Rescue oxygenation for hypoxaemia is common during anaesthesia for procedures in children with abnormal airways due to the complexity of balancing adequate depth of anaesthesia with maintenance of spontaneous breathing and providing an uninterrupted field of view for the proceduralist.
Inadvertent hypoxaemia during flexible bronchoscopy has implications for both procedural efficiency, efficacy, and patient safety. Infants and children desaturate more quickly than adults and are more prone to apnoea. Nasal High Flow oxygen insufflation can prolong safe apnoea time, preventing hypoxaemia and can facilitate oxygenation during anaesthesia for children with abnormal airways and lungs whilst spontaneously breathing. To date, there is no high-grade evidence comparing Nasal High Flow (NHF) with the standard face mask/laryngeal mask oxygen delivery techniques during flexible bronchoscopy.
The investigators aim to conduct a pilot randomised controlled trial, in 80 children, to establish feasibility of Nasal High Flow for children presenting for elective flexible bronchoscopy at Queensland Children’s Hospital and Perth Children’s Hospital. We will compare NHF with LMA/Facemask to determine if NHF is a feasible oxygenation technique and the incidence and severity of hypoxaemic events requiring rescue oxygenation. This has the potential to both improve both the safety and the success of these procedures for children.
Associate Professor Susan Humphreys, Queensland Children’s Hospital, Queensland, Professor Britta Regli von Ungern-Sternberg, Perth Children’s Hospital, WA, Professor Kristen Gibbens, Child Health Research Centre, The University of Queensland.
The project was awarded $A89,999 (including scholarship) through the ANZCA research grants program for 2022.
Infants and children with an abnormality in their airway and lungs often require procedures to further investigate their lungs and improve their breathing. A very common way to do this is a flexible bronchoscopy. During the anaesthesia for this procedure, the anaesthetist delivers oxygen and monitors the adequacy of the child’s breathing. In this situation both the respiratory physician and the anaesthetist share the child’s airway for both delivery of oxygen and for placement of a small telescope to directly view the anatomy within the airway and lungs. It is impractical for the anaesthetist to place a breathing tube into the airway for delivery of oxygen as this obstructs the view.
Infants and children with an abnormality in their airway and lungs often require procedures to further investigate their lungs and improve their breathing. A very common way to do this is a flexible bronchoscopy. During the anaesthesia for this procedure, the anaesthetist delivers oxygen and monitors the adequacy of the child’s breathing. In this situation both the respiratory physician and the anaesthetist share the child’s airway for both delivery of oxygen and for placement of a small telescope to directly view the anatomy within the airway and lungs. It is impractical for the anaesthetist to place a breathing tube into the airway for delivery of oxygen as this obstructs the view.
It is not uncommon for the oxygen levels in the blood to fall (hypoxaemia) during these procedures. The procedure may need to be interrupted to correct this which can potentially compromise the safety of the child, prolong the procedure, increase exposure to anaesthetic agents and affect the success of the procedure. The interruptions are necessary as hypoxaemia remains the primary cause of anaesthetic-related death and morbidity. A recent anaesthetic audit showed that nearly a third of children undergoing flexible bronchoscopy procedures experienced low oxygen levels one or more times during the procedure.
The method which the anaesthetist chooses to give the oxygen to the child may help to prevent the occurrence of low oxygen levels. Traditionally anaesthetists have delivered oxygen via face mask or airway device which is placed inside the mouth above the voice box part of the airway at flow rates of up to 6 litres per minute. Our research team have recently investigated a new mode of oxygen delivery called Nasal High Flow. In Nasal High Flow, warm humidified oxygen is delivered to the airway via nasal cannulae, at a rate determined by the child’s weight. For example, Nasal High Flow can be delivered at rates of 2L/kg/min. Therefore, a 10kg infant would receive 20 litres per minute. Matching the flow delivered to the patient’s breathing allows the anaesthetist to deliver oxygen to the child at the required concentration. Recent studies have demonstrated Nasal High Flow is an effective alternative technique for oxygen delivery that can be safely used in infants and children with abnormal airways.
To date there have been no large-scale studies evaluating Nasal High Flow in comparison to other oxygenation techniques during flexible bronchoscopy in children. Therefore, we aimed to compare the two techniques using a randomised controlled trial in infants and children during flexible bronchoscopy. If Nasal High Flow reduces the risk of low oxygen levels, this has the potential to both improve the safety and the success of these procedures.
The outcomes were chosen to assess the feasibility of implementation of this trial, in two clinical settings, specifically in its recruitment and adherence to the protocol. We found that the current high-flow protocol requires further education among both anaesthetic and respiratory physician teams to ensure successful implementation.
Conclusion. This protocol to compare the use of nasal high-flow with standard facemask/LMA oxygenation is likely feasible in its current form, however, clinical teams require significant training before trial start to increase acceptability of the technique clinically and in managing these cases with NHF.
A publication of the protocol can be found in Pilot and Feasibility Studies.
Flexible bronchoscopy insufflated and high-flow nasal oxygen pilot trial (BUFFALO protocol pilot trial)
S Humphreys, A Schibler, T Williams, S Spall, T Pham, T Atkins, V Goyal, ...Pilot and Feasibility Studies 10 (1), 45
The Main paper is being prepared for submission aiming for a paediatric anaesthesia journal.
Last modified: