15- Traumas Lethal Triad

KYJ15- the Lethal Triad.

The Lethal Triad is what I call the dark horses of the trauma room. The silent killers that creep out from nowhere and cause catastrophic deterioration.  The Lethal triad is:
• Hypothermia
• Coagulopathy
• Acidosis

Hypothermia is a common feature of the trauma patient who is a young child, elderly, burns or spinal. Whilst many mechanisms exist to cause hypothermia in trauma patients, the most common issue is hypovolaemia, and conduction as the patient lays on a cold bed, in an often 25 degrees (air conditioned) room.
 Loss of further heat must be avoided in the trauma room.
Hypothermia affects coagulation. In a bleeding patient where there is some reliance on the patients ability to stem haemorrhage, a cold patient has impaired haemostatic ability.
Hypothermia also causes alteration in oxygen transport. When cold, haemoglobin binds tightly to oxygen (left shift) and becomes reluctant to release oxygen at the cellular end . They appear well saturated (because they are) but hypoxic at cellular level (shock). The old adage of " keep them warm with a blanket so they don't go into shock", Is as true today as it ever was.

Coagulopathy as spoken about in a previous blog.  Is an altered ability to coagulate.  Coagulation is not the same as clotting

Blood is a suspension of water, proteins and cells. Traveling through pipes that are dynamic.
Your blood vessel walls actually secrete substances that keep your blood liquid.

Plasma will coagulate unless it is told not to by blood vessels. So what is coagulation?

Coagulation is a property whereby a liquid becomes a solid. In blood, it is a series of chemical reactions that convert a protein called prothrombin into thrombin, then fibrinogen into fibrin.
the plasma turns to jelly
Fibrin forms strands that mesh together clotting platelets in a spiderweb like net.  This forms a stable or Fibrin clot

Clotting is not the coagulation. It  is a process whereby platelets are stimulated (by vessel walls) to become activated and clump together.  Clotting works in synergy with coagulation to effect haemostasis (stop bleeding).
 But
In trauma patients who have bled, haemodilution (automatic shock response), the release of a protein called Thrombomodulin , cold, and over use of fluid resuscitation agents, contribute to poor coagulation.
Don't over hydrate your trauma patient ( see our shock series ).

Finally Acidosis.
Lowering of the pH occurs in shocked patients through three primary mechanisms
• Under ventilation leads to CO2 rise, which causes more CO2 to drag pH down.
• fluid overloading with Saline can lead to hyper chloraemic  acidosis
• hypo oxygenation of cells (Ischaemia) forces the cell to use anaerobic metabolism which (recalling 1st year cellular physiology) prevents pyruvate from entering the Kreb's cycle and instead, converts to lactic acid. - metabolic acidodis.

Ventilate the trauma patient with O2, keep them warm to promote cellular oxygenation and much of the problems with acidosis can be averted.

Lethal triad had been implicated in not only killing our trauma and shock patients early, but contributes to the third peak or delayed deaths by sepsis, multiple organ dysfunction, DIC, and ARDS.