Pulmonary hypertension and systemic vasoconstriction may offset the benefits of acellular hemoglobin blood substitutes.

OBJECTIVE: We tested the hypothesis that the pharmacologic properties of a small volume of alpha alpha-cross-linked hemoglobin (alpha alpha Hb) could effectively resuscitate pigs subjected to hemorrhage. METHODS: Fourteen pigs hemorrhaged to a mean arterial pressure (MAP) of 40 mm Hg for 60 minutes were treated with a 4-mL/kg 2-minute infusion of 10 g/dL alpha alpha Hb or 7 g/dL human serum albumin, an oncotically matched control solution. RESULTS: The removal of blood (17 +/- 1.5 mL/kg) caused the typical physiologic responses to hemorrhagic hypovolemia. Infusion of alpha alpha Hb restored mean arterial pressure and coronary perfusion pressure, but cardiac output and mixed venous O2 saturation did not improve significantly. Pulmonary arterial pressure and pulmonary vascular resistance increased markedly and were higher than baseline levels after alpha alpha Hb. Infusion of human serum albumin produced only minor hemodynamic changes. Brain blood flow did improve to baseline values after alpha alpha Hb, but was the only tissue to do so. In the human serum albumin group, superior mesenteric artery blood flow recovered to baseline values, whereas brain blood flow did not. Blood flows to other tissues were similar in both groups. CONCLUSION: Small-volume infusion of alpha alpha Hb restored mean arterial pressure and brain blood flow, but pulmonary hypertension and low peripheral perfusion may offset benefits for trauma patients.

Fluid compartments in hemorrhaged rats after hyperosmotic crystalloid and hyperoncotic colloid resuscitation.

Postresuscitation organ failure may be associated with detrimental changes in body fluid compartments. We measured how shock and resuscitation acutely alters the interstitial, cellular, and plasma compartments in different organs. Nephrectomized, anesthetized rats were bled to 50 mmHg mean arterial pressure for 1 h, followed by 60 min of resuscitation to restore blood pressure using 0.9% normal saline (NS,n = 10), 7.5% hypertonic saline (HS,n = 8), 10% hyperoncotic albumin (HA, n = 8), or 7.5% hypertonic saline and 10% hyperoncotic albumin (HSA, n = 7). A 2-h 51Cr-EDTA distribution space estimated extracellular fluid volume (ECFV), and a 5-min 125I-labeled albumin distribution space measured plasma volume (PV). Total tissue water (TW) was measured from wet and dry weights; interstitial fluid volume (ISFV) and cell water were calculated. NS resuscitation required 7 times more fluid (50.9 +/- 7.7 vs. 8.6 +/- 0.7 for HA, 5.9 +/- 0.4 for HS, and 3.9 +/- 0.5 ml/kg for HSA), but there were no differences between solutions in whole animal PV, ECFV, or ISFV. Fluid shifts within tissues depended on resuscitation solution and type of tissue. TW was significantly reduced by hypertonic saline groups in heart, muscle, and liver (P < 0.05). ISFV was significantly reduced by HA groups in the skin. In all tissues, mean cell water in groups receiving HS was smaller; this was significant for heart, lung, muscle, and skin. In conclusion, 1) HS solutions mobilize fluid from cells while expanding both PV and ISFV, and 2) TW and cellular water increase with both isotonic crystalloids and hyperoncotic colloids in many tissues.

Hypertonic saline/dextran for cardiopulmonary bypass reduces gut tissue water but does not improve mucosal perfusion.

Gut mucosal ischemia has been associated with cardiopulmonary bypass (CPB) and may contribute to postoperative systemic inflammatory response and multiorgan dysfunction. Hypertonic saline/dextran (HSD) has been previously shown to selectively increase mucosal blood flow in circulatory shock. To determine whether adding HSD to the prime solution for CPB improves gut mucosal blood flow and oxygenation, we performed normothermic, non-cross-clamped CPB in pigs with 1 ml/kg of HSD (25% NaCl/24% dextran 70) (HSD group, n = 9) or lactated Ringer's solution (LRS group, n = 9) as control added to a standard prime. Animals were instrumented with ultrasonic flow probes on the superior mesenteric artery (SMA), laser Doppler mucosal flow probes in the ileum, and indwelling portal vein catheters and tonometers for mucosal hydrogen ion measurements and pH calculations in the stomach, ileum, and rectum. The total infused volume and net fluid balance was significantly lower in the HSD than in the LRS group (649 +/- 171 ml vs 2075 +/- 385 ml and 502 +/- 182 ml vs 1891 +/- 363 ml, respectively, P < 0.01). SMA flow in the LRS group increased to 110-123% of baseline during CPB and was significantly higher than that in the HSD group which remained unchanged. Ileal mucosal blood flow decreased significantly to 70-50% of baseline in both groups with no difference between groups. Gut oxygen (O2) delivery decreased during CPB in both groups, but O2 consumption remained unchanged. Gastric, ileal, and rectal mucosal pH decreased progressively, and portal venous blood pH also decreased in both groups, but there was no significant difference between groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hypertonic saline dextran resuscitation on oxygen delivery, oxygen consumption, and lipid peroxidation after burn injury.

We compared the effects of lactated Ringer's (LR) and hypertonic saline dextran (HSD) on postburn cardiovascular function, O2 consumption, lipid peroxidation, and bacterial translocation. Miniature pigs with 40% total body surface area (TBSA), third-degree burns received, 30 minutes postburn, either Parkland resuscitation (LR group, n = 8) or HSD, 10 mL/kg/30 minutes, followed by LR, 4 mL/kg/%burn over the next 23 hours (HSD group, n = 8). The HSD prevented the early decrease in cardiac index (CI); the early increase in the resistance of the systemic, mesenteric, celiac, and renal vascular beds; and the decrease in mesenteric O2 consumption seen after burns when LR alone is used for resuscitation. The HSD also moderated the systemic and mesenteric lipid peroxidation. Bacterial translocation was less in the HSD group (3 of 8 animals) compared with the LR group (5 of 8 animals), but was not statistically different. Hypertonic saline dextran may be beneficial in improving the postburn microcirculation and attenuating postburn oxidant-induced lipid peroxidation in the systemic tissues and the gut.