Oxygen

oxygenOkay, so I am not choosing oxygen number 1. I am choosing oxygen number 3 of the 33 drugs we carry. How can I do this? Well, it’s my list and I’ll do what I want. Say what I want…

Now obviously I give oxygen more than any other drugs. I don’t even have a count for the number of times I give it. It is almost a given in any sick patient, but I do give it far less than I used to.

Here’s a couple assumptions I am making to justify oxygen as my third choice. I am going to say I can run nebs and CPAP on regular air. If you won’t give me that, I am going to say, the first responders will have oxygen at the scene and if I need it , I will take theirs.

The reason I don’t want to take oxygen as my number 1 drug is it is an over-rated drug, a misused drug, and a drug with little evidence-based research behind it. Also, as I said before, it is my list and I want to make statements with my number 2 and number 1 drugs that are more powerful if they are number 1 and number 2, instead of being number 2 and number 3.

The reasons I might want to put oxygen number one is if I have a cyanotic, hypoxic patient I would like to give them oxygen. And I would rather have CPAP and my nebs run on oxygen power. And as far as little scientific evidence, there is just no money in researching oxygen, so I shouldn’t hold that against oxygen.

But the number 3 pick is my decision and I’m sticking to it.

I now rerun an earlier post called Oxygen Heresy that further elaborates my thoughts on oxygen in EMS.

***

Oxygen has long been considered the mother’s milk of medicine, particularly in EMS.

The first thing many patients get on arrival of EMS responders is a nonrebreather oxygen mask over their face cranked at 15 lpm whether they are hypoxic or not.

The thinking is it can’t hurt and can only help.

Journal Review

But check out the conclusion of a recent article in the noted British medical journal Heart, Routine use of oxygen in the treatment of myocardial infarction: systematic review, which examined the only randomized placebo-controlled trials of oxygen therapy in MI.

Conclusion: The limited evidence that does exist suggests that the routine use of high-flow oxygen in uncomplicated MI may result in a greater infarct size and possibly increase the risk of mortality.

The authors postulate that high flow oxygen may vasoconstrict the coronary arteries as well as possibly causing increased reperfusion injury.

In an accompanying editorial, Challenging doctors’ lifelong habits may be good for their patients: oxygen therapy in acute myocardial infarction, the editorial writers begin with the following observation:

“Medical history is filled with widely applied therapeutic habits that replicate longstanding practices based upon theories that have no true scientific background.” They note “the extraordinary discrepancy between the high incidence of myocardial infarction, affecting millions of people each year, and the paucity of scientific data on one of its most widely used methods of treatment.”

Their conclusion:

“The case against routine use of oxygen therapy which is presented in the paper from Wijesinghe et al is barely sufficient to formally rule out this technique; it should rather be considered, as the authors state in their conclusion, an incentive to design future trials to assess whether this treatment as used in contemporary practice (ie, guided by arterial oxygen saturation monitoring) is truly useful.”

And in a September 2009 article Systematic review of studies of the effect of hyperoxia on coronary blood flow in the American Heart Journal, the authors of the previous article are at it again. This time, in a literature review looking specifically at coronary blood flow and oxygen, they conclude :

CONCLUSIONS: Hyperoxia from high-concentration oxygen therapy causes a marked reduction in coronary blood flow and myocardial oxygen consumption. These physiologic effects may have the potential to cause harm and are relevant to the use of high-concentration oxygen therapy in the treatment of cardiac and other disorders.

Bryan Bledsoe

Bryan Bledsoe, the noted EMS physician and educator, wrote a article in March of this year that also questioned the routine use of oxygen by EMS in The Oxygen Myth. He summarizes research on the use of oxygen in stroke, cardiac arrest, MI, trauma, and neonates, and concludes:

“If the patient’s oxygen saturation and ventilation are adequate, supplemental oxygen is probably not required. ”

American Heart Association

Here’s what the American Heart Association has to say about 02 and MI in the chapter Stabilization of the Patient With Acute Coronary Syndromes, which explains the science behind their 2005 guidelines.

EMS providers may administer oxygen to all patients. If the patient is hypoxemic, providers should titrate therapy based on monitoring of oxyhemoglobin saturation (Class I).

And

Administer oxygen to all patients with overt pulmonary congestion or arterial oxygen saturation _90% (Class I). It is also reasonable to administer supplementary oxygen to all patients with ACS for the first 6 hours of therapy (Class IIa). Supplementary oxygen limited ischemic myocardial injury in animals, and oxygen therapy in patients with STEMI reduced the amount of ST-segment elevation. Although a human trial of supplementary oxygen versus room air failed to show a long-term benefit of supplementary oxygen therapy for patients with MI, short-term oxygen administration is beneficial for the patient with unrecognized hypoxemia or unstable pulmonary function.

Regional Guidelines

My regional oxygen guidelines are confusing. In our appendix, the indication for oxygen is listed as:

Indications: Any hypoxic patient or patient who may have increased oxygen demands for any reason.

Dose: Patient dependent 1 liter/minute via Nasal Prongs to 100% via rebreather face mask.

Under Acute Coronary Syndrome, it says the following:

Oxygen: Oxygen Therapy (90-100%)

Is that 90%-100% referring to the patient’s oxygen saturation or that they should be given a 90-100% mixture of oxygen?

I sit on the protocol committee and would vote for the saturation interpretation, but it needs to be made clearer.

The Future

While we should all continue to follow our own EMS systems current medical guidelines, we may consider that in the future, we may talk about the old days when we gave everyone oxygen.

***

The comment section of my recent STEMI Redux post produded a discussion about the use of high-flow oxygen in the setting of an MI, thus spuring this post.

I previously addressed the issue of changing views on oxygen in a December 2007 post titled Oxygen).

***

Oxygen

Class: Gas

Action: Odorless, tasteless, colorless gas that that is necessary for life. Brought into the body via the respiratory system and delivered to each cell via the hemoglobin found in RBCs.

Indications: Any hypoxic patient or patient who may have increased oxygen demands for any reason.

Contraindications: None for field use

Precautions: If has COPD avoid rebreather or >50% oxygen. However O2 should never be withheld from any severely hypoxic patient (O2 sat <90%) In which case provide oxygen without reservations.

Side effects: Hypercarbia and somnolence in COPD patients who retain CO2

Dose: Patient dependent 1 liter/minute via Nasal Prongs to 100% via rebreather face mask. Note if
mouth breathing only nasal prongs still work.

Route: Inhaled, or delivered via supplemental respiratory drive.

7 Comments

  • ICU Nurse says:

    Just incase you’re interested, the British Thoracic Society has guidelines on emergency oxygen use (in and out of hospital), suggesting a much more cautious and sensible approach than the traditional “whack it up to 15 Litres” that you have obviously seen too.

    The guidelines are a bit lengthy but they’re available here: http://www.brit-thoracic.org.uk/Portals/0/Clinical%20Information/Emergency%20Oxygen/Emergency%20oxygen%20guideline/THX-63-Suppl_6.pdf

    For what it’s worth, I think adequate ventilation is far more important in the setting of hypoxaemia than is throwing a load of oxygen at the situation. We frequently get patients on 100% oxygen and barely maintaining their sats, yet as soon as we intubate and ventilate, once we’ve fiddled with the vent got them on a decent tidal volume their O2 requirements are rarely more than about 35%.

  • As a CFR in the UK, I used to use O2 like it was going out of fashion. We were not allowed a pulseox but had to base our decision to use oxygen on “clinical signs”. As oxygen could do no harm, we usd loads of it.

    This changed about a year ago. A pulseox went from being banned to being compulsory. We were also issued with 28% venturi masks and nasal canulae as well as trauma masks.

    We now use oxygen much less, and when we do use it, we use lower concentrations.

  • Dolph says:

    Amazing how things are changing! I am glad that research is being done and the bad part is it will take time to revise any protocols. I am curious if any folks have seen changes in the past two to five years?
    Logic tells us that we have technology that can aid us in determining if patients are not saturating and require O2 but the true indicator is to LOOK at your patient. Do they look like they are not perfusing well?
    Only time will tell if we can say “We used O2 on everyone years ago!”

  • CBEMT says:

    It’s certainly NO reflection on you, but damn if this article getting posted on the JEMS Facebook page didn’t bring out the morons!

  • totwtytr says:

    Oxygen therapy is in a state flux as there is some suggestion that it’s not as benign as we’ve always thought. OTOH, there is a doctor trying to put a study together to test high flow oxygen in Stroke patients. He seems to think it’s beneficial, although other studies show some down side. There are even some studies showing benefit from normoxic ventilation in cardiac arrest.

    It will be interesting to see what, if anything the AHA has to say in light of the British Thoracic Society recommendations.

    Since our protocol specifies oxygen by appropriate means, I’ve started using less when indicated by the patient’s condition.

    As Drudge says, “Developing…”

  • Paramedic Pete says:

    I have to say something about this. Yes giving every patient 15 Litres per minuten 0xygen by NRB is the wrong thing to do and can cause harm. Oxygen is a drug and should be treated as such. But in the same way that COAD patients should have their hypoxia treated initially with higher flow rates and only then have the oxygen titrated down to reflect their chronic condition. I have seen emphysema patients peri-cyanosed on a nasal cannula at 2 litres per minute because someone had bought into the hypoxic drive consensus. I worry that in the zeal to break down established practice we go too far.
    I would be intersted in the study which looks at limited supplemental oxygen in acute coronary syndromes and strokes, let alone patients who are short of breath with hypoxia. It seems to me that oxygen given at the ‘goldilocks’ concentration will not cause vasospasm and therefor worsen the condition, but also might help save the pnumbre of tissue which is not yet dead but which is not getting enough vital oxygen. I thing the consensus in the longer term will work out an better medium of care of not tons of oxygen or none at all. I think the rush to dispel the oxygen myth has the potential to confuse providers and cause harm to our patients. Are we sure the science is comprehensive and correct enough to advocate such a change.

  • medicscribe says:

    Thanks for all the great comments.

    It will be interesting to see how this changes in the future.

    Peter C

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Peter Canning

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