Persistent overhydration despite significant fluid reduction limits lung function improvement after a single haemodialysis session in CKD patients: A before and after study using BIA.

BACKGROUND: Hemodialysis (HD) is frequently employed to remove excess fluids and potentially enhance lung function in patients with Chronic Kidney Disease (CKD) by alleviating congestion. The authors utilized a combination of traditional Bioelectric Impedance Analysis (BIA) parameters and Bioelectric Impedance Vector Analysis (BIVA) to offer more detailed insights into hydration status before and after a single HD session, and correlated these findings with spirometry. METHODOLOGY: The authors conducted an observational before-and-after dialysis study of 45 clinically stable CKD patients attending routine dialysis care. They assessed fluid status and lung function before and after a four-hour dialysis session using a mulifrequency BIA deviceand a standard spirometer. RESULTS: Most study participants (71 %, n = 32) were overhydrated before hemodialysis. The HD session significantly reduced mean Total Body Water (TBW) [t(44) = -11, p < 0.001], Extracellular Water (ECW) [t(44) = -13, p < 0.001], Intracellular Water (ICW) [t(44) = -11, p < 0.001], and Transcellular Water (TSW) [t(44) = -9, p < 0.001]. Despite these reductions, 66 % of participants (n = 21) remained overhydrated based on BIVA. Regarding lung function, 73 % of participants (n = 33) exhibited abnormal pre-hemodialysis spirometry patterns, with 20 % portraying obstructive, 38 % restrictive, and 16 % mixed patterns. Post-hemodialysis, no significant changes were observed in spirometry parameters or their respective % predicted values and lung function patterns. Interestingly, a significant association was found between spirometry patterns and BIVA-determined hydration status both before and after 4 hours of hemodialysis (χ2 = 20, p = 0.002). CONCLUSIONS: The 4-hour dialysis session reduced fluid volumes but did not normalize hydration status for most CKD patients and did not improve lung function post-dialysis.