Thursday, September 26, 2019

High Flow Nasal Cannula: Does it Ventilate COPD Patients?

I've reviewed numerous mechanisms of action and functions of High Flow Nasal Cannula but I haven't touch on whether or not it works to help ventilate patients. I have discussed in the mechanisms of action that it does wash out the CO2 from the dead space in the nasopharynx, oropharynx, etc, but does that show a numerical decrease in the PCO2? The studies I had reviewed prior to this one weren't promising. 

One of the indirect ways that HFNC can bring down CO2 is by bringing down the patients respiratory rate. There's plenty of data to support the decrease in the respiratory rate. Since the person isn't breathing as hard nor as fast, less CO2 is produced. Less CO2 is produced means the patients needs to be ventilated less. Things get better. Prior to this study, though, the data just wasn't there to show that this actually happened in a statistically significant way. I've said this before and I'll say this again, I will not recommend HFNC to a patient with a COPD patient sucking wind in the ED with an exacerbation that has a gas that looks like 7.06/96/66. That patient either needs some non-invasive ventilation with a very close eye or the endotracheal tube.

In this study they placed COPD patients, not in exacerbation, on HFNC and measured a number of parameters but you and I are here for the CO2. Patients had their PCO2 measured at baseline, on 20L HFNC, and at 30L HFNC. At 20L the PCO2 was at approximately 91 (plus or minus 6.7)% of their baseline and at 30L their PCO2 was at approximately 87.4 (plus or minus 6.2) % of their baseline. That data was statistically significant.

This may be completely out of bounds but if we can (although I probably shouldn't) extrapolate that to a patient with a PCO2 of 60, 20L should bring them down to approximately 54.6 and 30L down to 52.4. Something is better than nothing and if you can hold the patient over while they get their steroids and nebulizations, it may be worth a try in the real world.

- EJ

Bräunlich J, Köhler M, Wirtz H. Nasal highflow improves ventilation in patients with COPD. International Journal of Chronic Obstructive Pulmonary Disease. 2016;1077-1085.

Link to Abstract

Link to Full Free Article

Although great care has been taken to ensure that the information in this post is accurate, eddyjoemd, LLC shall not be held responsible or in any way liable for the continued accuracy of the information, or for any errors, omissions or inaccuracies, or for any consequences arising therefrom.

The primary source of compensation I receive for this page and Instagram work is via Amazon Affiliates. All this free education you receive is much out of the kindness of my heart but I also like to receive a check every month from Affiliate Marketing. No one likes to work for free. The best part is that it's of no cost to you. Here's how it works. 

You click on the link for Will Owens' awesome ventilator book here: and whether or not you purchase the book I receive a small commission for whatever you buy on Amazon for the next 24 hours at no cost to you. For every copy of the Ventilator book people have bought off of my affiliate links, for example, I have earned $0.85. I know it's not big money but it helps motivate me to keep on plugging along doing this heavy lifting in Critical Care. Thank you for supporting my work! 

My Amazon Store

No comments:

Post a Comment