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

- Rogue Medic

Dextrose 10% or 50%: EMS Research Episode 10

Tue, 05 Jul 2011 06:30:06 -0400 by
–ResearchBlogging.org

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

On the EMS Research Podcast Harry Mueller, Dr. Bill Toon, and I discuss this paper. Go listen to the podcast. Dextrose 10% or 50%: EMS Research Episode 10.

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1. Is 50% dextrose as safe as 10% dextrose?

No.

    1 a. Can cautious administration eliminate that difference in safety?

Probably not.

2. Is 50% dextrose as efficacious as 10% dextrose?

Maybe.

3. Is 50% dextrose as affordable as 10% dextrose?

No.

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Out of 3 criteria, 50% dextrose fails two of the criteria.

If 10% dextrose is cheaper and it is safer to switch to 10% dextrose, why do so many of us in EMS resist this simple change?

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Two of the subjects contacted by the researchers after treatment reported that before the study they had often had difficulty bringing their blood glucose back to their expected usual level after being treated by paramedics using 50% dextrose.[1]

While this may indicate idiosyncratic responses, there is no mention of any similar negative responses to 10% dextrose. this might require a larger study to examine, but this is a great start.

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The picture is one I found labeled as being from Annals of Emergency Medicine of 50% Dextrose extravasation, but I do not know anything about which issue it is from or any other details. Issue information.[2]

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Go listen to the podcast..

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I have also written about this in –

Should EMS Still Use 50% Dextrose – 5/03/2011

Dextrose 10% or 50% in the treatment of hypoglycaemia out of hospital? A randomised controlled trial. – 5/04/2011

Comment on 10% Dextrose vs 50% Dextrose – 5/05/2011

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Footnotes:

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[1] Dextrose 10% or 50% in the treatment of hypoglycaemia out of hospital? A randomised controlled trial.
Moore C, Woollard M.
Emerg Med J. 2005 Jul;22(7):512-5.
PMID: 15983093 [PubMed – indexed for MEDLINE]

Free Full Text from PubMed Central           Free Full Text PDF Download from PubMed Central

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A review of the research on this topic, which is predominantly about the above paper.

A review of the efficacy of 10% dextrose as an alternative to high concentration glucose in the treatment of out-of-hospital hypoglycaemia
Ziad Nehme, Daniel Cudini
2009; Volume 7 : Issue 3; Article Number: 990341
Journal of Emergency Primary Health Care
Free Full Text with link to PDF Download

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[2] Images in emergency medicine. Dextrose extravasation causing skin necrosis.
Levy SB, Rosh AJ.
Ann Emerg Med. 2006 Sep;48(3):236, 239. Epub 2006 Feb 17. No abstract available.
PMID: 16934641 [PubMed – indexed for MEDLINE]

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Moore, C. (2005). Dextrose 10% or 50% in the treatment of hypoglycaemia out of hospital? A randomised controlled trial Emergency Medicine Journal, 22 (7), 512-515 DOI: 10.1136/emj.2004.020693

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Filed Under: Dextrose, EMS Research Podcast, Heresy, Mythology, Paramedicine 101, Research Blogging

Chart Version – Fentanyl in the out-of-hospital setting: variables associated with hypotension and hypoxemia

Sun, 05 Jun 2011 06:30:35 -0400 by
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Some charts for a more visual assessment of what I wrote in – Fentanyl in the out-of-hospital setting: variables associated with hypotension and hypoxemia.[1]

In this study, hypotension was defined as a systolic blood pressure less than 90 mm/Hg. The numbers in these charts are doses and not patients. A total of 1,055 doses were given to 500 patients.

If the patient was already hypotensive there was a 53% chance that the patient would still be hypotensive after a dose of fentanyl.

That means a 47% chance that the hypotensive patient would no longer be hypotensive after a dose of fentanyl.

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There were only 45 doses given to hypotensive patients, so we do not have a lot of data. We also do not know what the specific blood pressures were for each dose (before and after). A patient with a blood pressure of 72/50 before a dose of fentanyl, and a blood pressure of 88/56 after fentanyl is still hypotensive. A patient with a blood pressure of 88/56 before a dose of fentanyl, and a blood pressure of 90/56 after fentanyl is no longer hypotensive. I could go on for a while with the possibilities, but we do not have the raw data, so it is all just speculation. Similarly, a patient could be given fluids or pressors, but that does not appear to be the case in this study.

If this were a treatment for hypotension and with a much larger number of patients and about half had their hypotension resolve after fentanyl, then this might be an impressive treatment for hypotension. A lot of ifs. A lot of correlation.

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What about the possibility of new hypotension after a dose of fentanyl?

Out of 1010 doses, there were only 28 cases of new hypotension. We do not know if some of these were patients who were hypotensive before a dose of fentanyl, but had their blood pressure rise after receiving that earlier dose of fentanyl. Would these be considered new hypotension? Were there any cases of this? We don’t know.

We do know that they were giving fentanyl to patients with lower pressures than 90 systolic.

What is the risk of new hypotension in a patient with a blood pressure of at least 90, who is given a dose of fentanyl?

Very low. Less than 3%.

If only all of our treatments were this safe.

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When should we expect hypotension after giving a dose of fentanyl?

When the patient is already hypotensive.

A different way of looking at this chart –

Likelihood of no hypotension after a dose of fentanyl:

97+% if no hypotension at the time of the dose.

47% if there is already hypotension at the time of the dose.

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What about a chart of hypoxemia after fentanyl?

No hypoxemia after fentanyl.

Zero cases.

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Should we ignore the possibility of hypoxemia or hypotension after fentanyl?

No, but we should not avoid using fentanyl due to exaggerated possibilities from people who are not familiar with fentanyl.

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Footnotes:

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[1] Fentanyl in the out-of-hospital setting: variables associated with hypotension and hypoxemia
Rogue Medic
Article

This refers to the paper below and the podcast below that –

Fentanyl in the out-of-hospital setting: variables associated with hypotension and hypoxemia.
Krauss WC, Shah S, Shah S, Thomas SH.
J Emerg Med. 2011 Feb;40(2):182-7. Epub 2009 Mar 27.
PMID: 19327928 [PubMed – in process]

Full Text PDF Download at medicalscg.

Fentanyl Study: EMS Research Episode 9
EMS Research Podcast
Podcast

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Filed Under: Charts, EMS Research Podcast, Heresy, Research

Fentanyl in the out-of-hospital setting: variables associated with hypotension and hypoxemia

Fri, 27 May 2011 06:30:46 -0400 by
–ResearchBlogging.org

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Also posted over at Paramedicine 101 (now at EMS Blogs) and at Research Blogging. Go check out the rest of the excellent material at these sites.

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On the most recent episode of the EMS Research Podcast,[1] Harry Mueller, Bill Toon, and I discuss a recently published paper examining what effect prehospital fentanyl has on hypoxemia or on hypotension.

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This study’s objectives were to assess for association between prehospital fentanyl administration and the occurrence of either of the following: hypotension, defined as a drop in systolic blood pressure (SBP) to below 90 mm Hg in a patient at least 5 years of age, or hypoxemia, defined as a drop in peripheral oxygen saturation (SpO2) to below 90%.[2]

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There were 500 patients and many of them received more than one dose of fentanyl. Several received 6 separate doses of fentanyl.

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Even with so many doses given, the mean dose and maximum dose were not that high.[3]

The median dose of fentanyl per administration was 1.1 µg/kg (IQR 0.8–1.4; range 0.25–3.5 µg); the mean dose was 1.1 µg/kg (SD 0.46). Expressed as a total dose per patient (i.e., summing all doses in a given patient), the median dose was 2.5 µg/kg (IQR 1.7–3.9) with a mean of 3.0 µg/kg (SD 1.8).[2]

1.1 µg/kg per dose.

The maximum single dose is unusual and is not explained. range 0.25–3.5 µg which should be /kg.

How did one patient receive such a large single dose – 3.5 µg/kg? The thing that makes the most sense (if this was a dosing error) is that this was a small pediatric patient. I carry fentanyl in syringes that contain 100 µg in 2 ml (50 µg/ml), but they might carry vials that have a larger volume. for example, below is packaging for 250 µg in 5 ml (also 50 µg/ml). If an entire vial were given to a 140 kg patient, that would be a dose of 3.5 µg/kg.

Is that what happened?

I don’t know – and that is presuming that this is a dosing error, which may not be valid to presume.


Image credit.[4]

I like the idea of carrying 10 mg morphine syringes and 100 µg fentanyl syringes. The total dose of each syringe is roughly equivalent in its effect on a patient. Except in very unusual circumstances, even a full 10 mg morphine, or 100 µg fentanyl, is not going to produce significant problems – and that is assuming that there is no judgment going into the dosing of patients.

Should we assume that there is no judgment going into the dosing of patients?

No, but I will get back to this in a little bit.

If this was not a dosing error, it is extremely aggressive dosing. I am comfortable giving a bit more than 1 µg to otherwise healthy trauma patients or burn patients, but I will at least give this a couple of minutes to have some kind of effect and reassess the patient before giving more. Similarly, with morphine, I might give up to 0.15 mg/kg to these same patients. 3.5 µg/kg is about three times higher than I am comfortable with.

Does that make the dose inappropriate?

Without knowing the specifics, we really cannot tell.

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Should we assume that there is no judgment going into the dosing of patients?

There are prior data to support the safety of appropriately administered opioids, including fentanyl. The study of Kanowitz et al., although more methodologically rigorous than most reports, is typical in its demonstration of safety: of 2129 patients receiving an opioid (fentanyl), only 12 (0.6%) had a medication-related vital sign abnormality and an intervention was required only once (in a patient who had no sequelae)(8) [2]

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What about in this study?

It is noteworthy that, although the study HEMS program’s fentanyl protocol does not proscribe use of the drug in hypotensive patients, the crew are required to use the agent judiciously (in other words, at the lower end of the recommended dosage range). This means that the safety of fentanyl as demonstrated in the current study may be related to more conservative dosing in unstable patients, but the parallel message is that experienced EMS crews are able to exercise judgment in determining which patients should receive cautious drug dosing.[2]

Should we assume that there is no judgment going into the dosing of patients?

experienced EMS crews are able to exercise judgment in determining which patients should receive cautious drug dosing.

The authors of this study do not come to the conclusion that EMS crews cannot make dosing decisions independently. The authors come to exactly the opposite conclusion.

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What about the hypotension and hypoxemia?

New hypotension (i.e., post-fentanyl SBP < 90 in a patient at least 5 years of age, with pre-fentanyl SBP at least 90) was seen in 28 administrations (2.7% of 1055 administrations, 95% CI 1.8–3.8%).[2]

Vital signs were measured within ten minutes of each dose of fentanyl (usually within 5 minutes).

Does hypotension developing so soon after fentanyl mean that the fentanyl caused the hypotension?

No.

It is possible that fentanyl did cause the hypotension.

It is possible that fentanyl did contribute to a drop in the blood pressure.

It is possible that fentanyl did not affect the blood pressure at all.

It is possible that fentanyl had the effect of increasing the blood pressure, but that increase was outweighed by something else causing a greater drop in blood pressure.

We do not have enough information to determine what effect fentanyl has on blood pressure in these patients, but we no longer have a good reason for expecting that fentanyl will produce hypotension.

There are many possible side effects of fentanyl, but even in hypotensive patients we should not expect any sudden deterioration in blood pressure with judicious administration of fentanyl by competent EMS personnel.

The authors do make one error here. They use the total number of administrations of fentanyl in their calculation of the rate of new hypotension to come up with 2.7%.

Overall, in 45 cases (4.3% of 1055), fentanyl was administered to patients who were hypotensive.[2]

Those 45 patients should be excluded from the calculation of new hypotension. Therefore the rate should be 2.8%, rather than 2.7%. This does not change the conclusions in any way. This is just a technicality.

What about those 45 patients who were hypotensive before receiving fentanyl?

In 53% of these cases, hypotension (predictably) remained after the opioid was given—but in 47% of cases in which fentanyl was administered to hypotensive patients, the next SBP exceeded 90.[2]

About half of the patients who were hypotensive before fentanyl were not hypotensive after fentanyl.

While 45 is a small number of hypotensive patients, how many of us would like to have a treatment for hypotension that is effective on half of our patients?

I am only partly kidding.

We do not know what other treatments were being provided, but how many of these patients may have had changes to their vital signs due to severe pain?

We presume that fentanyl will make vital signs worse, but that is a mistake. We may make less of a mistake with worrying that morphine will cause hypotension, based its potential for histamine release.

What was the effect of fentanyl on vital sign abnormalities in the Kanowitz study of fentanyl?

Of the 2,315 patients who received fentanyl in the field, 66 patients had a vital sign abnormality. Of those 66 patients, three were excluded because they received a sedative in addition to the fentanyl. There were 46 patients who were excluded because their vital sign abnormalities occurred before the administration of fentanyl. Of the 46 patients who had a vital sign abnormality before the administration of fentanyl, 38 patients’ vital signs improved after the administration of fentanyl, eight patients’ vital signs remained the same, and none worsened.[5]

Of the 46 patients who had a vital sign abnormality before the administration of fentanyl, 38 patients’ vital signs improved after the administration of fentanyl, eight patients’ vital signs remained the same, and none worsened.

It is possible that fentanyl is improving vital signs by decreasing pain.

The problem is that so many of us do not take the pain of others seriously, so we do not expect pain to lead to problems with vital signs.

Does the improvement in vital signs so soon after fentanyl mean that the fentanyl caused the improvement in vital signs?

No.

It is possible that fentanyl did cause the improvement in vital signs.

It is possible that fentanyl did contribute to an improvement in vital signs.

It is possible that fentanyl did not affect the vital signs at all.

It is possible that fentanyl had the effect of worsening the vital signs, but that worsening was outweighed by something else causing a greater improvement in vital signs.

We do not have enough information to determine what effect fentanyl has on vital signs in these patients, but we no longer have a good reason for expecting that fentanyl will frequently produce bad vital signs. Fentanyl was much more likely to be followed by an improvement in vital signs.

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We almost forgot about hypoxemia. Hypoxemia is an even bigger concern than hypotension.

What effect did fentanyl have on hypoxemia?

Assessment of the 522 administrations in 279 non-intubated patients revealed no difference in the mean SpO 2 readings before (98.8%, 95% CI 98.5–98.9) and after (98.6%, 95% CI 98.3–99.0) fentanyl administration. There were no instances of hypoxemia in these non-intubated patients receiving fentanyl (one-sided 97.5% CI for 0/279: 0–1.3%).[2]

Not even a single instance of hypoxemia.

None.

This was such a big concern that one of the helicopter services near me (based in a university hospital) only permitted flight crews to give fentanyl after a patient was intubated.

No tube – no fentanyl.

Myth busted.

We do need to be cautious about the administration of fentanyl to any patient. We should continually monitor ECG, SpO2, blood pressure, respiratory drive, and level of consciousness. With higher doses we should also continuously monitor waveform capnography.

Fentanyl is safe in the hands of competent EMS providers.

Fentanyl should not require medical command contact for any dose.

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Go listen to the podcast.

Contact EMS Research at:
603-397-0367
emsresearchcast at gmail dot com
EMSResearchCast on Twitter
EMS Research at FaceBook

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Footnotes:

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[1] Fentanyl Study: EMS Research Episode 9
EMS Research Podcast
Podcast

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[2] Fentanyl in the out-of-hospital setting: variables associated with hypotension and hypoxemia.
Krauss WC, Shah S, Shah S, Thomas SH.
J Emerg Med. 2011 Feb;40(2):182-7. Epub 2009 Mar 27.
PMID: 19327928 [PubMed – in process]

Full Text PDF Download at medicalscg.

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[3] Mean, Median, Mode, and Range
Purplemath
Article

It is good to be clear on what the meaning of the terminology. This has the simplest explanation I found in a very brief search.

The “mean” is the “average” you’re used to, where you add up all the numbers and then divide by the number of numbers. The “median” is the “middle” value in the list of numbers. To find the median, your numbers have to be listed in numerical order, so you may have to rewrite your list first.

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[4] FENTANYL CITRATE injection, solution
[Baxter Healthcare Corporation]
FDA Label
DailyMed
How Supplied
Free Full Text FDA Label from DailyMed with links to Free Full Text PDF Download.

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[5] Safety and effectiveness of fentanyl administration for prehospital pain management.
Kanowitz A, Dunn TM, Kanowitz EM, Dunn WW, Vanbuskirk K.
Prehosp Emerg Care. 2006 Jan-Mar;10(1):1-7.
PMID: 16418084 [PubMed – indexed for MEDLINE]

Free Full Text PDF Download from MSTC.

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Krauss, W., Shah, S., Shah, S., & Thomas, S. (2011). Fentanyl in the Out-of-Hospital Setting: Variables Associated with Hypotension and Hypoxemia The Journal of Emergency Medicine, 40 (2), 182-187 DOI: 10.1016/j.jemermed.2009.02.009

Kanowitz A, Dunn TM, Kanowitz EM, Dunn WW, & Vanbuskirk K (2006). Safety and effectiveness of fentanyl administration for prehospital pain management. Prehospital emergency care : official journal of the National Association of EMS Physicians and the National Association of State EMS Directors, 10 (1), 1-7 PMID: 16418084

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Filed Under: Critical Judgment, EMS Research Podcast, Fentanyl, Heresy, Mythology, Pain Management, Paramedicine 101, Research Blogging

Utilization of warning lights and siren based on hospital time-critical interventions

Mon, 23 May 2011 06:30:53 -0400 by
–ResearchBlogging.org

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Also posted over at Paramedicine 101 (now at EMS Blogs), and at Research Blogging. Go check out the rest of the excellent material at these sites.

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This study was the topic for discussion on the EMS Research Podcast.[1]

Go listen to the podcast.

To simplify the title –

Does the use of lights and sirens get the patient to the hospital in time for life-saving treatment?

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The routine use of lights and siren (L&S) by emergency medical services (EMS) personnel has been a longstanding tradition, but with evidence mounting concerning its risks, many are now questioning their utility.1–4 [2]

This is not just appropriate, but essential.

We have too many treatments/procedures that are based on nothing more than superstition, tradition, and/or wishful thinking. We need to evaluate what we do in as unbiased a way as possible to find out if there is any benefit to any patient, rather than just blindly continue with each standard of care myth-based intervention.

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Morbidity and mortality from collisions involving emergency vehicles is a major public health hazard.[2]

Traffic fatality is always one of the top causes of line of duty death in EMS. If a patient is unstable, crashing on the way to the hospital is definitely not a good idea. Is there any benefit from the risk of L&S driving?

Roughly 70% of fatal ambulance crashes occur during utilization of warning L&S.14[2]

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As the EMS providers wrote the chart, there was a questionnaire to confirm if the times documented were accurate. If EMS personnel subjectively felt documented times were not accurate, the chart was excluded from the study.[2]

The time of travel in the control group was recorded by two medical students and one EMS fellow traveling in their personal vehicles from the location of the 9-1-1 response to the hospital. They drove during the same day of week and time of day as did the original call. They were instructed to obey all traffic laws and speed limits. All time was recorded in minutes. Any significant time delay due to weather patterns was noted and excluded from analysis.[2]

From the paper, it is not clear where they did this study. I have worked for all of the hospitals, except one. That is the University of Medicine and Dentistry of New Jersey – Robert Wood Johnson Medical School in New Brunswick, NJ. The demographics listed are not consistent with any of the other hospitals listed. RWJ is the most suburban of the hospitals and that is something that should have a bearing on the way we assess the applicability of this study to individual systems. This is a variable to consider in the way traffic affects transport times.

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A total of 112 charts were used in this analysis. The average difference in time with versus without L&S was -2.62 minutes (95% CI = -2.60– -2.63 minutes (min), paired t-test p-value <0.0001; signed rank p-value <0.0001) such that patient transport with no L&S took on average of 2.62 minutes longer than when using L&S.[2]

95% CI = -2.60– -2.63 minutes?

That is a surprisingly narrow confidence interval.

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The average transport time in minutes with L&S is 14.5 ±7.9 min (1SD) (range = 1–36 min). The average transport time without L&S is 17.1± 8.3 min (range = 1–40 min). The time difference ranged from 24 min faster with L&S to 16 min slower with L&S.[2]

Here is another point that raises questions that are not answered in the paper.

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Did one of the ambulances crash?

Did one of the ambulances get lost?

Or, should I ask, Did two of the ambulances crash/get lost/whatever?

All we know is that there were 2 transports that took dramatically longer with L&S than without L&S.The major roadway connecting the university hospital with neighboring towns was frequently under construction. Although this factor could account for prolonged times in the lights and sirens group, it also could have equally affected the control group.[2]

And it could explain the two extra-long L&S transports.

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Huber regression estimates no significant effect of time with L&S on the difference between the two mean transport times, with an increase of 0.02 minutes (95% CI = -0.06–0.10) in the difference due to a 10-minute addition in transport time with L&S. This finding is contrary to the expectation of L&S being even more useful for longer distances.[2]

In other words, the longer trips did not result in significantly more time saved using L&S.

3 1/2 seconds to 6 seconds (0.06 to 0.10 minutes) for every additional ten minutes of transport time. Travelling at 60 MPH (Miles Per Hour) for 10 minutes, this would save less time, than increasing the speed to 61 MPH. Travelling at 30 MPH (Miles Per Hour) for 10 minutes, this would save less time, than increasing the speed to 31 MPH.

If the ambulance increases speed from 60 to 61 MPH, it is going to be barely noticeable in the back.

If the ambulance increases speed from 60 to 61 MPH, it is going to be barely noticeable in the back.

If the ambulance turns on the Lights & Sirens, it is going to be very noticeable in the back.

Where is the benefit that justifies the increased risk?

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The complete logs of interventions provided to the study patients were evaluated. Of the 112 patients transported with L&S, 108 (96.4%) were treated with PIs only. Five (4.5%) patients transported with L&S also received time-critical HI.[2]

PIs are Prehospital Interventions – treatments that can be provided by the paramedics (ALS or Advanced Life Support personnel).

HIs are Hospital Interventions – treatments that cannot be provided by paramedics. Fibrinolytics, neurosurgical evacuation, cardiac catheteriztion, and transvenous pacing in this study.

In other words, they were racing to the hospital, to have treatments that could have been provided by the paramedics.

However, there are times when it may be more appropriate to have something done in the more controlled setting of the hospital, rather than on scene or in the ambulance.

It is also possible that the medical command physician ordered that the paramedic not provide a treatment that is within the paramedic’s scope of practice. This can be for a treatment that is only permitted with medical command contact or a treatment that is permitted on standing orders, but that the medical command physician specifically ordered be withheld until the patient is at the hospital.

What about certain procedures that are often unsuccessful due to operator error, such as transcutaneous pacing or cardioversion. Even in the hospital, it is not unusual for some operator error to be involved when using these procedures to treat unstable patients.

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The last patient was diagnosed with an unstable, third-degree heart block and required immediate transvenous pacemaker placement secondary to ineffective capture with a transcutaneous pacemaker.[2]

Immediate? This was not done within the time saved by L&S transport, so hardly immediate.

Ineffective capture?

Is that the same as complete lack of capture?

As in pronouncing a patient dead because of ineffective cardiac output as demonstrated by being pulseless, apneic, and asystlic?

As I frequently like to point out –

Failure to capture with a transcutaneous pacemaker is frequently operator error.

Tom Bouthillet of EMS 12 Lead was not on the podcast, but he has made similar statements about transcutaneous pacing.[3]

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No HI was administered within the first 2.62 minutes of arrival. All five patients were admitted to a critical care unit and the average length of stay in the hospital was 10 days. No deaths occurred in the group who received HI.[2]

Was any time saved that made any difference in outcome?

We do not know, but this study did not provide evidence to support L&S transport.

Were any treatments provided any sooner?

We do not know, but this study did not provide evidence to support L&S transport.

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it is possible that patients with more serious illnesses had lights and siren compared with those who were less critical. Since only 7% of patients during this time interval did not have L&S, it is unlikely that this influenced the results.[2]

93% of these ALS patients require treatment EMS cannot provide?

No.

Only 5 patients did and none of them needed these treatments in the amount of time saved by L&S.

93% of these ALS patients are unstable?

That has not been my experience in any of the systems where I have worked. If anything, even the reverse is too high.

7% of ALS patients being unstable is too high.

So why all the commotion?

Because a mentality exists in the system that L&S result in improved patient care,[2]

We need to expose these myths for what they are – superstitions.

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Go listen to the podcast.

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Footnotes:

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[1] Driving with Lights and Sirens: EMS Research Episode 8
EMS Research Podcast
Podcast

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[2] Utilization of warning lights and siren based on hospital time-critical interventions.
Marques-Baptista A, Ohman-Strickland P, Baldino KT, Prasto M, Merlin MA.
Prehosp Disaster Med. 2010 Jul-Aug;25(4):335-9.
PMID: 20845321 [PubMed – indexed for MEDLINE]

The full text of the paper is available as a free PDF download from Prehospital Disaster Medicine from that issue’s index. – PDM has moved, so these links do not work.

The download link is in the page number – page 335. – PDM has moved, so these links do not work.

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[3] Transcutaneous Pacing (TCP) – The Problem Of False Capture
EMS 12 Lead
Article

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Marques-Baptista A, Ohman-Strickland P, Baldino KT, Prasto M, & Merlin MA (2010). Utilization of warning lights and siren based on hospital time-critical interventions. Prehospital and disaster medicine : the official journal of the National Association of EMS Physicians and the World Association for Emergency and Disaster Medicine in association with the Acute Care Foundation, 25 (4), 335-9 PMID: 20845321

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Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Paramedicine 101, Research Blogging, Risk Management

Performance of the RAD-57 With a Lower Limit – Better?

Wed, 18 May 2011 06:30:46 -0400 by
–ResearchBlogging.org

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Also posted over at Paramedicine 101 (now at EMS Blogs), at Research Blogging, and Discussed on the EMS Research Podcast – RAD-57 v. Lab: EMS Research Episode 2. Go check out the rest of the excellent material at these sites.

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CO (Carbon monOxide) is a significant cause of poisoning in the US, with hundreds of fatalities each year. The Masimo RAD-57 non-invasive CO monitor is a device that is supposed to make identification of these patients quick and accurate in the out of hospital setting.

There has been one study of the RAD-57 on actual patients being evaluated for CO toxicity. In that study, the sensitivity was horrible. Only 48%.[1] I could do as well flipping a coin. So could you.

The low sensitivity has been the focus of the criticism. On the other hand, the 99% specificity has been seen as a confirmation of what was already known.

Is the high specificity real?

There is a study coming out that suggests that rather than 15%, we should use 6.6% as the cutoff to provide good sensitivity. What happens to this study’s calculation of 99% specificity (only one false positive for every 100 patients screened), when the cutoff is dropped to 7% (the RAD-57 does not provide a display in fractions).

COHb = CarbOxyHemoglobin.

Using the 15% cutoff, 99% of the time, when the RAD-57 indicates that the carboxyhemoglobin is over 15%, the carboxyhemoglobin is over 15%.

Only one false positive out of 120 patients.

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What happens when we change the cutoff to 7%?

Not so good on the specificity. There appear to be 14 false positives out of 120 screened patients.

What will happen in the real world with these results?

With time, we will probably start to ignore the results that do not tell us what we want to see.

We will have spent $4,000 per machine to have a piece of equipment that we ignore when we do not like the results.

How does that provide any benefit for anyone with CO toxicity?

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Footnotes:

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[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

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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

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Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Masimo, Paramedicine 101, Research Blogging

Motor Vehicle Intrusion – EMS Research Episode 7

Tue, 05 Apr 2011 06:30:47 -0400 by
–ResearchBlogging.org

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Also posted over at Paramedicine 101 (now at EMS Blogs) and at Research Blogging. Go check out the rest of the excellent material at these sites.

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This study looks at whether passenger compartment intrusion is an effective MOI (Mechanism Of Injury) assessment criterion. This study also looks at whether replacing passenger compartment intrusion with extrication would be better. This is discussed on the EMS Research podcast at Motor Vehicle Intrusion – EMS Research Episode 7.

We chose to define the “use of trauma center resources” as one of our outcome measures, but there is no consensus on what constitutes appropriate use of a trauma center.[1]

If there is little agreement on what is appropriate use of a trauma center, how well can we say that any of these criteria predict which patients are appropriately triaged to a trauma center?

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In summarizing these three studies, the CDC expert panel states that there is little evidence to support the use of the intrusion criteria, yet it is included in the latest set of guidelines.[1]

Why let reality get in the way of a protocol for trauma triage?

After all, we have never let reality interfere with trauma treatment before.

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From the prehospital PCRs and ED records, two researchers (DI and DCC) abstracted patient demographic data, MVC characteristics (e.g., rollover and intrusion), final ED diagnoses (as determined and documented by either the emergency physician or the trauma surgeon responsible for ED charting), and patient disposition.[1]

One problem is that the authors then tried to figure out what the predictive value would be for criteria not used.

How much attention is devoted to documenting information that is not used to make trauma triage decisions?

We want EMS to pay attention to the assessment of the actual patient, rather than the assessment of the possible cost of repair of the vehicle.

We calculated the sensitivity, specificity, and positive predictive value (PPV) for intrusion for each of the two outcome measures. Based on our observations, we made a post hoc adjustment where we recalculated the sensitivity, specificity, and PPV for entrapment in place of intrusion. We defined entrapment as any use of tools, other than simply opening (“popping”) a jammed door with simple hand tools, to extricate a vehicle occupant.[1]

I do not spend much time documenting mechanism criteria that are not backed up by assessment findings. My chart is a medical record, not an estimate of auto repair costs.

Without any need for documenting extrication information, is extrication information documented accurately?

If only the patients ending up at the trauma center are evaluated for specificity of trauma triage criteria, how specific can we say these triage criteria are?

If 90% of these patients are transported to the trauma center (and triage criteria have excellent sensitivity, i.e. no critical trauma patients are missed), then we should have accurate information to assess specificity.

If 50% of these patients are transported to the trauma center (and triage criteria have excellent sensitivity), then we do not have accurate information to assess specificity.

If 10% of these patients are transported to the trauma center (and triage criteria have excellent sensitivity), then we do not have even remotely accurate information to assess specificity.

Another thing to consider is whether the triage criteria being evaluated are superseded by criteria that are more impressive to EMS, or given more attention by the QA/QI/CYA department. For example, the impressive criterion documented might be that the A post was cut during extrication, rather than that there was greater than a foot and a half of intrusion to the passenger compartment.

Does this mean that the extrication was necessary?

That would be difficult to determine without seeing the car before extrication was begun.

Does this mean that the extrication is relevant, while the intrusion is not?

Nobody knows.

How much does this tell us about what are the best MOI triage criteria?

Not a lot.

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Why do we treat STEMIs (ST segment Elevation Myocardial Infarctions) with the opposite approach?

The dichotomy is that with trauma triage, we accept a 1,000% to 2,000% overtriage rate, while with STEMI triage, we consider a 5% overtriage rate to be unacceptably high.

What about cardiology has led us to focus exclusively on specificity, but to ignore sensitivity?

What about trauma has led us to focus exclusively on sensitivity, but to ignore specificity?

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What these criteria do is discourage the use of critical judgment, which should be more sensitive and more specific than any set of trauma criteria.

If we were to spend more time on assessment than on memorization of criteria, would patients be more appropriately triaged to trauma centers?

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Go listen to the podcast.

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Footnotes:

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[1] Motor vehicle intrusion alone does not predict trauma center admission or use of trauma center resources.
Isenberg D, Cone DC, Vaca FE.
Prehosp Emerg Care. 2011 Apr-Jun;15(2):203-7. Epub 2011 Jan 12.
PMID: 21226551 [PubMed – in process]

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Isenberg D, Cone DC, & Vaca FE (2011). Motor vehicle intrusion alone does not predict trauma center admission or use of trauma center resources. Prehospital emergency care : official journal of the National Association of EMS Physicians and the National Association of State EMS Directors, 15 (2), 203-7 PMID: 21226551

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Filed Under: EMS Research Podcast, Heresy, Paramedicine 101, Research Blogging

Correction to Spine Immobilization in Penetrating Trauma: More Harm Than Good

Tue, 15 Mar 2011 06:30:29 -0400 by
–ResearchBlogging.org

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Also posted over at Paramedicine 101 (now at EMS Blogs) and at Research Blogging. Go check out the rest of the excellent material at these sites.

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The most recent EMS Research podcast is available – Spine Immobilization in Penetrating Trauma: More Harm Than Good?: EMS Research Episode 6.

I let my biases get the better of me when I wrote about this earlier.[1]

While I spent a significant portion of that review explaining why evidence of benefit was not present in this study, I ignored the problems with the data when the authors concluded that there was harm.

That was a mistake on my part. While I do believe that harm is likely, this study does not provide evidence to support that belief.

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The study uses data from the NTDB (National Trauma Data Bank®). The problem is that the NTDB does not appear to provide reliable data. I described a lot of the problems in posts about the use of the NTDB to examine the effect of prehospital fluid on survival of trauma patients.[2] I will not repeat that here.

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One example is this –

The percentage of spine immobilized patients with penetrating trauma is small. This suggests an appropriate lack of immobilization, consistent with PHTLS (PreHospital Trauma Life Support) guidelines. The total percentage of spine immobilized patients is also small – much smaller than anyone should expect in any EMS (Emergency Medical Services) system in the US.

How many of the trauma patients were fully immobilized, but did not have the data entered accurately?

Penetrating Trauma –

4.3% spinal immobilization.[3]

All Trauma –

8.1% spinal immobilization.[4]

Moving the decimal place one digit to the right (81%) might still underestimate the actual percentage of all trauma patients immobilized. If the data may be off by more than a factor of ten, can we draw any conclusions from this paper?

What needs to be done to improve the quality of the data being recorded by the NTDB?

Go listen to the podcast.

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I apologize for the misleading post. I looked at my notes on the paper and I had the problems noted, but when it came to writing about the study, I ignored the problems where they supported my biases.

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Footnotes:

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[1] Spine Immobilization in Penetrating Trauma: More Harm Than Good?
Rogue Medic
01/21/2010
Article

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[2] Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients – Part I, Part II, and Part III
Rogue Medic

02/20/2011
Part I

02/22/2011
Part II

03/01/2011
Part III

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[3] Spine immobilization in penetrating trauma: more harm than good?
Haut ER, Kalish BT, Efron DT, Haider AH, Stevens KA, Kieninger AN, Cornwell EE 3rd, Chang DC.
J Trauma. 2010 Jan;68(1):115-20; discussion 120-1.
PMID: 20065766 [PubMed – in process]

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[4] Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients: A National Trauma Data Bank Analysis.
Haut ER, Kalish BT, Cotton BA, Efron DT, Haider AH, Stevens KA, Kieninger AN, Cornwell EE 3rd, Chang DC.
Ann Surg. 2010 Dec 20. [Epub ahead of print]
PMID: 21178760 [PubMed – as supplied by publisher]

Full Text in PDF format from www.medicalscg

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Haut, E., Kalish, B., Efron, D., Haider, A., Stevens, K., Kieninger, A., Cornwell, E., & Chang, D. (2010). Spine Immobilization in Penetrating Trauma: More Harm Than Good? The Journal of Trauma: Injury, Infection, and Critical Care, 68 (1), 115-121 DOI: 10.1097/TA.0b013e3181c9ee58

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Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Paramedicine 101, Research Blogging

Live Blogging from EMS Today and at EMS Office Hours

Fri, 04 Mar 2011 06:30:53 -0500 by

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I will be appearing on the MedicCast (10 AM) and the EMS Research (2 PM) podcasts today at EMS Today. The webpage with the link to listen live is EMS Today Live Podcasts.

If you don’t see the listen live button on their page, click here.

Thursday, March 3, 2011
3:00 pm: JEMScast Pre-Show Spotlight
5:00 pm: EMS Garage and MedicCast Kickoff Show
6:00 pm: EMS EduCast

Friday March 4, 2011
10:00 am: MedicCast
11:00 am: JEMScast
12:00 pm: EMS EduCast
1:00 pm: First Few Moments
2:00 pm: EMS Research
3:00 pm: EMS Garage

Saturday March 5, 2011
9:30 am: GenMed
10:30 am: JEMScast
11:30 am: EMS Garage and MedicCast Wrap Show

Times are Eastern Time.

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This is a turning into a busy live podcasting week for me. I was also Taking A Peek At The Latest EMS White Paper on EMS Office Hours a couple of nights ago. Along with Jim and Josh from WANTYNU, we discussed some initial thoughts on the latest EMS White Paper. This is the podcast I mentioned in Are You Ready For Real EMS Change. Jim writes –

It was just a peek since a short 45 minutes just isn’t enough time to even really begin to delve into this document.

Just a peek is certainly the case. I hope and expect that this will be covered on other podcasts and that Jim will cover this in more depth in more podcasts.

Go listen to some of the other topics on these podcasts and some of the podcasts I will not be on.

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Filed Under: EMS Office Hours, EMS Research Podcast, Heresy, MedicCast
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