Small-volume resuscitation from hemorrhagic shock in dogs: effects on systemic hemodynamics and systemic blood flow

This study compared canine systemic hemodynamics and organ blood flow (radioactive microsphere technique) after resuscitation with 0.8% saline (Na+ 137 mEq/L), 7.2% hypertonic saline (Na+ 1233 mEq/L), 20% hydroxyethyl starch in 0.8% saline, or 20% hydroxyethyl starch in 7.2% saline, each in a volume approximating 15% of shed blood volume. Twenty-four endotracheally intubated mongrel dogs (18 to 24 kg) underwent a 30-min period of hemorrhagic shock, from time 0 to 30 min into the shock period, followed by fluid resuscitation. Data were collected at baseline, 15 min into the shock period, immediately after fluid infusion, 5 min after the beginning of resuscitation, and at 60-min intervals for 2 hr, (65 min after the beginning of resuscitation, and 125 min after the beginning of resuscitation). The animals received one of four randomly assigned iv resuscitation fluids: saline (54 mL/kg), hypertonic saline (6.0 mL/kg), hydroxyethel starch (6.0 mL/kg) or hypertonic saline/hydroxyethyl starch (6.0 mL/kg).

Mean arterial pressure increased in all groups after resuscitation. Cardiac output increased with resuscitation in all groups, exceeding baseline in the saline and hypertonic saline/hydroxyethyl starch groups (p less than .05 compared with hypertonic saline or hydroxyethyl starch). Sixty-five minutes after the beginning of resuscitation, cardiac output was significantly (p less than .05) greater in either of the two colloid-containing groups than in the hypertonic saline group. After resuscitation, hypertonic saline and hydroxyethyl starch produced minimal improvements in hepatic arterial flow, hypertonic saline/hydroxyethyl starch increased hepatic arterial flow to near baseline levels, and saline markedly increased hepatic arterial flow to levels exceeding baseline (p less than .05, saline vs. hydroxyethyl starch). One hundred twenty-five minutes after the beginning of resuscitation, hepatic arterial flow had decreased in all groups; hepatic arterial flow in the hypertonic saline group had decreased to levels comparable with those during shock. Myocardial, renal, and brain blood flow were not significantly different between groups.

Small-volume resuscitation with the combination of hypertonic saline/hydroxyethyl starch is comparable with much larger volumes of 0.8% saline, and is equal to hypertonic saline or hydroxyethyl starch in the ability to restore and sustain BP and improve organ blood flow after resuscitation from hemorrhagic shock.