Risk Management | Paramedicine 101

Psychic vs. RAD-57

02/23/2012 by Rogue Medic 1 Comment

Also posted over at Rogue Medic (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.

Footnotes:

^[1] Accuracy of Noninvasive Multiwave Pulse Oximetry Compared With Carboxyhemoglobin From Blood Gas Analysis in Unselected Emergency Department Patients
Paramedicine 101
Tue, 21 Feb 2012
Article

^[2] Mass sociogenic illness initially reported as carbon monoxide poisoning.
Paramedicine 101
Wed, 22 Feb 2012
Article

^[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]

Annals of Emergency Medicine podcast
Podcast Download in MP3 Format

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
Masimo
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?

Filed Under: Critical Judgment, Heresy, Research, Risk Management, Rogue Medic

Accuracy of Noninvasive Multiwave Pulse Oximetry Compared With Carboxyhemoglobin From Blood Gas Analysis in Unselected Emergency Department Patients

02/21/2012 by Rogue Medic 3 Comments

Also posted over at Rogue Medic (now at EMS Blogs).

The Masimo RAD-57 non-invasive CO monitor is promoted as an accurate way to identify patients at risk of life-threatening complications of CO poisoning. CO (Carbon monOxide) is a significant cause of poisoning in the US, with hundreds of fatalities each year.

Masimo claims that their RAD-57 is able to accurately measure blood levels of CO without any complicated lab equipment. If it works, the RAD-57 might save some lives. Unfortunately, the research that has not been funded by Masimo does not support a decision to buy a RAD-57 until after they improve the device.

Suspicion of CO poisoning is very important in identifying CO poisoning. One study was conducted at a burn center among patients already suspected of having CO exposure.

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%).^[1]

A coin flip is going to be just as accurate as a test that identifies only 48% of the affected patients.

The RAD-57 was shooting at fish in a barrel and still missed most of the time.

Dr. Michael O’Reilly (Executive Vice President of Masimo Corporation) has claimed that those researchers, who are not on the Masimo payroll, are biased against his device.^[2]

What does he understand about science, objectivity, or controlling for biases?

Nothing comes to mind.

Even some people who are not on the Masimo payroll have suggested that the RAD-57 might be useful and that the next study (quoted below) would confirm the usefulness of the RAD-57.

Compared with the large population used for the calculation of bias and precision, the number of patients actually found to be poisoned was small, especially in the group of poisoned smokers. Therefore, the opportunity for false-negative results was limited. 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.^[3]

This does not contradict the first study.

What is the problem?

Symptoms of CO poisoning are nonspecific, ranging from mild headache, nausea, confusion, and dizziness to end-organ injury such as myocardial infarction,⁶ stroke,⁷ and death. ^{[8] and [9]} Diagnosis is therefore difficult and relies on clinical suspicion and confirmation by measurement of carboxyhemoglobin (COHb), using either venous or arterial10 blood gas analysis. However, COHb analyzers are not ubiquitously available.¹¹ As a result, many victims of CO poisoning might be overlooked and misdiagnosed. ^{[12] and [13]} ^[3]

Suspicion of illness/exposure is the most important part of identification.

If we examine patients without considering suspicion, does the RAD-57 improve identification?

Maybe, but this study is not capable of testing that hypothesis.

These are only patients who are going to have ABGs (Arterial Blood Gas measurements) regardless of what the RAD-57 shows. We don’t know how many of the patients who did not have ABGs, or did not have ABGs within one hour of RAD-57 measurement, actually had CO poisoning.

Blood gas analysis (arterial or venous) (Table 1) was performed later as a standard procedure in our ED on discretion of the treating physician for a variety of clinical reasons.^[3]

If the patient had a low reading on the RAD-57 and did not have an ABG, should we conclude that the unmeasured carboxyhemoglobin level was also low?

Of course not.

31% of patients who had ABGs were excluded because there was more than one hour between RAD-57 measurement and ABG measurement. How many of these patients were presenting as unstable and had the RAD-57 measurement omitted? How many of these patients were presenting as very stable and had the RAD-57 measurement over an hour before the ABG?

We do not know.

How many of the 17 patients in the documented sample had life-threatening symptoms?

We do not know.

Maybe all 17.

Maybe zero.

How many of the 17 patients in the documented sample had only minor symptoms?

We do not know.

Maybe all 17.

Maybe zero.

This kind of information is not included in the study.

What was the basis of diagnosis of CO poisoning?

The diagnosis of CO poisoning was based on increased COHb levels and clinical symptoms consistent with poisoning, including headache, vomiting, abdominal pain, and loss of consciousness.^[3]

Identifying 16 out of the 17 patients in the 1,578 patient sample is impressive, but when we limit the patients to those with symptoms suggesting CO poisoning, we lose any possible value of the non-invasive screening.

These are the patients who are going to have blood drawn to assess for CO poisoning regardless whether anyone uses a RAD-57.

There is no benefit to RAD-57 screening in this setting.

What about using the RAD-57 in 1,017 EMS patients, regardless of the reason for the 911 call?

Of the 11 patients with a SpCO >15%, 10 were transported to a hospital for which the investigators had institutional review board (IRB) approval to review the patient’ s medical record. Of those 10, none had confirmatory venous carboxyhemoglobin levels. The two patients with an SpCO level of 21% did have a repeat SpCO documented at triage upon arrival to the emergency department. Their repeat levels were 8% and 2%. None of the 10 patients with levels >15% ultimately were diagnosed with and treated for carbon monoxide exposure or toxicity.^[4]

The same idea, just not limited to patients chosen by having ABGs measured within one hour of RAD-57 measurement.

The result is very different.

None of the patients with elevated RAD-57 measurements had carboxyhemoglobin measured by drawing blood.

None of the patients with CO poisoning (according to the RAD-57) were treated for CO poisoning.

Is the RAD-57 reliable for determining if a patient should not go to the hospital?

Absolutely not.

What is the target audience of RAD-57 marketing?

Firefighters.

What is the patient population studied?

Patients already being treated in the hospital. They may include firefighters, but there is nothing in the study to indicate if there are any firefighters in the sample.

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

Dr. Michael O’Reilly (Executive Vice President of Masimo Corporation) had a bunch of excuses for the study that did not agree with the research paid for by Masimo. One excuse was that incorrect use of the RAD-57 interfered with results, even though Masimo trained the people using the RAD-57. Would Dr. O’Reilly have mentioned this if the study had produced the results he wanted?

Image credit.
Trust me. I am here to serve you.

Keep Firefighters Safe From CO Poisoning

> Have CO levels tested on the scene with the Masimo Rad-57.

• Just because firefighters don’t feel like they have CO poisoning doesn’t mean that they don’t have unsafe levels of carboxyhemoglobin (SpCO) in their bloodstream.

• That’s why rehab guidelines support the use of on-scene CO testing.⁶ To be safe, have SpCO levels tested with a Masimo Rad-57 before going back into the fire and during overhaul, even if firefighters think they’re okay.

> Get prompt on-scene treatment.

• Recognition is the key to immediate on-scene treatment. With early recognition, treatment for CO poisoning can begin immediately, which significantly reduces both immediate and long-term health risks.^[6]

To be safe, have SpCO levels tested with a Masimo Rad-57 before going back into the fire and during overhaul, even if firefighters think they’re okay.

Masimo is providing very bad advice. Is Masimo trying to kill firefighters?

And if the RAD-57 does not detect CO poisoning, is that any reason to allow a firefighter to go back into a fire?

Absolutely not.

The RAD-57 should NEVER be used to screen asymptomatic people for CO poisoning.

The RAD-57 should NEVER be used to rule out CO poisoning.

Footnotes:

^[1] 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

^[2] Performance of the Rad-57 pulse co-oximeter compared with standard laboratory carboxyhemoglobin measurement.
O’Reilly M.
Ann Emerg Med. 2010 Oct;56(4):442-4; author reply 444-5. No abstract available.
PMID: 20868919 [PubMed - indexed for MEDLINE]

Free Full Text of letter and author reply from Ann Emerg Med with links to Free Full Text PDF Download

^[3] Accuracy of noninvasive multiwave pulse oximetry compared with carboxyhemoglobin from blood gas analysis in unselected emergency department patients.
Annals of Emergency Medicine podcast
Podcast Download in MP3 Format

^[4] Non-invasive carboxyhemoglobin monitoring: screening emergency medical services patients for carbon monoxide exposure.
Nilson D, Partridge R, Suner S, Jay G.
Prehosp Disaster Med. 2010 May-Jun;25(3):253-6.
PMID: 20586019 [PubMed - indexed for MEDLINE]

Free Full Text PDF Download from Prehosp Disaster Med.

^[5] RAD-57
Masimo
Product information page

^[6] RAD-57 for Fire/EMS
Masimo
Product information page

Filed Under: Assessment, Critical Judgment, Heresy, Research, Risk Management, Rogue Medic

Intramuscular Midazolam for Seizures – Part III

02/20/2012 by Rogue Medic 1 Comment

Also posted over at Rogue Medic (now at EMS Blogs).

I have already pointed out my disappointment with the references of this large double-blind, randomized, noninferiority trial comparing IM (IntraMuscular) midazolam (Versed) with IV (IntraVenous) lorazepam (Ativan). One of those criticisms appears to be just due to a typographical error. The footnote in the text was ¹¹, but the footnote should have been ¹.

The relationships among benzodiazepine dose, respiratory depression, and subsequent need for endotracheal intubation are poorly characterized, but higher doses of benzodiazepines may actually reduce the number of airway interventions. Our data are consistent with the finding that endotracheal intubation is more commonly a sequela of continued seizures than it is an adverse effect of sedation from benzodiazepines.¹¹ ^[1]

Here is some of the information from footnote ¹. One interesting aspect of this double-blind study is that there is a placebo group. Patients received 2 mg IV lorazepam, 5 mg IV diazepam (Valium), or IV placebo. Treatment could be repeated one time if seizures continued for more than 4 minutes or if seizures recurred.

Cardiorespiratory complications before arrival at the hospital and at the time of transfer were important secondary outcomes that relate to the safety of out-of-hospital therapy with intravenous benzodiazepines. Despite concern regarding the adverse effects of these agents, we found a trend toward lower rates of out-of-hospital complications (primarily respiratory compromise) in the active-treatment groups than in the placebo group. This suggests that respiratory complications associated with prolonged seizures may be more pronounced than those caused by intravenous lorazepam and diazepam given at relatively low doses.^[2]

The doses are low. The lorazepam dose is only half of the 4 mg used in the IV lorazepam vs. IM midazolam study.

The doses of midazolam and lorazepam used in this trial are consistent with the most effective doses for the treatment of status epilepticus that are reported in the literature.^9,10 Although these initial doses are higher than the ones used by many EMS systems and emergency physicians, they are the same as those approved for this indication and are in line with those used by epileptologists.^[1]

Is there added safety from the lower doses?

The epilepsy specialists and the FDA (Food and Drug Administration) do not recommend lower doses.

Were the low doses effective?

2 mg midazolam?

Does anyone really expect such a small dose to make a difference?

Despite the beneficial outcomes associated with intravenous lorazepam and diazepam, 41 to 57 percent of patients who received active treatment were still in status epilepticus at the time of arrival at the emergency department. These patients were more than twice as likely to require intensive medical care as those whose seizures ended outside the hospital. Differences in the causes of the episodes of status epilepticus are unlikely to account for this difference. These observations, coupled with the favorable risk–benefit profile associated with lorazepam and diazepam in this trial, suggest that higher doses should be studied to define the optimal therapy for patients with out-of-hospital status epilepticus.^[2]

An editorial refers to the study just published^[1] and to the benzodiazepine vs. placebo study.^[2] Describing the complications in the placebo study, the author wrote –

Successful termination was much more common in the two groups that received benzodiazepines (59% with lorazepam, 43% with diazepam, and 21% with placebo). Since respiratory distress was twice as common in the group given placebo as in either of the groups given a benzodiazepine, the best way to avoid the need for intubation is to stop seizure activity.^[3]

This presents an interesting conundrum. Doses of benzodiazepines (midazolam, lorazepam, diazepam, . . .) are often limited, due to a fear of causing respiratory complications.

When treating seizures, higher doses of benzodiazepines may actually protect patients from respiratory complications.

With a fatality rate around 10%, seizures are certainly not benign.

Maybe early treatment with high dose benzodiazepines can significantly decrease that fatality rate.

Finally, relatively few out-of-hospital interventions have been evaluated in randomized controlled trials,¹⁶ and when they have been evaluated carefully, therapies with intuitive appeal have often been found either to lack benefit or to cause harm to patients.^17-20 ^[2]

The irony is that we may be doing the opposite by limiting doses of benzodiazepines to less than what is recommended by the FDA.

What do you think?

See also Part I and Part II. To be continued in Part IV.

Footnotes:

^[1] Intramuscular versus intravenous therapy for prehospital status epilepticus.
Silbergleit R, Durkalski V, Lowenstein D, Conwit R, Pancioli A, Palesch Y, Barsan W; NETT Investigators.
N Engl J Med. 2012 Feb 16;366(7):591-600.
PMID: 22335736 [PubMed - in process]

^[2] A comparison of lorazepam, diazepam, and placebo for the treatment of out-of-hospital status epilepticus.
Alldredge BK, Gelb AM, Isaacs SM, Corry MD, Allen F, Ulrich S, Gottwald MD, O’Neil N, Neuhaus JM, Segal MR, Lowenstein DH.
N Engl J Med. 2001 Aug 30;345(9):631-7. Erratum in: N Engl J Med 2001 Dec 20;345(25):1860.
PMID: 11547716 [PubMed - indexed for MEDLINE]

Free Full Text from N Engl J Med. with link to PDF Download

^[3] Intramuscular versus intravenous benzodiazepines for prehospital treatment of status epilepticus.
Hirsch LJ.
N Engl J Med. 2012 Feb 16;366(7):659-60. No abstract available.
PMID: 22335744 [PubMed - in process]

Filed Under: Heresy, Pharmacology, Research, Risk Management, Rogue Medic

Sleep quality and fatigue among prehospital providers

10/20/2011 by Rogue Medic 1 Comment

Also posted over at Rogue Medic (now at EMS Blogs).

Even though many in EMS will tell you that EMS stands not for Emergency Medical Services, but for Earn Money Sleeping, sleep deprivation is a problem for many in EMS, many in medicine, and many in other fields. I am a night person, much more awake and alert at 2 AM, than at 8 AM.

In spite of this, some early to bed, early to rise EMS administrators demand that employees adapt their schedule to the personal preferences of the administrator. This is not only an irrational attitude, but demonstrates such a lack of awareness of what others experience, that working in any patient care setting would be contraindicated.

Sleep deprivation produces impairments in central nervous system (CNS) activities from the most basic functions, such as appetite and temperature regulation, to higher functions, such as memory and vigilance. Sleepiness has been linked to increases in unintentional incidents such as motor vehicle collisons and occupational injuries.^3–5 ^[1]

We should not hesitate to give partial credit to those who insist on having everyone else adapt to their schedules.

Shift workers also tend to have to rely on sleep-inducing agents. A survey of emergency medicine residents revealed that 46% used some kind of sleep agent, including alcohol, benzodiazepines, and muscle relaxants, to fall asleep.⁸ ^[1]

About half of residents, not just EMS personnel, but there is no problem that needs to be addressed. Just gulp down some coffee and put on your war face.

There is some unintentional humor in the study. Probably due to lack of sleep.

We collected 119 completed surveys. Subjects were 54.0% female, and the largest age group was 40 to 49 years (39.3%; Table 1).^[1]

I do consume chocolate to ward off irritability. Maybe that is the 54% of me that is female. Those 40 to 49 years old were the largest group – by weight or volume or something else? I would ask the same about the 54% female, but I know when to not comment. OK, maybe not.

a moderate proportion of subjects reported employment at multiple EMS agencies (34.2%).^[1]

While not the only factor, I would expect that this strongly correlates with sleep deprivation and the resultant negative effects.

I am surprised at the low rate of people working multiple EMS jobs, maybe a lot of them ~~have real jobs~~ work outside of EMS.

The majority of subjects were overweight or obese (84.6%) based on body mass index (BMI).^[1]

Sleep deprivation produces impairments in central nervous system (CNS) activities from the most basic functions, such as appetite and temperature regulation, to higher functions, such as memory and vigilance.^[1]

No connection.

one-fifth reported being told that they have weight problems (22.7%).^[1]

More than 4/5 are obese, but only 1/5 have had a doctor notice this.

Nearly half of the subjects (44.5%) reported experiencing severe fatigue while at work (Fig. 2). The proportion of subjects with severe fatigue increased with years of experience (p < 0.0001),^[1]

A global score >5 suggests poor sleep quality.^[1]

At least this is something that we learn to adapt to, so it should be less of a problem with increased time on the job.

Or not. Maybe the increasing problems at over 20 years indicates an amount of time in EMS that causes more significant damage.

How much of what we do works out as a feedback loop that compounds problems as if we had heart failure?

Image credit.^[2] Click on the image to make it larger.

We know the simple treatments for heart failure – high doses of NTG (NiTroGlycerin) and CPAP (Continuous Positive Airway Pressure).

Maybe the solution to sleep deprivation is something equally simple, such as taking naps or being permitted to sleep when not treating patients.

Even though we have known for decades that NTG and CPAP are the best treatments for acute exacerbation of heart failure, few of us seem to use these treatments. When we do use them, we use homeopathic doses of NTG and we make excuses for not using CPAP.

Will there be any faster adoption of sensible approaches to sleep deprivation?

Will people in EMS be able to make enough to not have to work other jobs?

Federal law limits work hours for many sectors of the transportation industry, including commerical pilots (eight hours of flight time per 24 hours), shipboard personnel on tankers (15 hours per 24 hours), and long-haul truck drivers (14 hours per shift, with a maximum of 11 hours driving).^29–31 ^[1]

Will we only respond to rules set by others?

The mature thing to do would be for us to act first.

One of the reasons I work at my current job is the bosses allow the employees to sleep at any time – as long as calls are covered and other work is accomplished during the shift.

Footnotes:

^[1] Sleep quality and fatigue among prehospital providers.
Patterson PD, Suffoletto BP, Kupas DF, Weaver MD, Hostler D.
Prehosp Emerg Care. 2010 Apr 6;14(2):187-93.
PMID: 20199233 [PubMed - indexed for MEDLINE]

Free Full Text at PubMed Central with links to Free PDF Download

^[2] Prehospital therapy for acute congestive heart failure: state of the art.
Mosesso VN Jr, Dunford J, Blackwell T, Griswell JK.
Prehosp Emerg Care. 2003 Jan-Mar;7(1):13-23. Review.
PMID: 12540139 [PubMed - indexed for MEDLINE]

Free Full Text PDF

Filed Under: Heresy, Research, Risk Management, Rogue Medic

Patient Perceptions of Computed Tomographic Imaging and Their Understanding of Radiation Risk and Exposure – Part IV

09/12/2011 by Rogue Medic 1 Comment

Also posted over at Rogue Medic (now at EMS Blogs).

Continuing from Part I, Part II. and Part III.

After assessing what it is that the abdominal pain patients want/expect from a visit to the ED (Emergency Department), how many X-rays it takes to deliver the same radiation as an abdominal CT (Computed Tomographic imaging), whether CTs increase the lifetime risk of cancer, and how many abdominal CTs equal some sort of measure of the radiation exposure of Hiroshima survivors, the authors conclude that people do not understand the risks of radiation.^[1] This study is followed by an excellent editorial.

The easy conclusion from these ﬁndings is, unsurprisingly, that patients are ill informed, and thus efforts to improve their education and awareness should help to mitigate the overuse of imaging and its consequent risks.^[2]

Dr. Wears does not discuss the validity of assuming that there is only one right answer to the questions asked. There is also a podcast discussing this study and discussing the editorial, but the podcast is similarly missing the problem with the study taking for granted that there is a single right answer to the study’s questions.^[3]

First, the “rational person” assumption holds that, given correct information, people should arrive at consistent choices about alternatives (eg, to image or not) based on the net expectation of probabilities and outcomes.²^[2]

If we make rational decisions, why do so many of us smoke?

If we make rational decisions, why do so many of us eat to the point of obesity?

If we make rational decisions, why do so many of us spend so much time watching reality TV?

Dr. Wears cites some of the studies that show that we do not make rational decisions. To insist that we make rational decisions is also irrational. Isolated examples of decisions that appear rational do not mean that a person makes rational decisions any more than a stopped clock being right twice a day means that the stopped clock keeps accurate time.

The authors provide excellent examples of irrationality in one question they present.

Click on images to make them larger.

How a multiple choice question is presented will affect way the answers are chosen.

Why is there no choice for I don’t know?

For most people not familiar with X-rays and CTs, the only honest and rational answer is I don’t know.

When graphing the results, we can further distort the results by making the distances between numbers completely arbitrary. Why present the choices as the Same radiation (the same, or zero difference is 50 x 0), 50 times more (greater by a factor of 50 x 1), 100 times more (greater by a factor of 50 x 2), 250 times more (greater by a factor of 50 x 5), 300 times more (greater by a factor of 50 x 6), and Over 350 times more (greater by a factor of 50 x at least 7).

Why blur the distinction between 100 times and 250 times? When the numbers become blurred, the numbers lose their meaning. When there is no difference in meaning between one number and a number 2 1/2 times as large, are we providing information or are we providing confusion?

We seem to most insist on stripping information of its meaning when we create multiple choice tests. Correct answers become a simple matter of memorization separated from understanding. This is one way to create the protocol monkey – the automaton, whom we claim is rendered harmless by being prevented from thinking. This desire to prevent the use of judgment may be the ultimate irrational decision.

If the difference between 100 and 250 is the same as the difference between 250 and 300, how do we expect anyone to notice differences in dosages? 100 mg – 200 mg – 300 mg – what’s the difference? With memorized answers, the only difference is whether it is graded as correct. With real patients, the differences can be fatal.

We memorize our way to recklessness.

We do not memorize our way to safety.

Previous literature estimates the radiation dose for an abdomen-pelvis CT to be equivalent to 100 to 250 2-view chest series.^2,10-12 For the purpose of this investigation, we used the conservative estimate of 1 abdomen-pelvis CT = 100 2-view chest radiographs.^[1]

I agree with their choice to use the more conservative number, but what this still does not do is put this in a context that helps people to understand. Without understanding something about the radiation exposure of an X-ray, this is an unknown. 10 times an unknown – 100 times an unknown – 1,000 times an unknown – what’s the difference?

Presenting misleading information to medically naive people and proclaiming Eureka! is misleading. We are not finding anything. We are presenting a spectacle, although not as much of one as Archimedes did running naked through the streets (assuming the legend to be true).

The second assumption is that the problem is “out there” in patients, not “in here” in physicians. This might be viewed as a form of the psychologist’s fallacy,³ the idea that although patients’ preferences might suffer from irrationality, ignorance, or irrelevant considerations, ours (physicians’) do not.^[2]

An excellent point that should be extended to researchers.

How much of the problem is in the study design?

What are we measuring?

If the purpose of controlled trials is to examine things objectively, why use a study that seems to ~~depend~~ insist on subjectivity?

I will write more about Dr. Wears editorial later, because it covers a lot of important material on making decisions.

Footnotes:

^[1] Patient perceptions of computed tomographic imaging and their understanding of radiation risk and exposure.
Baumann BM, Chen EH, Mills AM, Glaspey L, Thompson NM, Jones MK, Farner MC.
Ann Emerg Med. 2011 Jul;58(1):1-7.e2. Epub 2010 Dec 13.
PMID: 21146900 [PubMed - indexed for MEDLINE]

Free Full Text from Annals of Emergency Medicine with links to Free Full Text PDF Download

^[2] Risk, radiation, and rationality.
Wears RL.
Ann Emerg Med. 2011 Jul;58(1):9-11. Epub 2011 Apr 2. No abstract available.
PMID: 21459481 [PubMed - indexed for MEDLINE]

^[3] What patients understand about radiation exposure from CTs
David H. Newman, MD, and Ashley Shreve (spelling?)
Annals of Emergency Medicine podcast page
2011 July
Free Podcast in MP3 format

Annals of Emergency Medicine provides a podcast that summarizes the articles published that month. This is an excellent resource. The full July 2011 podcast is – Free Full Podcast in MP3 format. The full archives of Annals of Emergency Medicine podcasts is – Page with links to podcast segments and full month podcasts.

Filed Under: Assessment, Critical Judgment, Education, Heresy, Medical Mythology, Research, Risk Management, Rogue Medic

Psychic vs. RAD-57

Accuracy of Noninvasive Multiwave Pulse Oximetry Compared With Carboxyhemoglobin From Blood Gas Analysis in Unselected Emergency Department Patients

Intramuscular Midazolam for Seizures – Part III

Sleep quality and fatigue among prehospital providers

Patient Perceptions of Computed Tomographic Imaging and Their Understanding of Radiation Risk and Exposure – Part IV

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Psychic vs. RAD-57

Accuracy of Noninvasive Multiwave Pulse Oximetry Compared With Carboxyhemoglobin From Blood Gas Analysis in Unselected Emergency Department Patients

Intramuscular Midazolam for Seizures – Part III

Sleep quality and fatigue among prehospital providers

Patient Perceptions of Computed Tomographic Imaging and Their Understanding of Radiation Risk and Exposure – Part IV

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