None listed
Conditions
Brief summary
Trans-nasal humidified rapid insufflation ventilatory exchange (THRIVE) has been widely taken up by anaesthetic and ear, nose and throat (ENT) departments worldwide for airway management. THRIVE is a technique that uses rapidly insufflated, heated and humidified oxygen administered via nasal cannula to maintain oxygenation during periods of apnoea. It is regularly used for ENT procedures, in particular microlaryngoscopy. It allows for maintenance of oxygenation and unobscured surgical field by anaesthetic endotracheal tubes. The mechanism by which THRIVE and other apnoeic techniques (such as low flow intra-tracheal oxygen insufflation) maintain oxygenation is well understood, i.e. bulk flow of oxygen from the upper airway to replace the volume of oxygen taken up from the alveoli. However, a concern with all apnoeic techniques is the rise of blood and tissue carbon dioxide (CO2) levels in the absence of ventilation. Much of the support for THRIVE has centred on claims that unlike other apnoeic techniques, it is effective at eliminating CO2.. Recently, however, a study (1) of THRIVE in ENT microlaryngoscopy patients has suggested that when arterial CO2 levels are measured, the rate of rise of CO2 is actually as much as would be expected with other apnoeic techniques. In our anaesthetic department, we have considerable experience of apneoic oxygenation by low flow intra-tracheal oxygen insufflation (Lo-Flo). An oxygen catheter is directly passed under vision using a laryngoscope through the glottic opening to sit at mid tracheal level. This is then attached to oxygen supply at 0.5-1L/min. Transcutaenous carbon dioxide (TcCO2) can be easily measured with a transcutaneous probe that attaches to the patient’s skin in a non painful, non invasive manner. It is applied a few minutes prior to the start of the procedure. This study would build on the previous departmental experience with apnoeic oxygenation research. We plan to compare the two techniques of apnoeic oxygenation for ENT microlaryngoscopy, focusing particularly on the rate of rise of TcCO2. We believe it is likely that we will disprove the now widely held belief that CO2 rises less quickly with THRIVE than with other apnoeic techniques. (1) Gustafsson IM, Lodenius A, Tunelli J, Ullman J, Jonsson-Fagerlund M. Apnoeic oxygenation in adults under general anaesthesia using transnasal humidified rapid-insufflation ventilatory exchange (THRIVE) – a physiological study. British Journal of Anaesthesia 2017; 118: 610–7
Interventions
This study will involve patients undergoing elective microlaryngoscopy procedures under care of ENT and anaesthetics. These patients will be randomised on day of surgery using simple randomisation, assigning patients to one of two anaesthetic techniques;
ARM 1: Trans-nasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE)
Those patients enrolled into the THRIVE arm will be induced with high flow nasal cannula attached but not yet turned on. As surgery begins, they will have their face
This study will involve patients undergoing elective microlaryngoscopy procedures under care of ENT and anaesthetics. These patients will be randomised on day of surgery using simple randomisation, assigning patients to one of two anaesthetic techniques; ARM 1: Trans-nasal Humidified Rapid Insufflation Ventilatory Exchange (THRIVE) Those patients enrolled into the THRIVE arm will be induced with high flow nasal cannula attached but not yet turned on. As surgery begins, they will have their face masks removed and high flow O2 at 100% 70L started via Optiflow THRIVETM apparatus (Fisher and Paykel Healthcare Ltd, Auckland, New Zealand). OR ARM 2: Low Flow Intra-tracheal Oxygen Insufflation (Lo-Flo) Those patients enrolled into the Lo-Flo arm will be induced. After face mask ventilation and waiting suitable time for paralysis, a low flow oxygen catheter will be passed through the glottic opening to sit mid tracheal level using standard intubating equipment (direct or indirect laryngoscopy). After this oxygen catheter has been place, the patient will be ventilated using face mask ventilation until the surgical start point. At this point, face mask will be removed and oxygen catheter attached to oxygen wall outlet will be started at 0.5L/min. The maximal allowable time for either apnoea technique will have a 30 minute cut off point. There will be 45 patients will be randomised into each trial arm. As the patient arrives in the holding bay prior to their operation, the transcutaneous carbon dioxide (TcCO2) monitor will be connected to the patient. Upon entering the operating room, routine anaesthetic monitoring will be established. The patient will be pre-oxygenated using an appropriately size face mask until the end tidal oxygen (EtO2) > 70 mmHg. The patient will be induced with propofol 1-2mg/kg and/or propofol infusion (target controlled infusion or mg/hr), 0.1mcg-0.4mcg/kg/min remifentanil infusion and paralysed using a muscle relaxant. Ventilation of the patient will occur using face mask technique until appropriate degree of paralysis and up to immediate commencement of surgery. This study will be powered to show a true “no difference” in the rate of rise of TcCO2 between the two anaesthetic techniques.
Sponsors
Monash Health Anaesthetic Department
Study design
Allocation
Randomised controlled trial
Intervention model
Parallel
Primary purpose
Treatment
Masking
Blinded (masking used) (Subject)
Eligibility
Sex/Gender
All
Age
18 Years to No maximum
Healthy volunteers
No
Inclusion criteria
All patients over the age of 18 years undergoing microlaryngoscopy procedure
Exclusion criteria
BMI > 40 Pregnancy Expected > 30 minutes procedure time Resting saturations on air < 92%
Outcome results
None listed