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Respiratory physiology
Poor cough flow in acute stroke patients is associated with reduced functional residual capacity and low cough inspired volume
  1. Katie Ward1,2,
  2. Prashant Rao3,
  3. Charles C Reilly1,
  4. Gerrard Francis Rafferty4,
  5. Michael I Polkey5,6,
  6. Lalit Kalra7 and
  7. John Moxham1
  1. 1 Division of Asthma Allergy and Lung Biology, Respiratory Medicine, King’s College London, London, London, UK
  2. 2 Respiratory Medicine, Royal Free Hospital, London, London, UK
  3. 3 Department of Medicine, University of Arizona, Tucson, Arizona, USA
  4. 4 Department of Child Health, Kings College London School of Medicine, London, UK
  5. 5 Respiratory Medicine, NIHR Biomedical Research Unit at the Royal Brompton and Harefield Foundation Trust, London, UK
  6. 6 Imperial College London, London, UK
  7. 7 Department of Neurosciences, Academic Neurosciences Centre, King’s College London, London, UK
  1. Correspondence to Dr Katie Ward; katieward{at}nhs.net

Abstract

Introduction Each year 7 million people die of stroke worldwide; most deaths are caused by chest infections. Patients with acute stroke have impaired voluntary cough flow, associated with increased risk of chest infections. Reduced functional residual capacity (FRC) could lead to impaired cough flow. We therefore compared FRC in acute hemiparetic stroke patients and controls and explored its relationship with volume inspired before cough and voluntary cough peak flow.

Methods 21 patients within 2 weeks of first-ever middle cerebral artery territory (MCA) infarct (mean (SD) age 68 (11) years, 10 females) and 30 controls (58 (11) years, 15 females) underwent FRC and voluntary cough testing (cough inspired volume and peak flow) while semirecumbent. FRC was expressed as % predicted; cough inspired volume was expressed as % predicted VC and cough peak flow as % predicted PEF. A clinician scored stroke severity using the National Institutes of Health Stroke Scale (NIHSS).

Results Patients’ reclined FRC, voluntary cough peak flowand cough inspired volume were reduced compared with controls (p<0.01 for all): patients’ median (IQR) FRC 76 (67–90) % predicted, mean (SD) cough inspired volume 64 (20) % predicted and mean (SD) peak cough flow 61 (32) % predicted despite them having only mild stroke-related impairments: median NIHSS score 4 (IQR 2–6). Univariate linear regression analyses showed FRC predicted cough inspired volume (adjusted R2=0.45) and cough inspired volume predicted cough flow (adjusted R2=0.56); p<0.01 for both. Sitting patients upright increased their FRC by median 0.210 L.

Conclusions FRC and cough inspired volume in the reclined position are significantly reduced in acute hemiparetic stroke patients with mild impairments; both factors are associated with poor voluntary cough peak flow.

  • cough/mechanisms/pharmacology
  • respiratory measurement
  • respiratory muscles
  • lung physiology

This is an Open Access article distributed in accordance with the terms of the Creative Commons Attribution (CC BY 4.0) license, which permits others to distribute, remix, adapt and build upon this work, for commercial use, provided the original work is properly cited. See: http://creativecommons.org/licenses/by/4.0/

https://doi.org/10.1136/bmjresp-2017-000230

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    Footnotes

    • Contributors KW was responsible for study inception and design, data collection, manuscript preparation and editing. PR performed data acquisition and helped in data analysis and interpretation. CCR was involved in the conception of the study and data collection. GFR contributed to the conception and design of the study and intellectual oversight. MIP, LK and JM were integral to the study conception and design, interpretation of data, revision of the manuscript and intellectual oversight. All authors read and approved the final manuscript.

    • Funding KW was funded by the Medical Research Council and the Royal College of Physicians (G070138) and was previously funded by the Stroke Association (Grant TSA 2004/05). MIP’s contribution to this paper was supported by the National Institute for Health Research (NIHR) Respiratory Biomedical Research Unit at the Royal Brompton and Harefield Foundation Trust and Imperial College (all London, UK), who part fund his salary.

    • Competing interests None declared.

    • Patient consent Obtained.

    • Ethics approval Institutional ethics approval was obtained (LREC 02-120).

    • Provenance and peer review Not commissioned; externally peer reviewed.

    • Data sharing statement Additional unpublished data are not available.