Dear Editor,

This paper stated prevalence of Tension Pneumothorax which is misleading and up to 20 times higher than that which might be seen by the standard pre-hospital care practitioner. Further analysis of the two references used for this statement is given and it can be seen that their results should not be extrapolated to the general pre-hospital environment without qualification.

Coats described tension pneumothorax in up to 5.4% of patients, 64% of whom were ventilated. They were also a major trauma sub-group.

McPherson looked retrospectively at US soldier fatalities in Vietnam - when there was no pre-hospital chest decompression. His abstract and discussion however, mis-represent the figures stated in his results and the study has methodological floors. Accepting these floors though, he observed that fatal tension pneumothorax may have occurred in up to: 0.3% of American casualties (26/7801) 3.9% of casualties who died and had signs of a chest wound (26/663)

Despite its floors McPherson’s paper may be more applicable to the average pre-hospital clinician as it looks purely at awake patients.

However, the external validity of both these papers (which look at high risk groups) to pre-hospital clinicians seeing a predominance of blunt trauma, awake patients should be questioned.

The inference that should be taken away by the reader is that "fatal tension pneumothorax is very unlikely to occur in more than 0.3% of awake patients encountered in pre-hospital care" Even this is probably too high, but may go some way to stemming the tide of iatrogenic, needle induced pneumothorax.

References

1. McPherson JJ, Feigin DS, Bellamy RF. Prevalence of tension pneumothorax in fatally wounded combat casualties. J Trauma 2006;60:573–8.[Medline]

2. Coats TJ, Wilson AW, Xeropotamous N. Pre-hospital management of patients with severe thoracic injury. Injury 1995;2:581–5.[CrossRef]

RE: Coats, Timothy J.: Future research in emergency medicine: explanation or pragmatism? Large or small? Simple or complex? Emerg Med J. 2011 Dec;28(12):1004-7.

Emergency Medicine Can! Response to Coats, Timothy J.: Future research in emergency medicine: explanation or pragmatism? Large or small? Simple or complex.

Coats highlights the potential role of emergency medicine in conducting large pragmatic trials and the shortcomings of the more traditional complex randomized controlled trials. He correctly points out that traditional phase III trials are difficult to run, extremely expensive, and restricted by highly competitive funding mechanisms. While many of the points made in the article are valid, the premise that emergency medicine researchers are not capable, or competitive in an arena of rigorously conducted clinical trials is disconcerting and inaccurate. Emergency physicians can compete, create niches, and succeed! The trial design is irrelevant.

Over the last 10 years, the number of emergency physicians conducting high quality RCTs has risen steadily1,2. These include both industry- sponsored and federally funded trials. As the specialty matures, it is only logical that emergency medicine expands its research footprint and relevance.

The concept that traditional clinical trials or research are restricted only to specialties that have narrowed their scope to a particular disease state, organ system, technical skill, or type of research is unsound. Emergency Medicine's uniqueness is that there are diverse interests and a broad base of expertise. Science in general, and clinical trials is particular, is a TEAM sport. The emergency physician is ideally poised to take the reins of the RCT team, since emergency medicine holds the key to the door (literally) and is the entry point for many diseases and conditions into the system. Indeed, emergency medicine's recent success in high-quality research has garnered substantial attention at NIH. Just in the past 3 years, a number of requests for proposals (RFPs) are targeted at emergency medicine researchers3. The Neurological Emergencies Treatment Trials (NETT) network4,5 is constructed primarily of emergency physicians as principal investigators. The NETT is being heralded as one of the most successful acute trials networks in the history of the NIH, and it has proven that emergency physicians not only can run complicated RCT's, but that they excel at it. Fortunately for other specialties, emergency medicine is collaborative by nature and seeks out the participation and expertise of its colleagues. Non-EM researchers now actively engage emergency physicians in acute trials because they realize EM's critical role (e.g. Stroke Hyperglycemia Insulin Network Effort (SHINE) Trial, Albumin in Acute Ischemic Stroke (ALIAS) Trial6).

Despite the specialty's relative young age and limited research infrastructure, EM researchers are leading the pack in many fields of research including traumatic brain injury, stroke, status epilepticus, asthma and others. The ProTECT III trial is one of the highest funded NINDS clinical trial ever awarded for TBI research, and the PI is an emergency physician. The RAMPART study was multimillion-dollar clinical trial for status epilepticus that recruited patients so fast and efficiently that, even with an expanded sample size, it was completed 2 years ahead of schedule...and the PI was an EM researcher7. There are numerous other examples. Clinical specialization based on a particular organ system does not inherently confer any unique talents or exclusive skills. Emergency medicine can compete with good science, training, and a passion to succeed.

The type of trial design that one chooses depends on the question to be answered. The distinction between efficacy and effectiveness is clearly an important one (treatments may be efficacious, but when employed to the broader population are not effective), but there are many reasons for why this may occur; not all are encompassed in the term generalizability. The small sample size in RCTs is more a function of poor trial design than a fundamental flaw in any particular trial methodology.

Even though the apparent underlying intent of Coates' article is to justify large simple trials, the argument is lost on the contention that emergency medicine is not competitive in disease-based sciences and therefore should become "known" for a particular methodology. There is no doubt that substantial inequalities in funding with our non-EM colleagues exist8 and numerous challenges abound for EM researchers. But, emergency medicine is making significant strides as the specialty matures. Furthermore, trial design does not trump good science. Both types of trials have merit, and emergency physicians can be great at and compete for both!

REFERENCES

1. Rosenzweig JS, Van Deusen SK, Okpara O, Datillo PA, Briggs WM, Birkhahn RH. Authorship, collaboration, and predictors of extramural funding in the emergency medicine literature. Am J Emerg Med. Jan 2008;26(1):5-9. 2. Birkhahn RH, Van Deusen SK, Okpara OI, Datillo PA, Briggs WM, Gaeta TJ. Funding and publishing trends of original research by emergency medicine investigators over the past decade. Acad Emerg Med. Jan 2006;13(1):95-101. 3. Funding Opportunities. 2011; http://search2.google.cit.nih.gov/search?q=Emergency+Medicine&Search.x=22&Search.y=1&site=GRANTS_ALL&client=GRANTS_ALL_frontend&proxystylesheet=GRANTS_ALL_frontend&output=xml_no_dtd&filter=0&getfields=*, 2012. 4. Hill MD, Martin RH, Palesch YY, et al. The Albumin in Acute Stroke Part 1 Trial: an exploratory efficacy analysis. Stroke; a journal of cerebral circulation. Jun 2011;42(6):1621-1625. 5. Silbergleit R. Response to Food and Drug Administration draft guidance statement on research into the treatment of life-threatening emergency conditions using exception from informed consent: testimony of the neurological emergencies treatment trials. Acad Emerg Med. Apr 2007;14(4):e63-68. 6. Ginsberg MD, Hill MD, Palesch YY, Ryckborst KJ, Tamariz D. The ALIAS Pilot Trial: a dose-escalation and safety study of albumin therapy for acute ischemic stroke--I: Physiological responses and safety results. Stroke. Vol 372006:2100-2106. 7. Silbergleit R, Lowenstein D, Durkalski V, Conwit R. RAMPART (Rapid Anticonvulsant Medication Prior to Arrival Trial): a double-blind randomized clinical trial of the efficacy of intramuscular midazolam versus intravenous lorazepam in the prehospital treatment of status epilepticus by paramedics. Epilepsia. Oct 2011;52 Suppl 8:45-47. 8. Bessman SC, Agada NO, Ding R, Chiang W, Bernstein SL, McCarthy ML. Comparing National Institutes of Health funding of emergency medicine to four medical specialties. Acad Emerg Med. Sep 2011;18(9):1001-1004.

Acknowledgements: The author thanks the members of the editorial board of Academic Emergency Medicine who participated in an email discussion of the source paper; particularly Drs. David Cone, Jill Baren, Clifton Callaway, Don Yealy, Christopher Moore, Lowell Gerson, Michelle Biros, and Gary Gaddis.

Conflict of Interest:

None declared

We are incredibly glad to hear that Dr. Sherren has taken an interest in our research (1). I concur with his position on this matter. I believe that cardiopulmonary resuscitation (CPR) issues in in-hospital cardiac arrest patients will be solved through near future technologies such as extracorporeal membrane oxygenators. However, if we divide cardiac arrests broadly into in-hospital and out-of-hospital, or on-site arrests, we must admit that, even in the future, on-site treatment will largely rely upon CPR administered by other persons who are on-hand. Therefore, it is necessary that resuscitation research on the often overlooked ergonomic aspects of CPR be revitalized and brought to greater focus. The starting point for an ergonomic approach to CRP research will have to begin with the effectiveness of chest compressions. Already, in the 2005 guidelines, the importance of chest compression was emphasized (2). Within such emphasis, our research group is especially interested in the influence the relative body positions of the patient in need of CPR and the rescuer have on the quality of CPR administered. Previous research in this area indicates that it is most effective to administer CPR from a kneeling position (CPRKP) on a patient who is on the floor (3). If this is true, there is a need to identify what factors cause CPR administered from a standing position (CPRSP) on a patient who lies on the bed to be less effective. Research such as this must look at the rescuer's changes in body positioning, as well as other factors, from an ergonomics perspective in order to be most effective. Under the assumption that making the conditions of performing CPRSP more similar to those of CPRKP would reduce the loss of effectiveness associated with CPRSP, our research team postulated the following hypotheses: 1) that if the bed on which the patient lies were to be lowered to the height of the rescuer's knees during CPRSP, the rescuer would be able to perform CPR in basically the same position as with CPRKP and 2) that rather than placing the patient on a mattress and then a backboard, removing the mattress altogether will improve the conditions of administering CPR. The current study that we are presenting is the first of several studies being conducted regarding these hypotheses. We feel that Dr. Sherren's suggestion of having the rescuer perform CPR while kneeling on the bed itself (CPRKOB) is also a valid hypothetical solution to solving the problem of loss of effectiveness associated with performing CPR on patients in beds. However, this too must undergo rigorous performance studies. While there are cases in which CPRKOB has been performed in clinical settings, most clinical beds are not very strong, and thus a level of instability is often a factor in such cases. This is especially true of smaller emergency-room gurneys. Indeed, it may be true that the simplest solution to preventing the loss of effectiveness in CPR performed on patients in beds is to remove the beds altogether. However, procedures such as endotracheal intubation and vascular access, as well as various monitors attached to a patient may make the act of removing a patient from a bed in order to perform CPR unrealistic; extensive performance studies would have to be performed in order to make any sort of a persuasive argument for such a procedure. As Dr. Sherren has pointed out, mannequin-based performance studies have not beed recognized as very important because they lack things as chest recoil and thoracic pump effects - therefore, making them less desirable than animal and clinical trials. However, considering that CPR is a procedure directly performed by persons, performance studies will give us the best evidence for the creation of guidelines for effective CPR. Again, we thank Dr. Sherren for his attention to our research and give him our regards.

References

1. PB Sherren. Effects of bed height on the performance of chest compressions - Clinical application of results. Emerg Med J 2010;eLetter

2. International Liaison Committee on Resuscitation. International consensus on cardiopulmonary resuscitation and emergency cardiovascular care science with treatment recommendations. Part 2. Adult basic life support. Resuscitation 2005;67:187-201.

3. Perkins GD, Benny R, Giles S, Gao F, Tweed MJ. Do different mattresses affect the quality of cardiopulmonary resuscitation? Intensive Care Med 2003;29:2330-5.

Conflict of Interest:

None declared

We read with interest the case report by Abeysinghe and colleagues reporting hyperinsulinaemic euglycaemic therapy (HIET) in the treatment of a patient presenting with persistent hypotension following an overdose of the lipophilic calcium channel blocker diltiazem.[1]

Diltiazem is extremely lipophilic with a log P value of 4.53 (a measure of lipid solubility). Thus we consider that it would have been amenable to treatment with intravenous lipid emulsion (ILE). This new and emerging addition to the treatment arsenal of lipophilic drug overdoses is supported by a rapidly expanding body of experimental work and clinical cases. The effectiveness of ILE in reversing local anaesthetic induced cardiovascular collapse has been unequivocally demonstrated in animal studies, and recent attention has turned to non-local anaesthetic applications.[2] The role of ILE has extended to include suppression of the toxic effects of verapamil and recently the first case report describing a successful outcome with the use of ILE combined with HIET for the treatment of diltiazem overdose has been published.[3]

Abeysinghe and colleagues astutely noted that in calcium channel blocker overdose 'myocardial extraction of free fatty acids is decreased despite maintained plasma levels'. ILE is believed to have several beneficial effects with enhancement of myocardial fatty acid transport appearing to be one of the ways in which physiological and metabolic integrity might be restored. Secondly, ILE binds lipophilic drugs within an expanded intravascular lipid phase (the 'lipid sink' effect), thereby reducing the amount of drug available to exert its toxic effects. Finally, ILE may act via a direct inotropic action by increasing cardiac intracellular calcium concentration.[2] With evidence for the effectiveness of ILE in lipophilic drug overdoses increasing we believe it may become a standard intervention in the treatment of calcium channel blocker overdose either as monotherapy or possibly alongside HIET.

Dr Theophilus Luke Samuels

Dr David R Uncles

Dr Johann W Willers

Dr Aikaterini Papadopoulou

References

1 Abeysinghe N, Aston J, Polouse S. Diltiazem overdose: a role for high-dose insulin. Emerg Med J 2010;27:802-3.

2 Cave G, Harvey M. Intravenous Lipid Emulsion as Antidote Beyond Local Anaesthetic Toxicity: A Systematic Review. Acad Emerg Med 2009;16:815-24.

3 Montiel V, Gougnard T, Hantson P. Diltiazem poisoning treated with hyperinsulinemic euglycemia therapy and intravenous lipid emulsion. Eur J Emerg Med Published Online First: 17 November 2010. doi: 10.1097/MEJ.0b013e32834130ab.

Conflict of Interest:

None declared