Effect of wound infiltration with bupivacaine on pulmonary function after elective lower abdominal operations.

BACKGROUND Subcutaneous or intrafascial wound infiltration of local anaesthetic with systemic opioids has been shown to enhance patient comfort with improved analgesia and reduced opioid requirements. OBJECTIVE To demonstrate improved pulmonary function when postoperative analgesia was provided by combined bupivacaine wound infiltration and systemic opioid. METHODS In a prospective, randomized, placebo-controlled study, 46 patients (23 per group) scheduled for elective gynaecological surgery under general anaesthesia had subcutaneous and intrafascial wound infiltration of 40 ml, 0.25% bupivacaine (study patients) or 40 ml 0.9% saline (control) just before the end of surgery. Forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1) and peak expiratory flow rate (PEFR) were done before surgery and at 6, 12 and 24 hours postoperatively. Student's T and chi-square tests were used for tests of significance set at P < 0.05. Postoperative analgesia was provided with intramuscular morphine 0.15 mg/kg 4 hourly and 10mg/kg of intravenous paracetamol as rescue analgesia. RESULTS PEFR, FVC and FEV1 were reduced in both the control and study groups but the reduction was greater in the control group. CONCLUSION Bupivacaine wound infiltration produced statistically significant elevations in pulmonary function tests results at all assessment periods.