COMPARATIVE EFFECTS OF 7-PERCENT NACL IN 6-PERCENT DEXTRAN-70 AND 0.9-PERCENT NACL ON OXYGEN-TRANSPORT IN ENDOTOXEMIC DOGS

We compared the effects of 7% NaCl in 6% dextran 70 (HSD) and 0.9% NaC l (IS) resuscitation of endotoxic dogs on hemodynamic and cardiorespir atory parameters and the oxygen consumption-delivery relationship. Esc herichia coli endotoxin (3 mg.kg-1, intravenously) was infused over 5 min into 13 paralyzed, chloralose-anesthetized, splenectomized dogs. S ix additional dogs received a sham endotoxin infusion (saline) and ser ved as controls. After 30 min, the endotoxic animals were resuscitated to 150% of their baseline cardiac output (CO) and maintained at this CO for 30 min using 7% NaCl in 6% dextran 70 (HSD at 1 ml.kg-1. min-1; n = 7) or 0.9% NaCl (IS at 4 ml.kg-1.min-1; n = 6). Oxygen consumptio n (VO2), measured by indirect calorimetry, hemodynamic parameters, and oxygen delivery (DO2), improved in similar temporal patterns in both groups during resuscitation and VO2 reached steady-state values. Oxyge n delivery, VO2, mean arterial pressure, and cardiac output did not si gnificantly differ between groups at the end of resuscitation, but VO2 increased significantly from baseline values only in the HSD group. T he total volume of HSD administered averaged 10.0 +/- 0.2 ml.kg-1 whic h was significantly less than the volume of IS, which averaged 67.2 +/ - 9.3 ml.kg-1. Incremental hemorrhages (2-5 ml.kg-1) were then perform ed in all dogs to determine the oxygen consumption-delivery relationsh ip and the critical level of oxygen delivery (DO2 Crit). The average D O2 Crit values of the HSD, IS, and control groups were 9.42, 9.15, and 6.82 ml.min-1.kg-1, respectively. The DO2 Crit values for the HSD and IS groups were not significantly different, but both were significant ly greater than the control group value. Our results demonstrate that HSD provides no measurable advantages over IS in the early resuscitati on period in terms of cardiorespiratory or hemodynamic parameters. Fur ther, the DO2 Crit values suggest that HSD provides no benefit over IS in terms of improving endotoxin-induced pathologic oxygen supply depe ndence.