Posts

Triage From Afar: Star Trek and Emergency Medicine

Multiple casualties in the tactical environment or a disaster area that exceed both human and materiel resources require rescuers to triage rapidly, so the limited resources may be used for the most critical casualties. In the tactical environment, one may have to do so under fire, thereby increasing the chance of sustaining injury. In disaster zone, precious time may be wasted by attempting to access and treat vocal casualties, while delaying treatment for higher priority patients. Nonetheless, current methods for triage require rescuers to assess casualties one-on-one, delaying further the time to locate, triage and treat the most critical. A recent article in The Army Department Medical Journal succinctly captured the crux of problem noting:

Physiologic status assessment in casualties can be problematic in the military setting, where physical access to the injured individual may be complicated by terrain, weather and hostile action. Likewise, some civil sector settings may challenge first responders, particularly when victims are located remotely. The lack of a remote triage capability may therefore result in the medic attending to either a) a Soldier who is uninjured but caught in the vicinity of combat; or b) a Soldier under severe fire who has an injury that is deemed unsalvageable. Indeed, a combat medic may place himself in harm’s way to assist a Soldier who may not even be injured or may be unsalvageable. Data collected during the Vietnam War indicate that the fatality rate of US Army medics was double that seen in infantrymen.1

There is an initiative to remedy this situation within the Departments of Defense and Homeland Security. DHS, in cooperation with Boeing and Washington’s School of Medicine in St. Louise, developed a “Standoff Patient Triage Tool” in 2009 that allows a rescuer to assess pulse, body temperature and respiration. As the article from Science Daily notes, “The magic behind SPTT is a technology known as Laser Doppler Vibrometry, which has been used in aircraft and automotive components, acoustic speakers, radar technology, and landmine detection. When connected to a camera, the vibrometer can measure the velocity and displacement of vibrating objects. An algorithm then converts those data points into measurements emergency medical responders can use in their rapid assessment of a patient’s critical medical conditions.”2 Although the technology is not yet available, it is an interesting approach.

In addition to the above-mentioned, the US Army is currently seeking technologies that will allow them to have stand-off monitoring capabilities. Researchers seek to assemble a system that is functional from a human factors perspective (i.e., Soldiers will wear it and it will not hindered the mission) and useful with regard to discerning physiological signs of hemorrhage from normal combat stress. For instance, mental status and blood pressure, while useful, are unreliable indicators of hemo-dynamic stability.1 Moreover, they take time to gather. Researchers have therefor sought other “markers” that one can use to discern hemorrhage from stress. To this end, they investigated ECG readings, which can be attained remotely. Unfortunately, the readings are not sensitive enough. Another alternative is using “energy monitors” and algorithms that can detect physiological changes. The challenges are many, however. Location of monitors, for example, require Soldiers to have an uninjured limb. In the age of IEDs, this may be difficult, though researches found that in all but 6% of reported casualties an arm was viable for monitoring.

While technological challenges remain, the ability to quickly triage casualties in a tactical or civil disaster scenario is becoming more likely. Although these futuristic Star Trek device or Soldier-worn monitors lack feasibility currently, researchers are getting closer.

Article:Triage Tech
References:

1. Ryan K, Rickards C, et al. Advanced Technology Development for Remote Triage Applications in Bleeding Combat Casualties. The Army Medical Department Journal. 2011;4/5/6:61-71.

2. Department of Homeland Security. “Triage Technology With A Star Trek Twist: Tricorder-like Device.” ScienceDaily, 1 Jun. 2009. Web. 8 Nov. 2012.

How to:One-handed Tourniquet Application

A principal learning objective taught in many tactical medical training programs is self-application of tourniquets. Although reports from current battlefields estimate the frequency of one-handed application at less 1/10 of 1% (o.oo1), it is still a valuable drill for those working alone (i.e., law enforcement officers). Unfortunately, the technique taught is often incorrect, as most disregard the fact that if one is applying a tourniquet to one’s limb, the limb is probably injured. Therefore, as the video demonstrates, one ought to train for real-world application.

Standard Gauze versus Hemostaic Agents: A New Look

A recent article published by the Academic Emergency Medicine journal found that when compared to standard gauze, hemostatic agents showed no improvement in hemorrhage control and prevention of re-bleeding. The findings indicated that the training is the the most important aspect of hemorrhage control. Obviously, hemostatics have their place, but they are not magic fairy-dust to be sprinkled on wounds, hoping for the best outcome. Moreover, it is clear that the basics saves lives, as the gauze and hemostatics were under direct pressure for five minutes. Finally, the study reveals the difficulties in accessing certain wounds–cavity versus puncture–with gauze and other delivery methods that ought to be considered.

(It should be noted that this study was funded by the US distributor of Celox, Sam Medical, but conducted by an agency within the Department of the Navy.)

Full Study
Littlejohn Hemostatic Comparison AEM 2011

Abstract

Objectives: Uncontrolled hemorrhage remains one of the leading causes of trauma deaths and one of
the most challenging problems facing emergency medical professionals. Several hemostatic agents have
emerged as effective adjuncts in controlling extremity hemorrhage. However, a review of the current literature
indicates that none of these agents have proven superior under all conditions and in all wound
types. This study compared several hemostatic agents in a lethal penetrating groin wound model where
the bleeding site could not be visualized.

Methods: A complex groin injury with a small penetrating wound, followed by transection of the
femoral vessels and 45 seconds of uncontrolled hemorrhage, was created in 80 swine. The animals
were then randomized to five treatment groups (16 animals each). Group 1 was Celox-A (CA),
group 2 was combat gauze (CG), group 3 was Chitoflex (CF), group 4 was WoundStat (WS),
and group 5 was standard gauze (SG) dressing. Each agent was applied with 5 minutes of manual
pressure. Hetastarch (500 mL) was infused over 30 minutes. Hemodynamic parameters were recorded
over 180 minutes. Primary endpoints were attainment of initial hemostasis and incidence of
re-bleeding.

Results: Overall, no difference was found among the agents with respect to initial hemostasis, rebleeding,
and survival. Localizing effects among the granular agents, with and without delivery mechanisms,
revealed that WS performed more poorly in initial hemostasis and survival when compared to
CA.

Risks of Rubber Band Tourniquet Use

Rubber band tourniquets (RBT) have gained popularity in the law enforcement community over the past 24 months. The compact size and nominal cost make them attractive to cash-strapped, and over loaded with respect to equipment, LEOs. Furthermore, as LEO commanders seek to outfit their personnel with live saving equipment while grappling with budget constraints, RBTs seem like a viable option. However, upon further consideration, they may not be the BEST choice due to inherit dangers of RBTs with regard to function and application.

The function of RBTs is simple: one applies it proximal to the injury, wrapping it around the limb until hemorrhage control is achieved, using the elasticity of the rubber to create greater circumferential pressure with each wrap. Initially, this seems easy and straight forward. However, due to the nature of elastic wraps one must be cautious when using one as a tourniquet, due to the difficulty in controlling the applied pressure. As noted in the Journal of Medicine and Biomedical Research, “[t]he pressure induced by the rubber bandage increases at a rate of 3 to 4 times the initial pressure when the bandage is stretched after each wrap.”(1)(3) This is dangerous due to the shearing effect generated on the underling tissues, specifically the nerves. In fact, Graham et al found that at above 300mm Hg shearing forces increased exponentially.(2)(3) With RBTs this is concerning as “[t]he pressure applied to the limb could easily exceed the safe limits and put the limb at risk of complications because the rubber bandage is capable of generating pressures in excess of 1000mmHg beneath it.” “At such extremely high pressure,” Ogbemudia continues, “neurovascular damage becomes likely and makes the use of the RBT relatively unsafe.”(1)(3) He does explain how, in a controlled environment such as a surgical suite, a RBT can be made safe by placing a BP cuff under to monitor pressure. Obviously, this is not optimal in the tactical environment.

There are also difficulties faced when applying a RBT with respect to generating adequate circumferential pressure to stop arterial hemorrhage. Applying a RBT to an extremity, especially an upper limb, mobility is required in order to wrap it around the limb a sufficient number of times. If there has been any bone involvement, this may be an excruciating affair. Furthermore, if, due to pain associated with application, the casualty does not achieve hemorrhage control, he must then un-wrap the RBT multiple times, then re-wrap it in the hopes of achieving enough pressure. Unfortunately, the reverse is true. In an attempt to generate enough pressure, one may generate too much unknowingly. Compared to a windlass-style tourniquet, for instance, one must only turn the windlass an additional 180 degrees, thereby tightening it to achieve more tension. Tourniquets issued within DOD, unlike RBTs, are difficult to over tighten when used one-handed and according to the manufacturers’ directions due to the nature of the webbing and knot interface.

Finally, when compared to standard tourniquets used by the majority of DOD and many state and local LEOs, a RBT has multiple variables that must be considered that relate to the pressure generated. In this case, variables are defined as inconsistencies between casualties and application each time a tourniquets is used. They are compared as follows:

Windlass style tourniquets have 2 variables:
1) limb circumference;
2) degrees rotated.

RBT tourniquets have 4 variables:
1) the percentage of stretch applied with each turn (composition and elasticity of the material, which affect the restoring force of the polymers);
2) the number of layers of the RBT;
3) the degree of overlap;
4) the circumference of the limb.

In the end, a RBT can be used as a field tourniquet. However, it is not the best option for LEOs. The benefits of cost savings do not outweigh the potential problems and risks associated with rubber band tourniquets.

References
[1] Ogbemudia A et al. Adaptation of the rubber bandage for the safe use as tourniquet. Journal of Medicine and biomedical Research 2006; Vol. 5 No. 2 pp-69-74.
[2] Graham B et al. Perinerual pressures under the pneumatic tourniquet in the upper and lower extremity. Journal of Hand Surgery 1992: 17B: 262-6.
[3] McEwen J. A. and Casey V. Measurement of hazardous pressure levels and gradients produced on human limbs by non-pneumatic tourniquets. Accessd at
http://www.tourniquets.org/pdf/CMBEC%2032%20McEwen%20and%20Casey%20Tourniquet%20Paper.pdf

Three-Step Cric?

Below you will find an article published in Military Medicine. It argues that traditional ways of providing a surgical airway in a tactical environment are flawed. Therefore, the authors continue, a new approach is needed. Three-step Cric

Objective: Surgical cricothyroidotomy is the airway of choice in combat. It is too dangerous for combat medics to perform orotracheal intubation, because of the time needed to complete the procedure and the light signature from the intubation equipment, which provides an easy target for the enemy. The purpose of this article was to provide a modified approach for obtaining a surgical airway in complete darkness, with night-vision goggles. Methods: At our desert surgical skills training location at Nellis Air Force Base (Las Vegas, Nevada), Air Force para-rescue personnel received training in this technique using human cadavers. This training was provided during the fall and winter months of 2003-2006. Results: Through trial and error, we developed a “quick and easy” method of obtaining a surgical airway in complete darkness, using three steps. The steps involve the traditional skin and cricothyroid membrane incisions but add the use of an elastic bougie as a guide for endotracheal tube placement. We have discovered that the bougie not only provides an excellent guide for tube placement but also eliminates the use of additional equipment, such as tracheal hooks or dilators. Furthermore, the bevel of the endotracheal tube displaces the cricothyroid membrane laterally, which allows placement of larger tubes and yields a better tracheal seal. Conclusion: Combat medics can perform the three-step surgical cricothyroidotomy quickly and efficiently in complete darkness. An elastic bougie is required to place a larger endotracheal tube. No additional surgical equipment is needed.

Tourniquets and Scientific Studies

A tourniquet is a piece of  live saving equipment.  With that in mind, it is troubling to know that officers are either carrying tourniquets, or contemplating the purchasing of tourniquets, that are questionable with regard to effectiveness. What is more, they are making these decisions based on a questionable scientific study, most of which they did not completely read ( TQReport). It is not being hyperbolic to state that what it is arguing is a matter of life or death. If you question that, then please revisit the last blog entry.

One not wanting to read the entire study is understandable. It is 90 pages of dry, scientific writing. At first glance, the study is methodologically sound. It is constructed to test the effectiveness of tourniquets in an environment that simulates combat conditions. However, after one reads the study completely, there is one glaring deficiency. The study did not test which tourniquets achieved 100% occlusion. I Repeat: IT DID NOT TEST IF TOURNIQUETS ACHIEVED 100% OCCLUSION.  That should be the FIRST criterion a tourniquet must meet to continue a study.  While the ISR study (see below) tested tourniquets that could achieve 100% occlusion, the Navy study did not, so all other criteria are irrelevant.  Instead, it tested how easy it was to apply an ineffective tourniquet. As the study states:

Applications to arms were performed one-handed, but use of both hands was allowed for applications to thighs. A maximum of 5 minutes was allowed to apply the tourniquet, after which time the trial was terminated as an “application failure.” Application of the tourniquet was successful if the subject vocally declared, “Tourniquet on” — indicating that he had reached a point just before continued tightening would produce unbearable pain and had secured the device — within 5 minutes of being handed the test tourniquet. Upon such a declaration, a double event mark was recorded to mark the end of the application time period. The subject was asked to remain still throughout the remainder of the procedure.

Although the above may not seem like an issue, it is. First, applying a tourniquet until one thinks he/she has achieved hemorrhage control is not how it works. One applies a tourniquet to stop bleeding. One must continue to apply pressure until the bleeding stops. It is as simple at that. Second, using pain as indicator to cease applying pressure is not a good indicator. Doing so requires one to extrapolate the findings of a conscious, non-traumatic subject and apply them to an injured patient that has experienced enough trauma to require catastrophic-hemorrhage control.

Savvy distributors and manufacturers of different tourniquets have begun using this study to tout the effectiveness of their product. Beware. They are doing so based on the age-old assumption that consumers will not take the time to read all 90 pages. For example, they are giving potential consumers a chart that gives you a snapshot of the test that enumerates the tourniquets from best to worst. Please read the studies for yourself and make an educated decision. There are two tourniquets approved for use by the Army’s Institute for Surgical Research (ISR) (ISR Tourniquet Study). Do not let the desire to carry a tourniquet that is small–and possibly ineffective–outweigh the need to achieve hemorrhage control. Furthermore, short transport times DO NOT compensate for an ineffective tourniquet that can INCREASE bleeding. Finally, rid yourself of the disturbingly-common attitude that you will not actually need one . If that is the case, save yourself both money and weight and just don’t carry one. However, read the below post before doing so.

If you have any comments, please email them to alan@tacmedsolutions.com