Effect of hemodialysis and fluid removal on lung function in patients with kidney failure-a pre-post study

Fluid overload may worsen pulmonary mechanics in patients with kidney failure. We evaluated the acute impact of a single hemodialysis (HD) session on lung volumes, flows, respiratory muscle strength, and the prevalence of preserved ratio impaired spirometry.

A pre-post observational study was conducted at a university hospital dialysis unit. Forced expiratory volume in one second (FEV1), peak expiratory flow, and FEV1 to forced vital capacity (FVC) ratio (FEV1/FVC) were measured by spirometry, while maximum inspiratory pressure and maximum expiratory pressure were measured by manovacumetry. Evaluations were performed before and after the HD session. The association between changes in respiratory volumes and pressures and the volume of ultrafiltration (UF) removed during the HD session was evaluated using adjusted linear regression.

The study included 104 patients (57% male), with a mean age of 54.7 (15.8) years. Both maximum expiratory pressure (71.3 ± 39.6 to 79.7 ± 35.4% predicted) and maximum inspiratory pressure (64.5 ± 29.0 to 69.9 ± 32.1% predicted) significantly increased from before to after the HD session (P < .001 for both). The ratio (FEV1/FVC) was 80.1 (77.1 to 83.14) % before and 83.5 (80.7 to 86.3) % after the HD session (P = .02). The proportion of participants meeting preserved ratio impaired spirometry criteria significantly decreased from 56.0% to 43.5% after HD (P < .001). The UF volume was positively correlated with changes in % FEV1/FVC ratio (β = 1.84, P = .04) and FEV1 (β = .09, P = .006).

HD was associated with acute improvements in respiratory muscle strength and in spirometry pattern (reduction in preserved ratio impaired spirometry prevalence). The magnitude of improvement in FEV1/FVC and FEV1 correlated with UF volume, suggesting a role of fluid removal. Further studies should confirm these findings longitudinally and investigate clinical outcomes.