Analgesic effectiveness and safety of single-dose intrathecal morphine

Introduction: The superior hemiabdomen postoperative pain is severe and essential to be managed in order to avoid complications. Objectives: To assess the analgesic effectiveness and safety of single-dose intrathecal morphine in the postoperative period of the upper hemiabdomen major surgery. Method: Single-blind randomized clinical trial in 40 patients, after upper hemiabdomen interventions. We used single doses of intrathecal morphine (ITM) of 1 or 2 mg/kg per patient weight according to the treatment group. The statistical analysis used the Chi-square test, Fisher's exact test, univariate analysis of variance, Mauchly's test and Univariate F-test; the significance level was 0.05. Results: Opioids administration during surgery was similar in both groups (3.1 ± 2.2 mL vs. 4.1 ± 2.7 mL). In the 2 mg/kg of ITM dose group, the patients reported no pain after 12 and 14 hours; there were differences between treatments regarding pain relief (p< 0.001) and also between the time when it was measured (p= 0.001). Rescue analgesia was used in 25 % of the patients. Respiratory depression was the only onset complication. Conclusions: ITM at a single dose of 2 μg/kg is an effective method for postoperative analgesia in upper hemiabdomen surgery, the incidence of complications was low and both doses proved safe.