Effects of positive expiratory pressure on chest wall volumes in subjects with stroke compared to healthy controls: a case–control study

BACKGROUND Alterations in respiratory system kinematics in stroke lead to restrictive pattern associated with decreased lung volumes. Chest physical therapy, such as positive expiratory pressure, may be useful in the treatment of these patients; however, the optimum intensity to promote volume and motion changes of the chest wall remains unclear. OBJECTIVE To assess the effect of different intensities of positive expiratory pressure on chest wall kinematics in subjects with stroke compared to healthy controls. METHODS 16 subjects with chronic stroke and 16 healthy controls matched for age, gender, and body mass index were recruited. Chest wall volumes were assessed using optoelectronic plethysmography during quiet breathing, 5 minutes, and recovery. Three different intensities of positive expiratory pressure (10, 15, and 20cmH2O) were administered in a random order with a 30 minutes rest interval between intensities. RESULTS During positive expiratory pressure, tidal chest wall expansion increased in both groups compared to quiet breathing; however, this increase was not significant in the subjects with stroke (0.41 vs. 1.32L, 0.56 vs. 1.54L, 0.52 vs. 1.8L, at 10, 15, 20cmH2O positive expiratory pressure, for stroke and control groups; p<0.001). End-expiratory chest wall volume decreased in controls, mainly due to the abdomen, and increased in the stroke group, mainly due the pulmonary rib cage. CONCLUSION Positive expiratory pressure administration facilitates acute lung expansion of the chest wall and its compartments in restricted subjects with stroke. Positive expiratory pressure intensities above 10cmH2O should be used with caution as the increase in end-expiratory volume led to hyperinflation in subjects with stroke.