Determination of Pulmonary Tissue volume,Pulmonary Capillary Blood Flow and Diffusing Capacity of the Lung before and after Hemodialysis

Abstract

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 (V_t), pulmonary capillary blood flow (Q̇_c), the diffusing capacity for carbon monoxide (D_LCO), arterial blood gases and body weight were measured before and after dialysis. A single breath, constant expiratory flow technique for determination of D_LCO, Q̇_c and V_t was used. D_LCO, Q̇_c, arterial carbon dioxide, and body weight were reduced post dialysis (P ≤ .01) while V_t failed to change. The alveolar-arterial oxygen difference rose 12 mmHg (P = .01). These results are consistent with pulmonary microembolization during dialysis with deterioration of gas exchange and Q̇_c. These changes appear to occur independent of significant changes in V_t. Possible physiologic mechanisms are discussed.