ISSN:
0942-0940
Keywords:
Acute head injury
;
CO2 reactivity
;
cerebral blood flow
;
cerebral ischaemia
;
ischaemic threshold
;
hyperventilation
;
intracranial pressure
Source:
Springer Online Journal Archives 1860-2000
Topics:
Medicine
Notes:
Summary In 27 comatose patients with acute head injury, 45 paired studies of regional cerebral blood flow (rCBF) were performed before and after hyperventilation. In total 676 regions were studied, and rCBF was calculated as initial slope index using the intracarotid washout technique of 133 Xe. The tests were applied from one day to three weeks after the acute trauma. In total hyperventilation from PaCO2 averaging 4.8 to 3.5 kPa increased the frequency of regions with oligaemia defined CBF〈20ml/100g/min from 5 to 16%. Before hyperventilation oligaemia was observed in 11 of 45 studies (9 of 27 patients); after hyperventilation the frequency increased to 21 studies (15 patients). The frequency of severe oligaemia (CBF〈15 ml) increased from 0.1 to 3% of all regions, or from 2 to 8 of all studies (from 2 to 9 patients). The increased frequency of oligaemia after hyperventilation was correlated to a poor outcome (dementia, vegetative survival or death), where it was observed in 21% of all regions, in 16 of 26 studies and 11 of 15 patients, whereas the frequency in patients with a good recovery was found to be 7% of all regions and observed in 5 of 19 studies (4 of 12 patients). The high frequency of oligaemia after hyperventilation was associated to a low hemispheric CBF before hyperventilation, but not to the level of PaCO2, the level of intracranial pressure, cerebral perfusion pressure or CSF-pH or lactate. These findings strongly suggest that acute hyperventilation might be controversial as it provokes a decrease in rCBF close to ischaemic threshold, especially in patients with reduced rCBF prior to acute hyperventilation. Furthermore, it suggest that rCBF〈20 ml indicate a poor outcome.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF01456166
