Without evidence of benefit, an intervention should not be presumed to be beneficial or safe.

- Rogue Medic

Does an Oxygen Saturation of 100% Mean an Overdose?


 

Are we harming patients with oxygen?[1]

This will offend many in the oxygen religion, but we should start thinking of oxygen overdose.

What is our use of oxygen for everything based on?

Received wisdom from authority figures. We need to stop using authority and tradition as excuses to harm people.

Tom Bouthillet, Kelly Arashin, and Mike McEvoy discuss the harms of oxygen and the evidence of harm.
 

Go listen to the podcast, or watch the video.
 

Then reconsider your answer to my question.

Are we overdosing our patients, when we raise their oxygen saturation to 100%?

What if the original oxygen saturation was 94%?

What if the original oxygen saturation was 74%?

What if the original oxygen saturation was 54%?

Does the original oxygen saturation matter?
 

Would we have the same worries if the drug (oxygen is a drug) is morphine, NTG, midazolam, or even amiodarone?

Why do we grant the beliefs of the religion of oxygen such immunity from examination?

 

According to Mike McEvoy, the goal is 92% to 96%.

Not 97%.

98% is worse.

99% is much worse.

100% is as bad as it can get – even worse than hypoxia.

 

Go listen to the podcast, or watch the video.
 

A couple of points. Mike McEvoy states that the intensive care community has been familiar with this since the 1990s. This has been studied, and there has been evidence of harm since at least as early as 1950.
 

The administration of 100 per cent oxygen may actually be contraindicated in patients in whom oxygen saturation of arterial blood is normal.[2]

 

This was a decade before we found out that internal mammary artery ligation is nothing more than a placebo surgery.[3] That extremely popular procedure was done away with so quickly, that few people even remember the use of internal mammary artery ligation as a treatment for angina?

Oxygen has tradition behind it encouraging us to keep killing patients.

We should have been smart enough to reconsider our devotion to received wisdom and authority in 1950.

Many of us still refuse to learn.

This is why we need evidence before applying treatments to everyone.

How many hundreds of thousands of patient have we killed with oxygen and our refusal to require evidence of improved outcomes?
 


 

Go listen to the podcast, or watch the video.
 

Footnotes:

[1] EMS 12-Lead podcast – Episode #11 – Are we harming patients with oxygen?
EMS 12 Lead Podcast
EMS 12 Lead
Page with podcast and video podcast.

[2] One hundred percent oxygen in the treatment of acute myocardial infarction and severe angina pectoris.
RUSSEK HI, REGAN FD, NAEGELE CF.
J Am Med Assoc. 1950 Sep 30;144(5):373-5. No abstract available.
PMID: 14774103 [PubMed – indexed for MEDLINE]
 

In five patients with angina pectoris the administration of 100 per cent oxygen did not favorably influence the onset or duration of pain or the electrocardiographic alterations induced by standard exercise. On the contrary, oxygen therapy actually appeared responsible for more pronounced and persistent electrocardiographic changes in several patients.

[3] An evaluation of internal-mammary-artery ligation by a double-blind technic.
COBB LA, THOMAS GI, DILLARD DH, MERENDINO KA, BRUCE RA.
N Engl J Med. 1959 May 28;260(22):1115-8. No abstract available.
PMID: 13657350 [PubMed – indexed for MEDLINE]

.

Comments

  1. Can’t do the podcast now but based on this article, if a person with a room air spo2 is at 98-100% they are self-over-medicating with oxygen. I know that too much oxygen is bad but with numbers like this it is hard to convince the masses. So what is the solution? Are we going to be doing ABGs in the medic now? Or continue to ‘wing it?’

    • Also, should our pulse oximeters read over 100%? Is that possible?

      • Alan W. Rose,

        Also, should our pulse oximeters read over 100%? Is that possible?

        The pulse oximeter only measures the saturation of the hemoglobin molecule. 100% is fully saturated. There is no beyond 100% saturation.

        .

        • My oxygen saturation is 100% normally. I do not use supplemental oxygen. So your saying that somehow I am getting too much oxygen. That is ridiculous and dangerous.

          Cancer cannot develop in an oxygen rich environment. I have no idea where you are getting this information, but if I have 100% oxygen saturation normally, doesn’t your theory fall apart?

          • My oxygen saturation is 100% normally.

            That would make you an unusual example of our species.

            I do not use supplemental oxygen. So your saying that somehow I am getting too much oxygen.

            I wrote – “Are we overdosing our patients, when we raise their oxygen saturation to 100%?”

            Raising the oxygen saturation to 100% with supplemental oxygen is what is bad. We give supplemental oxygen for many conditions, but without any evidence of benefit or evidence of safety.

            Cancer cannot develop in an oxygen rich environment.

            Apparently, the statement that cancer cannot survive in an oxygen rich environment is a myth promoted by alternative medicine sites. Here is one site addressing this –

            http://www.curezone.org/forums/am.asp?i=1450103

            If you know of some valid research on over-saturating patients with oxygen to prevent oxygen, I will look at it, but it seems as if this is a misrepresentation of the original information.

            I have no idea where you are getting this information,

            Did you listen to the podcast?

            Here are a couple of papers on the topic –

            Oxygen therapy for acute myocardial infarction: a systematic review and meta-analysis.
            Burls A, Cabello JB, Emparanza JI, Bayliss S, Quinn T.
            Emerg Med J. 2011 Nov;28(11):917-23. doi: 10.1136/emj.2010.103564. Epub 2011 Feb 23. Review.
            PMID: 21346260

            Free Full Text in PDF format from http://allmanmedicinbd.se/

            Supplementary oxygen for nonhypoxemic patients: O2 much of a good thing?
            Iscoe S, Beasley R, Fisher JA.
            Crit Care. 2011;15(3):305. doi: 10.1186/cc10229. Epub 2011 Jun 30. Review.
            PMID: 21722334

            Free Full Text at BioMed Central.

            but if I have 100% oxygen saturation normally, doesn’t your theory fall apart?

            No. Not even a little bit.

            You are referring to your room air oxygen saturation. I am referring to using supplemental oxygen to raise the oxygen saturation to 100%.

            I provided some evidence of harm. The podcast includes a discussion of other harms.

            Do you have any evidence that using supplemental oxygen to raise the oxygen saturation to 100% is good?

            .

            • Hello, I’m a 20yo male, have smoked while in high school but haven’t in the past year or 2. I’m currently hooked up to a vital SpO2 in the ER, I’m not on oxygen and I’ve been hovering between 98-100%. Unless they are positively oxygenating the entire ER, you are wrong. The problem with oxygen poisoning or overdose as you could call it is when you diminish the CO2 in the blood past a certain point, it becomes difficult to regulate breathing. For an individual who is sleeping or unconscious, this can be very dangerous. I work as an aircraft mechanic and we learn about the atmosphere for respiration at altitude and with supplied oxygen, pilots at 50000+ feet consistently breath 99.99% pure dry oxygen.

              • I’m currently hooked up to a vital SpO2 in the ER, I’m not on oxygen and I’ve been hovering between 98-100%. Unless they are positively oxygenating the entire ER, you are wrong.

                In what way does that contradict what I wrote? Use a quote to show what I wrote and explain why you think that particular quote is wrong.

                I stated that it is unusual for a person to have a 100% oxygen saturation on room air. You only appear to be stating that your oxygen saturation is higher than what is usual for our species (and only intermittently higher than what is usual).

                The problem with oxygen poisoning or overdose as you could call it is when you diminish the CO2 in the blood past a certain point, it becomes difficult to regulate breathing.

                I provided research to support what I wrote.

                Did you read any of the papers?

                I work as an aircraft mechanic and we learn about the atmosphere for respiration at altitude and with supplied oxygen, pilots at 50000+ feet consistently breath 99.99% pure dry oxygen.

                There is a reason that supplemental oxygen is provided. They would not be able to maintain an adequate oxygen saturation at lower concentrations. The atmospheric pressure is much lower, so oxygen is not effectively transferred to the blood.

                .

    • Alan W. Rose,

      Can’t do the podcast now

      When you get a chance, it is definitely worth listening to.

      but based on this article, if a person with a room air spo2 is at 98-100% they are self-over-medicating with oxygen.

      No.

      They are getting room air.

      They do not need supplemental oxygen, unless they are actually complaining of being short of breath. Conditions such as carbon monoxide toxicity is one example of a condition that could cause this.

      I know that too much oxygen is bad but with numbers like this it is hard to convince the masses. So what is the solution? Are we going to be doing ABGs in the medic now? Or continue to ‘wing it?’

      We will wing it.

      Venous blood gasses will probably be available in the ambulance eventually, then we will have a better idea for some patients.

      Even the AHA does not recommend supplemental oxygen as long as the oxygen saturation is at least 94%.

      EMS providers administer oxygen during the initial assessment of patients with suspected ACS. However, there is insufficient evidence to support its routine use in uncomplicated ACS. If the patient is dyspneic, hypoxemic, or has obvious signs of heart failure, providers should titrate therapy, based on monitoring of oxyhemoglobin saturation, to ≥94% (Class I, LOE C).36

      Part 10: Acute Coronary Syndromes
      2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
      http://circ.ahajournals.org/content/122/18_suppl_3/S787.full#sec-1

      That is for ACS, but not for cardiac arrest.

      The AHA makes the following unsupported claim –

      Empirical use of 100% inspired oxygen during CPR optimizes arterial oxyhemoglobin content and in turn oxygen delivery; therefore, use of 100% inspired oxygen (FIO2=1.0) as soon as it becomes available is reasonable during resuscitation from cardiac arrest (Class IIa, LOE C).

      Part 8: Adult Advanced Cardiovascular Life Support
      2010 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
      http://circ.ahajournals.org/content/122/18_suppl_3/S729.full

      One of the reasons that oxygen may cause harm is that high concentrations of oxygen act as an arterial vasoconstrictor.

      Giving more oxygen can paradoxically result in less delivery of oxygen to the organs that might actually be low in oxygen.

      The statement by the AHA is not empirical, even though they claim that it is.

      Maybe someday, the AHA will require that we have a good evidence-based reason to give drugs, but until then we are stuck with their “approved interpretation” of the inadequate research.

      The 2005 ACLS ACS recommendation was also not strongly recommending supplemental oxygen.

      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,31 and oxygen therapy in patients with STEMI reduced the amount of ST-segment elevation.35 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,30 short-term oxygen administration is beneficial for the patient with unrecognized hypoxemia or unstable pulmonary function. In patients with severe chronic obstructive pulmonary disease, as with any other patient, monitor for hypoventilation.

      Part 8: Stabilization of the Patient With Acute Coronary Syndromes
      2005 American Heart Association Guidelines for Cardiopulmonary Resuscitation and Emergency Cardiovascular Care
      http://circ.ahajournals.org/content/112/24_suppl/IV-89.full#sec-21

      .

    • What does it mean if your Sp02 is at 100% regularly? I just got back from the doctor and I’ve been to this university hospital once before and I was told I can go online and see all this info from appointments. Both appointments show my level of Sp02 at 100% and it’s over a year apart. I have lots of breathing issues, but I would think that would mean it would be lower, so I’m confused. Could there be an issue instead with my circulation? Please any information or links would be greatly appreciated.

      • Actually, I just figured it out. It means that I am not breathing properly. The doctor kept mentioning me being anxious and I didn’t know what she was talking about, but I think it was because I was being asked questions. I can’t breathe when I’m talking…. or at all.

        • Shilo, You came up with the most likely reason.

          Many people have white coat hypertension.

          https://en.wikipedia.org/wiki/White_coat_hypertension

          You may have a variation on this, since you were worried at the time of your visits. Worry can produce a faster heart rate and a faster respiratory rate, which can elevate the oxygen saturation above what is normal.

          I was writing about giving patients extra oxygen to produce an oxygen saturation of 100%. Sometimes talking will produce a higher oxygen saturation, because the person breathes more when talking. Sometimes it will do the opposite, because the person does not breathe in as much as usual while talking. It depends on the person and the circumstances.

          A lot of people would have had trouble figuring that out, but you figured it out on your own. Maybe you should consider work in a medical field.

          .

  2. My oxygen saturation is 100% It has been checked every year. Doctors and nurses are impressed. There is no oversaturation. When we inhale, we breath in 100% oxygen. When we exhale, 2-5% of that oxygen we inhaled departs. When I exhale, only used oxygen is departed. All my oxygen inhaled is used directly into the bloodstream.

    • Anonymous,

      When we inhale, we breath in 100% oxygen.

      Let me provide a more basic site for you to get some more accurate information. I appreciate your interest, but there are so many inaccuracies in what you wrote, that you should go to a site that is set up to provide information to someone completely unfamiliar with the topic.

      This is from How Stuff Works

      We breathe air that is 21 percent oxygen, and we require oxygen to live. So you might think that breathing 100 percent oxygen would be good for us — but actually it can be harmful. So, the short answer is, pure oxygen is generally bad, and sometimes toxic. To understand why, you need to go into some detail …

      https://science.howstuffworks.com/question493.htm

      .