RESPIRATORY PHYSIOLOGY BEFORE AND AFTER HEMODIALYSIS IN CHRONIC RENAL-FAILURE PATIENTS

Pulmonary function tests were performed immediately before and after hemodialysis in 11 normovolemic patients with chronic renal failure. In order to delineate the relative contributions of thoracic and abdominal musculature to the breathing process, lung volumes were determined in the horizontal (0°) and semiupright postures (75°). Maximal static inspiratory pressures, handgrip pressures, flow rates, and arterial blood gases were also determined. Vital capacity, inspiratory capacity, and expiratory reserve volume were significantly reduced and residual volume was significantly increased in both positions prior to dialysis (relative to predicted values). maximal static inspiratory pressure, maximal static expiratory pressure, and arterial oxygen tension were also significantly reduced. After dialysis, expiratory reserve volume decreased significantly and residual volume increased significantly in the 75° position. Maximal static expiratory pressure decreased after dialysis although the statistical significance of this result was only borderline (p=0.07). Hand-grip pressure also decreased (p=0.005) following dialysis. The results of this study indicate that chronic renal failure patients undergoing maintenance hemodialysis have predialysis abdominal and thoracic muscle weakness with further abdominal weakening postdialysis. The results also indicate that other muscle groups (such as those of the hand and arm) weaken during hemodialysis.