Hyperventilation-induced cerebral ischemia in patients with acute brain lesions: demonstration by xenon-enhanced CT.
OBJECTIVE
To examine the possibility that hyperventilation, commonly used to prevent or treat increased intracranial pressure in patients with acute brain lesions, may induce significant cerebral ischemia.


METHODS
Local cerebral blood flow and vascular reactivity were measured before and after hyperventilation using xenon-enhanced CT in 12 patients with acute brain lesions.


RESULTS
Five patients showed "paradoxical" reactivity (increased cerebral blood flow during hyperventilation) within the lesions. In five patients, hyperventilation induced ischemia in apparently normal regions of brain. In three patients, areas of luxury perfusion became ischemic during hyperventilation, while in three patients, lesions with moderate ischemia became more ischemic. Most patients showed more than one type of reactivity.


CONCLUSIONS
These findings document hyperventilation-induced ischemia in acute brain lesions, and demonstrate that this phenomenon affects both injured and apparently intact areas of the brain. Further studies are required to determine the clinical significance of these pathophysiologic changes.
Stringer
W A
WA
Department of Radiology, Loma Linda University Medical Center, CA 92350.
Hasso
A N
AN
Thompson
J R
JR
Hinshaw
D B
DB
Jordan
K G
KG
D000208:Acute Disease; D000328:Adult; D001921:Brain / Q000000981:diagnostic imaging; D001927:Brain Diseases / Q000150:complications* / Q000503:physiopathology; D001930:Brain Injuries / Q000150:complications* / Q000503:physiopathology; D002545:Brain Ischemia / Q000000981:diagnostic imaging* / Q000209:etiology; D002245:Carbon Dioxide / Q000502:physiology; D002560:Cerebrovascular Circulation; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D006985:Hyperventilation; D007223:Infant; D007427:Intracranial Pressure; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial / Q000009:adverse effects* / Q000379:methods; D014057:Tomography, X-Ray Computed; D014978:Xenon
D002245:Carbon Dioxide; D014978:Xenon