Abstract: 【Abstract】Objective To explore the relationship between fluid status and lung function in hemodialysis patients with end-stage renal disease (ESRD). Methods From April to October 2019, 54 ESRD patients receiving hemodialysis in the blood purification center of our hospital were enrolled. Respiratory function was measured before and after hemodialysis, and overhydration (OH), extracellular water (ECW), and OH/ECW% were measured using the DSM-BIA method. OH/ECW＞7% is considered overhydration. Results The levels of FVC, FVC% and FEV1 were significantly increased after hemodialysis. In terms of BIA parameters, patients’OH/ECW% after dialysis was statistically lower than that before dialysis (t value: 2.213, 2.389, 2.327 and 15.117, respectively，P value: 0.030,0.019, 0 .022 and＜0.001, respectively). Overhydration was seen in 15 patients (27.8%). The FVC, FVC%, FEV1, FEV1%, FEF25-75, FEF25-75%, PEFR and PEFR% in the overhydration group were all lower than those in the non-overhydration group, and the differences were statistically significant(t value: 4.740, 5.131, 4.902, 6.226, 4.263, 3.668, 2.904 and 3.694, respectively，P value:＜0.001,＜0.001,＜0.001,＜0.001, ＜0.001,＜0.001, 0.005 and＜0.001, respectively). OH/ECW was negatively correlated with FVC, FVC%, FEV1, FEV1%, FEF25-75, FEF25-75%, PEFR and PEFR% (r value:–0.411, –0.530, –0.395, –
0.491,–0.307,–0.272,–0.302and–0.425, respectively，P value: 0.002, ＜0.001, 0.003, ＜0.001, 0.024, 0.047, 0.027 and 0.001, respectively). Stepwise multiple linear regression model showed that increases in male and ultrafiltration were independently associated with higher FVC (Standard Beta value: 0.341 and 0.218 respectively，P value: 0.002 and 0.040 respectively), while increases in age and OH/ECW% were independently associated with lower FVC (Standard Beta value:–0.419 and -0.314 respectively, P value:＜0.001 and 0.002 respectively). Conclusion Overhydration is significantly related to respiratory dysfunction in ESRD patients who undergoing hemodialysis. Hemodialysis has a significant treatment to improve lung function, which may be due to the relief of overhydration after hemodialysis.

Key words: end- stage renal disease, hemodialysis, pulmonary function, fluid overload, bioimpedance analysis