Feasibility and analgesic efficacy of the transversus abdominis plane block after single-port laparoscopy in patients having bariatric surgery

PURPOSE The transversus abdominis plane (TAP) block is a technique increasingly used for analgesia after surgery on the anterior abdominal wall. We undertook this study to determine the feasibility and analgesic efficacy of ultrasound-guided TAP blocks in morbidly obese patients. We describe the dermatomal spread of local anesthetic in TAP blocks administered, and test the hypothesis that TAP blocks decrease visual analog scale (VAS) scores. PATIENTS AND METHODS After ethics committee approval and informed consent, 35 patients with body mass index >35 undergoing single-port sleeve gastrectomy (SPSG) were enrolled. All patients received balanced general anesthesia, followed by intravenous patient-controlled analgesia (IV-PCA; hydromorphone) postoperatively; all reported VAS >3 upon arrival to the recovery room. From the cohort of 35 patients having single-port laparoscopy (SPL), a sealed envelope method was used to randomly select ten patients to the TAP group and 25 patients to the control group. The ten patients in the TAP group received ultrasound-guided TAP blocks with 30 mL of 0.2% Ropivacaine injected bilaterally. The dermatomal distribution of the sensory block (by pinprick test) was recorded. VAS scores for the first 24 hours after surgery and opioid use were compared between the IV-PCA+TAP block and IV-PCA only groups. RESULTS Sensory block ranged from T5-L1. Mean VAS pain scores decreased from 8 ± 2 to 4 ± 3 (P=0.04) within 30 minutes of TAP block administration. Compared with patients given IV-PCA only, significantly fewer patients who received TAP block had moderate or severe pain (VAS 4-10) after block administration at 6 hours and 12 hours post-surgery. However, cumulative consumption of hydromorphone at 24 hours after SPSG surgery was similar for both groups. CONCLUSION Ultrasound-guided TAP blocks in morbidly obese patients are feasible and result in satisfactory analgesia following SPSG in the immediate postoperative period.