Hemodilution
Hemodilution leads to dilution of coagulation factors leading
to significant amount of coagulopathy post trauma. During
trauma and shock, there is a fall in intravascular hydrostatic
pressure which leads to shift of fluid from interstitial and
intracellular spaces into the intravascular compartment
leading to significant reduction in coagulation factors.3 This
resultant hemodilution is compounded by the administration
of crystalloids and colloids.
Hypothermia
Hypothermia is usually observed in trauma patients due to
environmental exposure, reduced heat production from
underperfused tissues, excessive losses, administration of
cold fluids and blood products.6 Clinically significant levels of
reductions in platelet function, aggregation and enzyme activity
occur at core body temperatures of 33 C and below.7
Drop in temperature by 1 C is associated with a 10% drop in
platelet function.
The activity of tissue factor or FVIIa complex reduces linearly
with temperature. The activity is reduced to about 50% at
temperatures of 28 C. At low temperatures, the attraction
between von Willebrand factor is reduced causing defective
platelet adhesions. However, within the temperature range of
33e36 C which is usually seen in trauma patients, hypothermia
in isolation rarely affects the coagulation system.8