Z. Feldman et al., NEUROLOGIC OUTCOME WITH HEMORRHAGIC HYPOTENSION AFTER CLOSED-HEAD TRAUMA IN RATS - EFFECT OF EARLY VERSUS DELAYED CONSERVATIVE FLUID THERAPY, The journal of trauma, injury, infection, and critical care, 43(4), 1997, pp. 667-672
Objective: This study examined (1) whether two previously reported, we
ll-established models in rats, one a model of hemorrhagic hypotension
and the other a model of closed head trauma, could be combined to eval
uate neurologic outcome when hemorrhage occurs subsequent to head inju
ry, and (2) the ability of the traditional, conservative approach to f
luid therapy (3 mL of intravenous fluid for 1 mL of blood loss) to rev
erse the detrimental effects of hemorrhagic hypotension after closed h
ead trauma, In addition, two strategies of fluid therapy (early and de
layed) were examined. Methods: Fifty-six Sprague-Dawley male rats were
divided into five groups with head injury at time 0 in groups 3 to 5,
hemorrhage at 1 hour in groups 1, 2, 4, and 5, and intravenous fluid
at 15 minutes (groups 2 and 5) or 60 minutes (groups 1 and 4) after he
morrhage. Head injury was delivered using a weight-drop impact of 0.5
J onto the closed cranium, Neurologic Severity Score (NSS) was determi
ned at 1 hour (just before hemorrhage) and at 4 hours. Results: NSS at
1 hour did not differ between groups 3 to 5 (15.5 (9-24) to 16 (2-21)
, median (range)), The amount of bleeding did not differ between group
s during the first 15 minutes of hemorrhage (2.8 +/- 0.8 to 3.7 +/- 2.
0 mL, mean +/- SD), After 60 minutes, cumulative blood loss in the del
ayed fluid therapy groups was less (3.1 +/- 1.13 mL in group 1 and 4.2
5 +/- 2.39 mL in group 4) than in the early fluid therapy groups (7.73
+/- 4.41 mL in group 2 and 6.85 +/- 2.36 mL in group 5) (analysis of
variance, p < 0.01), The NSS of group 3 (head injury only) improved at
4 hours after injury (12 (5-20)), whereas the NSS of groups 4 and 5 (
head injury followed by hemorrhage) deteriorated (24 (17-25) and 19.5
(9-25), respectively) (Kruskal-Wallis test, p < 0.05). In all the hemo
rrhage groups, fluid therapy failed to restore blood pressure to prehe
morrhage levels. Conclusion: It is concluded that the two individual m
odels of hemorrhagic hypotension and closed head trauma in rats can be
combined to evaluate outcome when hemorrhage occurs subsequent to hea
d injury, Furthermore, traditional, conservative fluid therapy, whethe
r early or delayed, failed to restore blood pressure or to improve NSS
when hemorrhage occurred after head injury, Blood loss was greater wi
th early fluid therapy whether or not head injury was present.