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The Golden Hour, MARCH, and the Lethal Triad

In my experience, when you learn how to do something, you can be good, but when you learn the "why", you can become excellent.  This is a quick glimpse at The Golden Hour, the Lethal Triad and how it relates to the Golden Hour, and why we use MARCH principles to save lives in trauma-based scenarios on the battlefield.

The "Golden Hour" is a term coined in 1968 by Dr. R. A. Crowley used to describe the critical, early period of traumatic injury in which you have a chance to, as we say, stay ahead of the 8-ball.  As we all know, once you fall behind the power curve, you work three times harder to catch up.  This goes with anything, especially in stabilizing a patient.  Uniquely, there is no peer-reviewed evidence supporting this "Golden Hour."  The term and its meaning come strictly from the observations of Dr. R.A. Crowley.  The Golden Hour states that early resuscitative efforts (in the first 60 minutes, with surgical cases landing on the OR table within that time) shorten recovery time on the back end and diminish overall secondary injury to the CNS and internal organs.  Taken less literally, and how I interpret it, is that the faster the patient is stabilized and care is administered, the better off they are.  ESPECIALLY in a combat scenario, where there are many, many more factors than in a civilian trauma scenario.

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The Lethal Triad is just what it says; a vicious cycle of three things that happen to the patient during massive trauma events that cascade quickly out of control of the operator.  The Triad is defined as Coagulopathy, Hypothermia, and Metabolic Acidosis.  Imagine this: your teammate, Jim, to your right takes one to the chest and two to his right leg.  He self-aids a tourniquet (TQ) and holds tight while the team secures the area.  Upon returning, you find Jim pale and with an altered mental state.  You curiously begin searching for the issue as you saw a TQ applied above the wound site.  You discover the TQ was not properly applied and he has been bleeding out the entire time.  While it seems you left him only minutes ago, it has been 20 minutes and he has had a partially occluded femoral bleed.  With the loss of blood, Jim has lost some of his ability to thermoregulate.  Hypothermia has already begun.  Certain clotting factors in his body are affected by the change of his core temperature and have been rendered ineffective -- Coagulopathy.  Jim is now cold and his body cannot stop a bleed effectively.  With the amount of blood loss, Jim also has many less red blood cells circulating oxygen and removing the waste product Carbon Dioxide (CO2).  Jim’s pH level has now become acidic -- Metabolic Acidosis.  The acidic level of the blood is now damaging to the bodies tissue and organs, especially the myocardium (heart muscle).  With Jim's heart working less, he's pumping less blood and the amount of heat being retained is lessened and also the amount of oxygen delivery is diminished.  Without playing the scenario further, you can see how these three things take part in either the death of or costly stabilization of Jim.  Costly to him during recovery, and to your supplies as a team medic.  And what was the critical point?  TQ placement and proper use.  Enter MARCH.

MARCH...Massive hemorrhage, Airway, Respirations, Circulation, Hypothermia/Head Injury.  These are the medical principles we follow as trauma medics on the battlefield.  We adhere to this until the patient is moved off the battlefield and into a more secured area.  We call battlefield medicine Care Under Fire and the next level is either Tactical Field Care or Extended Care.  We follow the principles in this order for the reasons seen in the previous scenario.  With proper hemorrhage control(HemCon), Jim has an ok day. Truly, in the beginning, only one principle was in play.  Without proper HemCon, Jim has an altered mental state and possibly will lose the ability to maintain his airway, facilitate respiration, circulate, and as we saw, thermoregulate.  Broken down into the simplest form, keep the red stuff inside the body.  No matter what!  The red stuff carries the oxygen we need to maintain proper pH for metabolic homeostasis.  The red stuff also removes and circulates heat, preventing hypothermia.  The red stuff also keeps your heart pumping at the right pressure to maintain perfusion throughout your body.

By understanding the "Golden Hour," the Lethal Triad, and these principles, perhaps you can better visualize what it is you are doing when you apply that TQ or apply pressure with your hand over a hole in your buddy's leg.  And, of course, let us not forget that the best medicine is fire superiority.

Thanks for reading,
Doc B.

Abigail RossComment