Ar. Laptook et al., MODEST HYPOTHERMIA PROVIDES PARTIAL NEUROPROTECTION WHEN USED FOR IMMEDIATE RESUSCITATION AFTER BRAIN ISCHEMIA, Pediatric research, 42(1), 1997, pp. 17-23
Intraischemic reduction in temperature of 2-3 degrees C (modest hypoth
ermia) has been demonstrated to provide partial neuroprotection in neo
natal animals. This investigation determined if modest hypothermia ini
tiated immediately after brain ischemia provides neuroprotection. Pigl
ets were studied with rectal temperature maintained during the Ist h a
fter 15 min of brain ischemia at either 38.3 +/- 0.3 degrees C (normot
hermia, n = 11) or at 35.8 +/- 0.5 degrees C (modest hypothermia, rt =
11). The severity of brain ischemia was similar between groups as ind
icated by equivalent reduction in mean blood pressure (90 +/- 15 to 24
+/- 3 versus 92 +/- 13 to 26 +/- 3 mmHg), and changes in cerebral met
abolites and intracellular pH (pH(i)) measured by magnetic resonance s
pectroscopy (P-nucleoside triphosphate = 44 +/- 9 versus 42 +/- 18% of
control, control = 100%, pH(i): 6.25 +/- .15 versus 6.24 +/- 0.22 for
normothermic and modestly hypothermic groups, respectively). In the f
irst 90 min after ischemia, there were no differences between groups i
n the duration and extent of brain acidosis, and relative concentratio
ns of phosphorylated metabolites. Categorical assessment of neurobehav
ior was evaluated at 72 h postischemia (n = 16), or earlier if an anim
al's condition deteriorated (n = 6). Postischemic hypothermia was asso
ciated with less severe stages of encephalopathy compared with normoth
ermia (p = 0.05). Histologic neuronal injury was assessed categoricall
y in 16 brain regions, and postischemic hypothermia resulted in less n
euronal injury in temporal (p = 0.024) and occipital (p = 0.044) corte
x at 10 mm beneath the cortical surface, and in the basal ganglia (p =
0.038) compared with that in normothermia. Modest hypothermia for 1 h
immediately after brain ischemia provides partial neuroprotection and
may represent an adjunct to resuscitative strategies.