Blood potassium level associated with recovery of post-operative gastrointestinal motility during continuous renal replacement therapy in critically ill patient undergoing open abdominal surgery

Background: The purpose of the present study was to explore the potential therapeutic goal of blood potassium level beneficial to the post-operative recovery of gastrointestinal motility during continuous renal replacement therapy (CRRT) in critically ill patient undergoing open abdominal surgery. Methods: 538 critically ill patients after open abdominal surgery and receiving CRRT were retrospectively recruited as the study cohort. Demographic and clinical data including plasma potassium levels were recorded along with evaluation of post-operative gastrointestinal motility. The median of first gastrointestinal motility recovery time was 4 days of the present study cohort, and we used gastrointestinal motility recovery during 4-day period and un-recovery at 4 days after the completion of surgery as the primary endpoints. Results: The received operating characteristic (ROC) curve analysis demonstrated that the post-operative blood potassium level during CRRT was significantly associated with the recovery of gastrointestinal motility (AUC = 0.72, p<0.001), and plasma potassium concentration at the cut-off point of the ROC curve was 4.00 mmol/L. Kaplan–Meier analysis indicated that compared with the patients with insufficient blood potassium level (plasma potassium concentration < 4.00mmol/L), those with sufficient level (plasma potassium concentration ≥4.00mmol/L) had higher rate of 4-day post-operative recovery of gastrointestinal motility (p<0.001). Logistic regression analysis indicated that the post-operative blood potassium level was independently associated with the recovery of gastrointestinal motility, patients with a sufficient blood potassium level conferred an increase in the rate of 4-day post-operative recovery of gastrointestinal motility (OR= 4.36, 95% CI 2.92-6.52, p<0.001). Conclusions: Our data indicated that keeping the blood potassium concentration at a relative high level of the regular blood potassium range during CRRT, would be beneficial to post-operative recovery of gastrointestinal motility, and eventually implied the potential therapeutic goal of blood potassium level for the recovery of post-operative gastrointestinal motility during CRRT in critically ill patient undergoing open abdominal surgery.