Safety and efficacy of multiple site thoracic paravertebral nerve block vs. modified pectoral nerve block for postoperative analgesia after modified radical mastectomies-a randomised controlled trial

This study compares the safety and efficacy of multiple level thoracic paravertebral block and modified Pecs block for postoperative pain relief after Modified Radical Mastectomies. After Institutional Review Board [IRB] and Human Ethics Committee [HEC approval, the study was conducted on 41 patients who were scheduled to undergo modified radical mastectomy. Written informed consent was taken. Female patients in the age group of 18-75 years who were ASA grade I and II were randomly allocated to two groups to either receive Ultrasound guided Thoracic paravertebral block TPVB at T2 and T4 levels (Group 2) or an ultrasound guided modified PECS block (Group 1) preoperatively in the block room. Paravertebral block was given at two vertebral levels T2 (10 ml) and T4 level (10 ml) under ultrasound guidance utilising the parasagital in-plane technique. Modified PEC block was administered to patients in the PEC group.10 ml of 0.5% Ropivacaine for Pec1 and 20ml for Pec 2. In all patients surgery was done under GA. Pain was assessed with Numerical Rating Scale (NRS) on a 0 to 10 scale, for 24 hours after surgery, at 0,0.5,1,1.5,2,4,6,12 and 24 hours after surgery by a blinded observer. Rescue opioid and Paracetamol requirement was recorded. The patients were also monitored for any specific block related complications. Primary outcome measures were the numerical rating scores for pain and rescue analgesic requirement. Secondary outcome measures was looking for any block related complications. Demographic categorical variables were expressed in frequency and percentage, and the continuous variables were reported in terms of mean and standard deviation. The comparison of pain scores between the thoracic paravertebral nerve block and modified pectoral nerve block was done using Mann-Whitney U test. Mean duration of analgesia and mean 24 hour Morphine, Paracetamol consumption was compared using Student's t test. There was no statistically significant difference between the two groups with respect to the pain scores at 0,0.5,1,1.5,2,4,6,12,and 24 hours at rest or with movement of the ipsilateral arm. The 24 hour Morphine consumption was not also statistically significant. [pec gp,mean 2.17, SD 1.09, tpvb gp mean 2 SD 0.77, p value 0.752.] Paracetamol consumption in the initial 24 hours after surgery was also not statistically significant between the two groups (pec gp. 36.8% and tpvb gp. 50% patients received paracetamol with a p value of 0.523). We found both the blocks, modified Pecs and multiple level paravertebral block were equally effective in treating postoperative pain.