Randomised controlled trial of continuous wound infusion of local anaesthetic agent (Bupivacaine) for pain relief in new born babies undergoing major abdominal surgery

Irrespective of which group the neonate will be randomised to, all study subjects will have access to systemic opioid analgesia by titratable intravenous infusion as per the current unit policy. INTRA-OPERATIVE MANAGEMENT OF BOTH GROUPS: Anaesthesia will be conducted according to current standards of care at the Children's Hospital at Westmead with several provisos. Anaesthesia induction will be either gaseous (oxygen and sevoflurane with or without nitrous oxide) or intravenously at the discretion of the consultant anaesthetist. Muscle relaxation (vecuronium or cis-atracurium), ventilation and intra-operative opioid analgesia will similarly be at the discretion of the anaesthetist. Intra-venous paracetamol will be administered regularly (10mg/Kg/dose qid for 72hours) and may commence intra-operatively. Adjunct analgesic agents such as – IV NSAIDs, ketamine, dexmeditomidine and clonidine will not be used. At the conclusion of surgery and before wound closure, a multi-hole wound catheter (appropriate to the size of the wound) will be inserted under direct vision in babies randomised to treatment group (see below). A bolus dose of local anaesthetic agent (0.3mL/Kg 0.25% Bupivacaine) will be injected through the catheter after wound closure. The catheter will then be capped until return to the Grace Centre of Newborn Care. The decision to extubate the baby at the conclusion of the surgery will be at the discretion of the anaesthetist. When the incision is closed, the transversus abdominis muscle with/without the peritoneum is closed first. The multi-orifice 19-gauge wound catheter of length 2.5 or 6.5 cm according to the length of the surgical incision is placed superficial to this layer but deep to the internal oblique so that the local anaesthetic/normal saline delivered can come in close contact with the cutaneous nerves which is embedded between the transversus and internal oblique muscle. The internal oblique and external oblique muscles are closed in one layer on top of the wound catheter. A transparent dressing will be applied on the skin. Immediately after skin closure, following a negative aspiration test to confirm that the tip of the catheter is not inserted intravenously, a bolus dose of bupivacaine will be administered through the wound catheter in babies who were randomised to treatment group. TREATMENT GROUP: Treatment group will have their wound catheters connected to a continuous infusion of bupivacaine (0.125%) after four hours from the surgery. The infusions will run at 0.16mL/kg/hr for 72 hours. CONTROL GROUP: Management of postoperative pain will be as per the current unit protocol.