Comparison of pectoralis plane blocks with ketamine-dexmedetomidine adjuncts and opioid-based general anaesthesia in patients undergoing modified radical mastectomy

BACKGROUND AND AIMS: Regional anaesthesia attenuates surgical stress-response, provides superior analgesia, reduces recovery time with early mobilisation and is opioid-sparing [addresses post-operative nausea vomiting (PONV), constipation, immunosuppression and cancer-progression concerns with opioids]. Hence, we studied pectoralis (PECS) blocks for modified radical mastectomy (MRM). METHODS: A prospective, interventional, double-blind, randomised, parallel-arm, active-controlled study comparing two anaesthetic techniques for post-operative pain relief in70 adult American Society of Anesthesiologists grade I/II carcinoma breast patients undergoing MRM was conducted. Patients were randomised to Group-O (opioids, sevoflurane) and Group-P (PECS-block, pre-incisional intravenous (IV) ketamine (0.5 mg/kg), pre-incisional IVdexmedetomidine (1 μg/kg over 10 min, then 0.6 μg/kg/h). Data were subjected to statistical analysis using the Statistical Package for Social Sciences, version-23 and independent sample t-test/Welch test for equality of means and expressed as dotted box-whisker plots. Nominal categorical intergroup data was compared using Chi-squared test/Fisher's exact test. P<0.05 was considered statistically significant. Clinical significance was calculated. RESULTS: Higher Visual Analogue Scale (VAS)-scores were recorded in Group-O versus Group-P, immediately post-extubation [mean (SD) 3.6 ± 1.5 and 0.76 ± 0.6] and at 1h (3.1 ± 1.2 and1.4 ± 0.5), 2h (2.5 ± 0.9 and 1.2 ± 0.6) and 4h (2.2 ± 0.5 and 1.7 ± 0.9) respectively. At 8h and 24h post-surgery VAS was comparable. Cumulative-VAS was lower in Group-P. Intraoperative haemodynamics were comparable. Incidence of PONV and constipation was higher in Group-O where each patient received average 27.46 mg morphine-equivalents of opioids. Time to discharge from surgical intensive care unit was 2h shorter in Group-P. CONCLUSION: Pre-emptive PECS-blocks supplemented with low-dose ketamine and dexmedetomidine comprise a practical and useful alternative technique to the standard opioid-based general anaesthetic technique for MRM.