COMPARISON OF 7.5-PERCENT NACL 6-PERCENT DEXTRAN-70 RESUSCITATION OF HEMORRHAGE BETWEEN EUHYDRATED AND DEHYDRATED SHEEP

7.5% NaCI/6% dextran-70 (HSD) has been shown to be an effective, small volume resuscitation fluid following hemorrhage (HEM) in euhydrated ( E) sheep. However, there is controversy whether hypertonic solutions w ould be effective in dehydrated (D) animals. Therefore, we used two gr oups (E and 4 days D) of chronically instrumented ewes to evaluate the responses to HSD following HEM. All sheep were bled and maintained at 50 mmHg mean arterial pressure (MAP) for 2 h, then resuscitated with a 4 mL/kg bolus of HSD. Dehydration did not affect baseline MAP, heart rate (HR), or total peripheral resistance (TPR), whereas cardiac outp ut (CO: E, 5.28 +/- 31; D, 4.00 +/- 31 L/min), stroke volume (SV: E, 6 1 +/- 4; D, 44 +/- 4 mL/beat), urine flow rate (V: E, .51 +/- 11; D, . 34 +/- .07 mL/min), and sodium excretion (UNaV: E, 22 +/- 8; D, 6 +/- 2 mu Eq/min) were reduced and plasma sodium (P-Na: E, 150 +/- 3; D, 15 7 +/- 2 mEq/L) and protein (PTP E, 7.8 +/- 1; D, 8.8 +/- .6 g/dl) were elevated. The only difference between groups during HEM were HR (E, 9 8 +/- 8; D, 150 +/- 17 bpm), SV (E, 31 +/- 3; D, 14 +/- 2), and TPR (E , 23 +/- 2; D, 32 +/- 3). Resuscitation with HSD restored MAP (E, 92 /- 3; D, 92 +/- 2), CO (E, 6.2 +/- .3; D, 4.2 +/- .2), and TPR (E, 15 +/- 1; D, 23 +/- 1) to baseline values. SV was increased above hemorrh age values but was not restored to baseline values in either group (E, 50 +/- 7; D, 27 +/- 3). HR increased further following HSD (E, 143 +/ - 11; D, 158 +/- 5). P-Na was raised 10 and 16 mEq/L in the E and D sh eep, respectively, following HSD infusion, but no adverse effects asso ciated with elevated P-Na were observed in either group. Thus, HSD was effective in restoring MAP, CO, and TPR to baseline values in D sheep but it was at the expense of a lower SV and a higher HR than in E she ep.