EMS Research Podcast | Paramedicine 101

Dextrose 10% or 50%: EMS Research Episode 10

07/05/2011 by Rogue Medic 2 Comments

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

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.

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.

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?

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.

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.

Go listen to the podcast..

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

Footnotes:

^[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

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

Filed Under: EMS Research Podcast, Heresy, Rogue Medic

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

05/27/2011 by Rogue Medic 1 Comment

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

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.

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]

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

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.

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]

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.

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.

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.

Go listen to the podcast.

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

Footnotes:

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

^[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.

^[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.

^[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.

^[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.

Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Medical Mythology, Pharmacology, Research, Rogue Medic

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

05/23/2011 by Rogue Medic 1 Comment

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

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?

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.

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]

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.

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.

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.

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.

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

Where is the benefit that justifies the increased risk?

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.

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]

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.

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.

Go listen to the podcast.

Footnotes:

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

^[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.

The download link is in the page number – page 335.

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

Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Research, Rogue Medic

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

05/18/2011 by Rogue Medic 1 Comment

Also posted over at Rogue Medic (now at EMS Blogs) and Discussed on the EMS Research Podcast – RAD-57 v. Lab: EMS Research Episode 2.

CO (Carbon monOxide) is a significant cause of poisoning in the US, with hundreds of fatalities each year. The 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).

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.

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?

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

Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Research, Rogue Medic

Motor Vehicle Intrusion – EMS Research Episode 7

04/05/2011 by Rogue Medic 1 Comment

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

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?

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.

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.

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?

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?

Go listen to the podcast.

Footnotes:

^[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]

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

Filed Under: EMS Research Podcast, Heresy, Research, Rogue Medic

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

03/15/2011 by Rogue Medic 2 Comments

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

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.

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.

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.

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.

Footnotes:

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

^[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

^[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]

^[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

Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Research, Rogue Medic

Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients – Part III

03/01/2011 by Rogue Medic Leave a Comment

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

This paper is discussed in Prehospital administration of IV fluids to trauma patients: EMS Research Episode 5.

This is also discussed by Dr. Chris Russi in the podcast Russi’s Research Review – Episode Two (Fluid Administration in Traumatic Injury Patients).

Continuing from Part I and Part II.

The 5 most common EMS procedures as documented in the NTDB (National Trauma Data Bank®) are listed in this table.

Click on images to make them larger.

In Part II, I explained the problems with the NTDB claiming that only 49.3% of trauma patients had IV ~~fluids~~ starts documented. While that should raise questions, looking at the data on the rest of the top 5 procedures makes the questions even more obvious.

Looking at the abridged Table 1 that I included in Part II, to show the problem with the number of IVs documented, only unit12medic mentioned recognizing the problems with the rest of the data. I changed the abridged Table 1 only changing what I underlined. I removed the underlining from the IV fluids and added underlining to the other procedures that are documented with unrealistic frequency.

Only 8.1% had spinal immobilization?

IV (IntraVenous) starts were over 6 times more common than spinal immobilization for these trauma patients?

Is there any place where this is the way EMS does things?

8.1% had needle decompression, but only 4.4% were hypotensive?

Is there any reason to assume that a patient who is not hypotensive will improve by having a large needle stuck in his chest?

Chest decompression is almost 3 times more common than intubation in these trauma patients?

More than one in every 12 1/2 trauma patients had chest decompression.

MAST application is 3 1/2 times more common than spinal immobilization?

Click on images to make them larger.

When broken down by procedure among those who did not have an IV start documented vs. those who did have an IV start documented, things become even more odd. The authors claim to have adjusted for all of these variables, but the difference in rate of application goes from small to what appears to be inexplicably huge. I can’t explain this except if the data do not reflect reality.

A total of 776,734 patients with complete prehospital procedure ﬁles were identified from the 1,466,887 total patients in the National Trauma Data Bank.^[1]

Multivariable logistic regression was used to examine the relationship between prehospital IV and mortality in the 311,071 patients with complete data.^[1]

1,466,887 total NTDB patients.

776,734 patients with complete prehospital procedure files (53% of 1,466,887).

311,071 patients with complete data (40% of 776,734 and 21% of 1,466,887).

What would result in such a dramatic difference between MAST with an IV Start and MAST without an IV Start?

53.4% is 281 times more common than 0.19%. What could possibly explain this? Differences in protocols?

Even though the authors concluded that IV Starts produced worse outcomes, the procedure most strongly correlated with IV Starts was determined to have produced a protective effect. Most IV Start patients had MAST applied, while less than one fifth of one percent of the No IV Start patients had MAST applied.

Intubation (OR 1.57) and spinal immobilization (OR 1.42) were found to increase the odds of death by much more than IV Starts (OR 1.11) were increasing the odds of death.

If these numbers were valid, the increased odds of death should result in strongly worded warning letters on the hazards of spinal immobilization and intubation of trauma patients.

The less frequent the procedure/condition, the larger the calculated increased risk of death. This also means that the larger the calculated increased risk of death, the larger the confidence interval.

With the unbelievably low rate of spinal immobilization, which is more likely the opposite of what is recorded, should we trust any of the numbers from the NTDB?

If we cannot trust any of the numbers from the NTDB, we must doubt the least frequent numbers.

We did not adjust for cardiopulmonary resuscitation because the data on cardiopulmonary resuscitation appeared to be biologically implausible:^[1]

I read this and thought that they were going to explain that compressions of the chest are pointless, when there is no blood in the vessels to circulate. And this is true.

I thought that they might also explain that compressions of the chest are pointless, when there is a complete obstruction to circulation. And this is true with arrests due to pulmonary embolus or cardiac tamponade.

But that was not their point.

the mean systolic blood pressure of penetrating trauma patients who received cardiopulmonary resuscitation was 118 mmHg.^[1]

That is higher than my blood pressure.

I am pretty sure that the AHA (American Heart Association) does not want anybody using CPR (CardioPulmonary Resuscitation) on people with good blood pressures. CPR is for people with no blood pressure (or for children with extremely low blood pressures).

Does this give us a hint about the reliability of the information used?

I think so.

Regardless of the problems with the data in this study, we still have no evidence that giving fluids to patients before bleeding is controlled improves outcomes.

Regardless of the problems with the data in this study, we still have no evidence that giving fluids to patients before bleeding is controlled is safe.

I generally agree with the conclusion, that fluids should not be given (I would add – before bleeding is controlled), but I do not think that this study provides valid evidence to support that conclusion.

I am adding the article below to Part I. This is the reporting by Medscape. This was not put on line after I wrote about it, but I missed it when I originally wrote this. Medscape is a web site edited by doctors, but even they did not seem to notice the flaws of this study.

From Medscape Medical News
Prehospital IV Fluids May Be Harmful for Trauma Victims
Medscape
Laurie Barclay, MD
January 20, 2011
Article

Footnotes:

^[1] 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.

Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Research, Rogue Medic

Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients – Part II

02/22/2011 by Rogue Medic 2 Comments

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

This paper is discussed in Prehospital administration of IV fluids to trauma patients: EMS Research Episode 5.

This is also discussed by Dr. Chris Russi in the podcast Russi’s Research Review – Episode Two (Fluid Administration in Traumatic Injury Patients).

As I pointed out in Part I, using placement of an IV (IntraVenous) line on a trauma patient as a surrogate for administration of IV fluids to maintain blood pressure, or to raise blood pressure, is a mistake. We do not know how much fluid was administered. I have often stated IVs on trauma patients and not given more than a few milliliters of fluid, which is an insignificant volume of fluid regardless of blood pressure. If I have given IV fluid, it has been because there is medication in the fluid – morphine (10 mg/ml) or fentanyl (50 mcg/ml). These are not significant amounts of fluid, but they are significant treatments.

The problem with this study is that the NTDB (National Trauma Data Bank®) does not produce information that appears to be accurate. The authors stated –

Patients without complete prehospital procedure information were excluded.^[1]

This presumes that what they describe as complete prehospital procedure information is the same as accurate prehospital procedure information.

On the podcast, we all agreed that the data do not appear to reflect reality. I have worked in EMS for 20 years and I have worked in four of the five states with the largest number of EMS providers. California, New York, Pennsylvania, and I worked at a trauma center in New Jersey. The others on the podcast, Tom Bouthillet, Dr. Bill Toon, and Harry Mueller have similar, or more, experience.

Here are the numbers on the 5 most common EMS procedures as documented in the NTDB.

Click on images to make them larger.

Only 49.3% had IV ~~fluids~~ starts documented?

Researchers dream of randomizing things this evenly. However, this is an unusually low rate of IV starts for trauma patients. I have never seen a protocol that does not indicate that an IV should at least be attempted on trauma patients.

Study Protocol
During the prehospital phase, patients assigned to receive immediate fluid resuscitation were treated with a standard paramedical protocol^1-3 that included endotracheal intubation and assisted ventilation with oxygen when appropriate, rapid transport to the emergency center, and insertion of two or more 14-gauge intravenous catheters in the upper extremities for rapid infusion of isotonic crystalloid (Ringer’s acetate solution) en route to the hospital. In accordance with recent recommendations, no patients were treated with antishock garments²⁴.^[2]

Patients assigned to the delayed-resuscitation group were cared for in an identical manner with the exception that after the insertion of the intravenous catheters, the catheter lumens were covered with an infusion cap that was then flushed with 1 to 2 ml of 1 percent heparin in normal saline.^[2]

Even the no fluids group in that study did have two 14 gauge IVs started. If we evaluated that study according to the criteria of the current study, both groups received IV fluids, since both had IVs started.

We know that is not true.

In the Bickell study,^[2] we know which of the patients who had IVs started received fluids and we know how much fluid patients received.

In the current study, we assume that everyone who had an IV started received fluids and we do not seem to care how much fluid patients received.

Can this possibly answer a question about the influence of fluids on trauma?

It is also hypothesized that delays to start IVs could have been the cause of the bad outcomes.

How many medics delayed on scene to start an IV?

We don’t know.

How many medics started IVs on the move and did not delay transport?

We don’t know.

Should we even try to explain results that are based on bad data?

No.

To be continued in Part III.

Footnotes:

Full Text in PDF format from www.medicalscg

^[2] Immediate versus delayed fluid resuscitation for hypotensive patients with penetrating torso injuries.
Bickell WH, Wall MJ Jr, Pepe PE, Martin RR, Ginger VF, Allen MK, Mattox KL.
N Engl J Med. 1994 Oct 27;331(17):1105-9.
PMID: 7935634 [PubMed - indexed for MEDLINE]

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

Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Research, Rogue Medic

Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients – Part I

02/20/2011 by Rogue Medic Leave a Comment

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

This is discussed in Prehospital administration of IV fluids to trauma patients: EMS Research Episode 5.

CONCLUSIONS: The harm associated with prehospital IV fluid administration is significant for victims of trauma. The routine use of prehospital IV fluid administration for all trauma patients should be discouraged.^[1]

That is the conclusion posted in the abstract available from PubMed. For many people, this may be all that they will read. Sometimes the full text is available for free, so a subscription is not required to read the full text. Even so, most people with access to the full article may not read it.

We expect the PubMed abstract to provide the important information.

In this case, we would be wrong.

This study does not look at Prehospital Intravenous Fluid Administration.

Prehospital IV Starts are Associated With Higher Mortality in Trauma Patients.

That would improve the accuracy of the title, but even that is not supportable.

We hypothesize that trauma patients receiving prehospital IV catheter placement (with or without IV ﬂuids) have higher mortality than trauma patients who did not receive an IV or ﬂuids.^[1]

But that is not the way this is being reported in the media, including medical media.

The primary independent variable was deﬁned as prehospital IV. The majority of patients with the word “intravenous” or “IV” in the prehospital procedure ﬁle of the NTDB were coded as having received “intravenous ﬂuids.” However, there were many different terms reported along the “intravenous” continuum and we could not deﬁnitively differentiate IV ﬂuid administration versus IV catheter placement alone. Therefore, we grouped both all patients under the heading of “pre-hospital IV”.^[1]

The very next sentence is –

We performed a descriptive analysis of our dependent and independent variables, and we conducted an unadjusted analysis that included a comparison of mortality rates among all patients with versus without prehospital IV ﬂuids.^[1]

with versus without prehospital IV ~~ﬂuids~~.

They don’t even know which patients received fluids.

They don’t know anything about the amount of fluids that might have been given.

All things are poison and nothing is without poison, only the dose permits something not to be poisonous. – Paracelsus.

We know nothing about the dose of fluids.

Was it 10 ml/patient?

Was it 100 ml/patient?

Was it 1,000 ml/patient?

Was it 10,000 ml/patient?

Your guess is as good as mine.

Your guess is probably also as good as the guesses of the authors of this study.

How did the media report this?

Giving IV fluids on scene might raise death risk for trauma victims
Updated 1/10/2011 4:52 PM
By Alan Mozes, HealthDay
USA Today
Article

The above article is also published at Bloomberg Business Week.

IV fluids may not always be good for accident victims, study finds
January 04, 2011
By Thomas H. Maugh II
Los Angeles Times
Article

These articles do not contain any explanation that the researchers have no idea which patients received fluids or how much fluid. Dr. Haut was interviewed and presented his information as if the abstract were accurate and informative. It is neither.

What about on line sources?

Prehospital Intravenous Fluids May Harm Trauma Patients
Mortality highest in patients with penetrating injuries, hypotension, or severe head injury
Modern Medicine
Article

Prehospital Intravenous Fluids May Harm Trauma Patients
Doctors Lounge
Article

Prehospital IV fluid administration
IVTEAM
Article

These essentially repeat only the information in the abstract, or they repeat small parts of the information in the abstract.

Did anybody get it right?

Pre-hospital iv and increased mortality
RESUS.me
Article

Does Fluid Resuscitation Harm Trauma Patients?
Skeptical Scalpel
Article

And the podcast I mentioned at the beginning –

Prehospital administration of IV fluids to trauma patients: EMS Research Episode 5
EMS Research Podcast
Podcast

Late entry – 02/21/11 Also covered by Dr. Chris Russi in the podcast Russi’s Research Review – Episode Two (Fluid Administration in Traumatic Injury Patients).

Part II and Part III will explain some of the problems with the study and some of the things to look for when evaluating the merits of a study.

Footnotes:

Filed Under: Critical Judgment, EMS Research Podcast, Heresy, Research, Rogue Medic

Inadequate needle thoracostomy rate . . . podcast is now available

02/14/2011 by Rogue Medic 1 Comment

The EMS Research podcast I wrote about last week in Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study – Full paper is now available to listen to. I apologize for misleading people by writing that it had been posted before it had been posted, but now it really is there.

The link below works.

Go listen to the podcast. Prehospital Needle Thoracostomy: EMS Research Episode4

Filed Under: EMS Research Podcast, Rogue Medic

Dextrose 10% or 50%: EMS Research Episode 10

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

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

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

Motor Vehicle Intrusion – EMS Research Episode 7

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

Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients – Part III

Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients – Part II

Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients – Part I

Inadequate needle thoracostomy rate . . . podcast is now available

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