In the LaMW: Ox Kills podcast, I discussed preoxygenation strategies. Sam Ghali had some questions; this wee has the answers.
Groombridge et al.
NRB @ 15 lpm = 52.6%
NRB @ 15 lpm + NC @ 5 lpm = 57.1%
Max with anesthesia circuit
Hayes-Bradley et al.
http://www.annemergmed.com/article/S0196-0644(15)01500-0/abstract
Here are their numbers (they also simulated air leaks in this study)
NRB @ 15 lpm alone = 52% ETO2
NRB @ 15 lpm + NC @ 10 lpm = 67%
BVM = 79%
BVM with Mask Leak: BVM markedly improved with NC
Russell_et_al.
Nasal cannula improved ETO2 when mask leak was created
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Scott Weingart
An ED Intensivist from NY. No conflicts of interest (coi).
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Hey Scott, Enjoyed listening to your excellent response! This is such a great topic and a super important one. If nothing else, I hope by now at least that 2 major points have been driven home: 1. How abysmal a job the traditional standard NRB mask at 15 lpm does at PreOx/DeNitro 2. O2 flow rates definitely do matter for PreOx/DeNitro But I must say that I don’t think the question on my end is: “Should a nasal cannula be part of Denitrogenation/Preoygenation?” NC for PreOx is perfectly fine, and it already being on for ApOx works out nicely. I think the better question is: “If we are gonna use the NRB/NC combo for DeNitrogenation/PreOxygenation: Is NRB @15 lpm + NC @15 lpm optimal?” Just to review the numbers we’re working with based on these studies again: NRB @ 15 lpm = ~ 52% NRB @ 15 lpm + NC @ 5 lpm ~ 57 % NRB @ 15 lpm + NC @ 10 lpm ~ 67% NRB @15 lpm + NC @ 15 lpm = ??% (I’m so with you – wish they would have used NC @ 15 lpm) If the addition of NC @ 15 lpm would… Read more »
Scott,
From prior studies and your experience does the addition of a NC during pre-ox and ap-ox increase risk of gastric insufflation and regurgitation?
P. Thompson
Intensivist
Baptist Health Lexington
i think you can extrapolate the safety of 15 lpm NC from the large 40-60 lpm Hi-Flow NC studies
Scott,
Thanks for the shout out. I will admit to slacking a bit over the last year, I moved to MT and even my HEMS colleagues accused me of taking a “microretirement”! But, I’m back. It is fortuitous that this shout out came when it did as I have just started using the LaMW lectures as part of my EMS education locally. My entire HEMS crew just went through them as part of monthly training. If they hear the Wee, they’ll probably think it was a set up.
Looking forward to ongoing review
Thanks again,
Mike
thanks guys. I listened to the wee on a flight today and kept thinking. Whats the point in all of this?
Dont critically unwell patients who require RSI, deserve the gold standard?
WHy are we making do with lesser measures?
I really dont see the point of using multiple different setups to achieve the same goal which should be gold standard preoxygenation and denitrogenation for a potentially homicidal procedure.(sic) (LaMW series)
If patient is going to end up on a ventilator then why not use it from the very start of the whole process?
These half measure setups and techniques speak to the issue of our problems of resources and staffing but should not detract from the goal of achieving the best practice standard for unwell patients.
don’t disagree. there are however realities and ideals. making the two meet is a life’s work–until they do, there still needs to be means to get things done. i have vents available always; the VAST majority do not.
One thing that has been getting drove into my skull for the last few years is “free radicals”, formed by what studies are showing to be cause by what you could say over oxygenation. When flowing NRM@15 and NC@5. wouldn’t this be textbook over oxygenation and cause free radicals? I am somewhat of a newer Paramedic, but I am always learning more.
Thanks in advance for any help
Joe Plouff
NREMT-P
The goal, in this case, is to increase oxygen saturation and wash out nitrogen prior to the induction of apnea pre-intubation in order to hold off hypoxia for longer. I think the use of high FiO2 leading to oxidative stress is more of a long-term concern and or in the case of high FiO2 being used on patients that do not require additional oxygen. I am by no means an authority on this but I hope this answer helps.
[…] Other links you should check out include; PHARM Podcast 134 Preoxygenation, and EMCrit Wee – Should a Nasal Cannula be Part of Denitrogenation / Preoxygenation […]
Has anyone tried to measure the actual peep generated by an NC @ 15lpm or the combination of NRB and NC both being at 15lpm? Any literature on this you would suggest. This technique is one of the only ones available to me in order to maximally oxygenate patients who do not require CPAP or BVM ventilation as we don’t carry HFNC.