None listed
Conditions
Brief summary
The aim of this study is to define the effect that high-flow nasal oxygen has on ventilation and oxygenation in both apnoeic and spontaneously breathing participants during a 30minute period of general anaesthesia. The use of high-flow nasal oxygen is gaining popularity in anaesthesia due to its benefits on oxygenation and ventilation. The precise effect that high-flow nasal oxygen has on oxygen and carbon dioxide levels during general anaesthesia during spontaneous respiration or apnoea is yet to be defined. Therefore it is not clear which technique may be more suitable for particular patient subgroups. No previous studies have directly compared apnoeic and spontaneously breathing techniques using high-flow nasal oxygen during general anaesthesia. We hypothesise that carbon dioxide levels will be different between spontaneously breathing and apnoeic patients while using high-flow nasal oxygen during a 30minute period of general anaesthesia.
Interventions
High-flow nasal oxygen during apnoea. Preoxygenation using the HFNO at a concentration of 100% will commence at a flow rate of 30L/min for 3 minutes then increase to 50L/min for 3 minutes and then increase to 70L/min for 3 minutes prior to the induction of anaesthesia. The oxygen concentration and flow rate will remain at 100% and 70L/min respectively throughout the rest of the procedure. Intravenous induction of general anaesthesia using target-controlled infusions of remifentanil and propofol
High-flow nasal oxygen during apnoea. Preoxygenation using the HFNO at a concentration of 100% will commence at a flow rate of 30L/min for 3 minutes then increase to 50L/min for 3 minutes and then increase to 70L/min for 3 minutes prior to the induction of anaesthesia. The oxygen concentration and flow rate will remain at 100% and 70L/min respectively throughout the rest of the procedure. Intravenous induction of general anaesthesia using target-controlled infusions of remifentanil and propofol will be titrated to haemodynamics and to maintain a BIS between 40-50. A 0.5mg/kg bolus of rocuronium will be administered when the patient loses consciousness. Jaw thrust will be used to maintain upper airway patency during the period of apnoea until the surgeon places a suspension laryngoscope. Direct and indirect laryngoscopy using a CMAC videolaryngoscope will be performed by the anaesthetist to assess the airway grade. The surgeon will then place a suspension laryngoscope and perform a microlaryngeal surgical procedure.. At the conclusion of the surgical procedure, a supraglottic airway will be placed, and positive pressure ventilation commenced. The patient will then have the rocuronium reversed with a 2mg/kg bolus of sugammadex, the propofol infusion will be ceased and the patient will be transitioned to spontaneous ventilation and allowed to emerge from general anaesthesia. The patient will be recovered in PACU and discharged to the ward with conventional post-operative orders including analgesia. The anaesthesia will be provided by consultant anaesthetists experienced with microlaryngeal surgery and the use of HFNO or trainee anaesthetists under their direction. The surgery will be provided by consultant surgeons experienced with microlaryngeal surgery and the use of HFNO or trainee surgeons under their direction. The intervention will occur once in operating theatre for an expected duration of 30minutes of general anaesthesia for each study participant.
Sponsors
Dr Anton Booth
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Open (masking not used)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
Ear, Nose and Throat surgical patients requiring microlaryngoscopy
Exclusion criteria
Severe obstructive airway pathology making potential intubation difficult. A requirement for laser. Severe pre-existing respiratory disease. A requirement for a suspension subglottiscope. Pre-operative criteria suggestive of a high risk of aspiration. Women who are pregnant and the human fetus Children and young people People highly dependent on medical care who may be unable to give consent People with a cognitive impairment, intellectual disability or mental illness People in dependent or unequal relationships People who may be involved in illegal activities People in other countries Aboriginal and Torres Strait Islander peoples
Outcome results
None listed