Cerebral blood flow and metabolism during infusion of norepinephrine and propofol in patients with bacterial meningitis.
OBJECTIVE
In patients with severe bacterial meningitis, norepinephrine is often infused to increase mean arterial pressure (MAP). This increases cerebral blood flow (CBF), but it is unknown if this increase is caused by impaired cerebral autoregulation or by a cerebral effect of norepinephrine through increased cerebral metabolism. The latter possibility implies a CBF-metabolism coupling. This has not been studied during meningitis. We studied the effect of norepinephrine and propofol on CBF and oxidative metabolism in patients with severe bacterial meningitis.


METHODS
In seven patients with pneumococcal meningitis and 7 healthy subjects, norepinephrine was infused intravenously; patients also underwent intravenous propofol infusion. Global CBF was measured by the Kety-Schmidt technique; cerebral oxidative metabolism and net flux of norepinephrine and epinephrine were calculated from measured arterial-to-jugular venous concentration differences (a-vD).


RESULTS
During norepinephrine infusion, MAP increased from a median value of 79 (range, 70 to 89) to 99 (98 to 129) mm Hg in patients, and from 87 (72 to 103) to 123 (112 to 132) mm Hg in controls. CBF increased in patients (51 [48 to 60] to 59 [54 to 77] mL/100 g per minute) but remained unchanged in controls. The cerebral metabolic rate of oxygen (CMRO2) decreased in patients and remained unchanged in controls. No cerebral net flux of norepinephrine or epinephrine was found at any time in the 2 groups. During propofol infusion, CMRO2, and the a-vDO2 decreased whereas CBF was unchanged.


CONCLUSIONS
In patients with severe bacterial meningitis, norepinephrine increases both MAP and CBF but not CMRO2, indicating impaired autoregulation. Propofol reduces CBF relatively less than cerebral metabolism, suggesting a resetting of the CBF-CMRO(2) relationship.
Møller
Kirsten
K
Department of Infectious Diseases, M5132, University Hospital Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen Ø, Denmark. kirsten.moller@dadlnet.dk
Qvist
Tavs
T
Tofteng
Flemming
F
Sahl
Christian
C
Sønderkaer
Signe
S
Dethloff
Thomas
T
Knudsen
Gitte Moos
GM
Larsen
Fin Stolze
FS
D000328:Adult; D000368:Aged; D001794:Blood Pressure / Q000187:drug effects; D002540:Cerebral Cortex / Q000098:blood supply* / Q000378:metabolism; D002560:Cerebrovascular Circulation / Q000187:drug effects; D004837:Epinephrine / Q000097:blood; D005260:Female; D006801:Humans; D007262:Infusions, Intravenous; D008297:Male; D016920:Meningitis, Bacterial / Q000188:drug therapy* / Q000378:metabolism / Q000503:physiopathology; D008875:Middle Aged; D009638:Norepinephrine / Q000008:administration & dosage / Q000097:blood / Q000627:therapeutic use*; D015742:Propofol / Q000008:administration & dosage / Q000627:therapeutic use*
D009638:Norepinephrine; D015742:Propofol; D004837:Epinephrine