High Flow Nasal Oxygen during Endobronchial Ultrasound to prevent low oxygen levels.

INTERVENTION: High flow humidified nasal oxygen. Oxygen administered via the Optiflow THRIVE device, at a flow rate of 50‐70LPM as tolerated, humidified using the Fisher and Paykel 850 humidifier, to a humidity of 70% relative humidity. The oxygen concentration delivered from the device will be 100%, but the actual inspired oxygen concentration will vary with the patient's inspiratory flow rate and degree of air entrainment. In the intervention group, patients will be put on a THRIVE device with oxygen delivering at 30 L/min immediately upon entering the room, but before sedation administration, for a minimum of 3 minutes. The oxygen delivering rate will be increased to 50 L/min via the THRIVE device immediately after sedation agent is given and will be maintained at 50 L/min during the procedure. The flow rate can be increased up to 70L/min if necessary by the anaesthetist or decreased to 30L/min if patient is not tolerating the device. The EBUS procedure will only commence once a clinically appropriate level of sedation is reached, titrated by the anaesthetist. As such, oxygen administration will have occurred for a minimum of 3‐5minutes before the procedure begins. Oxygen delivery will continue until the conclusion of the EBUS procedure, and will be removed when the patient is stable for transfer to the recovery room, as judged by the anaesthetist. CONDITION: Endobronchial Ultrasound PRIMARY OUTCOME: Proportion of patients experiencing desaturation (SpO2 below 90%) as measured by pulse oximetry. SECONDARY OUTCOME: Anaesthetists satisfaction score as reported using a Likert scale (0‐5) Any other complications, such as arrhythmia, myocardial ischaemia and cardiac arrest as identified by the treating anaesthetist. ; Duration of hypoxia (SpO2 below 90%) in seconds during the procedure as measured by pulse oximetry. End‐procedure end‐tidal CO2 in mmHg sampled via a catheter through the working channel of the bronchoscope and analysed via a standard infra‐red gas analyser on the anaesthetic machine. Lowest SpO2 during procedure as assessed by pulse oximetry Maximum oxygen delivering rate (L/min) as selected on the oxygen flow‐meter. ; Minimum oxygen delivering rate (L/min) as selected on the oxygen flow‐meter. ; Number of hypoxic episodes (SpO2 below 90%) during the procedure as measured by pulse oximetry. Number of interruptions to procedure to allow anaesthetic management, such as bag‐mask ventilation, insertion of an LMA, intubation or other rescue airway procedure. ; Patient satisfaction score as assessed with a Likert scale (0‐5). ; Proceduralist satisfaction score as reported using a Likert scale (0‐5) ; SpO2 after pre‐oxygenation before sedation is given as measured by pulse oximetry ; Total time for procedure in seconds as timed with a timing watch. ; INCLUSION CRITERIA: Inclusion criteria will be all of: ‐ Adults aged greater than or equal to 18 years ‐ Able to give informed consent ‐ Planned for endobronchial ultrasound and ‐ Planned for sedation for their endobronchial ultrasound