Hemodilution has been shown to increase cerebral blood flow (CBF) and reduce lesion volume in models of occlusive
cerebral ischemia, but it has not been evaluated in the setting of
head trauma and
shock in which
ischemia is thought to play a role in the evolution of secondary injury. In a porcine model of
brain injury and
shock the authors compared
hemodilution with
diaspirin cross-linked hemoglobin (
DCLHb) to a standard
resuscitation regimen using
Ringer's lactate solution and shed blood. After creation of a cryogenic
brain injury followed by
hemorrhage, the animals received a bolus of either 4 ml/kg of
Ringer's lactate solution (Group 1, six animals) or
DCLHb (Group 2, six animals), followed by infusion of
Ringer's lactate solution to restore mean arterial pressure (MAP) to baseline. Group 1 received shed blood 1 hour after
hemorrhage (R1) in the form of packed red blood cells. Group 2 received shed blood only for an Hb count of less than 5 g/dl. The animals were monitored for 24 hours. At R1, Group 2 had a significantly greater cerebral perfusion pressure ([
CPP] 88 +/- 5.7 vs. 68 +/- 2.4 mm Hg, p < 0.05). By 3 hours after
hemorrhage (R3) Group 2 had a significantly lower Hb concentration (8.5 +/- 0.4 vs. 12.1 +/- 0.3 g/dl, p < 0.05) and a significantly lower intracranial pressure ([ICP] 9 +/- 0.8 vs. 14 +/- 0.6 mm Hg, p < 0.05). The total 24-hour fluid requirement was significantly less in Group 2 (10,654 +/- 505 ml vs. 15,542 +/- 1094 ml, p < 0.05) There was no difference between the groups regarding levels of regional CBF in the injured hemisphere. Cerebral O2 delivery was not significantly different between groups at any time. Lesion volume as determined at postmortem examination was not significantly different between the groups. The increased MAP and
CPP and lower ICP observed in the Group 2 animals indicate that
hemodilution with
DCLHb may be beneficial in the treatment of
head injury and
shock.