Influences of traumatic brain injury on the outcomes of delayed and repeated hemorrhages.

Effects of traumatic brain injury (fluid percussion) on outcomes of hemorrhage, either delayed (70.5 min after the injury) or repeated (0.5 min after injury, then followed by a delayed hemorrhage), were examined in 4 groups of 10 anesthetized rats. Comparisons were made for delayed hemorrhage following sham injury (A1) vs. injury (A2) and for repeated hemorrhage following sham injury (B1) vs. injury (B2). No significant differences were observed in MAP, Cl, HR, SVI, SVRI, and CVP between groups A1 and A2. Hemodynamic recovery was significantly better in B1 than B2 at 70 min after the initial hemorrhage. The respective values of MAP and Cl for the groups B1 and B2 at 70 min were 65 +/- 3 vs. 56 +/- 4 mmHg and 220 +/- 15 vs. 182 +/- 15 ml/min/kg. Brain trauma did not affect survival rate (90 vs. 100%) following delayed hemorrhage, but significantly worsened the outcome of repeated hemorrhage. The 130 min survival rates for groups B1 and B2 were 50% and 10% (P = 0.08), respectively; their survival curves were significantly different (P = 0.02). Our data indicate that brain trauma has greater impact on responses to immediate hemorrhage than delayed hemorrhage, suggesting that traumatic brain injury may have a time-dependent effect on the response to hemorrhage.