S118 Acute hemispheric stroke patients have reduced functional residual capacity and cough flow rates

• Published in: Thorax Vol. 65; no. Suppl 4; pp. A54 - A55
• Main Authors: Rao, P R, Ward, K W, Reilly, C R, Rafferty, G R, Moxham, J
• Format: Journal Article
• Language: English
• Published: London BMJ Publishing Group LTD 01.12.2010
• ISSN: 0040-6376; 1468-3296
• DOI: 10.1136/thx.2010.150946.19

IntroductionCough is a complex manoeuvre, requiring coordinated action of the respiratory and upperairway musculature. The mechanisms of impaired cough following hemispheric stroke are unclear. Reduced functional residual capacity (FRC) may impair cough due to the effect of lung volume on the length and pressure generating capacity of the expiratory muscles. We compared FRC (primary outcome) and peak cough flowrate for voluntary cough (PCFR, secondary outcome) in stroke patients and healthy controls.Methods27patients and 30 healthy controls were studied. Stroke patients were within 2 weeks of first-ever middle cerebral artery infarct. Stroke severity was scored by a clinician (NIHSS score, worst=31). FRC was measured by helium dilution using a dry rolling seal spirometre. To measure PCFR, subjects wore a tight-fitting facemask and were asked to cough forcefully into the spirometre. During these measurements, the volume inspired before the cough manoeuvre was also recorded. Measurements were performed in a chair with the back reclined to 45°, mimicking patient position in hospital. FRC and PCFR data were expressed as % predicted.1ResultsPatients' median NIHSS score was 4 (IQR 2–6) reflecting mild disability. FRC % predicted, the volume inspired before cough and PCFR were significantly reduced in patients. Both FRC and the volume inspired before cough were significant predictors of PCFR.ConclusionsFRC (% predicted), the volume inspired before cough and PCFR were significantly reduced in acute hemispheric stroke patients. Higher peak cough flow rates are associated with greater lung volume prior to cough. Interventions that increase FRC, for example, continuous positive airway pressure and upright sitting may improve cough function in stroke patients.Abstract 118 Table 1StrokeControlDifference (95% CI)p ValueNumber of participants2730Age (years)Mean6858100.001SD11114 to 16SexMale/female17/2715/150.130.420†Proportion male0.630.50−0.12 to 0.36Height (centimetres)Mean169.6169.7−0.10.997SD7.912.2−5.6 to 5.6O2 saturations breathing air (%)Median979700.660*IQR92 to 9895 to 98−1 to 1SmokingNumber ever/never smoked13/1412/180.10.599†Proportion ever smoked0.300.40−0.2 to 0.3Functional residual capacity (litres)Median2.5002.780−0.2700.003*IQR2.323 to 3.6012.258 to 2.898−0.710 to 0.115Functional residual capacity (% predicted)Median76.090.0−14.0<0.001*IQR66.5 to 89.579.8 to 105.0−22.0 to −5.0Peak cough flow rate (litres/min)Mean297380−830.019SD133121−153 to −14Peak cough flow rate (% predicted PEF)Mean61.286.3−25.1<0.001SD32.617.3−38.8 to −11.4Volume inspired before cough (litres)Mean2.2193.409−1.190<0.001SD0.8280.720−1.715 to 0.665Volume Inspired before cough (% predicted VC)Mean64.394.6−30.1<0.001SD19.515.6−42.2 to 18.5p Values calculated using t tests except.*p Value calculated using Mann–Whitney U test.†p Value calculated using Fisher's exact test.PEF, peak expiratory flow rate; O2, oxygen.