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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.

Efficacy of small-volume resuscitation (4 ml/kg) with 7.5% NaCl in 6% Dextran 70 (HSD), 7.5% NaCl (HS), dextran (D), and 0.9% NaCl (NS) was evaluated in conscious swine bled 37.5 ml/kg over 60 min. Hemorrhage reduced cardiac index (CI), stroke volume (SV), and mean arterial pressure (MAP). Four-hour survival after HSD (67%) was significantly (P less than 0.05) greater than after HS (25%), D (17%), or NS (0%). The superior performance of HSD, and to a lesser extent HS, was associated with rapid plasma volume expansion, improved CI and SV, and decreased heart rate. The acute increases in cardiac index and stroke volume were greater following treatment with HSD and the improvement persisted for 4 hr. HSD also produced a transient increase in MAP. Plasma Na+ concentration and osmolality were increased to a similar extent with HSD and HS, while plasma K+ levels were initially decreased, returning to control levels within 60 min. HSD appears to be a superior small-volume resuscitation solution compared to the other treatments with no detrimental effects.