Cerebral blood flow and metabolism during isoflurane-induced hypotension in patients subjected to surgery for cerebral aneurysms.
Cerebral blood flow and cerebral metabolic rate for oxygen were measured during isoflurane-induced hypotension in 10 patients subjected to craniotomy for clipping of a cerebral aneurysm. Flow and metabolism were measured 5-13 days after the subarachnoid haemorrhage by a modification of the classical Kety-Schmidt technique using xenon-133 i.v. Anaesthesia was maintained with an inspired isoflurane concentration of 0.75% (plus 67% nitrous oxide in oxygen), during which CBF and CMRO2 were 34.3 +/- 2.1 ml/100 g min-1 and 2.32 +/- 0.16 ml/100 g min-1 at PaCO2 4.1 +/- 0.1 kPa (mean +/- SEM). Controlled hypotension to an average MAP of 50-55 mm Hg was induced by increasing the dose of isoflurane, and maintained at an inspired concentration of 2.2 +/- 0.2%. This resulted in a significant decrease in CMRO2 (to 1.73 +/- 0.16 ml/100 g min-1), while CBF was unchanged. After the clipping of the aneurysm the isoflurane concentration was reduced to 0.75%. There was a significant increase in CBF, although CMRO2 was unchanged, compared with pre-hypotensive values. These changes might offer protection to brain tissue during periods of induced hypotension.
Madsen
J B
JB
Department of Anaesthesia, Hvidovre Hospital, Denmark.
Cold
G E
GE
Hansen
E S
ES
Bardrum
B
B
Kruse-Larsen
C
C
D000328:Adult; D000769:Anesthesia, Inhalation; D001921:Brain / Q000187:drug effects / Q000378:metabolism*; D002560:Cerebrovascular Circulation / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects; D006801:Humans; D007023:Hypotension, Controlled; D002532:Intracranial Aneurysm / Q000601:surgery*; D007530:Isoflurane / Q000494:pharmacology; D008875:Middle Aged; D010101:Oxygen Consumption / Q000187:drug effects
D007530:Isoflurane