Street Science
Street Science (36)
These article pertain to medicine on the streets...the do's and do-not's of working in the EMS field and other things medics should know about.
Wednesday, 14 October 2009 17:10
Shocking Research
This study examined the outcomes of 738 cardiac arrest victims who presented with an initial rhythm of pulseless electrical activity (PEA) or asystole. Both are considered "Non-shock" rhythms, and the primary treatment is CPR and medication. If the patients developed V Fib or V Tach "shock" rhythms, then they were defibrillated.
Wednesday, 14 October 2009 17:07
Cardiac Arrest CPR
The Science:
Researchers in England were concerned with the potential impact that performing compression-only CPR would have on ventilation. They acknowledge the science supporting the vital importance of uninterrupted chest compression but wondered whether they could measure the amount of air that was moved in and out of an intubated cardiac arrest patient and from that decide whether this amount of passive ventilation was sufficient to oxygenate the lungs.
Wednesday, 14 October 2009 17:04
EMS Administration of Fibrinolytics to STEMI Patients
The Science:
I don't usually comment on science reported only in editorial remarks. However, this correspondence in the Journal of the American College of Cardiology caught my attention because it was only this past year that I and several other “experts” were asked whether we believed in any benefit from reduced dose fibrinolytics being administered by EMShe data presented was from a pilot trial of an on-going wider study. The question is, "Does the administration of a half-dose of retaplase by EMS significantly affect the time to reperfusion and subsequent angiographic perfusion scores when compared to fibrinolysis alone, primary coronary intervention (PCI) instead of EMS retaplase, or in combination with PCI?"
Wednesday, 14 October 2009 17:00
Hands-on Defibrillation
The Science
I'll attempt to describe this study without getting too technical for fear of being overwhelmed with e-mails from the techies out there. The researchers who were also the subjects of this study volunteered to maintain contact with a sedated patient who was undergoing elective cardioversion. They wore polyethelene medical gloves and simulated chest compressions. Pre-gelled electrodes similar to those used with AEDs were applied to their chests. The amount of stray current that passed through the "rescuer" was measured during biphasic cardioversion, and defibrillation energies ranged from 100 to 360 joules.
Wednesday, 14 October 2009 16:56
Treating Trauma - ALS vs. BLS
The Ontario Prehospital Advanced Life Support (OPALS) Major Trauma Study was a before-and-after, system-wide controlled clinical trial conducted in 17 cities. The researchers enrolled adult patients who had experienced major trauma in a basic life-support phase and a subsequent advanced life-support phase (during which paramedics were able to perform endotracheal intubation and administer fluids and drugs intravenously). The primary outcome was survival to hospital dischargeAmong the 2,867 patients enrolled in the BLS (n = 1,373) and ALS (n = 1,494) phases, characteristics were similar. This included mean age (44.8 v. 47.5 years), frequency of blunt injury (92.0% v. 91.4%), median injury severity score (24 v. 22) and percentage of patients with Glasgow Coma Scale (GCS) score less than 9 (27.2% v. 22.1%). Survival didn't differ overall (81.1% among patients in the ALS phase v. 81.8% among those in the BLS phase; p = 0.65).
Wednesday, 14 October 2009 16:50
CPAP Saves Lives and Money
The Science
This study is by the same authors who showed that prehospital CPAP reduced mortality by 18% and intubation by 16%. They follow that study with this assessment of the financial implications of instituting prehospital CPAP. The study accurately lists the cost of this implementation in their system. It then goes far beyond that to examine the cost of hospitalization across the nation as it's reported in many articles.
Wednesday, 14 October 2009 16:44
International Trauma Systems
The Science
This article, which appears in the journal Injury, accompanies one entitled “International comparison of prehospital trauma care systems.” Both report essentially the same findings.
The authors undertook a review of trauma care in the following countries: Australia, Austria, Canada, Greece, Germany, Mexico, Iran, New Zealand, the Netherlands, the United Kingdom and the United States. They extracted data from various trauma registries and examined what were felt to be common key indicators, such as patient demographics, response crew configuration, scene time, mode of transport and injury severity.
In their abstract, they report the following. A total of 30,339 subjects from one or several regions in 11 countries were included in this analysis. Austria (51%), Germany (41%) and Australia (30%) reported the highest proportion of air ambulance use. Monterrey, Mexico (median 10.1 min) and Montreal, Canada (median 16.1 min) reported the shortest, and Germany (median: 30 min) and Austria (median: 26 min) reported the longest scene times.
This study found that Canada had the largest percentage of trauma patients over the age of 65. (Photo Grant Therrien
They made no conclusions other than to acknowledge that this was one of the first comparison of international EMS delivery.
The Street
Although I applaud the authors for their heroic attempt to make sense of a subject that for most of us is indefinable, I would ask the authors to be more accurate in the use of titles and descriptors in their abstracts. This study is another example of how important it is to read the entire article and not make assumptions based on its title or abstract. This was not a study of EMS but rather a review of trauma patients by EMS.
Altough the title states “developed and developing countries,” there is only one study area that would be considered developing and that is Mexico. The other countries have mature and robust systems. Further, the specific systems in the countries reviewed may not be representative of the country as a whole. I’m no expert on most of the countries reviewed, but I question whether King County, Wash., is representative of trauma care in the entire United States.
Despite these issues, the authors do report some interesting findings. Of these, the relatively high use of air medical services by Austria, Germany and Australia is an interesting one worthy of a more intense review. The service area and population densities of these three countries varies dramatically.
Another interesting point raised in their results was that scene times for crews with physicians (Doc-ALS) were significantly longer than in other configurations. However, the accompanying article in this issue states that early fatality rates were significantly lower with (Doc-ALS).
What I found most interesting in this study were items that can be found only in the tables, which listed the demographics and injury severity scores of patients. In particular, Greece, Iran and Mexico had the largest percentage of trauma patients under the age of 15, with 22%, 20% and 16% respectively. On the other side of the age spectrum, Canada at 29% had the largest percentage of trauma patients over the age of 65. This degree of variability in demographics may or may not be representative of the nation but may reflect cultural differences as it relates to health care in general or even age-related activities that are prone to trauma, such as driving.
Again, I want to thank the authors for both of these articles. Trying to describe and compare international trauma systems is akin to the story of the blind men describing an elephant when each can only touch or smell are small part of the animal. It’s my hope that similar studies will be undertaken in the United States to compare data from all types of systems with the goal of defining best practices in trauma care.
Wednesday, 14 October 2009 16:42
he New National Standard for Equipment on Ambulances (USA)
The Science
Almost four decades ago, the Committee on Trauma (COT) of the American College of Surgeons (ACS) developed a list of standardized equipment for ambulances. Since 1988, the American College of Emergency Physicians (ACEP) has published a similar list. Both of those organizations collaborated on the existing joint document, published in 2000. With this revision, the National Association of EMS Physicians (NAEMSP) has agreed to participate in this collaboration
Almost four decades ago, the Committee on Trauma (COT) of the American College of Surgeons (ACS) developed a list of standardized equipment for ambulances. Since 1988, the American College of Emergency Physicians (ACEP) has published a similar list. Both of those organizations collaborated on the existing joint document, published in 2000. With this revision, the National Association of EMS Physicians (NAEMSP) has agreed to participate in this collaboration
Three groups have developed a revised list of standardized equipment for ambulances that addresses the resources needed for appropriate terrorism preparedness.
Based on the need for increased domestic preparedness, this current revision addresses for the first time those resources needed on ambulances for appropriate terrorism preparedness.
The Street
This paper is very important because it sets a national standard of care for what equipment should be available on the ambulance. While many of you will say that this is the responsibility of the state, I would argue that it is vital that we consider the role of national standards of care in everything we do. Somewhere, someone is going to allege that, despite the fact that your service was in compliance with your state standard, had you been compliant to the national standard the patient would have had access to life-saving equipment.
Regardless, position papers like this guide states in developing required equipment list. It is worth a read. There is a pervasive emphasis on pediatric equipment. This is most noted in the area of immobilization, where pediatric-sized traction splints are listed. Interestingly, PASG are listed as optional, despite the American College of Pediatrics’ position that they be required on ambulances.
Another important note is the emphasis placed on latex-free equipment. If you have not gone latex-free yet, you should. And finally, this position paper states that every ambulance should carry PPE and CBRNE equipment, including auto-injectors for the treatment of chemical exposures. This reflects our growing appreciation for domestic preparedness.
Wednesday, 14 October 2009 16:40
Alternative advanced airways
The Science
This interesting study comes to us from the STAT Med Evac air medical service in Pittsburgh. They implemented the King LTD non-visualized airway as a rescue tool for difficult airway management. During the 10 month study they had 575 pre-hospital intubations. The flight crews, nurse and flight medic, were instructed to use a non-visualized airway after three failed intubation attempts or initially if they felt that endotracheal intubation would be difficult. They were able to administer paralytics to all patients.
Of the 575 intubations, they resorted to the King LTD in 26 patients and the Combitube in one. They confirmed tube placement and efficacy of ventilations with wave-form capnography. The majority (23/26, or 88%) were trauma victims.
Ten patients required specialized efforts by anesthesia or surgery for definitive airway management with four patients requiring emergent tracheostomy. None of the 27 patients received pre-hospital surgical airways.
They concluded that the King LTD was a satisfactory alternate airway device.
The Street
This study joins a growing number of studies exploring the role of non-visualized airways in EMS. Clearly, this small sample can’t be extrapolated to other services or used to set a standard of care but it does highlight several issues relevant to pre-hospital airway management.
First, this was a highly qualified flight crew with a program that requires 12 live intubations a year to maintain proficiency. Despite this high level of training, combined with the use of RSI, they still had an ETI failure rate of 4.5%. How does your service compare?
Second, one has to wonder what the impact would be if they only allowed one ETI attempt, as does the San Diego Fire Department. Does a benefit exist in going to an alternate airway device earlier? This question is being examined by Regions Hospital EMS in Minnesota with a study of RSI followed by immediate King LTD placement.
And finally, this study underscores the point that all pre-hospital airway management should be considered difficult and approached with extreme caution armed with multiple back-up rescue plans.
Review of: Guyette FX, Wang H, Cole JS: "King Airway Use By Air Medical Providers." Prehospital Emergency Care. 11(4):473-476, 2007.
Wednesday, 14 October 2009 16:38
Another Look at Ketamine for EMS
The Science
This article describes the experience an air medical program has had with the use of ketamine as an analgesic. The researchers administered ketamine to 40 patients and tracked the occurrence of adverse outcomes. Ketamine was administered to wide range of patients -- from two months to 70 years of age -- suffering from an assortment of conditions such as acute coronary syndrome to multiple trauma and burns. The dose was 1 mg/kg administered intravenously or 5 mg/kg administered intramuscularly. Twelve patients required repeat dosing to sustain analgesia.
Although the authors don't provide any objective evidence to support their claims that the patients attained sufficient analgesia, they do tell us that none suffered any adverse reactions. However, again, they don't define what they would consider to be adverse reactions.
The researchers spend the majority of the paper explaining ketamine's suspected mechanism of action through its dissociative effects at low dose and analgesic effects at high doses. The authors contend that the drug is safe and should, therefore, be considered as a possible alternative to traditional narcotics.
The Street
I'm encouraged to see more programs expanding the horizon of pre-hospital analgesia. Unfortunately, this paper isn't a scientific comparison of ketamine with any other type of treatment. However, it is an excellent review of how ketamine works and why it may be superior to narcotics.
For instance, it's believed that the dissociative "out of body" state that has made this drug a popular one of abuse can also relieve the patient from pain. It does this by essentially disconnecting their consciousness from the pain. While doing this, ketamine induces a trance-like state. This trance-like state also has some hemodynamic consequences that could be useful in trauma, including an increase sympathetic tone leading to a rise in blood pressure. This very same effect could be deleterious to the cardiac patient, but morphine may share this negative cardiac effect through the release of histamine.
I'm not sure I'm ready to embrace the use of ketamine as a pre-hospital analgesic because it fails one or more of the Dr. Wesley EMS pharmacology rules. A pre-hospital medication should be rapid in onset (this one is), effect titratable (this one isn't), short half-life (depends on the ketamine dose) and have a reversal agent (no antidote but time for ketamine).
Still, a very interesting paper from my colleagues here in Wisconsin.
