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Reinhard PA, Archiza B, Welch JF, Benbaruj J, Guenette JA, Koehle MS, Sheel AW. Effects of hypoxia on exercise-induced diaphragm fatigue in healthy males and females. Physiol Rep 2023; 11:e15589. [PMID: 36695726 PMCID: PMC9875747 DOI: 10.14814/phy2.15589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Revised: 01/04/2023] [Accepted: 01/06/2023] [Indexed: 06/17/2023] Open
Abstract
Following high-intensity, normoxic exercise there is evidence to show that healthy females, on average, exhibit less fatigue of the diaphragm relative to males. In the present study, we combined hypoxia with exercise to test the hypothesis that males and females would develop a similar degree of diaphragm fatigue following cycle exercise at the same relative exercise intensity. Healthy young participants (n = 10 male; n = 10 female) with a high aerobic capacity (120% predicted) performed two time-to-exhaustion (TTE; ~85% maximum) cycle tests on separate days breathing either a normoxic or hypoxic (FiO2 = 0.15) gas mixture. Fatigue of the diaphragm was assessed in response to cervical magnetic stimulation prior to, immediately post-exercise, 10-, 30-, and 60-min post-exercise. Males and females had similar TTE durations in normoxia (males: 690 ± 181 s; females: 852 ± 401 s) and hypoxia (males: 381 ± 160 s; females: 400 ± 176 s) (p > 0.05). Cycling time was significantly shorter in hypoxia versus normoxia in both males and females (p < 0.05) and did not differ on the basis of sex (p > 0.05). Following the hypoxic TTE tests, males and females experienced a similar degree of diaphragm fatigue compared to normoxia as shown by 20%-25% reductions in transdiaphragmatic twitch pressure. This occurred despite the fact that exercise time in hypoxia was substantially shorter relative to normoxia and the cumulative diaphragm work was lower. We also observed that females did not fully recover from diaphragm fatigue in hypoxia, whereas males did (p < 0.05). Sex differences in the rate of diaphragm contractility recovery following exercise in hypoxia might relate to sex-based differences in substrate utilization or diaphragm blood flow.
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Affiliation(s)
- Paige A. Reinhard
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - Bruno Archiza
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Department of Physical TherapyFederal University of São CarlosSão CarlosSPBrazil
| | - Joseph F. Welch
- Breathing Research and Therapeutics Center, Department of Physical TherapyUniversity of FloridaGainesvilleFloridaUSA
- School of Sport, Exercise and Rehabilitation SciencesUniversity of BirminghamBirminghamUK
| | - Jenna Benbaruj
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - Jordan A. Guenette
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Department of Physical TherapyThe University of British ColumbiaVancouverBritish ColumbiaCanada
- Centre for Heart Lung Innovation, Providence ResearchThe University of British Columbia and St. Paul's HospitalVancouverBritish ColumbiaCanada
| | - Michael S. Koehle
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
| | - A. William Sheel
- School of KinesiologyThe University of British ColumbiaVancouverBritish ColumbiaCanada
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2
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Welch JF, Nair J, Argento PJ, Mitchell GS, Fox EJ. Acute intermittent hypercapnic-hypoxia elicits central neural respiratory motor plasticity in humans. J Physiol 2022; 600:2515-2533. [PMID: 35348218 DOI: 10.1113/jp282822] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2022] [Accepted: 03/25/2022] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The occurrence of respiratory long-term facilitation following acute exposure to intermittent hypoxia is believed to be dependent upon CO2 regulation - mechanisms governing the critical role of CO2 have seldom been explored. We tested the hypothesis that acute intermittent hypercapnic-hypoxia (AIHH) enhances cortico-phrenic neurotransmission in awake healthy humans. The amplitude of diaphragmatic motor-evoked potentials induced by transcranial magnetic stimulation was increased after AIHH, but not the amplitude of compound muscle action potentials evoked by cervical magnetic stimulation. Mouth occlusion pressure (P0.1 , indicator of neural respiratory drive) was also increased after AIHH, but not tidal volume or minute ventilation. Thus, moderate AIHH elicits central neural mechanisms of respiratory motor plasticity, without measurable ventilatory long-term facilitation in awake humans. ABSTRACT Acute intermittent hypoxia (AIH) elicits long-term facilitation (LTF) of respiration. Although LTF is observed when CO2 is elevated during AIH in awake humans, the influence of CO2 on corticospinal respiratory motor plasticity is unknown. Thus, we tested the hypotheses that acute intermittent hypercapnic-hypoxia (AIHH): 1) enhances cortico-phrenic neurotransmission (reflecting volitional respiratory control); and 2) elicits ventilatory LTF (reflecting automatic respiratory control). Eighteen healthy adults completed four study visits. Day 1 consisted of anthropometry and pulmonary function testing. On Days 2, 3 and 4, in a balanced alternating sequence, participants received: AIHH, poikilocapnic AIH, and normocapnic-normoxia (Sham). Protocols consisted of 15, 60-s exposures with 90-s normoxic intervals. Transcranial (TMS) and cervical (CMS) magnetic stimulation were used to induce diaphragmatic motor-evoked potentials and compound muscle action potentials, respectively. Respiratory drive was assessed via mouth occlusion pressure (P0.1 ), and minute ventilation measured at rest. Dependent variables were assessed at baseline and 30-60 min post-exposures. Increases in TMS-evoked diaphragm potential amplitudes were observed following AIHH versus Sham (+28 ± 41%, p = 0.003), but not after AIH. No changes were observed in CMS-evoked diaphragm potential amplitudes. Mouth occlusion pressure also increased after AIHH (+21 ± 34%, p = 0.033), but not after AIH. Ventilatory LTF was not observed after any treatment. We demonstrate that AIHH elicits central neural mechanisms of respiratory motor plasticity and increases resting respiratory drive in awake humans. These findings may have important implications for neurorehabilitation after spinal cord injury and other neuromuscular disorders compromising respiratory motor function. Abstract Figure Legend In a single-blind, cross-over, sham-controlled trial, 18 healthy adults received in a balanced alternating sequence: normocapnic-normoxia (Sham), poikilocapnic acute intermittent hypoxia (AIH), and acute intermittent hypercapnic-hypoxia (AIHH). The study tested the hypothesis that AIHH enhances cortico-phrenic neurotransmission and elicits ventilatory long-term facilitation. Note the increase in the mean amplitude of diaphragmatic motor-evoked potentials (MEP) induced by transcranial magnetic stimulation 60 min after AIHH only, whereas the amplitude of diaphragmatic compound muscle action potentials evoked by cervical (phrenic nerve) stimulation were unchanged after AIHH, AIH and Sham. Traces are composite averages of all participants. Mouth occlusion pressure (P0.1 ), an indicator of resting respiratory drive, was increased after AIHH, but not after AIH or Sham (see yellow shaded area). Traces are mouth pressure at the onset of an occluded inspiration during resting breathing. Finally, tidal volume (VT ) was unchanged 30-60 min after AIHH, AIH and Sham. Our results indicate that moderate AIHH elicits a central neural mechanism of respiratory motor plasticity and increases resting respiratory drive in awake humans, without measurable ventilatory long-term facilitation. This article is protected by copyright. All rights reserved.
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Affiliation(s)
- Joseph F Welch
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy
| | - Jayakrishnan Nair
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy.,Department of Physical Therapy, Thomas Jefferson University, Philadelphia, PA, USA
| | - Patrick J Argento
- Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy
| | - Emily J Fox
- Breathing Research and Therapeutics Centre.,Department of Physical Therapy.,Brooks Rehabilitation, Jacksonville, FL, USA
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3
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Abstract
While the traditional lung function tests are used to assess lung capacity and pulmonary function, they cannot evaluate respiratory driving function and the integrity of the conduction pathway from the central nervous system to the respiratory motor neuron in the spinal cord and to the diaphragm. The inspiratory trigger is sent from the central nervous system through the phrenic nerve and drives the diaphragm to generate inspiratory movement. Therefore, phrenic nerve stimulation and diaphragmatic electromyography are two fundamental methods to assess respiratory function. There are several useful tools to assess respiratory motor system including electrical or magnetic phrenic nerve stimulation, diaphragmatic needle electromyography, and diaphragmatic ultrasound. By these means, physicians can assess current respiratory status in different neurological diseases that affect respiratory muscles, follow-up of the severity of respiratory impairment, help to predict the chance of successfully weaning from ventilatory support, and confirm clinical diagnoses such as diaphragmatic myoclonus. Although some of these tests require special training, applying these neurophysiological assessments in clinical practice is highly recommended.
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Affiliation(s)
- Yih-Chih Jacinta Kuo
- Department of Neurology, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan
| | - Kai-Hsiang Stanley Chen
- Department of Neurology, National Taiwan University Hospital Hsin-Chu Branch, Hsin-Chu, Taiwan.
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4
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MacAskill W, Hoffman B, Johnson MA, Sharpe GR, Mills DE. Pressure measurement characteristics of a micro-transducer and balloon catheters. Physiol Rep 2021; 9:e14831. [PMID: 33938126 PMCID: PMC8090844 DOI: 10.14814/phy2.14831] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2021] [Accepted: 03/14/2021] [Indexed: 11/24/2022] Open
Abstract
Respiratory pressure responses to cervical magnetic stimulation are important measurements in monitoring the mechanical function of the respiratory muscles. Pressures can be measured using balloon catheters or a catheter containing integrated micro‐transducers. However, no research has provided a comprehensive analysis of their pressure measurement characteristics. Accordingly, the aim of this study was to provide a comparative analysis of these characteristics in two separate experiments: (1) in vitro with a reference pressure transducer following a controlled pressurization; and (2) in vivo following cervical magnetic stimulations. In vitro the micro‐transducer catheter recorded pressure amplitudes and areas which were in closer agreement to the reference pressure transducer than the balloon catheter. In vivo there was a main effect for stimulation power and catheter for esophageal (Pes), gastric (Pga), and transdiaphragmatic (Pdi) pressure amplitudes (p < 0.001) with the micro‐transducer catheter recording larger pressure amplitudes. There was a main effect of stimulation power (p < 0.001) and no main effect of catheter for esophageal (p = 0.481), gastric (p = 0.923), and transdiaphragmatic (p = 0.964) pressure areas. At 100% stimulator power agreement between catheters for Pdi amplitude (bias =6.9 cmH2O and LOA −0.61 to 14.27 cmH2O) and pressure areas (bias = −0.05 cmH2O·s and LOA −1.22 to 1.11 cmH2O·s) were assessed. At 100% stimulator power, and compared to the balloon catheters, the micro‐transducer catheter displayed a shorter 10–90% rise time, contraction time, latency, and half‐relaxation time, alongside greater maximal rates of change in pressure for esophageal, gastric, and transdiaphragmatic pressure amplitudes (p < 0.05). These results suggest that caution is warranted if comparing pressure amplitude results utilizing different catheter systems, or if micro‐transducers are used in clinical settings while applying balloon catheter‐derived normative values. However, pressure areas could be used as an alternative point of comparison between catheter systems.
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Affiliation(s)
- William MacAskill
- Respiratory and Exercise Physiology Research Group, School of Health and Wellbeing, University of Southern Queensland, Ipswich, Australia.,Centre for Health Research, Institute for Resilient Regions, University of Southern Queensland, Ipswich, Australia
| | - Ben Hoffman
- Respiratory and Exercise Physiology Research Group, School of Health and Wellbeing, University of Southern Queensland, Ipswich, Australia.,Centre for Health Research, Institute for Resilient Regions, University of Southern Queensland, Ipswich, Australia.,School of Human Movement and Nutrition Sciences, The University of Queensland, Brisbane, Australia
| | - Michael A Johnson
- Exercise and Health Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Graham R Sharpe
- Exercise and Health Research Group, Sport, Health and Performance Enhancement (SHAPE) Research Centre, School of Science and Technology, Nottingham Trent University, Nottingham, United Kingdom
| | - Dean E Mills
- Respiratory and Exercise Physiology Research Group, School of Health and Wellbeing, University of Southern Queensland, Ipswich, Australia.,Centre for Health Research, Institute for Resilient Regions, University of Southern Queensland, Ipswich, Australia
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5
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Welch JF, Perim RR, Argento PJ, Sutor TW, Vose AK, Nair J, Mitchell GS, Fox EJ. Effect of acute intermittent hypoxia on cortico-diaphragmatic conduction in healthy humans. Exp Neurol 2021; 339:113651. [PMID: 33607080 PMCID: PMC8678369 DOI: 10.1016/j.expneurol.2021.113651] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Revised: 02/11/2021] [Accepted: 02/12/2021] [Indexed: 01/06/2023]
Abstract
Acute intermittent hypoxia (AIH) is a strategy to improve motor output in humans with neuromotor impairment. A single AIH session increases the amplitude of motor evoked potentials (MEP) in a finger muscle (first dorsal interosseous), demonstrating enhanced corticospinal neurotransmission. Since AIH elicits phrenic/diaphragm long-term facilitation (LTF) in rodent models, we tested the hypothesis that AIH augments diaphragm MEPs in humans. Eleven healthy adults (7 males, age = 29 ± 6 years) were tested. Transcranial and cervical magnetic stimulation were used to induce diaphragm MEPs and compound muscle action potentials (CMAP) recorded by surface EMG, respectively. Stimulus-response curves were generated prior to and 30-60 min after AIH. Diaphragm LTF was assessed by measurement of integrated EMG burst amplitude and frequency during eupnoeic breathing before and after AIH. Following baseline measurements, AIH was delivered from an oxygen generator connected to a facemask under poikilocapnic conditions (15 one minute episodes of 9% inspired oxygen with one minute room air intervals). There were no detectable changes in MEP (-1.5 ± 12.1%, p = 0.96) or CMAP (+0.1 ± 7.8%, p = 0.97) amplitudes across the stimulus-response curve. At stimulation intensities approximating 50% of the difference between minimum and maximum baseline amplitudes, MEP and CMAP amplitudes were also unchanged (p > 0.05). Further, no AIH effect was observed on diaphragm EMG activity during eupnoea post-AIH (p > 0.05). We conclude that unlike hand muscles, poikilocapnic AIH does not enhance diaphragm MEPs or produce diaphragm LTF in healthy humans.
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Affiliation(s)
- Joseph F Welch
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA.
| | - Raphael R Perim
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Patrick J Argento
- Herbert Wertheim College of Engineering, University of Florida, Gainesville, FL, USA
| | - Tommy W Sutor
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Alicia K Vose
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Jayakrishnan Nair
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Emily J Fox
- Breathing Research and Therapeutics Centre, Department of Physical Therapy, University of Florida, Gainesville, FL, USA; Brooks Rehabilitation, Jacksonville, FL, USA
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6
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Archiza B, Reinhard PA, Welch JF, Sheel AW. Sex differences in diaphragmatic fatigue: Effects of hypoxia during inspiratory loading. J Physiol 2020; 599:1319-1333. [PMID: 33180958 DOI: 10.1113/jp280704] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 10/26/2020] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS Under normoxic conditions, both healthy female and male diaphragms fatigue at a similar degree when matched for absolute diaphragmatic work during inspiratory loading. We investigated whether similarities in diaphragm fatigability persist under acute hypoxic conditions. We found that, in acute hypoxia, fatigue of the diaphragm is greater in women compared to men, whereas the magnitude of fatigue in normoxia did not differ between sexes. When matched for maximal diaphragm strength, women and men had a similar pressor response to work-matched inspiratory loading, independent of oxygen availability. ABSTRACT In normoxia, women and men display a comparable magnitude of diaphragmatic fatigue (DF) after work-matched inspiratory loading. Whether these sex similarities are maintained under acute hypoxic conditions is unknown. We investigated the influence of acute hypoxia during work-matched inspiratory pressure-threshold loading (PTL) on DF in healthy women (n = 8) and men (n = 8). Two 5 min isocapnic PTL tasks targeting a transdiaphragmatic pressure (Pdi ) of 92 cmH2 O in normoxia and hypoxia (8% O2 ) were performed on separate days (≥48 h). DF was quantified by twitch Pdi (Pdi,tw ) via cervical magnetic stimulation post-PTL. Women and men had similar maximal Pdi (Pdi,max ; women: 171 ± 16, men: 178 ± 20 cmH2 O) and relative target workload (women: 54 ± 5%, men: 53 ± 6% Pdi,max ). The absolute cumulative diaphragmatic work did not differ between sexes in normoxia (women: 12,653 ± 1796 cmH2 O s-1 , men: 13,717 ± 1231 cmH2 O s-1 ; P = 0.202) or hypoxia (women: 11,624 ± 1860 cmH2 O s-1 , men: 12 722 ± 1502 cmH2 O s-1 ; P = 0.189). In normoxia, the magnitude of reduction in Pdi,tw post-PTL was similar between sexes (women: -21.1 ± 8.4%, men: -22.5 ± 4.9 %; P = 0.193); however, a higher degree of DF was observed in women compared to men following PTL in acute hypoxia (women: -27.6 ± 7.7%, men: -23.4 ± 9.6%, P = 0.019). We conclude that the female diaphragm is more susceptible to fatigue after inspiratory loading under acute hypoxic conditions. This finding may be related to sex differences in diaphragm muscle metabolism, such as fibre type composition, contractile properties, substrate utilisation and blood perfusion.
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Affiliation(s)
- Bruno Archiza
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Paige A Reinhard
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Joseph F Welch
- Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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7
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Spiesshoefer J, Henke C, Kabitz HJ, Bengel P, Schütt K, Nofer JR, Spieker M, Orwat S, Diller GP, Strecker JK, Giannoni A, Dreher M, Randerath WJ, Boentert M, Tuleta I. Heart Failure Results in Inspiratory Muscle Dysfunction Irrespective of Left Ventricular Ejection Fraction. Respiration 2020; 100:96-108. [PMID: 33171473 DOI: 10.1159/000509940] [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: 03/10/2020] [Accepted: 07/04/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Exercise intolerance in heart failure with reduced ejection fraction (HFrEF) or heart failure with preserved ejection fraction (HFpEF) results from both cardiac dysfunction and skeletal muscle weakness. Respiratory muscle dysfunction with restrictive ventilation disorder may be present irrespective of left ventricular ejection fraction and might be mediated by circulating pro-inflammatory cytokines. OBJECTIVE To determine lung and respiratory muscle function in patients with HFrEF/HFpEF and to determine its associations with exercise intolerance and markers of systemic inflammation. METHODS Adult patients with HFrEF (n = 22, 19 male, 61 ± 14 years) and HFpEF (n = 8, 7 male, 68 ± 8 years) and 19 matched healthy control subjects underwent spirometry, measurement of maximum mouth occlusion pressures, diaphragm ultrasound, and recording of transdiaphragmatic and gastric pressures following magnetic stimulation of the phrenic nerves and the lower thoracic nerve roots. New York Heart Association (NYHA) class and 6-min walking distance (6MWD) were used to quantify exercise intolerance. Levels of circulating interleukin 6 (IL-6) and tumor necrosis factor-α (TNF-α) were measured using ELISAs. RESULTS Compared with controls, both patient groups showed lower forced vital capacity (FVC) (p < 0.05), maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax) (p < 0.05), diaphragm thickening ratio (p = 0.01), and diaphragm strength (twitch transdiaphragmatic pressure in response to supramaximal cervical magnetic phrenic nerve stimulation) (p = 0.01). In patients with HFrEF, NYHA class and 6MWD were both inversely correlated with FVC, PImax, and PEmax. In those with HFpEF, there was an inverse correlation between amino terminal pro B-type natriuretic peptide levels and FVC (r = -0.77, p = 0.04). In all HF patients, IL-6 and TNF-α were statistically related to FVC. CONCLUSIONS Irrespective of left ventricular ejection fraction, HF is associated with respiratory muscle dysfunction, which is associated with increased levels of circulating IL-6 and TNF-α.
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Affiliation(s)
- Jens Spiesshoefer
- Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy, .,Department of Pneumology and Intensive Care Medicine, University Hospital RWTH Aachen, Aachen, Germany, .,Department of Neurology with Institute for Translational Neurology, University of Muenster, Muenster, Germany,
| | - Carolin Henke
- Department of Neurology, Herz-Jesu-Krankenhaus Hiltrup, Muenster, Germany
| | - Hans Joachim Kabitz
- Department of Pneumology, Cardiology and Intensive Care Medicine, Klinikum Konstanz, Konstanz, Germany
| | - Philipp Bengel
- Clinic for Cardiology and Pneumology/Heart Center, University Medical Center Goettingen, DZHK (German Centre for Cardiovascular Research), Goettingen, Germany
| | - Katharina Schütt
- Department of Internal Medicine I, University Hospital Aachen, RWTH Aachen University, Aachen, Germany
| | - Jerzy-Roch Nofer
- Center for Laboratory Medicine, University Hospital Muenster, University of Muenster, Muenster, Germany and Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Maximilian Spieker
- Division of Cardiology, Pulmonology and Vascular Medicine, University Hospital Düsseldorf, Heinrich Heine University Düsseldorf, Düsseldorf, Germany
| | - Stefan Orwat
- Department of Cardiology III, University Hospital Muenster, Muenster, Germany
| | - Gerhard Paul Diller
- Department of Cardiology III, University Hospital Muenster, Muenster, Germany
| | - Jan Kolia Strecker
- Department of Neurology with Institute for Translational Neurology, University of Muenster, Muenster, Germany
| | - Alberto Giannoni
- Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy
| | - Michael Dreher
- Department of Pneumology and Intensive Care Medicine, University Hospital RWTH Aachen, Aachen, Germany
| | - Winfried Johannes Randerath
- Institute for Pneumology at the University of Cologne, Solingen, Germany.,Bethanien Hospital gGmbH Solingen, Solingen, Germany
| | - Matthias Boentert
- Department of Neurology with Institute for Translational Neurology, University of Muenster, Muenster, Germany.,Department of Medicine, UKM Marienhospital Steinfurt, Steinfurt, Germany
| | - Izabela Tuleta
- Department of Cardiology I, University Hospital Muenster, Muenster, Germany
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8
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Welch JF, Argento PJ, Mitchell GS, Fox EJ. Reliability of diaphragmatic motor-evoked potentials induced by transcranial magnetic stimulation. J Appl Physiol (1985) 2020; 129:1393-1404. [PMID: 33031020 DOI: 10.1152/japplphysiol.00486.2020] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The diaphragmatic motor-evoked potential (MEP) induced by transcranial magnetic stimulation (TMS) permits electrophysiological assessment of the cortico-diaphragmatic pathway. Despite the value of TMS for investigating diaphragm motor integrity in health and disease, reliability of the technique has not been established. The study aim was to determine within- and between-session reproducibility of surface electromyogram recordings of TMS-evoked diaphragm potentials. Fifteen healthy young adults participated (6 females, age = 29 ± 7 yr). Diaphragm activation was determined by gradually increasing the stimulus intensity from 60 to 100% of maximal stimulator output (MSO). A minimum of seven stimulations were performed at each intensity. A second block of stimuli was delivered 30 min later for within-day comparisons, and a third block was performed on a separate day for between-day comparisons. Reliability of diaphragm MEPs was assessed at 100% MSO using intraclass correlation coefficients (ICC) and 95% limits of agreement (LOA). MEP latency (ICC = 0.984, P < 0.001), duration (ICC = 0.958, P < 0.001), amplitude (ICC = 0.950, P < 0.001), and area (ICC = 0.956, P < 0.001) were highly reproducible within-day. Between-day reproducibility was good to excellent for all MEP characteristics (latency ICC = 0.953, P < 0.001; duration ICC = 0.879, P = 0.002; amplitude ICC = 0.789, P = 0.019; area ICC = 0.815, P = 0.012). Data revealed less precision between-day versus within-day, as evidenced by wider LOA for all MEP characteristics. Large within- and between-subject variability in MEP amplitude and area was observed. In conclusion, TMS is a reliable means of inducing diaphragm potentials in most healthy individuals.NEW & NOTEWORTHY Transcranial magnetic stimulation (TMS) is a noninvasive technique to assess neural impulse conduction along the cortico-diaphragmatic pathway. The reliability of diaphragm motor-evoked potentials (MEP) induced by TMS is unknown. Notwithstanding large variability in MEP amplitude, we found good-to-excellent reproducibility of all MEP characteristics (latency, duration, amplitude, and area) both within- and between-day in healthy adult men and women. Our findings support the use of TMS and surface EMG to assess diaphragm activation in humans.
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Affiliation(s)
- Joseph F Welch
- Breathing Research and Therapeutics Center, Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Patrick J Argento
- Herbert Wertheim College of Engineering, University of Florida, Gainesville, Florida
| | - Gordon S Mitchell
- Breathing Research and Therapeutics Center, Department of Physical Therapy, University of Florida, Gainesville, Florida
| | - Emily J Fox
- Breathing Research and Therapeutics Center, Department of Physical Therapy, University of Florida, Gainesville, Florida.,Brooks Rehabilitation, Jacksonville, Florida
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9
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Ramsook AH, Molgat-Seon Y, Boyle KG, Mitchell RA, Puyat JH, Koehle MS, Sheel AW, Guenette JA. Reliability of diaphragm voluntary activation measurements in healthy adults. Appl Physiol Nutr Metab 2020; 46:247-256. [PMID: 32910865 DOI: 10.1139/apnm-2020-0221] [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: 11/22/2022]
Abstract
Voluntary activation can be used to assess central fatigue of the diaphragm after tasks such as exercise or inspiratory muscle loading. Cervical magnetic stimulation (CMS) of the phrenic nerves elicits an involuntary contraction, or twitch, of the diaphragm. This twitch is quantified based on a measure of transdiaphragmatic pressure and can be used to evaluate diaphragm contractile function and diaphragm voluntary activation (diaphragm-VA). The test-retest reliability of diaphragm-VA using CMS is currently unknown. Thirteen participants (4 male, 9 female; aged 25 ± 3 years) performed a series of interpolated twitch manoeuvres, which included a maximal inspiratory effort against a semi-occluded mouthpiece and 2 CMS-stimuli, 1 during the inspiratory manoeuvre and 1 after when the participant returned to functional residual capacity to quantify diaphragm-VA. Intraclass correlation coefficients (ICCs) and standard error of measurement (SEM) measured between-day and within-session reliability of diaphragm-VA, respectively. Maximal diaphragm-VA values were 91% (SD: 6; SEM: 3.9) and 92% (SD: 5; SEM: 2.2) during visits 1 and 2 (p = 0.68), respectively, and displayed "good" between-day reliability (ICC: 0.88; 95% confidence interval: 0.67-0.95; SEM: 2.7). Our results suggest that assessing diaphragm-VA using CMS is reliable in young healthy adults. Measuring diaphragm-VA may provide additional insight into the consequences and mechanisms of diaphragm fatigue. Novelty: Magnetic stimulation of the phrenic nerves can reliably measure voluntary activation of the diaphragm. Diaphragm voluntary activation can be used to provide additional insight into fatigability of the diaphragm.
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Affiliation(s)
- Andrew H Ramsook
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Yannick Molgat-Seon
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,Department of Kinesiology and Applied Health, Faculty of Kinesiology and Applied Health, The University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Kyle G Boyle
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Reid A Mitchell
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Joseph H Puyat
- Centre for Health Evaluation and Outcome Services, Providence Health Care Research Institute, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada
| | - Michael S Koehle
- School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, British Columbia, Canada.,Department of Family Practice, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada
| | - A William Sheel
- Centre for Heart Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, British Columbia, Canada
| | - Jordan A Guenette
- Department of Physical Therapy, Faculty of Medicine, The University of British Columbia, Vancouver, British Columbia, Canada.,Centre for Heart Lung Innovation, The University of British Columbia and St. Paul's Hospital, Vancouver, British Columbia, Canada.,School of Kinesiology, Faculty of Education, The University of British Columbia, Vancouver, British Columbia, Canada
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10
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Spiesshoefer J, Henke C, Kabitz HJ, Nofer JR, Mohr M, Evers G, Strecker JK, Brix T, Randerath WJ, Herkenrath S, Schmidt LH, Boentert M. Respiratory Muscle and Lung Function in Lung Allograft Recipients: Association with Exercise Intolerance. Respiration 2020; 99:398-408. [PMID: 32403109 DOI: 10.1159/000507264] [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] [Received: 11/12/2019] [Accepted: 03/15/2020] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND In lung transplant recipients (LTRs), restrictive ventilation disorder may be present due to respiratory muscle dysfunction that may reduce exercise capacity. This might be mediated by pro-inflammatory cytokines such as tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6). OBJECTIVE We investigated lung respiratory muscle function as well as circulating pro-inflammatory cytokines and exercise capacity in LTRs. METHODS Fifteen LTRs (6 female, age 56 ± 14 years, 63 ± 45 months post-transplantation) and 15 healthy controls matched for age, sex, and body mass index underwent spirometry, measurement of mouth occlusion pressures, diaphragm ultrasound, and recording of twitch transdiaphragmatic (twPdi) and gastric pressures (twPgas) following magnetic stimulation of the phrenic nerves and the lower thoracic nerve roots. Exercise capacity was quantified using the 6-min walking distance (6MWD). Plasma IL-6 and TNF-α were measured using enzyme-linked immunosorbent assays. RESULTS Compared with controls, patients had lower values for forced vital capacity (FVC; 81 ± 30 vs.109 ± 18% predicted, p = 0.01), maximum expiratory pressure (100 ± 21 vs.127 ± 17 cm H2O, p = 0.04), diaphragm thickening ratio (2.2 ± 0.4 vs. 3.0 ± 1.1, p = 0.01), and twPdi (10.4 ± 3.5 vs. 17.6 ± 6.7 cm H2O, p = 0.01). In LTRs, elevation of TNF-α was related to lung function (13 ± 3 vs. 11 ± 2 pg/mL in patients with FVC ≤80 vs. >80% predicted; p < 0.05), and lung function (forced expiratory volume after 1 s) was closely associated with diaphragm thickening ratio (r = 0.81; p < 0.01) and 6MWD (r = 0.63; p = 0.02). CONCLUSION There is marked restrictive ventilation disorder and respiratory muscle weakness in LTRs, especially inspiratory muscle weakness with diaphragm dysfunction. Lung function impairment relates to elevated levels of circulating TNF-α and diaphragm dysfunction and is associated with exercise intolerance.
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Affiliation(s)
- Jens Spiesshoefer
- Respiratory Physiology Laboratory, Department of Neurology with Institute for Translational Neurology, University Hospital Münster, Münster, Germany, .,Institute of Life Sciences, Scuola Superiore Sant'Anna, Pisa, Italy,
| | - Carolin Henke
- Respiratory Physiology Laboratory, Department of Neurology with Institute for Translational Neurology, University Hospital Münster, Münster, Germany
| | - Hans Joachim Kabitz
- Department of Pneumology, Cardiology and Intensive Care Medicine, Klinikum Konstanz, Konstanz, Germany
| | - Jerzy Roch Nofer
- Center for Laboratory Medicine, University Hospital Münster, University of Münster, Münster, Germany.,Institute of Clinical Chemistry and Laboratory Medicine, University Medical Center Hamburg-Eppendorf, Hamburg, Germany
| | - Michael Mohr
- Department of Medicine A, Hematology, Oncology and Pulmonary Medicine, University Hospital Münster, Münster, Germany
| | - Georg Evers
- Department of Medicine A, Hematology, Oncology and Pulmonary Medicine, University Hospital Münster, Münster, Germany
| | | | - Tobias Brix
- Institute of Medical Informatics, University of Münster, Münster, Germany
| | - Winfried Johannes Randerath
- Bethanien Hospital gGmbH, Solingen, Germany.,Institute for Pneumology at the University of Cologne, Solingen, Germany
| | - Simon Herkenrath
- Bethanien Hospital gGmbH, Solingen, Germany.,Institute for Pneumology at the University of Cologne, Solingen, Germany
| | - Lars Henning Schmidt
- Department of Medicine A, Hematology, Oncology and Pulmonary Medicine, University Hospital Münster, Münster, Germany
| | - Matthias Boentert
- Respiratory Physiology Laboratory, Department of Neurology with Institute for Translational Neurology, University Hospital Münster, Münster, Germany
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11
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Spiesshoefer J, Henke C, Kabitz H, Akova‐Oeztuerk E, Draeger B, Herkenrath S, Randerath W, Young P, Brix T, Boentert M. Phrenic nerve involvement and respiratory muscle weakness in patients with Charcot‐Marie‐Tooth disease 1A. J Peripher Nerv Syst 2019; 24:283-293. [DOI: 10.1111/jns.12341] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2019] [Revised: 07/13/2019] [Accepted: 08/05/2019] [Indexed: 11/27/2022]
Affiliation(s)
- Jens Spiesshoefer
- Respiratory Physiology Laboratory, Department of Neurology, University of Münster Münster Germany
| | - Carolin Henke
- Respiratory Physiology Laboratory, Department of Neurology, University of Münster Münster Germany
| | - Hans‐Joachim Kabitz
- Department of PneumologyCardiology and Intensive Care Medicine, Klinikum Konstanz Konstanz Germany
| | - Esra Akova‐Oeztuerk
- Respiratory Physiology Laboratory, Department of Neurology, University of Münster Münster Germany
| | - Bianca Draeger
- Respiratory Physiology Laboratory, Department of Neurology, University of Münster Münster Germany
| | - Simon Herkenrath
- Bethanien Hospital gGmbH Solingen Solingen Germany
- Institute for Pneumology at the University of Cologne Cologne Germany
| | - Winfried Randerath
- Bethanien Hospital gGmbH Solingen Solingen Germany
- Institute for Pneumology at the University of Cologne Cologne Germany
| | | | - Tobias Brix
- Institute of Medical Informatics, University of Münster Münster Germany
| | - Matthias Boentert
- Respiratory Physiology Laboratory, Department of Neurology, University of Münster Münster Germany
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12
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Geary CM, Welch JF, McDonald MR, Peters CM, Leahy MG, Reinhard PA, Sheel AW. Diaphragm fatigue and inspiratory muscle metaboreflex in men and women matched for absolute diaphragmatic work during pressure-threshold loading. J Physiol 2019; 597:4797-4808. [PMID: 31348520 DOI: 10.1113/jp278380] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Accepted: 07/23/2019] [Indexed: 11/08/2022] Open
Abstract
KEY POINTS The female diaphragm fatigues at a slower rate compared to that of males, with blunted cardiovascular consequences (i.e. inspiratory muscle metaboreflex). It is unclear if these findings are a function of relative or absolute diaphragmatic work. We asked if sex differences in diaphragm fatigue and the inspiratory muscle metaboreflex persisted during inspiratory loading performed at equal absolute intensities. We found that matching men and women for absolute diaphragmatic work resulted in an equal degree of diaphragm fatigue, despite women performing significantly greater work relative to body mass. Metabolite-induced reflex influences in sympathetic outflow originating from the diaphragm are attenuated in women, with potential implications for blood flow distribution during exercise. ABSTRACT In response to inspiratory pressure-threshold loading (PTL), women have greater inspiratory muscle endurance time, slower rate of diaphragm fatigue development, and a blunted pressor response compared to men. It is unclear if these differences are due to discrepancies in absolute diaphragm force output. We tested the hypothesis that following inspirations performed at equal absolute intensities, females would develop a similar level of diaphragm fatigue and an attenuated cardiovascular response relative to men. Healthy young men (n = 8, age = 24 ± 3 years) and women (n = 8, age = 23 ± 3 years) performed PTL whilst targeting a transdiaphragmatic pressure (Pdi ) of 92 cmH2 O for 5 min. Diaphragm fatigue was assessed via twitch Pdi (Pdi,tw ) using cervical magnetic stimulation. Heart rate (HR) and mean arterial blood pressure were monitored continuously. During PTL, the absolute amount of diaphragm work was not different between men (13,399 ± 2019 cmH2 O s) and women (12,986 ± 1846 cmH2 O s; P > 0.05); however, women performed the PTL task at a higher relative P ¯ di /Pdi,max . Following inspiratory PTL, the magnitude of reduction in Pdi,tw was similar between men (-27.1 ± 7.2%) and women (-23.8 ± 13.8%; P > 0.05). There were significant increases in HR over time (P < 0.05), but this did not differ on the basis of sex (P > 0.05). Mean arterial blood pressure increased significantly over time in both men and women (P < 0.05); however, the rate of change was higher in men (6.24 ± 2.54 mmHg min-1 ) than in women (4.15 ± 2.52 mmHg min-1 ) (P < 0.05). We conclude that the female diaphragm is protected against severe fatigue when inspiratory work is excessive and as a result does not evoke overt sympathoexcitation.
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Affiliation(s)
- Caitlin M Geary
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Joseph F Welch
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Department of Physical Therapy, University of Florida, Gainesville, FL, USA
| | - Malcolm R McDonald
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Carli M Peters
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Michael G Leahy
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Paige A Reinhard
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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13
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Electrophysiological Properties of the Human Diaphragm Assessed by Magnetic Phrenic Nerve Stimulation: Normal Values and Theoretical Considerations in Healthy Adults. J Clin Neurophysiol 2019; 36:375-384. [PMID: 31145172 DOI: 10.1097/wnp.0000000000000608] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE This study determined normal values for motor evoked potentials (MEPs) and compound muscle action potentials (CMAPs) of the diaphragm following cortical and cervical magnetic stimulation (COMS and CEMS) of the phrenic nerves in healthy adults. METHODS Using surface electrodes, diaphragmatic MEP and CMAP were recorded in 70 subjects (34 ± 13 years, 25 men) following supramaximal cortical magnetic stimulation and CEMS at functional residual capacity and using a standardized inspiratory pressure trigger (-0.5 kPa). All healthy volunteers underwent standard spirometry and measurement of maximum inspiratory and expiratory pressure. RESULTS At functional residual capacity, upper limit of normal for MEP latency was 25 ms in men and 23 ms in women (p < 0.05), and upper limit of normal for CMAP latency was 6 ms. In contrast to MEP and CMAP amplitude, corresponding latencies showed little interindividual and intraindividual variability. Use of an inspiratory pressure trigger enhanced reproducibility and amplitude of diaphragm MEP. Diaphragm responses to both cortical and cervical magnetic stimulation were symmetrical and independent of age (in our cohort), with higher values for latency and amplitude in men (each p < 0.05). Diaphragm CMAP amplitude showed weak-moderate correlations with forced vital capacity (r = 0.47; p < 0.01), maximum inspiratory pressure (r = 0.39; p < 0.01), and maximum expiratory pressure (r = 0.32; p < 0.01). CONCLUSIONS Combination of cortical magnetic stimulation and CEMS of the phrenic nerves is feasible and allows noninvasive assessment of both central and peripheral conductivity of the diaphragm and the inspiratory pathway.
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14
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Abstract
Respiratory failure is common during acute exacerbation of chronic obstructive pulmonary disease (AE-COPD). Phrenic nerve conduction (PNC), transcranial magnetic stimulation (TMS), and cervical magnetic stimulation (CMS) are of great value in identifying the feature and site of AE-COPD.PNC, TMS, and CMS were performed in 20 AE-COPD patients with respiratory failure, and re-examined after weaning. Latencies and amplitudes of the diaphragmatic compound muscle action potential (dCMAP), motor evoked potential of the diaphragm (dMEP) evoked by TMS and CMS, and central motor conduction time (CMCT) were measured. Blood gas analysis and serum electrolyte levels were also evaluated. The results were compared with those from 20 healthy subjects.AE-COPD patients showed prolonged CMCT and latencies of dCMAP and dMEP, decreased amplitudes of dCMAP and dMEP evoked by CMS, while CMCT and the latency of dMEP evoked by TMS were shortened after weaning. Significant correlation was identified between arterial blood gas analysis, serum electrolyte levels, disease duration, the duration of mechanical ventilation and the electrophysiological findings in AE-COPD patients prior to weaning.The central and peripheral respiratory pathway is involved in AE-COPD. Central respiratory pathway function is improved after weaning in AE-COPD patients with respiratory failure.
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Affiliation(s)
- Yu Wang
- Department of Neurology, Third Central Hospital of Tianjin
- Tianjin Institute of Hepatobiliary Disease
- Tianjin Key Laboratory of Artificial Cell
- Artificial Cell Engineering Technology Research Center of Public Health Ministry, Tianjin, China
| | - Na Liu
- Department of Neurology, Third Central Hospital of Tianjin
- Tianjin Institute of Hepatobiliary Disease
- Tianjin Key Laboratory of Artificial Cell
- Artificial Cell Engineering Technology Research Center of Public Health Ministry, Tianjin, China
| | - Zhecheng Zhang
- Department of Neurology, Third Central Hospital of Tianjin
- Tianjin Institute of Hepatobiliary Disease
- Tianjin Key Laboratory of Artificial Cell
- Artificial Cell Engineering Technology Research Center of Public Health Ministry, Tianjin, China
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15
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Welch JF, Archiza B, Guenette JA, West CR, Sheel AW. Effect of diaphragm fatigue on subsequent exercise tolerance in healthy men and women. J Appl Physiol (1985) 2018; 125:1987-1996. [PMID: 30307818 DOI: 10.1152/japplphysiol.00630.2018] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Women are more resistant to diaphragmatic fatigue (DF) and experience an attenuated inspiratory muscle metaboreflex relative to men. The effects of such sex-based differences on whole body exercise tolerance are yet to be examined. It was hypothesized that DF induced prior to exercise would cause less of a reduction in subsequent exercise time in women compared to men. Healthy men ( n = 9, age = 24 ± 3 yr) and women ( n = 9, age = 24 ± 3 yr) completed a maximal incremental cycle test on day 1. On day 2, subjects performed isocapnic inspiratory pressure-threshold loading (PTL) to task failure followed by a constant load submaximal time-to-exhaustion (TTE) exercise test at 85% of the predetermined peak work rate. On day 3, subjects performed the same exercise test without prior induced DF. Days 2 and 3 were randomized and counterbalanced. Magnetic stimulation of the phrenic nerve roots was used to nonvolitionally assess DF by measurement of transdiaphragmatic twitch pressure ( Pdi,tw). A similar degree of DF was produced in both sexes following PTL [ Pdi,tw (% change from baseline): M = -24.6 ± 7.8%, W = -23.1 ± 5.4%; P = 0.54)]. There was a significant reduction in TTE with prior induced DF compared with the control condition in both men (10.9 ± 3.5 min vs. 13.0 ± 3.2 min, P = 0.05) and women (10.1 ± 2.4 min vs. 12.2 ± 3.3 min, P = 0.03) that did not differ in magnitude between the sexes (M = -15.8 ± 19.5%, W = -14.5 ± 19.2%, P = 0.89). In conclusion, DF negatively and equally impairs exercise tolerance independent of sex. NEW & NOTEWORTHY Women are more resistant to diaphragmatic fatigue (DF) relative to men. The effect of DF on exercise tolerance is currently being debated. Our findings show that DF negatively and equally affects exercise tolerance in healthy men and women. Mechanisms beyond the inspiratory muscle metaboreflex (e.g., dyspnea, central fatigue, breathing pattern) may explain the absence of a sex-based difference.
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Affiliation(s)
- Joseph F Welch
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Bruno Archiza
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada.,Department of Physical Therapy, Federal University of Sao Carlos , Sao Carlos , Brazil
| | - Jordan A Guenette
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada.,Department of Physical Therapy, University of British Columbia , Vancouver, British Columbia , Canada.,Centre for Heart Lung Innovation, Providence Health Care Research Institute, University of British Columbia and St. Paul's Hospital , Vancouver, British Columbia , Canada
| | - Christopher R West
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada.,International Collaboration on Repair Discoveries, University of British Columbia , Vancouver, British Columbia , Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
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16
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Welch JF, Archiza B, Guenette JA, West CR, Sheel AW. Sex differences in diaphragmatic fatigue: the cardiovascular response to inspiratory resistance. J Physiol 2018; 596:4017-4032. [PMID: 29756638 DOI: 10.1113/jp275794] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2018] [Accepted: 05/01/2018] [Indexed: 12/16/2022] Open
Abstract
KEY POINTS Diaphragmatic fatigue (DF) elicits a sympathetically mediated metaboreflex resulting in increased heart rate, blood pressure and limb vascular resistance. Women may be more resistant to DF compared to men, and therefore it was hypothesised that women would experience an attenuated inspiratory muscle metaboreflex during inspiratory pressure-threshold loading (PTL) performed to task failure. At the time of PTL task failure, the severity of DF was not different between sexes; however, inspiratory muscle endurance time was significantly longer in women than in men. For a given cumulative diaphragmatic force output, the severity of DF was less in women than in men. Women exhibited a blunted cardiovascular response to inspiratory resistance (i.e. metaboreflex) that may have implications for exercise tolerance. ABSTRACT Diaphragmatic fatigue (DF) elicits reflexive increases in sympathetic vasomotor outflow (i.e. metaboreflex). There is some evidence suggesting women may be more resistant to DF compared to men, and therefore may experience an attenuated inspiratory muscle metaboreflex. To this end, we sought to examine the cardiovascular response to inspiratory resistance in healthy young men (n = 9, age = 24 ± 3 years) and women (n = 9, age = 24 ± 3 years). Subjects performed isocapnic inspiratory pressure-threshold loading (PTL, 60% maximal inspiratory mouth pressure) to task failure. Diaphragmatic fatigue was assessed by measuring transdiaphragmatic twitch pressure (Pdi,tw ) using cervical magnetic stimulation. Heart rate (HR) and mean arterial pressure (MAP) were measured beat-by-beat throughout PTL via photoplethysmography, and low-frequency systolic pressure (LFSBP ; a surrogate for sympathetic vasomotor tone) calculated from arterial waveforms using power spectrum analysis. At PTL task failure, the degree of DF was similar between sexes (∼23% reduction in Pdi,tw ; P = 0.33). However, time to task failure was significantly longer in women than in men (27 ± 11 vs. 16 ± 11 min, respectively; P = 0.02). Women exhibited less of an increase in HR (13 ± 8 vs. 19 ± 12 bpm; P = 0.02) and MAP (10 ± 8 vs. 14 ± 9 mmHg; P = 0.01), and significantly lower LFSBP (23 ± 11 vs. 34 ± 8 mmHg2 ; P = 0.04) during PTL compared to men. An attenuation of the inspiratory muscle metaboreflex may influence limb and respiratory muscle haemodynamics with implications for exercise performance.
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Affiliation(s)
- Joseph F Welch
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
| | - Bruno Archiza
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Department of Physical Therapy, Federal University of Sao Carlos, Sao Carlos, SP, Brazil
| | - Jordan A Guenette
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,Department of Physical Therapy, Providence Health Care Research Institute, University of British Columbia, Vancouver, BC, Canada.,Centre for Heart Lung Innovation, Providence Health Care Research Institute, University of British Columbia, Vancouver, BC, Canada
| | - Christopher R West
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada.,International Collaboration on Repair Discoveries, University of British Columbia, Vancouver, BC, Canada
| | - A William Sheel
- School of Kinesiology, University of British Columbia, Vancouver, BC, Canada
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17
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Archiza B, Welch JF, Geary CM, Allen GP, Borghi-Silva A, Sheel AW. Temporal characteristics of exercise-induced diaphragmatic fatigue. J Appl Physiol (1985) 2017; 124:906-914. [PMID: 29357497 DOI: 10.1152/japplphysiol.00942.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
There is evidence suggesting diaphragmatic fatigue (DF) occurs relatively early during high-intensity exercise; however, studies investigating the temporal characteristics of exercise-induced DF are limited by incongruent methodology. Eight healthy adult males (25 ± 5 yr) performed a maximal incremental exercise test on a cycle ergometer on day 1. A constant-load time-to-exhaustion (TTE) exercise test was conducted on day 2 at 60% delta between the calculated gas exchange threshold and peak work rate. Two additional constant-load exercise tests were performed at the same intensity on days 3 and 4 in a random order to either 50 or 75% TTE. DF was assessed on days 2, 3, and 4 by measuring transdiaphragmatic twitch pressure (Pdi,tw) in response to cervical magnetic stimulation. DF was present after 75 and 100% TTE (≥20% decrease in Pdi,tw). The magnitude of fatigue was 15.5 ± 5.7%, 23.6 ± 6.4%, and 35.0 ± 12.1% at 50, 75, and 100% TTE, respectively. Significant differences were found between 100 to 75 and 50% TTE (both P < 0.01), and 75 to 50% TTE ( P < 0.01). There was a significant relationship between the magnitude of fatigue and cumulative diaphragm force output ( r = 0.785; P < 0.001). Ventilation, the mechanical work of breathing (WOB), and pressure-time products were not different between trials ( P > 0.05). Our data indicate that exercise-induced DF presents a relatively late onset and is proportional to the cumulative WOB; thus the ability of the diaphragm to generate pressure progressively declines throughout exercise. NEW & NOTEWORTHY The notion that diaphragmatic fatigue (DF) occurs relatively early during exercise is equivocal. Our results indicate that DF occurs during high-intensity endurance exercise in healthy men and its magnitude is strongly related to the amount of pressure and work generated by respiratory muscles. Thus we conclude that the work of breathing is the major determinant of exercise-induced DF.
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Affiliation(s)
- Bruno Archiza
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada.,Department of Physical Therapy, Federal University of São Carlos, São Carlos, São Paolo, Brazil
| | - Joseph F Welch
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Caitlin M Geary
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Grayson P Allen
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
| | - Audrey Borghi-Silva
- Department of Physical Therapy, Federal University of São Carlos, São Carlos, São Paolo, Brazil
| | - A William Sheel
- School of Kinesiology, University of British Columbia , Vancouver, British Columbia , Canada
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