Safety evaluation of therapeutic plasma exchange in patients with lower hematocrit levels

[Objective] To retrospectively assess whether a lower hematocrit level (between 18% and 20%) had any impact on the safety of patients undergoing therapeutic plasma exchange (TPE), and to further determine the threshold for red blood cell supplementation prior to TPE. [Methods] Clinical data from 181 adult patients who underwent TPE treatment at the Department of Blood Transfusion of our hospital from March 2023 to July 2024 were collected. The patients were divided into a study group of 44 patients (Hct ≥18% and <20%) and a control group of 137 patients (Hct≥20%). In two groups, blood volume-related safety indicators including respiration rate, heart rate, systolic blood pressure, and blood oxygen saturation levels before and after TPE were compared using t-test. Between-group differences in the grading of adverse reactions such as allergies and hypotension were analyzed using chi-square test. [Results] A total of 659 TPE treatments were performed on 181 patients, with 169 TPE treatments on 44 patients in the study group (Hct≥18% and <20%) and 490 TPE treatments on 137 patients in the control group (Hct≥20%). There were no statistically significant differences in age, gender, BMI category, and the presence of cardiac insufficiency between the two groups. In the study group, there were no statistically significant differences in safety indicators such as respiration rate, heart rate, systolic blood pressure, and blood oxygen saturation level before and after TPE. In the control group, there were no statistically significant differences in heart rate and systolic blood pressure before and after TPE, but there were statistically significant differences in respiration rate and blood oxygen saturation level (P<0.05). There were no statistically significant differences in the grading of adverse reactions such as allergic reactions and hypotension between the two groups. [Conclusion] For adult patients with stable conditions, maintaining a lower hematocrit level (Hct ≥18% and <20%) during TPE is relatively safe. It is feasible to lower the TPE red blood cell supplementation threshold to 18%≤Hct<20%，which may save blood resources while potentially benefit patients by avoiding unnecessary red blood cell transfusion.