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

Abstract

• Severe overhydration often follows long dialysis-free periods in CKD patients. • Hemodialysis removes excess fluids, potentially reducing lung congestion. • A single dialysis session reduces fluids but fails to restore normal hydration. • Persistent overhydration after dialysis limits lung function improvement. • BIA-guided dialysis monitoring may optimize fluid balance and patient outcomes. 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. 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. 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 (χ 2 = 20, p = 0.002). 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.