LAUSR

Introduction Opioid analgesia for thoracic surgery and trauma may be associated with adverse effects including respiratory depression, cough suppression and diminished consciousness. These adverse effects can be minimised using interfascial plane regional analgesia such as the erector spinae and serratus anterior plane blocks (ESPB and SAPB) as first described by Forero and colleagues and Blanco and colleagues, respectively.1,2 This systematic review aims to evaluate the anatomical evidence underlying innervation and dermatomal distribution of these two regional analgesic techniques. Additionally, the pharmacokinetics of ESPB and SAPB were compared. Methods Google Scholar, DiscoverEd, and PubMed were searched using key words: ESPB, SAPB, nerve block, local anaesthetic systemic toxicity, dermatomal spread, pharmacokinetics. Results The search yielded 39 papers investigating anatomical and pharmacokinetic evidence of which 11 were identified as relevant (Table 1). Table 1 found as an attachment Pharmacokinetic Results: The most commonly used local anaesthetic was bupivacaine and the use of adjuvants was infrequent. As proposed by Luftig and colleagues,3 a larger volume of a weaker concentration appears to reduce the chance of local anaesthetic systemic toxicity. Anatomical spread is dependent upon the dose and site of injection. Techniques can be easily taught and reproduced. Discussion The anatomical and pharmacokinetic evidence supports use of both techniques for thoracic regional analgesia with ESPB spreading more caudally than SAPB. However, there is anatomical variance between patients in the spread of each block. Pharmacokinetic evidence supports the use of low-concentration, high-volume local anaesthetic for optimal efficacy and limited toxicity.