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

- Rogue Medic

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

ResearchBlogging.org

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.

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, unit12medic recognized 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.

Haut ER, Kalish BT, Cotton BA, Efron DT, Haider AH, Stevens KA, Kieninger AN, Cornwell EE 3rd, & Chang DC (2010). Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients: A National Trauma Data Bank Analysis. Annals of surgery PMID: 21178760

.

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

ResearchBlogging.org

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.

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 protocol1-3 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:

[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

[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

Haut ER, Kalish BT, Cotton BA, Efron DT, Haider AH, Stevens KA, Kieninger AN, Cornwell EE 3rd, & Chang DC (2010). Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients: A National Trauma Data Bank Analysis. Annals of surgery PMID: 21178760

Bickell, W., Wall, M., Pepe, P., Martin, R., Ginger, V., Allen, M., & Mattox, K. (1994). Immediate versus Delayed Fluid Resuscitation for Hypotensive Patients with Penetrating Torso Injuries New England Journal of Medicine, 331 (17), 1105-1109 DOI: 10.1056/NEJM199410273311701

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

ResearchBlogging.org

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.

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.

A late entry – 03/01/11 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

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:

[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.

Haut ER, Kalish BT, Cotton BA, Efron DT, Haider AH, Stevens KA, Kieninger AN, Cornwell EE 3rd, & Chang DC (2010). Prehospital Intravenous Fluid Administration is Associated With Higher Mortality in Trauma Patients: A National Trauma Data Bank Analysis. Annals of surgery PMID: 21178760

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Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study – Full paper

ResearchBlogging.org

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.

When I wrote Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study – abstract, I was only looking at the abstract. Now that I have seen the entire paper, I have not seen anything weaken the results of the study. There are plenty of points to discuss.

On the EMS Research Podcast Harry Mueller, Patrick Lickiss, Dr. Bill Toon, and I discuss this paper. In about half an hour, we go into the details. Here I will present the highlights. First, go listen to the podcast. Prehospital Needle Thoracostomy: EMS Research Episode4

During the podcast, I suggested that Dr. Blaivas is a radiologist, or some other specialist in imaging medicine, as opposed to being an emergency physician. That is not correct. Dr. Blaivas is Professor of Emergency Medicine in the Department of Emergency Medicine at Northside Hospital Forsyth in Cumming, Georgia. Dr. Blaivas is also either the world’s first or second emergency ultrasound fellowship graduate. Therefore he is very well qualified to examine all aspects of emergency medicine and ultrasound.

Let’s look at the paper.

An unstable trauma patient who is not oxygenating well or is hypotensive and has decreased breath sounds unilaterally on auscultation may be assumed by paramedics to have a PTX.2 Not unreasonably, with lack of a more definite way to rule in or rule out the presence of a PTX, needle thoracostomy is opted for to relieve the tension that is assumed to be present.[1]

Previous experience and this study lead me to the doubt this not unreasonable conclusion.

In the prehospital setting where external noise and distractions may be overwhelming, release of air is frequently not audible.[1]

This focus on decreased breath sounds may be one of the important factors in the misdiagnosis of tension pneumothorax.

How many medics are good at assessing lung sounds?

How many medics can tell the difference between the diminished lung sounds that are indicative of a tension pneumothorax and the diminished lung sounds that are consistent with any of the normal variations of lung sounds?

I would also change part of a sentence –

In the prehospital setting where external noise and distractions may be overwhelming, release of air is frequently not audible imaginary.

Typically, in such critically ill patients, the chest tube is placed before review of a chest radiograph to confirm that the tension PTX has improved. The natural assumption is that regardless of whether a PTX was present, proper penetration of the chest wall would lead to a PTX even if it were not originally present.[1]

Should any doctor be using this logic to decide to place a chest tube without assessing the patient?

Should any doctor be placing a chest tube without assessing the patient?

However, if the needle did not penetrate the lung and no PTX was initially present, a chest tube could be avoided.[1]

In the absence of a pneumothorax, a chest tube could should be avoided.

What justification is there for placing a chest tube in a patient with no indication for a chest tube?

Maybe the needle is in the chest because the medic has really scary IV skills. In this study, at least a quarter of the medics treating these patients (unless some are repeat offenders) have really scary needle decompression skills.

The main outcome measure was whether a PTX was present. The secondary outcome measure was whether a PTX developed after catheter removal.[1]

There does not appear to be any discussion of whether a pneumothorax developed after catheter removal.

Physicians performed the ultrasound examinations during the secondary survey. Chest radiographs were obtained immediately after the ultrasound examinations. Examiners were not blinded to physical findings or on which side needle thoracostomy was performed.[1]

blinding would have been nice, but this study seems to be more to demonstrate the concept that needle decompression may not even produce a simple pneumothorax. This can be left for a later study.

It would also be nice to follow up on the patients to find out if any showed any of the no pneumothorax patients showed any signs of pneumothorax later on, which could cast doubt on the ultrasound findings.

A total of 57 patients were enrolled in the study over a 3-year period. Fifty-six patients had 1 needle thoracostomy performed, and 1 patient had 3 needle thoracostomy procedures on the same side for hypotension and persistent unilateral decreased breath sounds.[1]

It should not surprise anyone that the patient with the multiple stab wounds 3 attempts at needle decompression did not have any kind of pneumothorax.

A tension PTX is a life-threatening process that must be treated immediately either through needle thoracostomy or tube thoracostomy. Despite frequent use of chest radiography on patient arrival to emergency departments, many PTXs are initially missed.[1]

It seems that a lot is missed.

Needles misses lungs.

Medics miss the absence of a tension pneumothoraces.

Doctors miss the presence of pneumothoraces.

If there is an important point to this, maybe it should be that we all need to improve our assessment for pneumothoraces and be more conservative in our treatment in the absence of unmistakable signs of a tension pneumothorax.

The combination of unilateral decreased or absent breath sounds with instability is justifiably interpreted as the presence of a PTX. There is no way to verify or refute such a finding.[1]

Maybe.

Maybe not.

Should we assume that a tension pneumothorax is subtle?

I don’t think so.

Why do we teach about tension pneumothorax as if it is the same as an easily missed simple pneumothorax?

I think it is because we don’t realize just how unsubtle a tension pneumothorax is.

This study had several limitations. The first was the small sample size. Second, the sonologists were not blinded to the side on which needle decompression was attempted. Third, it is possible that some patients did in fact have a PTX that was completely relieved by needle decompression, and no more air leaked after catheter removal. Thus, the CT scan would not show even a trace PTX. Although this is possible, it is clinically very unlikely.[1]

There are limitations, but are these results consistent with what we know about the shortcomings of EMS education and understanding of infrequently done procedures?

Absolutely.


Click on the image to make it larger.

From this study we cannot tell if the number that should be in the place of the double question marks is 42. Maybe it is 32. Maybe it is 22. Maybe it is 12. Maybe it is 2. Maybe it is zero. We don’t know and this study cannot tell us, which is not a fault of the study.

The same problem exists for trying to figure out the number that should be in the place of the single question mark.

We know that of the patients treated for claimed tension pneumothorax, 26% were treated by paramedics so poorly that the needle never even made it to the lung.

Should we assume that all of the patients treated with needles that actually reached the lung did have tension pneumothoraces?

There is nothing in this paper to suggest that.

There is no good reason to assume that all of the medics who missed the diagnosis also missed the lung. 26% missed the lung and missed the diagnosis.

It is reasonable to assume that some of the medics missed the diagnosis, but used a long enough needle to hit the lung. What we do not know is how many of those who hit the lung with a needle missed the diagnosis.

Another possibility is that the patient had a pneumothorax, most likely a simple pneumothorax, and the medic missed the lung with the needle, but since it was not a tension pneumothorax there was no dramatic deterioration of the patient. The needle decompression would be no more indicated for these patients than for those without any pneumothorax.

Also covered at EMS Research Podcast Episode 4 at 510Medic.

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

Footnotes:

[1] Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study.
Blaivas M.
J Ultrasound Med. 2010 Sep;29(9):1285-9.
PMID: 20733183 [PubMed – in process]

Free Full Text from J Ultrasound Med.

Blaivas M (2010). Inadequate needle thoracostomy rate in the prehospital setting for presumed pneumothorax: an ultrasound study. Journal of ultrasound in medicine : official journal of the American Institute of Ultrasound in Medicine, 29 (9), 1285-9 PMID: 20733183

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Comment on Is EMS Research Provincial by Dr. Russi

Also posted over at Paramedicine 101. Go check out the rest of what is posted there.

In response to Is EMS Research Provincial is this comment by Christopher S Russi

I am one of the co-hosts from a new podcast called Standing Orders (emsstandingorders.com) and I am the associate director for prehospital research at the Mayo Clinic.

The Standing Orders podcast looks sounds great. Only one episode, so far, but on a very important, too often ignored, topic – Sepsis.

We may think that we do not see much sepsis, or that we may not have much of an ability to affect the outcomes of septic patients, but their debut podcast should change our minds. Go listen.

I will write some more about the sepsis podcast. I look forward to more great podcasts from everyone at Standing Orders.

While I haven’t heard the entire podcast by Dr. Wesley, what you posted needs clarification. To answer your question about location of research and validity, it depends.

There are a few types of validity. Likely what Dr. Wesley is referring to is called external validity. Better understood in this way: can what was done via the methods be replicated in my current situation / system? Further, you have to understand the population where the intervention was delivered and the inclusion / exclusion criteria used for the subjects. As you can imagine, it is imperative that you read the methods section with a critical eye and consider the confounding variables taken or not taken into account.

These are important points and critical to understanding all research.

So while the location of the research has to be taken into consideration for comparison with your own environment, it does not mean that it serves as a litmus for throwing away data or considering it useless.

Exactly. While there may be important differences between the way EMS is provided in the US versus another country, there are plenty of differences even among the ways EMS is delivered in the US.

A well done study done in another country may be designed and carried out much better than similar studies done in the US.

I think that is part of what Dr. Wesley was getting at, just expressing it in passing during a podcast that covered a lot of different aspects of how to read EMS research. Reading EMS Research: EMS Research Episode 3

I am much more interested in the way the research was done, than I am in where the research was done. Sometimes the different levels of providers, in other places, can help us to learn something about the way EMS might be improved by better educating our providers, or the claims that doctors would not be able to intubate as well as paramedics, if they were working in the same environment.

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Is EMS Research Provincial

Also posted over at Paramedicine 101. Go check out the rest of what is posted there.

During the third episode of the EMS Research podcast – Reading EMS Research: EMS Research Episode 3 – Dr. Keith Wesley suggested that research from other countries is not as valid as US research.

One of the reasons is the varied methods of delivering EMS, with Spain and Germany using doctors on ambulances, while France and the UK often use nurses.

The study that Dr. Wesley was commenting on as not as valid to US research was a review article published in the UK.

The article examined the evidence that oxygen is harmful.

Routine use of oxygen in the treatment of myocardial infarction: systematic review.
Wijesinghe M, Perrin K, Ranchord A, Simmonds M, Weatherall M, Beasley R.
Heart. 2009 Mar;95(3):198-202. Epub 2008 Aug 15. Review.
PMID: 18708420 [PubMed – indexed for MEDLINE]

Does the location of the research matter, especially if the research demonstrates harm to patients, when determining whether we should avoid treatments?

Does oxygen cause more damage, if delivered by a nurse, or by a doctor?

Do Americans react to oxygen differently?

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Reading EMS Research – EMS Research Episode 3

Also posted over at Paramedicine 101. Go check out the rest of what is posted there.

The third episode of the EMS Research podcast is available.

Reading EMS Research: EMS Research Episode 3

If you are not comfortable with the idea of reading medical research, with all of the complicated terminology, statistics/math, and any other concerns, we try to put those in the proper context in this podcast. We don’t need to focus on these to learn from research.

Dr. Keith Wesley is our guest and he explains a lot about the way he approaches research. Dr. Wesley is the State Medical Director for Minnesota, past State Medical Director for Wisconsin, author of the Street Science column in JEMS.

Dr. Bill Toon

Tom Bouthillet

Harry Mueller

Dr. Keith Wesley

Go listen.

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How Not to Respond to Negative Research – Addendum

ResearchBlogging.org

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. There is a new research podcast specifically for EMS – EMS Research Podcast. On episode 2 we discuss several topics, including the research on the RAD-57 non-invasive monitor.

In How Not to Respond to Negative Research, I forgot to address one of the more important problems with the response of Dr. Michael O’Reilly.

Because the study used the same type of device and sensor and evaluated patients similar to those in previous studies, the differences in results were likely due to different methods by the investigators. The possible reasons for the discrepancy between the results reported in this study include multiple items addressed in the directions for use of the device and sensor, including:

•inappropriate finger positioning in the sensor

•inappropriately sized sensor for the subject’s finger

•timing of SpCO and COHb measurements not being exactly simultaneous

•increased methemoglobin level (which can be ruled out by measuring noninvasive methemoglobin levels [SpMet] with the Rad-57)

    •patient motion

    •external light interference

    •device or sensor malfunction (there were many zero readings by Rad57 in which HbCO was considerably higher, which could be due to device malfunction and may indicate a need for service)[1]

Dr. O’Reilly is telling us that the RAD-57 is too difficult to use in the ED (Emergency Department), but miraculously acquires accuracy and reliability at a fire scene.

timing of SpCO and COHb measurements not being exactly simultaneous

Exactly simultaneous?

Exactly?

Does carboxyhemoglobin vary that much that a few seconds later, the HbCO is wildly different?

If that is the case, why buy a machine that will only give us a snap shot of a rapidly fluctuating and unreliable number?

Is there any reason to believe that carboxyhemoglobin changes that rapidly and unpredictably?

No.

Three RAD devices and training in their use were supplied by Masimo Corporation for the duration of the study. Clinicians underwent training in use of the RAD device before study initiation. Measurement of RAD carboxyhemoglobin was performed simultaneously with sampling of arterial or venous blood for laboratory determination of carboxyhemoglobin level.[2]

Simultaneously, but not exactly simultaneously?

Dr. O’Reilly is creating the impression that this is a difference. Should we believe that, in the ED, the levels of carboxyhemoglobin are rising dramatically between the application of the RAD-57 and the simultaneous drawing of blood, just because the word exact was not used?

The big problem with the RAD-57 was that it missed over half of the significantly elevated carboxyhemoglobin levels – some while indicating a carboxyhemoglobin level of zero. Did patients have a zero carboxyhemoglobin level one minute and a significantly elevated carboxyhemoglobin level the next minute?

Dr. O’Reilly seems to be indicating that carboxyhemoglobin operates on the same principle of uncertainty as Scrödinger’s Cat, but with a free random number generator.

There are several problems with researching EMS equipment in the much more stable environment of the ED.

The ED environment has much less variability than the EMS environment.

If vasoconstriction is a problem, the warmer ED is much less likely to produce vasoconstriction than being out in the cold, which is often where the RAD-57 will be used.

The people using the equipment are generally paying much more attention to what they are doing, if only because they have to document compliance with study protocols.

As stated in the study, the participants are often trained by the people most familiar with the equipment – not somebody who read a package insert, or watched a video, or was once trained by someone from the manufacturer.

Compared with use in the EMS environment, the ED environment can be seen as much closer to the ideal testing environment.

Is Dr. Reilly complaining that Masimo provides bad training on the use of the RAD-57?

If our device does not work in your hands, it’s your fault.

It is always a pleasure to deal with someone who stands behind a product and is looking out for the patients assessed/treated with that product.

Dr. Michael O’Reilly, who is Executive Vice President of Masimo Corporation, an officer of the corporation, and holds stock options in Masimo[1], is not that person.

The RAD-57 may have some role in identifying elevated carboxyhemoglobin levels, but so far nobody can tell what that role is. As I pointed out earlier

Less than half of the patients with elevated COHb were correctly identified.

If we screen a fire fighter for COHb, then we need to keep that fire fighter out of the fire.

Should anyone ever use a low RAD-57 reading to justify returning a fire fighter to a fire?

No.

Footnotes:

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

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

[2] 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

O’Reilly M (2010). Performance of the Rad-57 pulse co-oximeter compared with standard laboratory carboxyhemoglobin measurement. Annals of emergency medicine, 56 (4) PMID: 20868919

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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