The postoperative analgesic efficacy of wound instillation with ropivacaine 0.1% versus ropivacaine 0.2%

Study objectives To assess the influence of ropivacaine concentration on wound instillation-induced postoperative analgesia following total abdominal hysterectomy with bilateral salpingo-oophorectomy. Design Prospective, randomized, double-blind study. Setting Large referral hospital. Patients 40 ASA physical status I and II patients undergoing total abdominal hysterectomy with bilateral salpingo-oophorectomy. Interventions A standard general anesthetic was administered. In all cases surgery was performed via a Pfannenstiel incision. On completion of the surgery, a multi-orifice, 20-gauge epidural catheter was placed above the fascia such that the tip was sited at the point that demarcated 50% of the length of the surgical wound. Thereafter, the catheter was connected to an electronic patient-controlled analgesia (PCA) device programmed to deliver 9 mL of drug, with a lockout time of 60 minutes and no basal infusion. Patients were randomized to receive PCA with ropivacaine 0.1% (Group 0.1) or ropivacaine 0.2% (Group 0.2). During the first 6 postoperative hours, a co-investigator administered "rescue" morphine (2 mg IV). Thereafter, "rescue" meperidine 1 mg/kg was administered on patient request. Measurements and main results The number of attempts to activate the PCA device and actual PCA instillations during the 24 hour study period were similar between the groups. The number of 2 mg "rescue" morphine dosages administered was 4.3 ± 1.7 versus 4.4 ± 2.5 for the Group 0.1 and Group 0.2, respectively. For Group 0.1 and Group 0.2, the total dose of "rescue" morphine administered during the first 6 postoperative hours was 8.7 mg ± 3.6 versus 9.1 mg ± 5, respectively. "Rescue" meperidine administration during the subsequent 18 hours was similar between the groups. Throughout the study period, pain scores were similar between the groups. Conclusion With a pre-set volume, varying the concentration of ropivacaine (0.1% versus 0.2%) does not affect the analgesic efficacy of wound instillation following total abdominal hysterectomy with bilateral salpingo-oophorectomy.