( image attribution Ballon ventilation Wikipedia)
An incredible week for me recently! Caught up with my airway skills mentor Dr Richard Levitan
A bit more on the nose thing in an upcoming post…
During his workshop, Richard gave some great insights into oxygenation issues in emergency airway management. As you know he coined the term NODESAT, which is about using nasal cannula oxygenation in the perintubation phase of RSI.
My anaesthesia colleagues have always seemed amused/puzzled by the benefit of nasal oxygenation despite most of the research into its benefit coming from anaesthesia!
After the workshop I suddenly realised the reason why anaesthesia folks just dont seem to think there is a need for NODESAT? You ever wondered that too?
Well the secret is that the BVM ( Bag Valve Mask) manual resuscitator ( aka self inflating resuscitation bag mask) is a potential murder weapon…in fact more so than the laryngoscope!
(Editorial aside – if you have never heard of Scott Weingart’s seminal podcast series on Laryngoscope as a murder a weapon then check it out NOW WE WANT WEINGART)
Well if you have been using the BVM to preoxygenate your emergency patients for RSI then it may come as a surprise to you that some BVM designs do not provide any more than FiO2 60% oxygen for spontaneously breathing patients! So much for assumed 100% oxygenation prior to RSI!
Which then answers the question why anaesthesia folks just dont get nasal cannula oxygenation.
Anaesthesia do NOT use BVM/self inflating manual resuscitators to oxygenate their patients prior to RSI. They use fresh gas flow circuits that deliver 100% oxygen to the patient mask. They preoxygenate their patients fully . They also use advanced gas monitoring with end tidal oxygen monitoring so they know when adequate denitrogenation of the lungs has occurred.
This is why they dont see much extra benefit from the nasal cannula oxygenation technique. For their purposes full preoxygenation gives most of the benefit.
This fact that some BVM designs do not deliver high oxygen concentrations to the spontaneous breathing patient has been known for some time with several studies showing this.
1. Inadequate preoxygenation during spontaneous ventilation with single patient use self-inflating resuscitation bags.
2. Efficacy of preoxygenation with tidal volume breathing. Comparison of breathing systems.
3. Oxygen delivery using self inflating resuscitation bags
4. Oxygen outflow delivered by manually operated self-inflating resuscitation bags in patients breathing spontaneously*
BOTTOM LINE : Know what your own BVM/manual resuscitation device system does in terms of oxygen delivery performance in spontaneously breathing patients as well as with manual ventilation!
If you are going to use it to preoxygenate Dr Levitan ( and now I !!) suggest adding in nasal cannula oxygenation technique to improve oxygen delivery !