A randomized, placebo-controlled, doubleblind study of the analgesic efficacy of extraperitoneal wound instillation of bupivacaine and morphine in abdominal surgeries

Abstract

surgical settings but with a variable response. However, the use of morphine for extraperitoneal instillation after abdominal surgery has not been studied. We designed this study to evaluate the analgesic efficacy of extraperitoneal wound instillation of bupivacaine and morphine in abdominal surgeries. We also evaluated whether using this combination could lead to improvement of the respiratory functions.Methodology: After ethical committee clearance, this prospective, randomized, placebo-controlled, double blind study was carried out in sixty patients of age group 18-65 years, undergoing abdominal surgery and specifically requiring midline incision. In the operating room, a standardized technique of general anesthesia was followed. At the end of the surgery a multiport Romovac® suction catheter (Romsons Group of Companies India) was placed along the length of the wound between the peritoneal layer and muscle layers and led out through a separate stab wound. The patients were then randomized into three groups: Group C (n-20): Wound perfused with normal saline; Group B (n-20): Wound perfused with 0.5% bupivacaine; Group BM (n-20): Wound perfused
with 0.5% bupivacaine along plus morphine (0.05 mg/kg). 15 ml of solution was given as slow bolus over 2-3 minutes via the catheter. Rescue analgesia was provided with intravenous tramadol (50 mg) if VAS score>30 mm. The VAS score at rest and on coughing was noted at 1, 3, 6, 9, 12, 24 hours. Time to demand the first rescue analgesia was recorded. Vital signs, peak expiratory flow rate and inspiratory flow rate were also recorded at 1, 3, 6, 9, 12 and 24 hour after operation. Results: The demographic profile, type of surgery, duration of surgery were comparable among the three groups (p>0.05). The peak expiratory flow rate was maximum at any point of time in Group BM as compared to Group C and B (p value <0.05). But inspiratory flow rate with respect to time was almost same in the three groups (p value >0.05). The VAS scores (on rest and cough) were significantly lower at all time intervals in Group BM
as compared to Group B and C (p value (0.001). The first rescue analgesia was demanded at 1.25± 0.3 hours in Group C as compared to 3.68± 0.71 hours in Group B and 10.7±4.1 hours in Group BM (p value 0.001). Conclusion: We observed from our study that wound perfusion with 0.5% bupivacaine and morphine combination reduces pain and thus the need of rescue analgesia. The combination was also associated with significant improvement in lung functions postoperatively without any additional side effects.