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The neuroendocrine responses to resuscitation with 7.5% hypertonic saline/6% Dextran-70 (HSD) following hemorrhagic hypotension were evaluated in conscious swine. Following hemorrhage (37.5 ml/kg/60 min) animals received 4 ml/kg of HSD (n = 6) or 0.9% saline (n = 8). Administration of normal saline did not alter cardiovascular function nor attenuate an increase in hormones. HSD rapidly improved cardiovascular function and acutely decreased ACTH, plasma renin activity (PRA), cortisol, norepinephrine (NE), epinephrine (E), aldosterone, and lysine vasopressin levels (LVP). The initial decreased in ACTH, cortisol, and aldosterone levels was due primarily to hemodilution associated with the expansion of plasma volume. The reductions in NE, E, LVP, and PRA were greater than those attributed to hemodilution alone. Values for LVP, NE, and E remained at values below those at the end of hemorrhage, but greater than basal levels, while PRA returned to values similar to these at the end of hemorrhage. The decrease in LVP, NE, and E following HSD resuscitation for the treatment of hemorrhagic hypotension may result from and contribute to the rectification of cardiovascular and metabolic function.

Arterial blood lactate concentration at the end of fixed volume hemorrhage was evaluated as a predictor of survival in unmedicated chronically instrumented immature swine. Compared to basal values, 8.4 +/- 4.5 mg/dl (means +/- SD, n = 52), hemorrhaged animals (n = 71) with a lactate of 43.9 +/- 37.1 mg/dl lived while animals (n = 65) with a lactate of 106.5 +/- 40.4 mg/dl died. Lactate concentration at the end of hemorrhage successfully predicted survival (81.0%). Prospective evaluation, using a blood lactate concentration of 125 mg/dl (n = 27), showed a predictive success of 81.0%. Arterial plasma lactate concentration at the end of hemorrhage thus may be used to predict survival in the conscious swine.