Effectiveness of continuous wound infusion of local anesthetics after abdominal surgeries

Abstract

Background: To assess the effectiveness of continuous preperitoneal wound infusion of local anesthetic drug bupivacaine in providing pain relief, reducing opioid consumption, and enhancing postoperative recovery.

Methods: Eligible patients were randomly allocated to two groups (study group: bupivacaine and control group: normal saline). There were 47 patients in each group. The patients received continuous infusion of either 0.25% bupivacaine or 0.9% normal saline at 6 mL/h, for 48 h, based on their group allocation, through a multiholed wound infiltration catheter placed preperitoneally. All patients also received intravenous morphine through patient-controlled analgesia pump. Pain scores at rest and on cough, morphine consumption, and peak expiratory flow rate were assessed at 12, 24, and 48 h postoperatively. The time to first perception of bowel sounds and first passage of flatus was noted. All patients were assessed for postoperative nausea and vomiting and any local or systemic complications. Chi-square test was used to compare categorical variables. The morphine consumption was compared using Student t-test, the visual analogue scale (VAS) scores were compared using repeated-measures analysis of variance.

Results: The mean total morphine consumption in the study group was significantly lower than the control group (18.8 ± 2.21 versus 30.8 ± 2.58 mg, P = 0.001). The median VAS scores were significantly lower in the study group than those in the control group both at rest (3 [1-4] versus 4 [2-5], P = 0.04) and during cough (4 [3-6] versus 6 [4-6] P = 0.03), except at 48 h, when the median VAS score at rest was similar (3 [1-4] versus 3 [2-4], P = 0.56). Bowel function returned earlier in study group (67.34 ± 2.61 versus 76.34 ± 5.29 h, P = 0.03). Postoperative nausea and vomiting was less in study group. Respiratory function, assessed by peak expiratory flow rate, was better in the study group (192.55 ± 12.93 versus 165.31 ± 9.32 mL, P = 0.03). The incidence of surgical site infection was similar in both the groups (3/47 versus 5/47, P = 0.06). There was no systemic toxicity of local anesthetic.

Conclusion: Continuous preperitoneal wound infusion of local anesthetic provides effective analgesia, reduces morphine consumption and its associated side effects, and enhances the postoperative recovery by reducing the incidence of prolonged postoperative ileus.

Keywords: Continuous wound infusion; Local anesthetic; Pain relief.