【Abstract】Objective To study the relationship between high frequency dialysis related intradialytic hypotension (IDH) and post-dialysis lactic acid level in maintenance hemodialysis (MHD) patients. Methods A total of 115 patients with regular MHD were enrolled in this study. These patients were treated in the Department of Blood Purification, Beijing Chao-Yang Hospital, Capital Medical University during the period from January 1st, 2018 to January 1st, 2019. According to the prevalence of high frequency dialysis related IDH in the 3 months of dialysis period, they were divided into observation group (the prevalence ≥30%) and control group (the prevalence <30%). Their clinical and laboratory data were recorded. Independent sample t test was used to investigate the relationships between the blood gas changes before and after dialysis and the pre- dialytic blood routine, renal function, ions, uric acid, blood sugar and C-reactive protein in observation group and control group. Binary logistic regression was used to analyze the important factors influencing the high frequency dialysis related IDH. Receiver operating characteristic (ROC) curve was used to evaluate the value of lactic acid for the diagnosis of high frequency dialysis related IDH. P<0.05 was considered to be statistically significant. Results Patients with high- frequency dialysis related IDH accounted for 23.48% (27/115) of the patients. Compared with those in control group, mean hemoglobin concentration of red blood cells was lower (321.670±10.144g/L vs. 328.659±10.974g/L, t=-2.944, P=0.004), red blood cell distribution width
(RDW-CV) was higher (14.496±1.535% vs. 13.686±0.945%, t=2.594, P=0.014), and post-dialysis lactic acid was higher (1.881±0.627mmol/L vs. 1.437±0.7mmol/L, t=2.949, P=0.004) in observation group. Binary logistic regression showed that the higher levels of red blood cell distribution width and post- dialysis lactic acid were the risk factors for high- frequency dialysis related IDH (OR=1.630, 95% CI 1.046~2.539, P=0.031; OR=2.364, 95% CI 1.237~4.517, P=0.009). ROC curve demonstrated that the area under the curve (AUC) of lactic acid was 0.721 (95% CI 0.605~0.837, P=0.001). Conclusions The increase of post-dialysis lactic acid is an important risk factor for high frequency dialysis related IDH and is valuable for the prediction of the IDH.