Transversus abdominis plane block provides postoperative analgesic effects after cesarean section: Additional analgesia to epidural morphine alone

Abstract

The aim of our study was: (i) to investigate whether transversus abdominis plane (TAP) block confers additional analgesic effects to epidural morphine alone; and (ii) to determine plasma levels of local anesthetics after TAP block in post-cesarean women. The subjects were parturients undergoing cesarean section under combined spinal-epidural anesthesia. Morphine (2 mg) was administered to the epidural space close to the end of surgery. Women who desired TAP block were allocated to the TAP group. Women who did not undergo TAP block were allocated to the control group. In the TAP group, 20 mL of either 0.375% ropivacaine or 0.3% levobupivacaine was infused to both sides of the transversus abdominis plane after surgery. All patients were placed on a patient-controlled i.v. analgesia regimen with morphine after surgery. Time to the first morphine request and amount of morphine consumption within 24 h after surgery were compared in patients with and without TAP block. Plasma concentrations of local anesthetics were determined at 15, 30 and 60 min after TAP block. Forty and 54 patients were allocated to the control and TAP group, respectively. The median time to the first morphine request was longer (555 vs 215 min), and the median cumulative morphine consumption within 24 h was lower (5.3 vs 7.7 mg) in the TAP group than in the control group. The maximum median concentrations of ropivacaine and bupivacaine after TAP block were 784 and 553 ng/mL, respectively. TAP block had additional analgesic effects to epidural morphine alone.