Mid-axillary transversus abdominis plane block and stress response after abdominal hysterectomy

BACKGROUND The hormonal response to surgical trauma can have detrimental effects on patients. Transversus abdominis plane (TAP) block, which can improve analgesia after total abdominal hysterectomy (TAH) might attenuate the peri-operative stress response. OBJECTIVE To evaluate the ability of the TAP block to reduce stress response, opioid consumption and pain following TAH and multimodal analgesia. DESIGN Randomised, placebo-controlled double-blind study. SETTING The current study was conducted at a university hospital from July 2016 to September 2017. PATIENTS Fifty patients scheduled for TAH were included. Anaesthesia and postoperative analgesia were standardised. INTERVENTION After induction of anaesthesia, patients were allocated into two groups: ultrasound-guided bilateral mid-axillary TAP block with 20 ml of bupivacaine 0.25% (Group T) or 0.9% saline (Group C). MAIN OUTCOME MEASURES Levels of free serum cortisol, metanephrine and normetanephrine at 60 min and 6, 12 and 24 h after surgical incision. Pain scores and opioid consumption during the first 24 h after surgery. RESULTS There was no statistically significant difference between the median [IQR] peri-operative levels of stress hormones and pain scores between groups. Compared with baseline value 9.90 [4.2 to 23.1], free serum median cortisol levels were significantly high at 6 h in Group T, 23.6 [10.1 to 42.9] P = 0.015 and Group C 23.6 [9.9 to 46.3] P = 0.014. Only Group C showed significant elevation from the baseline median levels of plasma metanephrine at 60 min, 52.8 [33.4 to 193.2] P = 0.001, 6 h, 92.70 [2.4 to 202.6] P = 0.005 and normetanephrine at 60 min 83.44 [28.98 to 114.86] P = 0.004, 6 h 78.62 [36.6 to 162.31] P = 0.0005 and 24 h 80.96 [8.6 to 110.5] P = 0.025. Mean ± SD opioid consumption was similar in both groups: 39.60 ± 14.87 in Group T vs. 43.68 ± 14.93 in Group C (P = 0.338). CONCLUSION Mid-axillary TAP block does not improve stress response and analgesia in patients undergoing TAH receiving multimodal analgesia. TRAIL REGISTRATION ClinicalTrial.gov identifier: NCT03443271.