Fall in peak expiratory flow during haemodialysis in patients with chronic renal failure.

Peak expiratory flow rate (PEF) was measured during haemodialysis in 30 unselected patients with chronic renal failure. The patients attended the hospital dialysis unit, where they received regular dialysis using a cuprophan dialyser with acetate buffered dialysate. Mean PEF had fallen by 60 l/min (13%) 30 minutes after the start of dialysis. In 10 of the 30 patients the fall in PEF was over 15%, the maximum fall being 32%. After the initial fall PEF increased throughout the next 2.5 hours of haemodialysis, but it fell again at five hours in the 14 patients who had been dialysed for four hours. During dialysis there was a reduction in blood white cell and platelet counts and in arterial oxygen tension at 30 and 60 minutes (p less than 0.05) and the white cell count and arterial oxygen tension were still reduced at three hours. The coincidence of the fall in PEF at 30 minutes and the fall in arterial oxygen tension suggests that bronchoconstriction might contribute to dialysis induced hypoxaemia by causing ventilation-perfusion disturbances. Appreciable airway dysfunction occurred in all the patients undergoing regular haemodialysis with new cuprophan dialysers and acetate buffered dialysate.