased from 4.5 (SD 2.2) to −7.7 (SD 3.8) cmH2O ( P < 0.001); 3) ΔVdi·Ti−1, W˙di, RMSdi, and Effdi increased 2.7 (SD 0.6), 4.9 (SD 1.8), 2.6 (SD 0.9), and 1.8 (SD 0.3) times, respectively ( P < 0.01 for all); and 4) net and inspiratory W˙di were not different ( P = 0.4). Effdi was predicted from Ldiee ( P < 0.001), Pgee ( P < 0.001), ΔPg·Ti−1 ( P = 0.03), and ΔPg ( P = 0.04) ( r2 = 0.52) (multivariate regression analysis). We conclude that, with hypercapnic hyperpnea, 1) ∼47% of the maximum increase of W˙di was attributable to increased Effdi; 2) Effdi increased due to preinspiratory lengthening and inspiratory unloading of the diaphragm, consistent with muscle behavior in vitro; 3) passive recoil of the diaphragm did not contribute to inspiratory W˙di or Effdi; and 4) phasic abdominal muscle activity with hyperpnea reduces diaphragm energy consumption.
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Affiliation(s)
- Kevin E. Finucane
- Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands; and West Australian Sleep Disorders Research Institute, Queen Elizabeth II Medical Centre, Perth, Western Australia, Australia
| | - Bhajan Singh
- Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Nedlands; and West Australian Sleep Disorders Research Institute, Queen Elizabeth II Medical Centre, Perth, Western Australia, Australia
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Is One Fixed Level of Assist Sufficient to Mechanically Ventilate Spontaneously Breathing Patients? Intensive Care Med 2007. [DOI: 10.1007/978-0-387-49518-7_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Finucane KE, Panizza JA, Singh B. Efficiency of the normal human diaphragm with hyperinflation. J Appl Physiol (1985) 2005; 99:1402-11. [PMID: 15961606 DOI: 10.1152/japplphysiol.01165.2004] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
We evaluated an index of diaphragm efficiency (Eff(di)), diaphragm power output (Wdi) relative to electrical activation, in five healthy adults during tidal breathing at usual end-expiratory lung volume (EELV) and diaphragm length (L(di ee)) and at shorter L(di ee) during hyperinflation with expiratory positive airway pressure (EPAP). Measurements were repeated with an inspiratory threshold (7.5 cmH(2)O) plus resistive (6.5 cmH(2)O.l(-1).s) load. Wdi was the product of mean inspiratory transdiaphragmatic pressure (DeltaPdi(mean)), diaphragm volume displacement measured fluoroscopically, and 1/inspiratory duration (Ti(-1)). Diaphragm activation, measured with esophageal electrodes, was quantified by computing root-mean-square values (RMS(di)). With EPAP, 1) EELV increased [mean r(2) = 0.91 (SD 0.01)]; 2) in four subjects, L(di ee) decreased [mean r(2) = 0.85 (SD 0.07)] and mean Eff(di) decreased 34% per 10% decrease in L(di ee) (P < 0.001); and 3) in one subject, gastric pressure at EELV increased two- to threefold, L(di ee) was unchanged or increased, and Eff(di) increased at two of four levels of EPAP (P < or = 0.006, ANOVA). Inspiratory loading increased Wdi (P = 0.003) and RMS(di) (P = 0.004) with no change in Eff(di) (P = 0.63) or its relationship with L(di ee). Eff(di) was more accurate in defining changes in L(di ee) [(true positives + true negatives)/total = 0.78 (SD 0.13)] than DeltaPdi(mean).RMS(di)(-1), RMS(di), or DeltaPdi(mean).Ti (all <0.7, P < or = 0.05, without load). Thus Eff(di) was principally a function of L(di ee) independent of inspiratory loading, behavior consistent with muscle force-length-velocity properties. We conclude that Eff(di), measured during tidal breathing and in the absence of expiratory muscle activity at EELV, is a valid and accurate measure of diaphragm contractile function.
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Affiliation(s)
- Kevin E Finucane
- Department of Pulmonary Physiology, Sir Charles Gairdner Hospital, Western Australia.
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