Changes in pulmonary function in patients with chronic renal failure after successful renal transplantation

Pulmonary function abnormalities have been described in patients with chronic renal failure. There are very few longitudinal studies showing the effect of renal transplantation on pulmonary function. We aimed to study the effects of renal failure on pulmonary functions and to observe the changes following successful renal transplantation.

Patients with end-stage renal failure (n=25) of various etiologies who presented to the renal transplant unit of a teaching hospital were included in this prospective, longitudinal study. Patients with a prior history of pulmonary disease and chronic smokers were excluded. Pulmonary function tests were performed and blood gases evaluated before and 6 months after successful renal transplantation.

Most patients showed pulmonary function abnormalities which improved significantly after transplantation. The mean vital capacity increased from 2.89 (95% CI 2.63-3.15) l pre-transplantation to 3.32 (95% CI 3.09-3.54) l post-transplantation (p<0.001), indicating that subjects had a restrictive pulmonary function defect which improved after transplantation. The large airways were normal, as evidenced by normal forced expiratory volume in the first second:forced vital capacity ratios. There was significant small airways dysfunction, as shown by low maximal mid-expiratory flow rates, which tended to improve after renal transplantation (p=0.013). There was also a highly significant (p<0.001) improvement in maximal voluntary ventilation (MVV) after transplantation. The MVV test is a composite test which measures all aspects of pulmonary function, including respiratory muscle strength. However, not all patients achieved normal pulmonary function due to uremia-induced irreversible pre-transplantation changes.

Pulmonary function abnormalities are common in patients with chronic renal failure but can be significantly ameliorated following successful renal transplantation.