Which of the following conclusions can be drawn from prospective randomized studies involving restoration of circulation in the field?

a. Pneumatic anti-shock garment is of benefit only in patients with a field blood pressure less than 50

b. Patients with major vascular injury should not receive intravenous fluid infusion until bleeding can be controlled in the operating room

The most common cause of death during the first hour after injury is hemorrhage. Therefore, after establishment of patent airway and adequate air exchange, the next priority is to support the circulation. The standard of care in the prehospital setting for hypotensive patients has been volume replacement and application of pneumatic anti-shock garment. In a recent large prospective randomized study, pneumatic anti-shock garments offered no survival advantage and actually increased mortality when used in patients with thoracic injuries. On the other hand, there was the suggestion that patients with a field blood pressure less than 50 mm Hg may benefit from this treatment. A second prospective study confirmed this result, indicating that the pneumatic anti-shock garment is of value to selected patients with field blood pressure less than 50 mm Hg. A recent clinical study has also demonstrated that internal hemorrhage from major vascular injuries should not be treated with intravenous fluid infusion until bleeding can be controlled in the operating room. In the hypotensive state, such major vascular injuries have a chance to clot and temporarily stop bleeding. But if intravenous volume restores blood pressure, the clot may dislodge and the rate of bleeding significantly increases. This may lead to both loss of oxygen carrying capacity and clotting factors, and ultimately exsanguination. Hypertonic saline restores intravascular volume and blood pressure to near normal very rapidly. The prospective randomized trial of normal saline versus hypertonic saline demonstrated a significant improvement in survival when the data were normalized to a select group of patients. There was no evidence that nontamponaded bleeding was exacerbated by the use of hypertonic saline despite the fact that blood pressure and intravascular volume increased.