Hypertonic saline/dextran treatment for severe pressure-driven hemorrhage in dehydrated conscious swine

Although dehydration impairs the response to a fixed volume hemorrhage, both 7.5% hypertonic saline/6% dextran 70 (HSD; 4 mL/kg) and standard Ringer's lactate (33 mL/kg) are effective resuscitation fluids. However, the efficacy of resuscitation during continuing hemorrhage remains in question. Using a conscious swine model of continuous pressure-driven hemorrhage, we evaluated the effects of dehydration and HSD resuscitation on survival time, hemorrhage volume, regional blood flows, and central hemodynamics. Three groups of pigs were compared: euhydrated control (EC); dehydrated control (48 h water deprived) (DC); and dehydrated and resuscitated with HSD (D+HSD). All pigs were subjected to an initial 37% blood volume hemorrhage for 60 min followed by a continuous hemorrhage proportional to the instantaneous mean arterial pressure. The D+HSD pigs were resuscitated at the end of the 37% blood volume hemorrhage. Dehydration reduced body weight (-6.5 +/- .3%) and increased hematocrit (8.9 +/- 1.8%), serum osmolality (11.6 +/- .9%), serum sodium (11.9 +/- .9%), and serum total protein (9.4 +/- 1.8%). Compared with the EC group, DC had a greater increase in heart rate and arterial base deficit in response to the pressure-driven hemorrhage and a reduced pH and survival time (159 vs. 107 min). In contrast to the DC group, D+HSD had increased mean arterial pressure, cardiac output, oxygen delivery, and regional blood flows to the gut (superior mesenteric artery), kidneys, liver (hepatic artery), and adrenals at 5 min after HSD resuscitation. The HSD did not increase blood loss but tended to prolong survival (+26 min; p = .1079). Thus, dehydration compromises survival time (-33%) and the hemodynamic and metabolic responses to pressure-driven hemorrhage, while treatment with HSD improves the hemodynamic responses.