A comparison of depth of muscle relaxation to improve performance of percutaneous ablation of liver tumours

This is a single-center, prospective, double-blinded, randomized controlled trial involving a sample size of 100 patients (50 per group) undergoing CT-guided radiofrequency ablation of primary and secondary liver tumours in the Department of Biomedical Imaging, University Malaya Medical Centre. All patients who are eligible to enroll will be given a patient information sheet and have their consent taken prior to procedure. There will be 2 groups in this study: Group (1) deep neuromuscular blockade (DMB) will receive 1.0mg/kg IV Rocuronium bolus during induction followed by infusion to maintain post-tetanic count (PTC) of 1 or 2. Initial pump rate will be set at 0.6mg/kg/hr and adjusted accordingly by increments of 0.1 to maintain PTC of 1 or 2. Group (2) moderate neuromuscular blockade (MMB) will receive 0.5mg/kg IV Atracurium bolus during induction followed by infusion to maintain train-of-four count (TOF) of 1 or 2. Initial pump rate will be set at 0.3mg/kg/hr and adjusted accordingly by increments of 0.1 to maintain TOF count of 1 or 2. Further boluses of 10mg Rocuronium or Atracurium will be given if requested by the interventional radiologist and documented. All patients will be intubated with cuffed Portex ETT and anaesthesia maintained with a balanced technique to achieve MAC of 1.0-1.3. They will be ventilated with intermittent positive pressure ventilation using pressure control to achieve a tidal volume of not more than 7mls/kg and ETCO2 of 35-40 mmHg. Ventilation will be intermittently suspended at varying lengths of time when required by the radiologist (only allowed if patient is stable with SpO2 of at least 97%). Suspension of ventilation must resume should the oxygen saturation starts to drop below 96% or >4% from baseline. Depth of neuromuscular blockade will be monitored with TOF-Watch (Registered Trade Mark) Organon (Ireland) Ltd which will be calibrated prior to use. After completion of procedure, infusions of drugs in both Groups 1 and 2 will be terminated. Group (1) will be reversed with IV Sugammadex 4mg/kg while Group (2) with IV Neostigmine 0.05mg/kg and IV Atropine 0.02mg/kg. Patients will be extubated when TOF ratio becomes 0.9 or more and will be monitored in the recovery area for at least half an hour. If patients cannot be extubated, reasons will be documented. Analgesics such as 0.05 - 0.1 mg/kg IV morphine or 40 mg IV Parecoxib will be given after induction with additional boluses of analgesia in the recovery after extubation based on pain scores. Dexamethasone 4mg will be given as anti emetics when required after induction. Follow up with records and phone call at 1 year after tumor percutaneous ablation procedure