Subcostal versus Posterior approach of ultrasound guided transverse abdominis plane block for postoperative analgesia following laparoscopic cholecystectomy: A Randomised controlled trial

There is scanty data comparing the subcostal versus posterior approach of TAP block after laparoscopic cholecystectomy.

AIM: To compare postoperative analgesic efficacy of subcostal and posterior approach of ultrasound guided TAP block following laparoscopic cholecystectomy, with dexamethasone as an adjuvant to local anaesthetics.

**Primary Objective:**To compare the duration of analgesia (time to first postoperative analgesic request) following ultrasound guided subcostal versus posterior approach TAP block in patients undergoing laparoscopic cholecystectomy.; using levobupivacaine (0.25%, 15 ml each side) along with dexamethasone (4 mg each side) in both groups.

**Secondary Objective:**To evaluate and compare the following in both groups:

1. NRS score (pain) at 2 hour, 6 hour, and 24 hours after surgery.

2. Total dose of paracetamol required in 24 hours after surgery.

3. Total dose of tramadol (rescue analgesic) required in 24 hours after surgery.

Methodolgy: The anaesthetic management for all patients in either cohort will be standardized as per routine practice. The ultrasound-guided TAP block will be performed using a linear high frequency 6–11 MHz probe. In the subcostal-TAP block, the external oblique, internal oblique and transverse abdominis muscles will be visualized at the anterior axillary line, between the 12th rib and the iliac crest. In contrast, in the posterior-TAP block the transducer will be placed in axial plane in the midaxillary line and moved posteriorly to the most posterior limit of the TAP between the internal oblique and transversus abdominis muscles. After successful extubation, patient will be shifted to post-operative ward. Postoperative multimodal analgesia will be provided using the routine technique in our institution (paracetamol 10 mg/kg i.v., every 6 hours). If at any time in the first 24 hours after surgery patient complains of pain, with a Numeric Rating Scale (NRS) score > 3, rescue analgesia will 4 be provided with tramadol (50 mg i.v.). The NRS score will be graded on a scale of 0-10, where 0 represents no pain and 10 represents the worst imaginable pain.

Statistical Analysis: Statistical analysis will be performed using SPSS (SPSS Inc., Chicago, IL, USA). Intergroup comparison of data will be done using unpaired t-test (normally distributed quantitative data), or Mann-Whitney (non-normally distributed quantitative data), or Chi-square/Fishers exact test (qualitative data). A value of p < 0.05 will be considered statistically significant.