What is this page about?
Scott Weingart, MD and Richard Levitan, MD published an article in the Annals of Emergency Medicine entitled Preoxygenation and Prevention of Desaturation during Emergency Airway Management.
This page serves as a repository for supplementary material on the subjects raised in the article.
The article is available for free on the Annals EM Site (pdf)
CPAP for Preoxygenation
In a patient with shunt, CPAP is needed for preoxygenation. In my ED, we make this happen with the ventilators installed next to every resuscitation bed.
However, not every ED has ventilators readily available and it might take >15 minutes to have respiratory bring a NIV machine or a vent. In that case, you want to use a BVM with a PEEP valve.
PEEP Valve Fits on any BVM
However, this device provides CPAP only when the patient is expiring. In a patient who is not breathing rapidly, most of the cycle will be spent at zero PEEP. Once the patient is apneic, the device won’t supply PEEP unless you manually give ventilations–even then the PEEP will only be there immediately following the ventilation. However, if you add a constant source of flow, like a nasal cannula set to 15 lpm then the BVM/PEEP Valve combo will give continuous PEEP regardless of the patients resp rate or even when they become apneic. In the following video, a PEEP valve set to 10 cm H20 provides between 6-8 cm H2) of PEEP throughout the cycle. This same nasal cannula should be on the patient anyway for apenic oxygenation and NO DESAT (Nasal Oxygen During Efforts Securing A Tube) during the intubation procedure.
Other Articles of Interest on Preoxygenation/Reoxygenation/Preventing Deoxygenation
Dr. Levitan’s site for airway videos and courses
The airwaycam site is an amazing source for educational materials and equipment to help you manage ED airways.
If you liked the article and/or this page, you’ll probably like the EMCrit Blog and Podcast…
why not check it out at emcrit.org?
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Email us on the contact page.
Additional Articles for Version 2.0
More evidence that if the patient starts low, their risk of desat is much greater (Acta Anaesthesiologica Scandinavica Volume 57, Issue 2, pages 199–205, February 2013)
ApOx for PanEndoscopy (10.1177/0194599813486248 Otolaryngol Head Neck Surg April 12, 2013 0194599813486248)
Hi, my name is Scott Weingart. 
This ‘poor-man’ NIPPV method (high flow NP+BVM) requires 2 Oxygen sources?
George
Clarification: This ‘poor-man’ NIPPV method (high flow Nasal Prongs+BVM/PEEP valve) requires 2 Oxygen sources?
George
This may be a silly question but is o2 flowing through the bvm when the bag is not being squeezed?
nope, nothing comes out of the bag unless you squeeze
Hi, I think that might be wrong. O2 flows through the one way valve constantly- this can be felt and heard when checking the BVM.
When the patient inspires the flutter valve will open further and they will draw in O2 from the bag and reservoir, providing there is a good seal.
Nope, a majority of bags are manufactured with valves that put the oxygen out the back unless the front duckbill is open.
In the breathing patient, which is the more effective oxygen delivery method:
1. Commercial CPAP device (Flow-safe, Boussingnac)
2. BVM with PEEP
I assume the combination BVM/PEEP with Nasal Prongs is better than above but requires 2 sources of O2.
George
Best would be commercial cpap with nasal cannula; which also requires 2 sources O2
It was nice to be able to cite (after the fact) anaesthetic literature (via your article) to an anaesthetist who tried to tell me that nasal cannula oxygenation would not be helpful during a high risk RSI.
Scott,
Just clarification, but if we’re using an LTV1200 for CPAP during PreOx, it would be easier to continue using the vent during ApOx? If in a situation where you have NIV capabilities, one could leave the mask on, and just switch to A/C to use the vent while patient is apneic, right?
Lee, Sorry I missed this comment originally. You still need the nasal cannula for even vented apneic ox as the vent will not pick up the small O2 utilization as a breath. But a vent set to PEEP or a very low RR with a NC underneath would work wonderfully.
Scott, excellent, … great tips regarding oxygenation, thank you. A word re the use of NIV during the apneic period. The LTV 1200 that Lee is using does provide a continuous bias flow of O2 at 10 lpm and will maintain CPAP (as long as the conserve O2 feature is “off”) whether the patient is spontaneouly breathing or apneic. The addition of NC may not add any advantage as the ventilator will maintain constant CPAP by adding gas flow at whatever FiO2 is set on the ventilator. NIV devices that I am familiar with all behave this way.
Thanks for the information. Where I trained (Australia and UK) we have always prexoygenated with BVM. The cited superiority of high flow NRM over BVM actually refers to an abstract on the internet and the article written by Dr Weingart (1) does state without reference that standard flow meters are capable of achieving very high flows in the order of 30-60 l/min if dialled right up. The data presented in the reference (abstract form on net) shows NRM achieving 77-89% at 30-60l/min respectively (and not greater than 90% as stated). Iis there any data to support these higher flow rates are achievable with standard flowmeters as would have to have a 60 l/min flow rate to achieve the higher FiO2? Otherwise if you were contemplating this technique a high flow (=expensive) flowmeter would be needed and then would achieve up to 89% if data cited was accurate and verifiable. I think overall this article is excellent but do have these doubts about NRB for preoxygenation. Nasal oxygen would improve things of course and perhaps the combination if better than BVM with inadequate seal.
1. Earl JW. Delivery of high FiO2. from http://www.rcjournal.com/abstracts/2003/?id=OF-03-257.
2. Weingart SD, Levitan RM. Preoxygenation and prevention of desaturation during emergency airway management. Ann Emerg Med. 2012;59:165-75.e1.
Today I had the opportunity to visit our biomedical equipment division. I tested a standard (15l/min) flow meter with a Fluke VT mobile gas flow analyzer. The calibrated flows on the wall flow meter were accurate. When the valve was fully opened past 15 l/min it only generates a maximum 19l/min flow.
May be the flow meters are different pressures in the USA ( I work in Australia). But the flow meters I checked would not produce the required flow rates to achieve FiO2 > 90% with NRB mask alone.
Is there a benefit to using the nonrebreather on its own at 30-60 lpm as opposed to using the nonrebreather at 15 lpm plus the use of nasal cannula to the max? I’ve been reading Dr. Levitan’s NO DESAT material, which recommends nonrebreather plus nasal cannula…
thanks!
The NRB should ALWAYS be put up as high as your flowmeter will allow. NC adds little to this, but there is no reason not to put it on at 15 lpm right at the start if you have enough flowmeters. When using oxygen tank (limited to 15 lpm) with the NRB, there is prob. an advantage to NC in addition. Dr. Levitan was my co-author on the paper recommending always try to get 30-40 lpm with NRB.