Effects of TIVA Versus Inhalational Anaesthesia on Circulating Tumour Cells in Hepatocellular Carcinoma Patients

Pre-operative care

Pre-operative assessment will be performed at the preadmission clinic or at the general ward. Patients will be fasted for intake of solid food for 6 hours and clear liquids for 2 hours. Sedative premedication will not be prescribed.

Anaesthesia and intraoperative care

SEVO Group

Patients from the SEVO group will be anaesthetized according to the following protocol:

On arrival at the operation theatre, an intravenous cannula will be inserted. Standard monitoring with pulse oximeter, non-invasive blood pressure, and three-lead electrocardiogram will be applied prior to induction. Non-invasive blood pressure (NIBP) will be checked at least every 5 minutes throughout the operation. An arterial line may be inserted at the discretion of the anaesthetist before or after induction, with invasive blood pressure monitoring in lieu of NIBP if deemed necessary. Additional intravenous cannulas or central lines may also be inserted to facilitate fluid therapy, measure the central venous pressure or administer drugs, also at the discretion of the attending anaesthetist.

Anaesthesia will be induced with titrated, manual propofol injection of 1-2 mg.kg-1. Remifentanil infusion will be given for analgesia at a rate of 0.1 - 0.35 mcg.kg.min-1 as required, according to haemodynamic parameters. Cisatracurium 0.15 mg.kg-1 or atracurium 0.5 mg.kg-1 will be used for muscle relaxation. Tracheal Intubation will be performed after induction of general anaesthesia. General anaesthesia monitoring will be used. Sevoflurane at 0.5- 1 MAC, air and oxygen will be used for maintenance of general anaesthesia. Processed EEG (BIS™) will be utilized to monitor depth of anaesthesia, aiming at a BIS value of 40-60. FiO2 will be kept between 35-50% to maintain and SaO2 of > 95%. Further muscle relaxants can be given during the operation if required.

In accordance with British consensus guidelines on intravenous fluid therapy for Adult Surgical Patients [22], intraoperative fluid or blood loss will be initially replaced with balanced crystalloid solution, preferably Plasmalyte A (a physiologically balanced electrolyte solution similar to extracellular fluid), for up to 20% of body volume, with additional fluid replacement with colloid or crystalloid at the discretion of the anaesthetist. Intravenous phenylephrine, ephedrine or fluid administration may also be given for management of hypotension. Intravenous anti-hypertensive agents such as beta blockers (e.g. esmolol, labetalol) and glyceryl trinitrate can be given if hypertension occurs.

Patients will receive standardized opioid analgesia of 0.1 mg.kg-1 intravenous morphine intra-operatively followed by patient-controlled analgesia (PCA) morphine post-operatively, as well as local anaesthesia (0.5% levobupivacaine) injected in the areas of surgical incision during wound closure for pain control.

Forced air warming blankets will be used with the aim of keeping a core temperature of 35.5-37.5 degrees Celsius. Ondansetron 4mg IV will be given 30 minutes before end of surgery.

Sevoflurane and remifentanil infusion will be switched off at the end of the procedure. Reversal of muscle relaxation can be achieved if required with neostigmine 50 mcg.kg-1 IV and atropine 20 mcg.kg-1 IV. Patients will subsequently be transferred to the post anaesthetic care unit (PACU) for monitoring for at least 30 minutes.

TIVA Group

Patients in the TIVA group will be anaesthetized according to the following protocol:

Monitoring and other anaesthetic procedures including the management of hypertension and hypotension will be the same as SEVO group. Induction and maintenance of general anaesthesia will be conducted using total intravenous infusion of propofol. Sevoflurane will not be used, and oxygen and air would be given to provide a FiO2 of 30-50%.

Target controlled infusion (TCI) with a modified Marsh effect site model (Fresenius Kabi) will be used for induction and maintenance of general anaesthesia and titrated to effect. The usual effect site concentration is 1.5-3 mcg.ml-1 and BIS monitoring will also be used to produce a value of between 40-60. As with patients in the SEVO group, remifentanil will be infused at a rate of between 0.1-0.3 mcg.kg.min-1.

Post-operative care for both groups In the recovery room after surgery, numerical rating pain score (NRS) will be used to assess level of pain. Patients will select a whole number (0-10 integers) that best reflects the intensity of his/her pain, in which 10 represents the maximal imaginable pain. Boluses of 2 mg intravenous morphine will be given every 5 minutes until the numerical rating scale (NRS) is less than or equal to 4/10. A patient controlled analgesia (PCA) machine will then be connected. The machine will be configured to give 1 mg of morphine whenever the patient demands with the lockout duration set to 5 minutes. No background infusion will be given and the maximum dose limit will be 0.1 mg.kg-1 per hour of morphine.

On post-operative day 1, when the patient resumes a fluid diet, oral celecoxib 200 mg will be given twice daily for 3 days.

Whilst on PCA morphine, the patient's respiratory rate, oxygen saturation (SpO2) and sedation score will be monitored every hour. Heart rate and blood pressure will be checked every 4 hours. NRS pain scores at rest and during cough/movement, cumulative PCA morphine doses, and number of PCA demands/goods delivered, and side effects (nausea, vomiting, dizziness, hypotension, desaturation) will be recorded every 4 hours. Patients will be assessed by a "pain team" every day to determine sufficiency of analgesia, as per usual practice.

Patients will be kept on PCA morphine for at least 2 days. If NRS pain scores during cough/ movement on postoperative day 2 are less than or equal to 3/10, PCA morphine will be stopped. PCA morphine will be continued if NRS is equal or greater than 4, or if the patient remains on a high PCA use. Assessment for analgesia will be conducted daily. Evaluation for complications will be required if NRS pain score is 4 or higher on postoperative day 5. The patient will be further managed at the discretion of the anaesthetist.

After PCA morphine has been withdrawn, NRS pain scores at rest and during cough/ movement, as well as the dose and frequency of rescue analgesia used will be charted once a day until discharge.