Effects of propofol on cerebral oxygenation and metabolism after head injury.
BACKGROUND
Flow-metabolism coupling is thought to be deranged after traumatic brain injury, while the effects of propofol on flow-metabolism coupling are controversial. We have used a step increase in target plasma propofol concentration in head injured patients to explore flow-metabolism coupling in these patients.


METHODS
Ten patients with a moderate to severe head injury received a step increase in propofol target controlled infusion of 2 microg x ml(-1). Cerebral tissue gas measurements were recorded using a multimodal sensor, and regional chemistry was assessed using microdialysis. Arterial-jugular venous oxygen differences (AVDO(2)) were measured and all patients had cortical function monitoring (EEG).


RESULTS
The step increase in propofol led to a large increase in EEG burst-suppression ratio (0% (range 0-1.1) to 46.1% (range 0-61.7), P<0.05); however, this did not significantly change tissue gas levels, tissue chemistry, or AVDO(2).


CONCLUSIONS
Flow-metabolism coupling remains intact during a step increase in propofol after traumatic brain injury. The EEG burst-suppression induced by propofol after traumatic brain injury does not appear to be a useful therapeutic tool in reducing the level of regional ischaemic burden.
Johnston
A J
AJ
University of Cambridge Department of Anaesthesia, Box 93, Cambridge CB2 2QQ, UK. ajj29@cam.ac.uk
Steiner
L A
LA
Chatfield
D A
DA
Coleman
M R
MR
Coles
J P
JP
Al-Rawi
P G
PG
Menon
D K
DK
Gupta
A K
AK
D000328:Adult; D018686:Anesthetics, Intravenous / Q000097:blood / Q000494:pharmacology*; D001921:Brain / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D006259:Craniocerebral Trauma / Q000378:metabolism* / Q000503:physiopathology; D004569:Electroencephalography / Q000187:drug effects; D005260:Female; D006706:Homeostasis / Q000187:drug effects; D006801:Humans; D007427:Intracranial Pressure / Q000187:drug effects; D008297:Male; D017551:Microdialysis; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010101:Oxygen Consumption / Q000187:drug effects*; D010313:Partial Pressure; D015742:Propofol / Q000097:blood / Q000494:pharmacology*
D018686:Anesthetics, Intravenous; D010100:Oxygen; D015742:Propofol