Quality and quantity of volume replacement in trauma patients.

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.