Effect of hypothermia on brain tissue oxygenation in patients with severe head injury.
BACKGROUND
There is renewed interest in the use of induced hypothermia as a method of neuroprotection both intraoperatively and in the intensive care management of severe brain injury. In this study we have investigated the effects of hypothermia on brain tissue oxygenation in patients with severe head injury.


METHODS
Thirty patients with severe head injury (Glasgow coma score <8) were monitored with a multimodal sensor inserted into the brain which measures tissue PO2, PCO2, pH and temperature in addition to routine monitoring. Patients were cooled to a minimum of 33 degrees C when clinically indicated.


RESULTS
For all 30 patients brain and systemic temperature correlated well (r=0.96). Brain temperature was consistently higher than systemic temperature by 0.41 +/- 0.26 degrees C (confidence limits). Brain tissue PO2 decreased with hypothermia, with a significant reduction below 35 degrees C (P<0.05).


CONCLUSIONS
These results emphasize the advantage of measuring brain temperature directly, and suggest that decreasing brain temperature below 35 degrees C may impair brain tissue oxygenation.
Gupta
A K
AK
Department of Anaesthesia, University of Cambridge, Addenbrooke's Hospital, UK.
Al-Rawi
P G
PG
Hutchinson
P J
PJ
Kirkpatrick
P J
PJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D001921:Brain / Q000378:metabolism*; D002245:Carbon Dioxide / Q000097:blood / Q000378:metabolism; D006259:Craniocerebral Trauma / Q000378:metabolism*; D003422:Critical Care / Q000379:methods; D005260:Female; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007036:Hypothermia, Induced / Q000009:adverse effects*; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology; D010313:Partial Pressure; D011446:Prospective Studies; D013696:Temperature
D002245:Carbon Dioxide; D010100:Oxygen