Analgesic efficacy of ultrasound-guided subcostal transversus abdominis plane block

Background: To evaluate the analgesic efficacy on defined areas of the abdomen and back after ultrasound-guided subcostal transversus abdominis plane (TAP) block using 0.25% levobupivacaine 0.5mL/kg. Methods: Twenty patients undergoing elective laparoscopic cholecystectomy, between 20 and 60 years of age with operative time < 1 hour, received subcostal TAP block using 0.25% levobupivacaine 0.5mL/kg on the left side. Surgery started after 1 hour of observation. Sensory assessment was undertaken using pinprick and 75% ethyl alcohol at 10, 20, 30 minutes, 1, 3, and 12 hours after TAP block at 19 testing zones that were divided by anatomic landmark lines on the abdomen and the back. Efficacy of zone was defined as loss of cold temperature sensation or loss of pinprick pain sensation in more than 50% patients in that testing zone. Duration was determined by analgesia and loss of temperature sensation beginning within 30 minutes of TAP block placement lasting until time points of 1, 3, and 12 hours. All of the testing zones were divided as Group I effective at 20 minutes in less than 50% patients (0%-50%), Group II 50% to 70% patients, Group III 70% to 90% patients, and Group IV 90% to 100% patients. Results: Twenty patients meeting the study requirements were included. At each time point, the efficacies among 4 groups were significantly different. Subcostal TAP had good efficacy and stable duration in zones 1, 2, 3, 5, and 6. Conclusion: Subcostal TAP block with 0.25% levobupivacaine 0.5mL/kg dose provided effective analgesia in the anterior abdominal wall between medioventral line to anterior axillary line except the lateral upper abdominal region.