The majority of major trauma patients are hypothermic on arrival
in the emergency department due to environmental conditions at
the scene. Inadequate protection, intravenous fluid administration
and ongoing blood loss will worsen the hypothermic state. Haemorrhagic
shock leads to decreased cellular perfusion and oxygenation and
so inadequate heat production. Hypothermia has dramatic systemic
effects on the bodies functions but most importantly in this context
exacerbates coagulopathy and interferes with blood homeostatic
Uncorrected haemorrhagic shock will lead into inadequate cellular
perfusion, anaerobic metabolism and the production of lactic acid.
This leads to profound metabolic acidosis which also interferes
with blood clotting mechanisms and promotes coagulopathy and blood
Hypothermia, acidosis and the consequences of massive
blood transfusion all lead to the development of a coagulopathy.
Even if control of mechanical bleeding is achievable, patients
may continue to bleed from all cut surfaces. This leads to a worsening
of haemorrhagic shock and so a worsening of hypothermia and acidosis,
prolonging the vicious cycle.
Some studies have attempted to place threshold levels on these
parameters. Some state that conversion to a damage control procedure
should take place if the pH is below 7.2, core temperature is
below 32C or the patient has received more than one blood volume
transfusion. However, once these levels are reached, it is already
The trauma surgeon must make the decision to convert to a
limited procedure within 5 minutes of starting the operative procedure.
This decision is made on the initial physiological state of the
patient and the rapid initial assessment of internal injuries.
Do not wait for metabolic failure to set in. This early decision
is imperative to the patients survival.