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

- Rogue Medic

Psychic vs. RAD-57

Also posted over at Paramedicine 101 (now at EMS Blogs).

Continuing what I wrote Tuesday and Wednesday about the repeated failure of Masimo’s RAD-57 to correctly discriminate between CO (Carbon monOxide) poisoning and no exposure to CO.[1], [2]

Given the whimsical nature lack of reliability of the RAD-57, should this be an example of what ambulances will look like?

Maybe I should ask a psychic.

Image credits – 1, 2, and 3.

There are two big advantages that the RAD-57 has over the psychic.

1. Many cases of CO poisoning are probably not diagnosed due to vague symptoms that go away when the person leaves the environment.

2. Sometimes the RAD-57 does seem to get it right, but only sometimes.

There is one big disadvantage of the RAD-57 compared to the psychic.

Nobody is going to send a firefighter back to fight a fire based on the word of a psychic – at least I hope not.

Firefighters are probably being screened to safety with the RAD-57.

How many hospitalized firefighters, or dead firefighters, will it take to demonstrate that the RAD-57 is not accurate enough to use to screen for CO poisoning?

MK, from Probie To Practitioner, writes –

We have the RAD-57, and I would agree that it’s a fairly unreliable device. I once put it on my finger to try it out on the way to a call, and it gave me a reading of 7%. I have never smoked a day in my life, and before getting on the ambulance, I had spent almost 4 hours doing station chores outside.[3]

This is above the 6.6% cut-off for CO poisoning recommended in the most recent study.[4]

Maybe MK did not use the RAD-57 correctly.

Quick and easy-to-use—requires no user calibration and does not require patient cooperation or consciousness.[5]

While Masimo is not exactly stating that the RAD-57 is So easy a caveman could use it, ease of use and simplicity are emphasized in their sales pitch.

Claims of operator error demonstrate dishonesty on the part of Masimo.

Is the RAD-57 easy to use, or do we have to align it with the patient’s chi forces, when the moon is just right, after doing a voodoo dance?

The Masimo slogan appears to be –

Trust Masimo. It’s always operator error, never equipment failure.

Too Old To Work, from Too Old To Work, Too Young To Retire, writes –

Funny you should bring this up. A few months ago we were sent to a “possible CO leak” with mulitple patients. The only problem was the the FD got readins of 0 when they tested the air for CO. Which was confusing to say the least because the first unit on scene with a RAD 57 got a reading of 18 ppm on an elderly gentleman who had some dypnea and chest pain.

The supervisor was convinced that the FD didn’t know what they were doing because of the RAD 57 readings.

Too Old To Work goes on to provide more details in the rest of his comment.[6]

The problem identified in the Touger study was that the RAD-57 was not sensitive enough. The Rad-57 missed most of the actual cases of CO poisoning.[7] The solution seems to be to increase the sensitivity to the point where saying, Carbon monoxide, will set it off.

The question still unanswered is –


How many cases of CO poisoning does the RAD-57 miss?


We will probably only learn this from the lawyers, because Masimo has not been providing useful information.


[1] Accuracy of Noninvasive Multiwave Pulse Oximetry Compared With Carboxyhemoglobin From Blood Gas Analysis in Unselected Emergency Department Patients
Rogue Medic
Tue, 21 Feb 2012

[2] Mass sociogenic illness initially reported as carbon monoxide poisoning.
Rogue Medic
Wed, 22 Feb 2012

[3] Mass sociogenic illness initially reported as carbon monoxide poisoning.
Paramedicine 101
02/22/2012 at 13:44

Comment by MK

[4] Accuracy of noninvasive multiwave pulse oximetry compared with carboxyhemoglobin from blood gas analysis in unselected emergency department patients.
Roth D, Herkner H, Schreiber W, Hubmann N, Gamper G, Laggner AN, Havel C.
Ann Emerg Med. 2011 Jul;58(1):74-9. Epub 2011 Apr 2.
PMID: 21459480 [PubMed – indexed for MEDLINE]

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Because a false-negative reading could have serious medical consequences, this device should be tested in a much larger number of poisoned patients to confirm the generalizability of our stated cutoff values.

[5] RAD-57
Product information page

[6] Mass sociogenic illness initially reported as carbon monoxide poisoning.
Paramedicine 101
02/23/2012 at 03:00
Comment by Too Old To Work

[7] 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]

Free Full Text Article from Ann Emerg Med with links to Free Full Text PDF Download

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%).

Less than half?