RESUSCITATION OF HEMORRHAGIC-SHOCK WITH HYPERTONIC SALINE DEXTRAN OR LACTATED RINGERS SUPPLEMENTED WITH AICA RIBOSIDE

Anesthetized and ventilated swine were bled 23 ml/kg (34% of calculate d blood volume) to' a mean arterial pressure <50 mm Hg. After 60 min, a bolus of either 7.5% hypertonic saline/6% dextran 70 (HSD, 4 ml/kg x 5 min) or lactated. Ringer's (LR, 32 ml/kg x 5 min) was infused i.v. LR (25-30 ml/kg) was administered to all animals for the next 60 min. Amino imidazole carboxamide riboside (AICAR), which increases endogeno us adenosine in ischemic tissues, was added to the initial bolus and t he subsequent LR (1 0 mg/kg bolus + 0.5 mg/kg x 60 min) in half the st udy population. At 2 hr post-shock, hematocrit, urine output, arterial pressure, pulmonary artery pressure, pulmonary capillary wedge pressu re, portal venous 02 saturation, and pulmonary arterial 02 saturation were similar in all groups. With HSD vs. LR, cardiac outputs and strok e volumes were each significantly higher, while right atrial pressures and pulmonary vascular resistances were each significantly lower, whi ch is consistent with augmented cardiac contractility with HSD. Furthe rmore, systemic oxygen consumptions were significantly higher, and int racranial pressures were each significantly lower with HSD. Neverthele ss, no variables were far outside the normal range in either group. Th e addition of AICAR to LR and HSD eliminated the difference in intracr anial pressure, systemic oxygen consumption, reduced heart rate by 30- 40 beats/min during the first hour of resuscitation, and increased str oke volume by 20-30%. Therefore 1) aggressive resuscitation of hemorrh agic shock with either HSD or LR can stabilize hemodynamics, but some variables were improved with HSD; 2) an AICAR supplement in HSD or LR eliminated some, but not all, of the hemodynamic differences between H SD and LR; 3) AICAR did not cause the hypotension or secondary tachyca rdia expected with an ATP or adenosine supplement. In context with oth er work, these data suggest that in many cases (e.g., the trauma patie nt without critical injuries), LR alone provides adequate resuscitatio n, and HSD might have no obvious benefit, other than a lower total flu id requirement. In other cases (e.g., head injury, the severely injure d trauma patient), the salutary effects of HSD or AICAR could translat e to a clinical improvement.