An epidemiologic evaluation of
trauma-related deaths in trauma centers reveals that the majority of patients die within 6 hours from
exsanguination, whereas secondary
brain injuries predominate between 6 and 24 hours. Late deaths remain attributable to
sepsis and pulmonary embolism,1-3 while early deaths are due in part to multiple
bleeding injuries or to a set of complex and untreatable
injuries, mainly of the liver and pelvis. Before
trauma systems existed, these patients died at the scene of the
trauma, whereas since the establishment of the
trauma system, they die in emergency or operating rooms. Another subset of early deaths result from severe
bleeding injuries, which could be prevented if recognized early. For instance, if a 70 kg adult had a blood volume of 70 mL/kg (5 L),
hypotension (systolic blood pressure [SBP]<90 mmHg) would usually occur after a one third-loss of blood volume, and death would follow with a 50% loss. A patient
bleeding at a rate of 25 mL/min will become hypotensive within one hour and die within two hours, while a patient
bleeding at a rate of 100 mL/min will be hypotensive within 15 minutes and die within 30 minutes. These considerations indicate a narrow window of opportunity for targeting fluid
resuscitation. Moreover, increases in blood pressure before
surgical hemostasis have been shown to disrupt clotting and increase
bleeding, a fact that has been confirmed by a number of animal and human studies on uncontrolled
hemorrhage. Furthermore,
oxygen must be delivered to vital organs (brain, heart) to prevent death during
hemorrhage. In summary, several constraints account for the differences in fluid use, timing of infusions, and determinations of whether to administer fluids at all.