Analysis of the causes of arrhythmia induced by citrate anticoagulation in continuous renal replacement therapy

OBJECTIVE To analyze the possible causes of arrhythmia in patients receiving continuous renal replacement therapy (CRRT) with regional citrate anticoagulation (RCA). METHODS A retrospective cohort study was conducted. All patients underwent RCA-CRRT treatment from January 1, 2020 to October 31, 2020 in the intensive care unit (ICU) of Tianjin Third Central Hospital were enrolled. The patients were divided into arrhythmia group and non-arrhythmia group according to whether arrhythmia occurred. The gender, age, acute physiology and chronic health evaluation II (APACHE II) score, catheterization site, underlying diseases, electrocardiogram (ECG), electrolytes [total calcium, serum free calcium (iCa2+), phosphorus, magnesium, potassium] and blood gas analysis (pH value, HCO3-) of patients in the two groups were recorded. The changes of ECG were observed, the differences in electrolyte and blood gas analysis indexes between the two groups of patients at different time points (before CRRT, 24, 48, 72 hours after CRRT, and when arrhythmia occurred) were compared. RESULTS A total of 86 RCA-CRRT patients were enrolled, of which 12 cases (13.95%) had arrhythmia, and the remaining 74 cases (86.05%) had no arrhythmia. The average time for the occurrence of arrhythmia in the 12 patients was (44.00±16.82) hours. There was no significant ST-segment change in the ECG when the arrhythmia occurred compared with that before CRRT, the total calcium level was significantly higher than that before CRRT (mmol/L: 2.48±0.40 vs. 2.13±0.35, P < 0.05), the blood magnesium level was significantly lower than that before CRRT (mmol/L: 0.73±0.20 vs. 0.95±0.25, P < 0.05). There was no significant difference in iCa2+, blood phosphorus, blood potassium, pH value and HCO3- between before CRRT and when arrhythmia occurred. Over time, the total calcium levels in the two groups increased, and there was a statistical difference between the 48 hours after CRRT and before CRRT (mmol/L: 2.48±0.33 vs. 2.13±0.35 in the arrhythmia group, and 2.30±0.22 vs. 2.15±0.48 in non-arrhythmia group, both P < 0.05). The linear change trend of iCa2+, pH value and HCO3- was not obvious in the two groups. The blood phosphorus and blood magnesium levels in the two groups decreased. The blood potassium in the arrhythmia group decreased, however, the blood potassium level in non-arrhythmia group did not change significantly. The total calcium level in the arrhythmia group was significantly higher than that in the non-arrhythmia group at 72 hours after CRRT (mmol/L: 2.69±0.35 vs. 2.45±0.23, P < 0.05); however, there was no significant difference in serum iCa2+, phosphorus, magnesium, potassium, pH value and HCO3- between the two groups. CONCLUSIONS Patients receiving RCA-CRRT were less likely to develop arrhythmia, the causes may be related to the accumulation of citric acid and electrolyte disturbances such as calcium, phosphorus, and magnesium.