Effect of dehydration on cardiovascular responses and electrolytes after hypertonic saline/dextran treatment for moderate hemorrhage.

STUDY OBJECTIVE: To determine if hypertonic saline/dextran (HSD) is effective in treating hemorrhage in the presence of dehydration. DESIGN: After surgical preparation, swine were euhydrated or dehydrated for 24 or 48 hours. Animals were bled 25 mL/kg over 60 minutes and treated with HSD. SETTING: Laboratory. PARTICIPANTS: Seventeen immature Yorkshire pigs. INTERVENTIONS: 4 mL/kg HSD (7.5% NaCl in 6% dextran-70) administered over one minute. MEASUREMENTS AND MAIN RESULTS: All euhydrated animals survived; 100% of the pigs survived 180 minutes after treatment. Two animals dehydrated for 24 hours and three animals dehydrated for 48 hours died within three hours of HSD treatment. In all groups, plasma potassium was reduced significantly and equally; cardiac output was increased; mean arterial pressure rose rapidly within first five minutes, but was sustained only in euhydrated animals; hematocrit, hemoglobin, and plasma total protein levels were reduced; and plasma glucose increased with persistent between-group differences. RESULTS: HSD immediately rectified the decreases in mean arterial pressure and cardiac output incurred during hemorrhage; over time, however, the improvement in pressure was not sustained in dehydrated pigs. Parallel increases in plasma osmolality and sodium concentrations were offset by the initial group differences resulting from dehydration. CONCLUSION: Dehydration does not compromise the efficacy of HSD as a resuscitation treatment for hemorrhagic shock.

Small-volume infusion of 7.5% NaCl in 6% Dextran 70 for the treatment of severe hemorrhagic shock in swine.

In the initial treatment of the hypovolemic trauma patient, commonly used crystalloids have little clinical benefit in the small volumes generally infused during transport. We evaluated the efficacy of a small-volume infusion of 7.5% NaCl in 6% Dextran 70 as a treatment modality for an otherwise lethal hemorrhage in swine. Sixty chronically instrumented swine were randomized into one of four treatment groups: 0.9% NaCl (NS, n = 15), 7.5% NaCl (HS, n = 15), 6% Dextran 70 (DEX, n = 16), and 7.5% NaCl in 6% Dextran 70 (HSD, n = 14). Each animal was bled 46 mL/kg in 15 minutes. Five minutes after the completion of hemorrhage, the animals were infused with their respective treatment in a volume (11.5 mL/kg) equal to 25% of the shed blood. Of those animals receiving HSD, 100% survived until euthanized at 96 hours. In comparison, animals infused with NS, HS, and DEX had 96-hour survival values of 13%, 53%, and 69%, respectively. The survival rate of the HSD group was significantly better than that of the NS group (P less than .001) and the HS group (P less than .01). The infusion of HSD increased mean arterial pressure, PCO2, and plasma bicarbonate to a significantly greater extent than NS alone (P less than .05). These results demonstrate that a small-volume infusion of the hypertonic sodium chloride/dextran solution is superior to equal volumes of a standard crystalloid in resuscitating animals from hemorrhagic shock.

A clinically applicable exsanguination shock model in swine.

In order to evaluate treatments of the rapid exsanguination seen in the majority of civilian trauma or combat fatalities, we designed a rapid exsanguination, conscious, unheparinized 100% fatal porcine hemorrhage model. Immature female swine were bled 60% of their estimated blood volume 5 days after placement of a bleeding catheter. The change in arterial base excess concentration (BE) and hematocrit (Hct) was followed after hemorrhage. Variables were bleeding time (120, 60, 30, and 15 min) and catheter placement (carotid, 7 cases; and distal aorta, 24 cases). The Hcts before hemorrhage were similar in both groups. The time for removal of 60% EBV for routine mortality was longer with the carotid (60 min) versus the distal aorta (15 min) catheter group. At autopsy the carotid catheters partially obstructed the orifice of the opposite carotid. In the aortic group, a rate of hemorrhage of 2.65 +/- 0.97 ml/kg/min was required to provide the ischemia necessary for 100% mortality. The BE after hemorrhage was significantly different in survivors versus nonsurvivors. A carotid artery catheter that extends into the porcine brachiocephalic artery appears to cause artifactual mortality by interfering with blood flow to the opposite carotid. A conscious, unheparinized, and reliably fatal exsanguination model has been standardized. The animal must sustain a 60% EBV loss from the distal aorta in 15 min.