Determination of pulmonary tissue volume, pulmonary capillary blood flow and diffusing capacity of the lung before and after hemodialysis.

In order to better understand changes in lung function before and after dialysis, we studied eight patients with end-stage renal disease undergoing chronic hemodialysis. Pulmonary tissue volume (Vt), pulmonary capillary blood flow (Qc), the diffusion capacity for carbon monoxide (DLCO), arterial blood gases and body weight were measured before and after dialysis. A single breath, constant expiratory flow technique for determination of of DLCO, Qc and Vt was used. DLCO, Qc, arterial carbon dioxide, and body weight were reduced post dialysis (P less than or equal to .01) while Vt failed to change. The alveolar-arterial oxygen difference rose 123 mmHg (P = .01). These results are consistent with pulmonary microembolization during dialysis with deterioration of gas exchange and Qc. These changes appear to occur independent of significant changes in Vt. Possible physiologic mechanisms are discussed.