Preoperative infiltration of bupivacaine--effects on pain relief and trauma response (cortisol and interleukin-6).

Abstract

Subcutaneous infiltration of bupivacaine before skin incision can reduce postoperative pain and modulate the stress response. In a randomized study on pain relief after hysterectomy 29 patients were referred into one of three groups, receiving 30 ml of bupivacaine 0.25% with adrenaline, 30 ml of saline or no infiltration along the line of the proposed incision 10 min before start of surgery. A Visual Analogue Scale was used for repeated pain ratings. Postoperative pain relief was provided with patient-controlled analgesia with intravenous morphine 0.04 mg/kg. Lockout time was 10 min. The immunological and endocrine stress response to trauma was reflected by blood interleukin-6 (IL-6) and cortisol concentrations measured during 72 h following skin incision. There were large individual variations in the accumulated postoperative consumption of morphine at 20 h after start of surgery. It was significantly reduced in patients receiving infiltration of bupivacaine. They used 39 mg (9-62) median (range) of intravenous morphine whereas the patients in the saline group used 65 mg (47-120) and patients in the control group used 54 mg (36-130) (P < 0.05). Significant elevation of plasma IL-6 and serum cortisol levels appeared in all groups with peak values at 3 h. There were no differences between the groups. There was a correlation between cortisol and IL-6. Six of the 29 patients had a postoperative infection which was reflected in increased IL-6 levels. Preoperative subcutaneous infiltration of bupivacaine significantly reduced the postoperative consumption of intravenous morphine.