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 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=0.040, 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.
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