EFFECTS OF A PERFLUOROCARBON EMULSION ON REGIONAL CEREBRAL BLOOD-FLOWAND METABOLISM AFTER FLUID RESUSCITATION FROM HEMORRHAGE IN CONSCIOUSRATS

Regional cerebral blood flow and metabolism were investigated after ad dition of a small volume of perfluorocarbon (PFC) emulsion to the resu scitation fluid after hemorrhage. Severe volume-controlled hemorrhage (40 mL/kg body weight (bw) withdrawn over 30 min followed by hypovolem ia of 30 min duration) was induced in conscious rats. While breathing 100% oxygen, the intravascular volume was repleted by the infusion of either 6% hydroxyethyl starch (mean mol wt 200,000/0.5; HES) or 6% hyd roxyethyl starch plus perflubron (90% wt/vol emulsion of perfluoroctyl bromide, 3 mL/kg bw; HES-PFOB). Two hours after fluid resuscitation ei ther iodo[C-14]antipyrine or 2[C-14]deoxy-D-glucose were infused. Loca l cerebral blood flow (LCBF) or local cerebral glucose utilization (LC GU) were determined in 34 brain structures using quantitative autoradi ography. Local cerebral metabolism was not disturbed in the HES and th e HES-PFOB groups after fluid resuscitation, although slight reduction s (mean -14%) were measured (HES-PFOB vs HES; P < 0.05). The HES-PFOB group showed LCBF values that were higher in the different brain struc tures than those of the HES group (mean +30%). A close correlation was found between LCGU and LCBF of the 34 brain structures in both groups (HES: r = 0.96, P < 0.01; HES-PFOB: r = 0.98, P < 0.01), whereas the LCBP-to-LCGU ratio was reset from 2.2 mL/mu mol in the HES group to 3. 4 mL/mu mol in the HES-PFOB group (P < 0.05). The higher blood flows i n the HES-PFOB group were sufficient to restore cerebral oxygen delive ry to normal levels at a reduced arterial oxygen content. The results indicate that the addition of a small amount of perflubron to HES afte r fluid resuscitation from hemorrhage results in a restitution of cere bral oxygen delivery to normal levels due to an increased cerebral blo od flow.