Oxygen in advanced care

[Aussieaid]

Hmmm, interesting thread. I agree that sometimes you can have too much of a good thing but in other circumstances a patient may look like they are fine but really at a cellular level they aren't. I think it requires a solid knowledge base and thinking skills to know when and how much oxygen to use. Unfortunately it seems like most protocols subscribe to the all or nothing theories to account for the lowest common denominators.

There is growing evidence that O2 can be harmful in simple MIs as well as newborns (especially premature) and some cardiac defects. In MIs hyperoxia is known to increase coronary artery tone which can lead to decreased coronary artery blood flow. It also causes a decreased cardiac output and stroke volume. Not to mention the damage from free radical production. Of course if the pt has cardiogenic shock, CHF or other complicating factors they are going to need that extra oxygen.

On the other hand there are 4 types of hypoxia not just hypoxic hypoxia: Hypoxic hypoxia where there is decreased oxygen in the air or an inability for it to diffuse across the lungs (most common type). Eg: lung disease, altitude.
Hypemic hypoxia where there is a reduction in the oxygen carrying capacity of the blood. Eg: anemia, bleeding, CO poisoning
Stagnant hypoxia (or distributive) where there is reduced cardiac output. Eg. CHF, hypovolemia, arterial stenosis.
Histotoxic hypoxia is where the O2 is available but the cells can't "take" or use the O2 from the blood. Eg: cyanide poisoning.

What this is leading to is that even though a pt's pulse oximeter reading is giving you a "good" number that may not equate to adequate oxygenation of the patient. Someone with CO poisoning may have a great SpO2 number and still be extremely hypoxic as the oximeter is actually reading the carboxyhemoglobin as oxyhemoglobin. You also have to lose a significant amount of blood sometimes before it is reflected in your pulse oximeter reading. One of the first signs of hypoxia is often agitation before you start seeing significantly decreased numbers. In some pts they need the extra oxygen for increased metabolic oxygen demands such as in sepsis or fevers.

So, yes you can do harm with oxygen but you can also do significant harm by withholding it when it is warranted even without significant signs of hypoxia. In other words you need to use sound clinical judgment before just withholding it on the majority of pts or giving it to everyone.

Sorry I got a little carried away and rambled a bit. :blush:

 

[JPINFV]

However, outside of hypoxic hypoxia, most of those (there's an argument for CO poisoning and higher FiO2 being able to bump the CO off) are not going to be helped by increased FiO2. For example, what good is O2 in the capillary if the cell can't utilize it because of cyanide?

 

[usalsfyre]

JPINFV beat me to it. None of the other forms of hypoxia (with the possible exception of CO poisoning) respond particularly well to supplemental O2 alone. Stagnant hypoxias generally need inotropes and/or pressors, hypemic hypoxias blood and histotoxic hypoxias antidotes. None of which supplemental O2 provides.

What is important is to be able to distinguish the differing types of hypoxia, and initiate the appropriate treatment.

 

[Amycus]

Exactly the point I've reached.

The reason this is in the advanced forum is I would prefer to get opinons from folks who should be able to corectly interpret if a pt needs O2. This is not something I'm convinced the current EMT-B curriculm is preparing folks for.

On my first day, we had a patient with shortness of breath. Immediately I went for the NRB, and my training officer laughed so hard. From there I found out that 2-4LPM by a cannula is common practice and even then, rarely necessary

 

[DrParasite]

As a simple bandaid provider, I think this thread shows quite a few things:

1) the majority of the providers on here don't see that many sick patients
2) the majority of the ALS providers on here don't see that many sick patients.
3) the majority of the people on here don't like using a NRB, and even more don't like giving oxygen at all, despite some educators teaching that sick patients should get high flow oxygen (despite if its needed or not).

Most patients don't need oxygen via a NRB at 15lpm (despite what some protocols push for, high flow oxygen on any sick or injured patient).

However, the fact that many medics on here say they put oxygen on only 3 patients in the past month? I mean, do you not give oxygen to cardiac arrest patients? I know my area is probably the asthma (and TB also) capital of the US, but do you not give oxygen to asthma patients? What about major traumas (penetrating or multi-system trauma patients), do you not give oxygen to them? what about cardiac patients?

Now, either you don't give oxygen to those patients (which I doubt), or you don't get those types of calls that frequently (which scares me, since if a medic doesn't see sick patients, their skills deteriorate). So if you are only a BLS provider, I can see you dealing with non-sick patients. But if you are an ALS, and you don't deal with sick people, well, I guess it's sad to say that my BLS coworkers deal with more sick patients than you do.

 

[Aidey]

*raises hand*

In the last 30 days I have not had 3 asthma, major trauma and cardiac arrest patients combined.

But only becuase I haven't had an asthma patient, oddly enough. I had a way major trauma (who did get a mask) and a unwitnessed, unknown down time ROSC (who was intubated).

 

[usalsfyre]

Just because work has been call free for 24hrs, I'll bite.

However, the fact that many medics on here say they put oxygen on only 3 patients in the past month? I mean, do you not give oxygen to cardiac arrest patients? I know my area is probably the asthma (and TB also) capital of the US, but do you not give oxygen to asthma patients? What about major traumas (penetrating or multi-system trauma patients), do you not give oxygen to them? what about cardiac patients?

Let's discuss each call type. I have seen all 4 in the last 30 days.

1. My cardiac arrest patients get O2, pretty much because I don't have a choice. However, with the exception of hypoxic arrest (mostly pediatric arrest) what help does O2 provide? The primar reason pt's arrest out of the hospital is AMI, see our previous discussion regarding getting O2 to the distal end of a blocked artery. Pedi codes are different, but I bet most providers on here can count on their fingers the number of those they've run.

2. My asthma pts get O2 as a delivery device mainly. Oxygen is required to run the nebulizer. Oxygen by itself can not break bronchospasm. Bronchodilators and steroids do that. If their hypoxic then sure, give them O2. Most of your asthma patiets that are hypoxic are going to require a lot more than a 2L out of a NC though. Generally by the time their hypoxic, their CO2 is through the roof, CPAP and/or intubation is a better choice. If it's just a run of the mill asthma attack, no O2 once the neb is done.

3. My major traumas get no O2 or 2l via NC unless hypoxia or other respiratory comprimise is noted.

4. See the above discussion about oxygen in AMI. CHF pt's get O2, but their usually slightly hypoxic. I usually give them either 2L or CPAP.

Now, either you don't give oxygen to those patients (which I doubt), or you don't get those types of calls that frequently (which scares me, since if a medic doesn't see sick patients, their skills deteriorate). So if you are only a BLS provider, I can see you dealing with non-sick patients. But if you are an ALS, and you don't deal with sick people, well, I guess it's sad to say that my BLS coworkers deal with more sick patients than you do.

Like I just said, I see these people regularly. Many of them I don't put on O2. I'm not breaking protocol either.

Let's discuss who I do put on O2.

1. Hypoxic people

2. People who I suspect might get hypoxic, including boderline pt's I administer sedating medications to; people who I'm about to RSI; pt's with severe respiratory comprimise who just haven't swung over to hypoxia yet; ect.

That's it, notice there is nothing about mechanisim of injury or specific disease process. Q: What's the only drug you can administer to levels FAR above it's theraputic range and it be considered "good patient care"? A: Oxygen! Any other drug it's an overdose.

 

[Aidey]

2. My asthma pts get O2 as a delivery device mainly. Oxygen is required to run the nebulizer. Oxygen by itself can not break bronchospasm. Bronchodilators and steroids do that. If their hypoxic then sure, give them O2. Most of your asthma patiets that are hypoxic are going to require a lot more than a 2L out of a NC though. Generally by the time their hypoxic, their CO2 is through the roof, CPAP and/or intubation is a better choice. If it's just a run of the mill asthma attack, no O2 once the neb is done.

Good point. How many asthmatics do home nebulizers using an air compressor. Its the drugs not the oxygen that do the most.

 

[Smash]

In the past 6 shifts I've intubated 7 patients using pharmacology for things ranging from status epilepticus to multi-system trauma to respiratory failure to burns and including a 10 month old with sepsis secondary to pneumonia. I've also treated COPD patients, asthmatics, a couple of STEMIs and a conscious VT. I think I'm doing ok for seeing sick people...

But I don't give everyone O2 and even in those patients I do give O2 to, I give consideration to what is wrong with them, what O2 may do to help or hinder and therefore what FiO2 I am going to give.

 

[MasterIntubator]

No shortage of calls here... 15 to 20 calls a shift... plenty to hand out...