Transversus abdominis plane block with 0.25 % levobupivacaine: a prospective, randomized, double-blinded clinical study

Purpose Because blood concentrations of local anesthetics sometimes reach toxic levels after transversus abdominis plane (TAP) block, reduction of the dose has been necessary to reduce the risk of systemic toxicity. We therefore investigated the effects of TAP block with 0.25 % levobupivacaine (100 mg) on postoperative pain and measured its plasma concentration after gynecological surgery. Methods Forty women undergoing elective open gynecological surgery were randomized to receive bilateral TAP block with 20 ml 0.25 % levobupivacaine on each side (TAP group) or not (non-TAP group) before surgery. Postoperative pain was treated with intravenous patient-controlled analgesia by use of morphine. Patients were evaluated 3 and 24 h after the end of surgery. Visual analog scale (VAS) for pain at rest and with movement, and morphine consumption were recorded. Plasma concentrations of levobupivacaine after TAP block were measured. Results Three hours after surgery, total morphine consumption was significantly lower in the TAP group (2.8 ± 1.6 mg) than in the non-TAP group (6.4 ± 4.8 mg, P = 0.03). There were no significant differences between VAS in the two groups. Mean plasma concentration of levobupivacaine peaked 10 min after TAP block (0.99 ± 0.43 μg/ml), and the highest concentration was 1.99 μg/ml. Conclusion TAP block with 100 mg levobupivacaine is a safe and efficacious multimodal analgesic regimen for postoperative pain after open gynecological surgery.