Interpleural analgesia following hepatic resection

Abstract

We read with interest the publication by Weinberg et al. [1] comparing the use of interpleural analgesia and patient controlled analgesia following hepatic resection. As the authors state, the use of a levobupivacaine infusion using an interpleural catheter has been previously described for postoperative analgesia, but not in the context of liver resection. Levobupivacaine is metabolised in the liver by CYP3A4 isoform and CYP1A2 isoform [2]. Although the metabolism of levobupivacaine may not be significantly affected following cholecystectomy [3] or renal surgery [4], a similar assumption cannot be made about levobupivacaine following hepatic resection. Hepatic metabolism of drugs may be affected by two mechanisms following hepatic resection. Although it is relatively safe to excise up to 70% of healthy liver parenchyma during hepatectomy [5], the capacity to manage the potential increased workload of metabolising levobupivacaine may be substantially impaired. Furthermore, the use of a Pringle manoeuvre to reduce hepatic venous blood loss renders the liver transiently ischaemic [6], which may additionally impair postoperative metabolic function. We believe confirmation of safe postoperative levobupivacaine serum levels needs to be demonstrated before interpleural techniques can be recommended. We also question the statement by the authors that ‘derangements in coagulation after hepatic resection have favoured systemic multimodal analgesia in preference to neuraxial techniques as the preferred method for effective delivery of postoperative analgesia in many institutions’. Numerous publications have confirmed the safety of peri-operative neuraxial blockade [7, 8]. Not only does this method provide excellent postoperative analgesia, it also contributes significantly to the intra-operative central venous pressure manipulation that is widely used to reduce blood loss during hepatic resection [9]. Using this technique a median blood loss of 100 ml can readily be achieved, avoiding postoperative coagulopathy and reducing the frequency of blood transfusion [10]. The avoidance of blood transfusion has been demonstrated to reduce the incidence of peri-operative liver impairment, which probably translates to a significant increase in long-term overall survival [5]. No external funding and no competing interests declared. Previously posted at the Anaesthesia Correspondence website: http://www.anaesthesiacorrespondence.com.