The assessment of the vasoreactivity measured with transcranial doppler(TCD) provides information regarding to the reserve capacity of the cerebral circulation in patients with acute head injuries, which has important therapeutic consequencies because it allows for the diagnosis of impending ischemia and for the control of the effect of initiated corrective measures.

The authors performed TCD study to measure the CO₂ reactivity to the entire basal cerebral arteries in 30 cases of control group and 14 cases of head inury group between the 3rd and the 7th day after insult. All patients were examined by single photon emission computed tomography and their results were compared to CO₂ reactivities at 8 basal cerebral arteries. All of these results were analyzed by statistical analysis system(SAS).

The increase of MBFV(mean blood flow velocity) and decrease of PI(pulsatility index)were noted in the cerebral arteries with decreased CO₂ reactivity. It meant that the arterial walls were dilated. There was no close relationship between region of interest(ROI) index and CO₂ index but CO₂ reactivity was remarkably decreased in the region which showed abnormal regional cerebral blood flow in SPECT(single photon emission computed tomogram)(P=0.04). In the relationship between the variables, ROI increased as the clinical status worsen(r=0.5, P=0.0008), the prognosis of the patients had positive correlation with CO₂ index(r=0.32, P=0.04) or clinical status had negative correlation with ROI index(r=0.40, P=0.0094).

The doppler CO₂ test in patients with head injury provides useful information regarding hemodynamic state, prognosis and determination of beneficial effects of specific therapy, especially during subacute stage. In the various TCD parameters CO₂ index was correlated well with prognosis.

The assessment of the cerebral vasoreactivity provides information regarding to the reserve capacity of the cerebral circulation in patients with cerebrovascular disease, which has important therapeutic consequencies because it allows for the diagnosis of impending ischemia and for the control of the effect of initiated correcitive measures.

The author performed transcranial doppler study to measure the CO2 reactivity to the entire basal cerebral arteries in 30 cases of control group and 10 cases of disease group between 3rd and 7th day after insult. The control persons involved 10 cases of 3rd decade, 10 cases of 5th, 10 cases of 7th, and the diasease persons involved 10 cases of spotanenous subarachnoid hemorrhages. All disease patients were examined by single photon emission computed tomography and their results were compared to Doppler CO2 reactivities.

In control group, the mean blood flow velocity and pulsatility index increased with age, but the CO2 reactivity decreased. In patient group, MBFV, PI index, MI ratio were not correlated to the presence of disease, but only CO2 index was decreased than the same age group of normal control. The regions showing abnormal ROI by SPECT well corresponded with the regions showing decreased CO2 reactivity. There was no close correlation between ROI(Region of Interest) index and CO2 index, but the CO2 reactivity was remarkably decreased in the region which showed abnormal regional cerebral blood flow in SPECT findings(p=0.04). In the relationship between the various prognostic factors, ROI increased as the clinical status worse(r=-0.05, p=0.0008), the acute prognosis(3Mo) had positive correlation with CO2 omdex(r=0.32, p=0.04) or clinical status, and negative correlation with ROI index(r=0.40, p=0.0094).

Transcranial doppler CO2 testing in patients with spotanenous subarachnoid hemorrhage provides useful information regarding hemodynamic state, prognosis and determination of beneficial effects specific therapy. In the various TCD parameters, CO2 index was correlated well with the acute prognosis.