Pulmonary function in chronic renal failure: effects of dialysis and transplantation

Many possible pulmonary complications of renal disease have been described, but little is known of their physiological importance or the effects on them of different forms of renal replacement therapy. Four groups were recruited, each containing 20 patients. The groups consisted of patients with chronic renal failure before dialysis (group 1); patients receiving continuous ambulatory peritoneal dialysis, never having received a transplant (group 2); patients receiving haemodialysis, never having received a transplant (group 3); and patients after their first successful cadaveric renal transplant (group 4). All were attending the same regional dialysis and transplant unit. None was known to have clinically important lung or chest wall disease. Flow-volume loops were recorded before and after 400 micrograms of salbutamol, and plethysmographic lung volumes and airway conductance and single breath carbon monoxide transfer factor were measured. Only nine of 80 patients had normal lung function. The reductions in spirometric values were minor. Whole lung carbon monoxide transfer factor was reduced in all groups (mean % predicted with 95% confidence intervals: group 1 81.7% (74-89%); group 2 69.7% (62-77%); group 3 87.5% (80-96%); group 4 82.5% (78-87%]. The values were significantly lower in those having continuous ambulatory peritoneal dialysis (group 2). Residual volume was reduced significantly in the group who had undergone renal transplantation (85.7%, 77-94%). There was no correlation between these changes and smoking habit, age, duration or severity of renal failure, duration of treatment, or biochemical derangement. It is concluded that abnormal lung function is common in renal disease. The main change is a reduction in carbon monoxide transfer that persists after transplantation. The likeliest explanation is that subclinical pulmonary oedema progresses to fibrosis before transplantation. The fibrosis may worsen further to cause the reduced residual volume in the recipients of grafts.