titrating FIO2

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    Hi,all. New to Trauma ICU at a teaching hopspital. Know well that Fio2 at 100% can be damaging and it ought to be used for short periods only. Pt was on PC. His blood gases were not great, PO2 like 120 hovering. Initially, (night before) when he was originally intubated, I can see he needed the 100%. PO2 was 90 approx. But when I got there next night, PO2 was as above, higher. From what I have read and halfway understand from the R.T I ask a lot of questions of, the PO2 of a 'normal' person, should be 3 to 4 times that of the FIO2. Of course, our patients aren't 'normal'....but when titrating down, which is a nursing duty, what would you expect that your PO2 ought to look like when you finally get down to 40% or 50%? The resident explained to me to titrate this down via evidence from the pulse oximeter on the moniter. I understand this and this is what I did....next blood gas at 60% was only slightly poorer than the one at 100%. The pulse oximetry only went to 96 at the end of this change. I also think I understand that pulse oximetry doesn't truly tell you the saturation because other molecules can hook on to a hemoglobin...and oximetry is not sensitive to what is hooked onto the hemoglobin, only that something is hooked to it. I am so brand new in the ICU! Understanding the relation to blood gases and vent changes is a big challenge for me. When titrating down the FIO2, do you want to do this in increments of 5, 10?....and how many minutes do you leave before titrating down again if the oximetry looks ok? And also, what is a decent PO2 to seek in this situation. Know this is an elementary question, but nurses on my unit have lots of different answers.

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  2. 0
    We titrate down over several hours but usually we go down by 10 each time if the pt tolerates it. RT does the titrating and setting changes based on ABG's. Nursing really does very little with the vent or its setting other than sxn PRN in my facility.
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    Thanks Sun. The thing us RNs do with the vents is titrate the FIO2 only. Thank goodness we have so many amazing R/Ts! A question for you as the RN....how much do you stay aware of the changes in the vent r/t your blood gas results; and how much discourse do you initiate with the R/T and docs regarding changes, response affects? Many of the RNs on my unit seem to almost ignore the vent settings completely and hand this over entirely to docs and R/Ts. Although I would love to do this....(so much learning needed in this area); I still feel like when I have an order (which is often) for the RN to mess with the FIO2, than I need to have some kind of at least elementary understanding of what is expected to change with the patient. A few seasoned ICU RNs know every little thing. I try to pick their brains when I can, but they work opposite shifts than I. And to tell the truth, my brain goes into tilt when I try to understand all of the factors! What does the average ICU RN focus on when interpreting the gases and the vent settings? How bout you? Again, thank you so much for response!
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    First make sure the PH is in normal range. If the Ph is normal, then there's nothing major to really do (except some fine tuning). It's compensated. When starting out, nurses have an obsession with oxygen levels. As time goes on, you will see that the CO2 is more important. If a pt has a normal co2 level, but a reduced O2 level, they get a nasal cannula. If the o2 is normal to low, but the co2 is high, the pt just bought a Bipap or vent. The body is much more sensitive to co2 as a driving force to breath. When you hold your breath, the crave to breath is from your CO2 level rising, not the O2 dropping. If you hyperventilate, you will get dizzy...not because anything is happening to the O2, but because your Co2 significantly drops. So, make sure the co2 is properly corrected. Kind in mind that not everyone needs a CO2 of 34-45. COPDers can live with a CO2 above 60 and be fully compensated.

    Look at the bicarb to see if they are respiratory or metabolic. Chronic CO2 retainers should have higher bicarb levels to buffer the acidic CO2. That's why they are compensated. fyi...If a COPDer goes into renal failure, their ph will bottom out. That's b/c your kidneys produce bicarbonate. Without that, that's not much else to help buffer....except tachypnea or a bicarb gtt.

    So, to answer your question on O2. The oxygen saturation is actually pretty accurate. There are times when the O2 sat can be false, but that is from other things going on, like carbon monoxide poisoning (house fire inhalations or car emissions) and other conditions. The O2 sat won't really be saturated with different stuff unless you already know about it (usually). You can go by the O2 sat most of the time. If a pt has a 100% sat, but their PO2 is very low...something else is going on...and it's an emergency. When you are titrating Fi02 on a vent, first note the PO2 level on the blood gas. Many resources say 75-100 for the PO2, but you can be above 60 or 70 and be ok. If the PO2 level is like 150 and you are on 100% Fio2, you can knock it down to 60% (maybe 70% if you want to be cautious). Let them ride for a little bit (1-3 hrs). Then, go by increment of 10-15 %. Watch their o2. Go with each change for a couple hrs. You don't have to have the o2 sat be 100%. 94% is fine. For bad COPDers, you can keep them above 90% (make sure you have a doc's order for the O2 sat range). And, it's ok to even titrate over a couple of days if the lungs are bad. As you start titrating below 45%, go by increments of 5-10%. 40 to 35 to 30. A titration from 90% to 80% isn't a big deal b/c they are already in the plus, but a titration of 40 to 30 can be a big deal b/c you are fine tuning on the lower end of the spectrum. Make sure their o2 sat is staying within range. Some pt's just can't tolerate being below 40%. That's ok. Maybe they just need some time.

    Don't feel bad if you need to go back up on the FiO2. It's not a race. Many times, you have to go up and down, up and down. It's not your fault if you can't get them to the good 'ol 30% by the end of your shift.

    The other thing is to look at the pt. If their resp rate goes from 16 to 31, then they are not getting what they need. See if they are air hungry. If you see forced inhalation, nasal flaring, and the head bobbing back with each breath (along with the mouth opening wide with each breath) then the pt is air hungry. If all is quiet, then you have a good idea of their respiratory status. I have seen pts with 93% O2 sat, and relatively normal blood gas, but they look like a fish out of water. The vent needs to be adjusted.

    Remember your side of the clinical aspect. Is the pt anemic? Do they need blood? Does the PEEP need to be increased b/c of atelectasis? Do they have pneumonia or pulmonary edema? Do they need lasix? Are you mobilizing the pt as much as possible. Could they have a mucus plug or do they need not a bronchoscopy? Is the albuterol treatment cutting it or do they need atrovent and mucomyst added? Are they just way to snowed with sedatives? Maybe they need extensive pulmonary toileting. Is there a lung injury or do you suspect ARDS? Hope this helps
    phea, Mully, sethmctenn, and 5 others like this.
  5. 1
    At our facility, both the primary RN AND the charge stay informed of all vent changes. While RT has the in-depth knowledge regarding that system, the RN is ultimately responsible for the patient. There have been numerous times a patient has been persistently tachy but had a scheduled breathing tx. The RT often doesn't look at the big picture and will plan on giving that albuterol. If close communication isn't maintained between the RT and the RN, the RT won't have a chance to find out a call was just made to the MD for some diltiazem - it just needs to be pulled and administered. Also, you may find yourself working with an RT that has an aggressive weaning technique. A pt could be on trach collar for a few days straight. You may look at his resp trend, though, and see he's gone from the teens to the 30's throughout the day. From a nursing standpoint, it might be prudent to have the pt rest on the vent for the night. If you and the RT disagree on this, however, you may find yourself needing to tactfully 'put your foot down' to provide the best pt care possible. And keep asking questions!
    nightengalegoddess likes this.
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    Thank you so much Hodgie. I am not too far afield in my assessments in the trauma ICU by reading your response, (just a little unconfident). But this has helped much!!! Thank you Jackie too! Luckily, our R/Ts in general are helpful, experienced; and I have found very non-egoistic. Some have stated they wished for more RN input often. This information is well taken. I thank you so much.
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    No problem! Your gut feeling on weaning is correct. You will get a feel of how the O2 sat will react with various Fio2 titration as time goes on. Since you are in the trauma ICU, you will become a pro once you deal with pts that have ARDS. They are hard pts to treat.
    nightengalegoddess likes this.
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    Some patients tolerate more titration/weaning than others; it depends on their condition and comordities. Your doctor, RT's, and other more experienced nurses can assist you in your learning process especially if you find the ones who like to teach! When I started ICU, vents were intimidating; now I wean vents, change vent settings and modes without thinking much about it especially if my RT is busy! Just keep on trying to learn more about it and don't be afraid to make adjustments to oxygen, vents, bipap, etc.
    nightengalegoddess likes this.


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