The effect of intraperitoneal local anaesthetic in colonic surgery

Abstract

Millions of years of symbiosis between micro-organisms in the colon and the host have resulted in a unique neural system to detect adverse stimuli. The vagus nerve links the intraperitoneal cavity directly to the brainstem, hence bypassing somatic nerve blockade often utilised after major abdominal surgery. This thesis describes the intraperitoneal autonomic wound as a target for intervention after major abdominal surgery to accelerate recovery. Chapter One introduces the topic. Chapter Two focuses on events that lead to prolonged convalescence, and presents the hypothesis that the intraperitoneal autonomic wound is an important and potential target for interventions when the somatic wound is controlled. Current interventions are also reviewed. Chapter Three describes a systematic review on the use of intraperitoneal local anaesthetic (IPLA) in order to assess this clinical intervention. It will be shown that this intervention may lead to important clinical benefits. Chapter Four systematically reviews published data on the intravascular (systemic) level of drug after IPLA compared to other techniques. Chapter Five brings this information together in the form of a pilot study concerned with safety of concomitant IPLA and epidural anaesthesia infusions. A protocol was devised in order to infuse ropivacaine into the epidural and intraperitoneal space whilst monitoring safety. Chapter Six describes the methodology used to carry out a double-blinded placebo controlled randomised clinical trial infusing IPLA after colon resection within the context of an Enhanced Recovery after Surgery (ERAS) program (IPLA trial). In chapter Seven the results of the IPLA trial are presented. It will be seen that benefits of IPLA were observed, including improvement in functional recovery, reduced systemic markers of inflammation, reduced neuro-endocrine upset, and significantly reduced pain and opioid consumption over the epidural somatic blockade. Chapter Eight summarises these findings and makes the conclusion that it is possible to target the intraperitoneal wound in order to further enhance recovery after surgery. Chapter Nine draws a conclusion on the topic of this thesis.