Risk Factors for Hypotension within 24 Hours after Operations in Patients Receiving Epidural Analgesia

Abstract

Objective: Post-operative analgesia is imperative to prevent post-operative complications. Epidural analgesia provides effectiveness superior to systemic analgesia, but might be complicated with motor block or hypotension. The aim of this study was to identify risk factors related to hypotension within 24 hours after operations in patients receiving epidural analgesia.
Methods: A case-control study was conducted in 60 case patients and 240 control patients.  Patient, surgical and anesthetic risk factors were collected. Patient factors included body mass index, pre-operative blood pressure, ASA classification, underlying diseases, current medications, bowel preparation, intravenous fluid replacement after fasting, and pre- and post-operative anemia. Surgical factors were operation for malignancy, operative time, blood loss, blood transfusion and urine output status. Anesthetic factors including choice of anesthesia, site of epidural catheter and its appropriateness, agents administered via epidural route, post-operative patient-controlled epidural analgesia use, additional systemic analgesia, and agents administered were recorded.  Univariate and multiple logistic regression analysis were used to identify risk factors.
Results: The probability of hypotension increased in patients with coronary artery disease (odds ratio (OR) = 6.36, 95% Confidence interval (CI) = 1.38, 29.33) and post-operative anemia with hemoglobin concentration less than 10 gm/dL (OR = 4.13, 95% CI = 2.03, 8.43). The other factors showed no correlations with hypotension.  No serious consequences occurred in hypotensive patients.
Conclusion: Risk factors associated with hypotension within 24 hours after operations in patients receiving epidural analgesia were coronary artery disease and post-operative hemoglobin less than 10 gm/dL.

Keywords: Epidural analgesia, post-operative hypotension, risk factor