Brandon Oto of EMS Basics and Degrees of Clarity organized The First EMS What-if-We’re-Wrong-a-Thon. I did not participate, because I was taking a break from blogging at the time. Brandon is doing it again, so I decided to look for something I wrote that I have been wrong about to contribute. I thought about Masimo. I had been very critical of Dr. Michael O’Reilly (then Executive Vice President of Masimo Corporation) for being an advocate of bad science. He has since been hired away by Apple. He should be less dangerous with a telephone than he was with the RAD-57. At the time, he wrote –
Masimo stands by its products’ performance and knows that when SpCO-enabled devices are used according to their directions for use, they provide accurate SpCO measurements that provide significant clinical utility, helping clinicians detect carbon monoxide poisoning in patients otherwise not suspected of having it and rule out carbon monoxide poisoning in patients with suspected carbon monoxide poisoning.
The problem is that there is no evidence that the RAD-57 is safe or effective at ruling out carbon monoxide poisoning in anyone.
There is evidence that the RAD-57 will fail, if used to try to rule out carbon monoxide poisoning. One study showed that the RAD-57 will miss half of the people with elevated carbon monoxide levels.
The RAD device correctly identified 11 of 23 patients with laboratory values greater than or equal to 15% carboxyhemoglobin (sensitivity 48%; 95% CI 27% to 69%).
What if I was wrong?
Is there any evidence that the RAD-57 is able to rule out covert, but life threatening carbon monoxide poisoning?
Was I wrong?
While there have been several studies of the RAD-57, I could not find any evidence that the RAD-57 is safe or effective at ruling out carbon monoxide poisoning.
There does not appear to be any research on the use of the RAD-57 to screen firefighters to rule out carbon monoxide poisoning, even though advertising shows using the RAD-57 to screen firefighters.
Was I wrong? No. That is why this is not a part of The First EMS What-if-We’re-Wrong-a-Thon.
However, I did find some interesting carbon monoxide poisoning papers –
One shows that we may be causing harm by aggressively providing oxygen. This is not enough of a reason to stop providing oxygen, but if this hypothesis is supported by further research, we will need to change treatment.
While CO’s affinity for hemoglobin remains undisputed, new research suggests that its role in nitric oxide release, reactive oxygen species formation, and its direct action on ion channels is much more significant. In the course of understanding the multifaceted character of this simple molecule it becomes apparent that current oxygen based therapies meant to displace CO from hemoglobin may be insufficient and possibly harmful.
Another shows that the addition of catalytic converters seems to have dramatically decreased the car exhaust suicide rate and the level of carbon monoxide in survivors of these suicide attempts.
Since 1985, the CDR for suicidal motor vehicle-related CO poisoning has decreased in parallel with CO emissions (R2 = 0.985). Non-fatal motor vehicle-related intentional CO poisoning cases decreased 63% over 33 years (p = 0.0017). COHb levels decreased 35% in these patients (p < 0.0001).
CO is Carbon monOxide.
CDR is Crude Death Rate.
COHb is CarbOxyHemoglobin.
There are still some papers that show that we do not understand what the RAD-57 can’t do –
The fact that all the Paramedic Rescue Squads were equipped with medical triage sets and were able to conduct non-invasive measurements of carboxyhemoglobin made it possible to introduce effective procedures in the cases of suspected carbon monoxide poisoning and abandon costly and complicated organisational procedures when they proved to be unnecessary.
No. The Magic 8 Ball did not indicate a problem, but that does not mean that it is safe to rule out carbon monoxide poisoning with a Magic 8 Ball. The
Magic 8 Ball RAD-57 is not accurate enough to rule out carbon monoxide poisoning.
The RAD-57 is only appropriate for sending more people to the hospital. While the extra cost of these false positives is a problem and will cause people to mock Masimo, this may save some lives or just prevent more serious consequences of carbon monoxide poisoning.
If you use the RAD-57 to determine that someone does not need to go to the hospital, get a lot of very good insurance, because eventually one of those patients will have a heart attack, or a stroke, or die and carbon monoxide will be part of the reason for the bad outcome. Your advice will have contributed.
If you send a firefighter back into a fire because you think you have ruled out carbon monoxide poisoning, eventually you will be the cause of death or disability of firefighters. Don’t do it.
While the Rad-57 pulse oximeter functioned within the manufacturer’s specifications, clinicians using the Rad-57 should expect some SpCO readings to be significantly higher or lower than COHb measurements, and should not use SpCO to direct triage or patient management. An elevated S(pCO) could broaden the diagnosis of CO poisoning in patients with non-specific symptoms. However, a negative SpCO level in patients suspected of having CO poisoning should never rule out CO poisoning, and should always be confirmed by COHb.
Highlighting in bold is mine.
SpCO is Masimo’s registered trademark for their noninvasive indirect measurement of carbon monoxide using the RAD-57.
Was I wrong? I will find something else to write about, because there is even more evidence that the RAD-57 should not be used to try to rule out carbon monoxide poisoning now than when I originally criticized Masimo.
Also read the article by Dr. Brooks Walsh on the RAD-57 and screening for carbon monoxide poisoning in fire fighters – Checking firefighters for carbon monoxide – recent studies, persistent concerns.
Here is the rest of what I have written about the Dr. O’Reilly, Masimo, and the RAD-57 –
The RAD-57 Pulse Co-Oximeter – Does It Work – Part I
Fri, 12 Nov 2010
The RAD-57 Pulse Co-Oximeter – Does It Work – Part II
Wed, 17 Nov 2010
How Not to Respond to Negative Research
Fri, 26 Nov 2010
How Not to Respond to Negative Research – Addendum
Fri, 26 Nov 2010
How TO Respond to Negative Research
Sun, 05 Dec 2010
Bad Advice on Masimo’s RAD-57 – Part I
Fri, 18 Feb 2011
Bad Advice on Masimo’s RAD-57 – Part II
Mon, 21 Feb 2011
Bad Advice on Masimo’s RAD-57 – Part III
Thu, 24 Feb 2011
Bad Advice on Masimo’s RAD-57 – Part IV
Mon, 28 Feb 2011
Performance of the RAD-57 With a Lower Limit – Better?
Wed, 18 May 2011
Psychic vs. RAD-57
Thu, 23 Feb 2012
 Performance of the Rad-57 pulse co-oximeter compared with standard laboratory carboxyhemoglobin measurement.
Ann Emerg Med. 2010 Oct;56(4):442-4; author reply 444-5. No abstract available.
PMID: 20868919 [PubMed – indexed for MEDLINE]
 Performance of the RAD-57 pulse CO-oximeter compared with standard laboratory carboxyhemoglobin measurement.
Touger M, Birnbaum A, Wang J, Chou K, Pearson D, Bijur P.
Ann Emerg Med. 2010 Oct;56(4):382-8. Epub 2010 Jun 3.
PMID: 20605259 [PubMed – indexed for MEDLINE]
 A modern literature review of carbon monoxide poisoning theories, therapies, and potential targets for therapy advancement.
Roderique JD, Josef CS, Feldman MJ, Spiess BD.
Toxicology. 2015 Aug 6;334:45-58. doi: 10.1016/j.tox.2015.05.004. Epub 2015 May 18. Review.
 False positive rate of carbon monoxide saturation by pulse oximetry of emergency department patients.
Weaver LK, Churchill SK, Deru K, Cooney D.
Respir Care. 2013 Feb;58(2):232-40. doi: 10.4187/respcare.01744.
Weaver, L., Churchill, S., Deru, K., & Cooney, D. (2012). False Positive Rate of Carbon Monoxide Saturation by Pulse Oximetry of Emergency Department Patients Respiratory Care DOI: 10.4187/respcare.01744
Hampson NB, & Holm JR (2015). Suicidal carbon monoxide poisoning has decreased with controls on automobile emissions. Undersea & hyperbaric medicine : journal of the Undersea and Hyperbaric Medical Society, Inc, 42 (2), 159-64 PMID: 26094291
Roderique, J., Josef, C., Feldman, M., & Spiess, B. (2015). A modern literature review of carbon monoxide poisoning theories, therapies, and potential targets for therapy advancement. Toxicology, 334, 45-58 DOI: 10.1016/j.tox.2015.05.004
Touger, M., Birnbaum, A., Wang, J., Chou, K., Pearson, D., & Bijur, P. (2010). Performance of the RAD-57 Pulse Co-Oximeter Compared With Standard Laboratory Carboxyhemoglobin Measurement Annals of Emergency Medicine, 56 (4), 382-388 DOI: 10.1016/j.annemergmed.2010.03.041
O’Reilly, M. (2010). Performance of the Rad-57 Pulse Co-Oximeter Compared With Standard Laboratory Carboxyhemoglobin Measurement Annals of Emergency Medicine, 56 (4), 442-444 DOI: 10.1016/j.annemergmed.2010.08.016