Lethal Triad The triad of acidosis, hypothermia, and coagul | International surgical boards

Lethal Triad

The triad of acidosis, hypothermia, and coagulopathy is common
in resuscitated patients who are bleeding or in shock from various
factors.

Our basic understanding is that inadequate tissue perfusion results in acidosis caused by lactate production.

In the shock
state, the delivery of nutrients to the cells is thought to be inadequate, so adenosine triphosphate (ATP) production decreases.

The human body relies on ATP production to maintain homeo static temperatures, ATP is the source of heat in all homeothermic
(warm-blooded) animals Thus, if ATP production is inadequate to maintain body temperature, the body will trend toward the
ambient temperature. For most human patients, this is 22°C
(72°F), the temperature inside typical hospitals. The resulting
hypothermia then affects the efficiency of enzymes, which work best at 37°C. For surgeons, the critical problem with hypothermia is that the coagulation cascade depends on enzymes that are
affected by hypothermia, If enzymes are not functioning optimally because of hypothermia, coagulopathy worsens, which,
in surgical patients, can contribute to uncontrolled bleeding from injuries or the surgery itself, Further bleeding continues to fuel
the triad.

The optimal method to break the “vicious circle of
death” is to stop the bleeding and the causes of hypothermia. In most typical scenarios, hypothermia is not spontaneous from ischemia but is induced because of use of room temperature fluid or
cold blood products.