Do you humidify high-flow oxygen with a nonrebreather?

[Freedom42]

New nurse here. Last night I was caring for a patient in CHF whose 02 sat plummeted into the seventies while she was on a cannula and receiving 5 litres/minute. The on-call physician ordered a nonrebreather and said to push her up to 10 litres/miute or whatever it took to inflate the bag. Ten litres did the trick. Her sat immediately came up to 93 percent and stayed there.

Later on in the evening, an aide asked me why the patient's oxygen was not humidified. I told her that it was not ordered, and that normally I see humidification as part of the order. She replied that I did not need an order.

Correct? I don't know. When I asked the nursing supervisor if a) the oxygen should be humidified on a nonrebreather, she said she did not know and b) she was uncertain whether I needed an order for it. I'm presuming the latter is facility policy, but I could not find any policy nor a definitive answer about humidification in the clinical handbook that we are supposed to follow.

So which is it? Do you humidify a nonrebreather? Is that creating a Petri dish or protecting the patient? Necessary or unnecessary? And would you expect humidification to be ordered or something you could do as a nursing judgment?

[BrnEyedGirl, BSN, MSN, RN, APRN]

Where I work it is almost always humidified,....anyone on O2 has a standing order for resp to assess and tx,...they decided to humidify.

[07302003, ASN, RN]

No, O2 at 15L cannot be humidified, it would blow off the water attachment... humidity comes from the re-breathing, as far as I know NRB bags should always be at 15L, you want them to stay inflated. And a NRB is the next step to an ICU and being vented, so I would be worried more about that than humidification (not to sound mean, but humidification is the last of your worries... patient cannot stay on NRB indefinitely)

Best of luck!

[GilaRRT]

It would be rather difficult to use a bubble humidifier with a non-rebreather mask. This is especially true at flows of 10 LPM or greater because contact time decreases and temperature decreases, both play an important role in determining the effectiveness of the humidifying device.

You could heat the bubbler if you have the proper setup; however, water would form condensate and quickly occlude the small bore tubing of the non-rebreather mask. There exist no good options for humidification associated with a non-rebreather mask IMHO.

Better options would mean not using a non-rebreather mask. However, many devices can be used with proper equipment to properly humidify. A passover type of humidifier could be utilized and we are all familiar with HME's; however, we are not going to use these devices with a non-rebreather mask.

A better question to ask IMHO is "why was a patient placed on a NRM all night?" IF somebody is only saturating 93% on a non-rebreather mask, this patient has significant underlying problems. This indicates a rather significant barrier to oxygen diffusion exists. You are giving somebody 100% oxygen and only ~93% of their hemoglobin is actually being saturated. In a CHF patient I can think of a few significant problems that can cause such a profound situation. This patients A-a and V/Q rations were most likely significantly altered and oxygen via a NRM will not cure the underlying cause.

Hopefully, the physician ordered other interventions? In addition, CPAP or BiPAP is always a good consideration with CHF patients.

My thoughts, and clearly I am not aware of the entire situation.

[Freedom42]

Thanks for your responses. In addition to putting the patient on the nonrebreather, I obtained stat orders for Lasix. She lost 5 pounds overnight. I don't understand why she was moved to my unit -- a step-down rehab unit attached to a hospital -- in the first place. I monitored her very closely but to some extent at the expense of the other 20 patients on my assignment. The on-call physician did not want her transferred. I called the patiet's primary first thing in the morning, and he came in immediately to evaluate her. She did improve dramatically following heavy doses of Lasix. She's still my patient.

[vincejojo]

With an oxygen flow rate higher than 4 L/min, humidity is needed to prevent drying of mucous membranes (Ignatavicius & Workman) p. 546

[vincejojo]

07302003 said:

No, O2 at 15L cannot be humidified, it would blow off the water attachment... humidity comes from the re-breathing, as far as I know NRB bags should always be at 15L, you want them to stay inflated. And a NRB is the next step to an ICU and being vented, so I would be worried more about that than humidification (not to sound mean, but humidification is the last of your worries... patient cannot stay on NRB indefinitely)

Best of luck!

And where did you get your theory from?

[sunnycalifRN]

07302003 said:

No, O2 at 15L cannot be humidified, it would blow off the water attachment... humidity comes from the re-breathing, as far as I know NRB bags should always be at 15L, you want them to stay inflated. And a NRB is the next step to an ICU and being vented, so I would be worried more about that than humidification (not to sound mean, but humidification is the last of your worries... patient cannot stay on NRB indefinitely)

Best of luck!

You are correct that you cannot humidify a non-rebreather mask because the bubble humidifier will not allow flow much higher than 10 L/min . . . the NRB should be run at 15 L/min or flush.

However, you can provide humidified O2 at 100% via a high flow aerosol mask . . . just ask your friendly RT to provide one for you.

[chenoaspirit, ASN, RN]

At our hospital, we never humidified a nonrebreather. Not sure why but RT said it was a BIG no no.

[sunnycalifRN]

chenoaspirit said:

At our hospital, we never humidified a nonrebreather. Not sure why but RT said it was a BIG no no.

The reason you cannot is because the bubble humidifier has a flow restriction of about 10 L/min . . . if you don't believe me, just try it . . . hook up the bubbler and then crank the flowmeter to flush . . . you will see that it can only provide about 10 L/min. Additionally, it often will spray water through the tubing into the non-rebreather.

That's the reason the RT said it's a NO-NO.

A non-rebreather should be run at 15 L/min or at "flush" (full open on flowmeter) to provide the highest possible O2 level . . . even though it is called a 100% non-rebreather, it actually only can provide about 80 - 90% because the mask may allow some room air to be pulled in around the mask edges.

I worked as an RT for 10 yrs before switching to nursing.

[chenoaspirit, ASN, RN]

Thanks sunnycalifRN, I always wondered.

[GilaRRT]

chenoaspirit said:

Thanks sunnycalifRN, I always wondered.

Also remember what I stated in my post. It is not possible to adequately humidify a NRM with a bubble humidifier. The contact time is so small that proper humidification cannot occur. As stated, we could heat the bubbler to enhance humidification; however, the oxygen would quickly cool and water would condense out clogging the oxygen tubing and generally making a mess as stated earlier. This is in addition to what other people have stated about things popping off at such high flows through the bubbler.

Another important concept to remember is that a NRM is not a high flow device. A flow of 15 LPM will not meet the flow demands of may patients. If patients require additional flow, an air entrainment mask or other high flow modality may be needed. In the case of a CHF patient who meets criteria, CPAP or BiPAP would be another good consideration.