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Discussion

Oxygen Therapy

I just have a general question about giving someone oxygen I was never really given a guide on this so I was wondering for example if I had a patient whose spo2 is 90 if this value is not normal for a patient would I start off with NP or would I start off with a simple mask or a non-rebreather.

So in other words my question is, at what range of Spo2 would I use each oxygen therapy device for (Nasal prongs, simple mask, non-rebreather)?

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    • Featured Replies

    It's unbelievable that you were "never given a guide," with the oxygenation.
    Anyway, to answer your question, 90% of SpO2 can be normal for some people, but it's "not normal," for most people.   What I noticed, I generally see 2L per minute.  Always check your patient first. How are they feeling? Start with the mental status (A&Ox__?). Check the order for oxygenation after your patients are safe.  What do they look like to you? If they're bluish but alert and orientated maybe they received medications that can make them look like they're cyanotic or silver or gray. 

    Read your theory-prescribed textbook(s). That's something you need or have to know. ABC. Build your knowledge from this.

    Again, check what's appropriate oxygenation for a certain patient. You don't want to hyperoxygenized someone who cannot tolerate 95%< oxygenation. 
     

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    • Author
    3 minutes ago, ThursdayNight said:

    It's unbelievable that you were "never given a guide," with the oxygenation.
    Anyway, to answer your question, 90% of SpO2 can be normal for some people, but it's "not normal," for most people.   What I noticed, I generally see 2L per minute.  Always check your patient first. How are they feeling? Start with the mental status (A&Ox__?). Check the order for oxygenation after your patients are safe.  What do they look like to you? If they're bluish but alert and orientated maybe they received medications that can make them look like they're cyanotic or silver or gray. 

    Read your theory-prescribed textbook(s). That's something you need or have to know. ABC. Build your knowledge from this.
     

    Haha! I guess that's apart of the consequences of learning how to be a nurse during a pandemic.

    I don't think my question was clear enough though! At school, I was taught that there are times in which I can give oxygen before being prescribed an order. So for example, during an emergency. I was just wondering in these scenarios how would I know how much oxygen I should give them. Based on what you said it seems like you use your clinical judgment but as of now I don't have much of it haha, so I was wondering what I should do?

    For example, if a patient had a septic shock and I gave them 2L of oxygen while their spo2 is at 75% that seems kind of inappropriate to me so based on their spo2 and symptoms I was wondering if I could have a range for each oxygen delivery device (NP, simple mask, non-rebreather) I should give based on their spo2 and symptoms.  

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    • Expert

    You have confused SpO2 and PaO2. 

    An oxygen saturation (the “S” part) refers to the percentage of red blood cells that carry oxygen at the instant of measurement. Normal is 95-100%, meaning that lung function and perfusion results in just about all red cells picking up oxygen in their way thru the pulmonary capillary bed. Note also that somebody with a hematocrit of 20 and a SpO2 of 100% is delivering only one half the amount of oxygen to his tissues that somebody with a hct of 40 can deliver, because he has only half as many red cells. Always check both to get an idea if your pt is actually oxygenating OK.

    PaO2 looks at the pressure (P) of oxygen carried in  arterial (the “a”) blood and is measured in torr or mmHg. A normal PaO2 is 80-100 torr on room air. As a rough rule of thumb, PaO2 should be about 4-5 times the fraction of inspired oxygen (FIO2), where room air is about 21%  or FIO2 of .21, and 100%  oxygen is FIO2 of 1.0.

    {{So as an aside, if you have normal lungs and are breathing 50% O2 (FIO2 .5) your arterial oxygen (PaO2) should be around 200-250. If you are breathing 50% oxygen and your PaO2 is 100, sure, it’s in the normal range but you are not getting good oxygenation because your lungs are not good at getting oxygen thru the alveolar walls to the capillaries. This is sometimes referred to as the “A-a gradient,” the difference between the oxygen in your alveoli (A) and how much of it gets into your arterial (a) blood. The bigger the gradient, the poorer the gas exchange is. Ahem.}}

    Now you can see that a PaO2 of 75 and a SpO2 of 75 are wildly different things. There’s actually a graph that can help you see why when lots of people might be OK with a PaO2 of 75 torr, somebody with a SpO2 of 75% is in **really big trouble**  because his PaO2 is somewhere south of 60, waaaay low. 

    You can’t just slap oxygen in somebody based on a single value or color without a prescription by a legal provider (MD, NP, etc) or a set of standing protocols which would indicate route (nasal prongs, nonrebreather mask, etc) and flow rate or FIO2 for a given measured SpO2 or PaO2. 

    If this basic outline isn’t clear, please ask again. I’ll see if I can dig out that graph for you but it’s called the oxygen-hemoglobin dissociation curve if you want to Google or Youtube it. (It shows how SpO2 and PaO2 have a relationship but it’s not a straight line at all.)

     

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    On ‎3‎/‎5‎/‎2021 at 4:15 PM, Hannahbanana said:



    If this basic outline isn’t clear, please ask again. I’ll see if I can dig out that graph for you but it’s called the oxygen-hemoglobin dissociation curve if you want to Google or Youtube it. (It shows how SpO2 and PaO2 have a relationship but it’s not a straight line at all.)

     

    That's a real blast from the past. Right up there with the Krebs Cycle.

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    • Expert

    Found it. The dotted lines indicate how the curve changes with different pH, temp, etc (remember that CO2 is acidic; somebody with acidosis will deliver a wee bit more oxygen for a given SpO2, as will fever; alkalosis and hypothermia, less)1843755930_Oxyhgbdissociationcurve.thumb.jpg.28db1cc0c526c34c6f0e94a48865c256.jpg

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    Oh, the nightmares are coming back!!

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    • Expert

    Oh noooo! I’m trying to make it easier! 

    Golly, really, now then, even all

    the folks who are terrified of physiology can learn this one! You know I’d never

    want to hurt you, amoLucia! 

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    On 3/1/2021 at 7:08 PM, Deli said:

    spo2 is at 75%

     

    On 3/5/2021 at 3:15 PM, Hannahbanana said:

    You have confused SpO2 and PaO2.

     I think the OP was citing SpO2. I have had this happen a couple of times in my life - I have pulmonary fibrosis. Indeed it was a pulse ox reading. I didn't think I was that bad (because I had limited  O2 getting to my brain!)but when I entered the clinic nurse said "Let's check that pulse ox, your lips are so dark. With pulmonary fibrosis I go up and down and don't realize it until I am SOB or so tired.

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    To be honest, I liked chem & the bio studies. And I did well for my grades.I was terrified when I started school. But I was blessed in that I had great instructors that made the sciences just 'POP' for me.

    I cringe when I read posters here that bemoan the significant application ce of the sciences in nsg. They just don't 'see the forest for the trees'.

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    • Expert
    21 hours ago, londonflo said:
    On 3/5/2021 at 4:15 PM, Hannahbanana said:

    You have confused SpO2 and PaO2.

     I think the OP was citing SpO2.

    Maybe so, it was hard for me to tell whether she said SpO2 she was referring to a number that would look OK for that but bad for PaO2, or the other way around. So I gave the whole answer for everyone who might read the thread, LOL.

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    FYI, in the real world you have a standing order to apply oxygen is the spO/2 is less than a certain percent.  It’s with every single admission.  Nursing school is ridiculous.  It’s a standing order with literally ever single admission.

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    No need to overcomplicate it. Focus more on the limitations of each device. For example, nasal cannula is the least intrusive, but is limited to 6 L/min at a partial oxygen concentration (not 100%). A simple mask is more intrusive, but can go up to 12 L/min at a partial concentration. A non-rebreather is even more intrusive, but goes at 10-15 L/min at a full 100% oxygen.

    So basically, a low need patient will likely do with a nasal cannula. For respiratory distress, you're going straight for that non-rebreather.

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