Deep versus superficial erector spinae block for modified radical mastectomy: A randomised controlled pilot study

BACKGROUND AND AIMS: Forero et al. described two approaches of erector spinae (ES) plane block: superficial and deep to erector spinae muscle. We hypothesised that the superficial technique would not lead to optimum analgesia as the drug would have to cross one more muscle layer. We aimed to compare the techniques in terms of analgesia and sensory blockade in patients undergoing modified radical mastectomy (MRM). METHODS: Forty American Society of Anesthesiologists (ASA) I/II female patients in age group 18–60 years undergoing unilateral MRM were included in this prospective study. Group D patients received 20 mL 0.2% ropivacaine deep to erector spinae at the T4 level. Group S patients received 20 mL 0.2% ropivacaine superficial to erector spinae. Sensory level of block, perioperative opioid consumption, and adverse effects were noted. RESULTS: Twenty four hours morphine consumption was less in group D: 5.47 ± 1.1 mg and in group S was 7.66 ± 0.74 mg (P < 0.001). The sensory spread was more in deep group in the posterior axillary and mid axillary line. There were no reported adverse effects in either group. CONCLUSION: Injection of drug deep to ES muscle provides more cranio-caudal blockade of posterior and lateral chest wall, hence providing better analgesia following breast surgery. Injection of the drug superficial to the muscle leads to inferior analgesia.