|Budget Amount *help
¥2,100,000 (Direct Cost : ¥2,100,000)
Fiscal Year 1993 : ¥400,000 (Direct Cost : ¥400,000)
Fiscal Year 1992 : ¥1,700,000 (Direct Cost : ¥1,700,000)
Transcranial Doppler ultrasonography (TCD) has recently emerged as a useful method for the assessment of cerebral hemodynamics. This non-invasive technique allows the measurement of blood velocity in the major intracranial vessels in various pathological states associated with intracranial hypertension including brain death. However, the interpretation of velocity and waveform changes are by no means straightforward. Therefore, Doppler ultrasonic recordings were undertaken experimentally using a simple vascular model which was contracted from Silastic tube. The results were as follows :
1. A correlation exists between CPP and TCD waveforms. Stages of systolic flow, to-and-fro, and no flow were caused by the reduction to near zero of the diastolic, mean, and systolic perfusion pressures, respectively. 2. Flow volumes during the stages of sytolic flow, to-and-fro, and no flow were reduced by 86, 96, and 100per cent, respectively.
In consequence, these flow pattens were considered to indicate severe impairment of intracranial circulation. Indeed, these pattern also have been demonstrated in clinical situations of braindeath as systolic flow, to-and-fro, systolic spike, and no flow. The experimental evidence suggests that TCD is a useful means of evaluating cerebral hemodynamics in raised intracranial pressure.