The use of high flow nasal oxygen device for pre-oxygenation in neurosurgical patients: a randomised controlled trial

Intervention group will receive Optiflow Transnasal Humidified Rapid-Insufflation Ventilatory Exchange (THRIVE) as their device for pre-oxygenation. Oxygen will be delivered through two nasal prongs. The procedure will be carried out by the treating anaesthetist. Pre-oxygenation phase: After the patient is placed at a “sniffing” position with a pillow under the head, pre-oxygenation is commenced with appropriate monitoring, resuscitation equipment and assistance in accordance with the Australian and New Zealand College of the Anaesthetists’ guidelines. Bispectral index (BIS) monitor will also be put on the patient. Oxygen is delivered via THRIVE device, which will be turned on for at least 10 minutes before the start of the operation to ensure the air is humidified sufficiently. Patients will be put on a THRIVE device with oxygen (FiO2 of 1.0) delivering at 30 L/min for 30 seconds and then increased to 50 L/min. The humidity and temperature will follow its default setting which is at 37 degree celsius and 100% humidity. After 5 minutes of pre-oxygenation, anaesthetic induction will then begin. THRIVE device will continue to delivery high flow oxygen at 50L/min throughout pre-oxygenation until successful intubation. There will be no pause until we secure the airway. Induction phase: Propofol will be administered using target controlled infusion (TCI) technique aiming to maintain BIS between 40-60. Opioids will be given at the discretion of the treating anaesthetist. Nerve stimulator will then be calibrated and train of four count (TOF) will commence every 20 seconds. Rocuronium will be given at 1.0mg/kg. Oxygenation via the THRIVE device is continued after patient loses consciousness. Upper airway patency needs to be maintained to ensure adequate apoeic ventilation. If there is any sign of desaturation (SpO2 < 95%) during apoeic oxygenation, the treating anaesthetist is allowed to manage the airway at his/her own discretion, including conversion to bag and mask ventilation if necessary. Airway maneouvres, such as chin lift and jaw thrust; and airway adjuncts, such as oropharyngeal airway will be used at the discretion of the anaesthetist. Once the TOF = 0, the patient will be intubated. After successful intubation, THRIVE will be discontinued and mechanical ventilation will commence. If an unexpected intubation is encountered, the anaesthetist can convert to facemask ventilation if necessary. After this time, the anaesthetist may modify their anaesthetic technique at their discretion.