Effect of immediate fluid resuscitation on the rate, volume, and duration of pulmonary vascular hemorrhage in a sheep model of penetrating thoracic trauma.

STUDY OBJECTIVE: To determine the effects of early fluid resuscitation on the rate, volume, and duration of hemorrhage using a sheep model of uncontrolled pulmonary vascular hemorrhage.

METHODS: Sixteen adult sheep were anesthetized and fitted with catheters to measure systemic and pulmonary artery pressures. A branch of the pulmonary vein was then lacerated through an anterolateral thoracotomy, and a chest tube was inserted to monitor hemorrhage volume. Eight animals were assigned to the immediate fluid (IF) resuscitation group and were given 30 mL/kg of lactated Ringer's solution over a period of 10 minutes; this treatment was repeated once if normotension was not achieved. The other eight animals received no fluid (NF) and served as nonresuscitated controls.

RESULTS: The IF animals had a mean hemorrhage volume of 3,494 +/- 1,525 mL, compared with 1,594 +/- 689 mL in the NF group (P < .001). Hemorrhage stopped spontaneously in the NF group at a mean of 29 +/- 9 minutes but took 48 +/- 11 minutes in the IF group (P = .003). During the 20-minute period of fluid resuscitation, the IF animals bled at twice the rate of the NF animals (90 +/- 33 versus 46 +/- 22 mL/minute, respectively; P = .02). During the 10-minute interval after fluids were administered, the rate of hemorrhage remained brisk at 73 +/- 57 mL/minute in the IF group but virtually stopped in the NF group (6 +/- 7 mL/minute; P = .02).

CONCLUSION: In this sheep model of uncontrolled pulmonary vascular hemorrhage, immediate fluid resuscitation significantly increased the rate, volume, and duration of hemorrhage. The vigorous administration of fluids to patients with penetrating chest trauma has the potential to significantly increase blood loss.