Blood loss and transcapillary refill in uncontrolled treated hemorrhage in dogs

This study evaluated retroperitoneal hematomas produced by bilateral injury of iliac arteries (uncontrolled hemorrhage), blood volume loss, transcapillary refill, the effects of volume replacement on retroperitoneal bleeding and the hemodynamic changes with and without treatment.

Initial blood volume was determined with Tc(99m)-labelled red cells, and bleeding was evaluated by means of a portable scintillation camera positioned over the abdomen. Previously splenectomized mongrel dogs (16.8 +/- 2.2 kg) were submitted to hemorrhage for 30 minutes and randomized into three groups: I - no treatment (n=7); II - treatment with 32 mL/kg of Lactated Ringer's for three to five minutes (n=7); and III - treatment with 4 mL/kg of 7.5% NaCl plus 6.0% dextran 70 for three to five minutes (n=7). They were studied for an additional 45 minutes.

Volume replacement produced transitory recovery in hemodynamic variables, including mean pulmonary artery pressure, pulmonary capillary wedge pressure and cardiac index, with significant increase in dogs treated with 32 mL/kg of Lactated Ringer's and 7.5% NaCl plus 6.0% dextran 70 (p<0.001, against no treatment), along with a decrease (p<0.001) in the systemic vascular resistance index. Groups II and III had significant initial decreases in hematocrit and hemoglobin. The treated dogs (groups II and III) presented rebleeding, which was greater during treatment with 32 mL/kg of Lactated Ringer's (group II).

Despite the rebleeding observed in treated groups, the utilization of hypertonic saline solution with dextran proved to be effective in the initial reanimation, producing evident transcapillary refill, while the Lactated Ringer's solution produced capillary extravasation and was ineffective in the initial volume replacement in this model of uncontrolled hemorrhage.