Increase of intracranial pressure after hypothermic circulatory arrest in a chronic porcine model.
OBJECTIVE
An increase in intracranial pressure has been shown to threaten the outcome of patients with ischemic or traumatic brain injury. Its impact on the outcome of pigs undergoing hypothermic circulatory arrest has been evaluated in this study.


METHODS
Fifty-six pigs underwent a 75-min period of hypothermic circulatory arrest at 20 degrees C. Intracranial pressure, cerebral microdialysis, hemodynamic and metabolic parameters were monitored throughout the experiment. The animals were allowed to survive until the 7th postoperative day and, then, electively killed.


RESULTS
The 7-day survival rate was 60.7%, and among survivors, 20 of them (58.8%) developed brain infarction. A significant increase in intracranial pressure as compared with the baseline level was observed since the end of cooling (p = 0.047) and the difference became larger during all the postoperative intervals (p < 0.0001). Animals that died postoperatively tended to have higher intracranial pressure levels during all the postoperative intervals, but such a difference reached significance only at the 4-h postoperative interval (p = 0.040). The same tendency was observed among animals that survived until the 7th postoperative day and that developed brain infarction or not, but the difference between these two groups did not reach statistical significance. The animals that died or developed postoperatively brain infarction had higher intracranial pressure values postoperatively as compared with those that survived without developing brain infarction and such a difference reached significance at the 2-h (p = 0.015) and 4-h postoperative intervals (p = 0.035). The peak intracranial pressure was 17.2 mmHg (IQR, 13.7-20.8) in animals that died or developed brain infarction and 14.1 mmHg (IQR, 11.8-16.4) in those that survived 7 days without developing brain infarction (p = NS).


CONCLUSIONS
Intracranial pressure increases significantly after 75 min of experimental hypothermic circulatory arrest and such an increase is associated with a high risk of postoperative death and brain infarction.
Pokela
Matti
M
Department of Surgery, University of Oulu, Oulu, Finland.
Romsi
Pekka
P
Biancari
Fausto
F
Kiviluoma
Kai
K
Vainionpää
Vilho
V
Heikkinen
Janne
J
Rönkä
Erkka
E
Kaakinen
Timo
T
Hirvonen
Jorma
J
Rimpiläinen
Jussi
J
Anttila
Vesa
V
Leo
Enrico
E
Juvonen
Tatu
T
D000818:Animals; D001786:Blood Glucose / Q000378:metabolism; D001921:Brain / Q000098:blood supply / Q000378:metabolism / Q000503:physiopathology; D020520:Brain Infarction / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D002560:Cerebrovascular Circulation / Q000502:physiology*; D004195:Disease Models, Animal; D005260:Female; D006324:Heart Arrest, Induced; D006439:Hemodynamics / Q000502:physiology; D007036:Hypothermia, Induced; D019586:Intracranial Hypertension / Q000209:etiology* / Q000401:mortality / Q000503:physiopathology*; D007773:Lactates / Q000097:blood; D011183:Postoperative Complications / Q000209:etiology / Q000401:mortality / Q000503:physiopathology; D011897:Random Allocation; D013223:Statistics as Topic; D016019:Survival Analysis; D013552:Swine; D013997:Time Factors; D016896:Treatment Outcome
D001786:Blood Glucose; D007773:Lactates