EEG burst recovery is predictive of brain injury after experimental hypothermic circulatory arrest.
OBJECTIVE
To evaluate whether electroencephalography (EEG) recovery could be considered a reliable marker of brain injury after experimental hypothermic circulatory arrest (HCA).


METHODS
Cortical electrical activity was registered before and after a 75-min period of HCA in 27 pigs that survived 7 days after the experiment. The sum of EEG bursts was counted as a percentage of the sum of artifact-free bursts and suppressions, and this percentage was used as a measure of EEG activity in the analysis.


RESULTS
Brain infarction developed in 13 animals (48.1%), in 12 cases (44.4%) having involved the cortex, in 1 case the thalamus (3.7%) and in another the hippocampus (3.7%). The mean EEG burst percentage significantly correlated with the total brain histopathological score (rho = -0.588, P = 0.001). EEG burst percentage from the 2 h 20 min to the 7 h 20 min interval correlated with the total brain histopathological score and with the cortex, brainstem and cerebellum scores. The mean EEG burst percentage rate was higher, but not significantly, among the animals without brain infarction (38.5% vs 32.4%), but such a difference was significant at the 3 h 20 min postoperative interval (P = 0.02). The mean EEG burst percentage significantly correlated with brain glucose concentration at the 1 h interval (rho = 0.387; P = 0.046), brain lactate concentration at the 2 h interval (rho = -0.431; P = 0.025), and the brain lactate/glucose ratio at the 1 h 30 min interval from the start of rewarming (rho = -0.433; P = 0.024).


CONCLUSIONS
A decreased EEG burst percentage seems to be associated with an increased risk of developing histologically evident brain ischemic injury in the cortex, brainstem and cerebellum after experimental HCA.
Pokela
Matti
M
Department of Surgery, Oulu University Hospital, Finland.
Jäntti
Ville
V
Lepola
Pasi
P
Romsi
Pekka
P
Rimpiläinen
Jussi
J
Kiviluoma
Kai
K
Salomäki
Timo
T
Vainionpää
Vilho
V
Biancari
Fausto
F
Hirvonen
Jorma
J
Kaakinen
Timo
T
Juvonen
Tatu
T
D000818:Animals; D020520:Brain Infarction / Q000175:diagnosis* / Q000209:etiology*; D020208:Brain Injury, Chronic / Q000175:diagnosis / Q000209:etiology; D002560:Cerebrovascular Circulation / Q000502:physiology; D004195:Disease Models, Animal; D004569:Electroencephalography; D005260:Female; D005500:Follow-Up Studies; D006324:Heart Arrest, Induced / Q000009:adverse effects*; D007036:Hypothermia, Induced / Q000379:methods; D015601:Injury Severity Score; D011237:Predictive Value of Tests; D011336:Probability; D011897:Random Allocation; D011930:Reaction Time; D020127:Recovery of Function; D012680:Sensitivity and Specificity; D018709:Statistics, Nonparametric; D013552:Swine; D013997:Time Factors