Pulmonary function in uremic patients on long-term hemodialysis

Twenty patients with end-stage renal failure who were on maintenance hemodialysis (HD) underwent pulmonary function testing (PFT) before and shortly after an HD session. On pre-HD PFT, the mean values of all parameters except residual volume (RV) were in the normal range. Mean RV was high (152.9%), and mean diffusing capacity of the lung for carbon monoxide (DLCO) was high-normal (110.4%). The pre-HD static inspiratory (PImax) and expiratory pressures (PEmax) were much lower than normal (67.4% and 36.3%, respectively). After the HD session, repeat PFT revealed a small increase in expiratory flow rates, and a significant drop in PImax. There was a strong correlation between PImax and PEmax (r=0.567,p<0.01) at the pre- and post-HD stages, indicating that common mechanism(s) are responsible for impairment of both inspiratory and expiratory muscle strength. The well-preserved DLCO was thought to be due to the use of biocompatible dialyzer membranes. Chronic vascular congestion might be the other explanation of high DLCO.