Buccal RAE Tubes and Apneic Oxygenation- Bottom Line - Critical Care Practitioner

Buccal RAE Tubes and Apneic Oxygenation- Bottom Line


Apneic Oxygenation During Prolonged Laryngoscopy in Obese Patients: A Randomised, Controlled Trial of Buccal RAE Tube Oxygen Administration.

 Heard A Toner AJ, Evans JR, Palacios AM, Lauer S.

 RAE tube

Clinical question.

Does apneic oxygenation via the mouth and a modified R.A.E tube extend the safe apnea time during prolonged laryngoscopy in obese patients.



Single centre, non-blinded, randomised controlled trial.



Elective surgical patients requiring general anaesthesia in Australia.



  • Elective surgical patients over >18 years, ASA 1-2, BMI 30-40.
  • Exclusions= chronic respiratory disease, SpO2 <98% after pre oxygenation, known difficult airway, uncontrolled HTN, IHD, CHF, raised ICP, GORD or anaesthetic allergy.
  • Power calculation 14 patients per group using a p-value of 0.05. 15% increase in sample size to account for abnormal distribution, further 20% increase in sample size to account for dropout, N=20 per group.
  • Demographic characteristics between groups were similar.



  • Both groups had an adapted Ring-Adair-Elwyn tube (R.A.E tube, typically used for oral tracheal intubation for ENT procedures) which was connected to oxygen tubing. The R.A.E was placed on the left side of the mouth in the buccal space and secured to the left cheek.
  • The intervention arm had 10L per minute of oxygen entrained through the R.A.E tube and no oxygen in the case of the control group.
  • Patients were anaesthetised with propofol and remifentanyl using targeted controlled intravenous infusion(TCI)
  • A grade 1 Cormack-Lehan view was achieved with a Glidescope, thereafter, a deliberate grade 3 view was maintained for the duration of the apnea time.
  • Time 0 was recored from the time TCI was commenced, neuromuscular blockade was administer 60 seconds after commencement of TCI.
  • Patients were intubated when SpO2 fell below 95% or 750 seconds of apnea.



  • The primary outcome was SpO2 less than 95% or no desaturation before 750 seconds.
  • In the treatment arm risk of desaturation before 750 seconds hazard ratio 0.159, 95% confidence interval 0.044–226, P < .0001
  • Interquartile range of safe apnea time; 750 seconds (389–750) versus 296 seconds (244–314), P < .0001
  • In obese patients receiving buccal RAE tube oxygenation; a 2.5-fold increase in safe apnea time compared with standard care.
  • 66% of the intervention arm reached 750 seconds without desaturation.
  • 400 seconds was the maximum apnea time in the control arm.
  • Number need to treat of 2 for no desaturation at 750 seconds.

Authors conclusions.

  • Buccal oxygenation is cheap and readily available.
  • It is an effective means of apneic oxygenation in obese patients and an alternative to the nasal route.




Both groups appear well matched.

Clear description of induction.



  • Single centre.
  • Mode of maintaining airway patentcy is not real world or normal practice. Not clear why they did not simply use a jaw thrust.
  • BMI was limited to a maximum of 45 and may limit extrapolation to even higher BMI.
  • Oxygen flow was limited to 10L/minute.
  • Patient positioning was not reported, this may have influenced apnea times if positioning was not uniform.
  • Low risk ASA grade 1-2 population may limit extrapolation to high risk or higher acuity populations.


Bottom Line.

Buccal oxygenation is an effective way to deliver apneaic oxygenation in obese patients and significantly extent the safe apnea time following induction of anaesthesia.




Gavin DentonGavin Denton @dentongavin – Current role: Critical care practitioner, critical care, West Midlands. Roles include; assessment and management of the critically ill patient, insertion of invasive lines, advanced airway management (under supervision), transfer of the critically ill patient, resuscitation (from airway, to team leader to post resus care). Trenching and support of junior doctors of the above.
Graduated from the University of Birmingham with BN(hons). BSc from Birmingham City University. About to complete MSc in health sciences from the University of Warwick.
Working background: 15 years working within various aspects of critical care. 7 years in critical care, 6 years in critical care outreach, 2 years as a critical care practitioner. Adult life support instructor. Independent non-medical prescriber.
Future aims: faculty of critical care medicine affiliation. FEEL course, POCUS training.
Clinical interests: USS, airway management.

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