Effect of chronic renal failure on respiratory muscle strength

In 10 patients with chronic renal failure (CRF), undergoing hemodialysis, we studied respiratory muscle strength and endurance.The data obtained was compared with those acquired from 10age−,sex−, weight− and height−matched normal volunteers. Maximalstatic inspiratory pressures (PI_max) measured at residualvolume and maximal static expiratory pressures (PE_max) measured at total lung capacity were significantly lower in the CRF group, 58.2 ± (SD)24.9 and 50.8 ± (SD)24.2% of predicted, respectively (p [ 0.005, p [ 0.01). There was a significant correlation between PI_max and PE_max(r = 0.827, p [ 0.001), indicating similar involvement of both inspiratory and expiratory muscle groups. Maximal voluntary ventilation (MVV), although 84.4% of the predicted value in the CRF group, was significantly lower than in the control group, where it was 114% of predicted (p [ 0.001). MVV also correlated significantly with PI_max and PE_ma(r = 0.764, p [ 0.001 and r = 0.807, p [ 0.001, respectively). All but one CRF patient had elevated serum inorganic phosphorus levels, and a significant correlation was found between the serum inorganic phosphorus levels and PI_max and PE_max (r = 0.718, p [ 0.001). These data indicate that there is an impairment of respiratory muscle strength and endurance in patients with CRF which may predispose the patient to respiratory muscle fatigue.