Resuscitation from hemorrhagic shock with hypertonic saline or lactated Ringer's (effect on the pulmonary and systemic microcirculations).

We compared the use of hypertonic salt solution (300 mEq Na/liter) with Ringer's lactate as an initial resuscitation fluid for the treatment of hemorrhagic shock. We monitored vascular pressures and cardiac output as well as microvascular function using chronic lymph fistulae in the lung and soft tissues to reflect transvascular fluid and protein flux. Seven unanesthetized sheep were bled to an aortic pressure of 50 mm Hg (2 hours) on two occasions 4-5 days apart, and were resuscitated initially with either lactated Ringer's (LR) or hypertonic saline (HS) to restore left atrial pressure to baseline. This was followed later by the blood return. We found that cardiac output with HS was significantly increased over that with LR, 8.9 +/- 1.8, compared with 6.0 +/- 1.1, in the immediate postresuscitation period with comparable volumes in both groups. Urine output was increased twofold with HS over LR. The initial pulmonary hypertension seen with LR was eliminated with HS. Lymph flow in lung and soft tissue increased to a comparable degree in both groups, the increase being explained by the degree of plasma hypoproteinemia which was present. We conclude that HS increases cardiac output with less net fluid, decreases pulmonary vascular resistance, and does not result in more edema formation when compared with lactated Ringer's as an initial fluid for treatment of hemorrhagic shock.