Respiratory muscle strength and training in stroke and neurology: a systematic review

We undertook two systematic reviews to determine the levels of respiratory muscle weakness and effects of respiratory muscle training in stroke patients. Two systematic reviews were conducted in June 2011 using a number of electronic databases. Review 1 compared respiratory muscle strength in stroke and healthy controls. Review 2 was expanded to include randomized controlled trials assessing the effects of respiratory muscle training on stroke and other neurological conditions. The primary outcomes of interest were maximum inspiratory and expiratory mouth pressure (maximum inspiratory pressure and maximum expiratory pressure, respectively). Meta-analysis of four studies revealed that the maximum inspiratory pressure and maximum expiratory pressure were significantly lower (P < 0.00001) in stroke patients compared with healthy individuals (weighted mean difference -41.39 and -54.62 cmH2O, respectively). Nine randomized controlled trials indicate a significantly (P = 0.0009) greater effect of respiratory muscle training on maximum inspiratory pressure in neurological patients compared with control subjects (weighted mean difference 6.94 cmH2O) while no effect on maximum expiratory pressure. Respiratory muscle strength appears to be impaired after stroke, possibly contributing to increased incidence of chest infection. Respiratory muscle training can improve inspiratory but not expiratory muscle strength in neurological conditions, although the paucity of studies in the area and considerable variability between them is a limiting factor. Respiratory muscle training may improve respiratory muscle function in neurological conditions, but its clinical benefit remains unknown.