[Transcranial Doppler sonography in acute intracranial hypertension model--usefulness of pulsatility index].

The authors studied intracranial hemodynamics in experimental animals (Macaca Fuscatus) with acute intracranial hypertension by use of transcranial Doppler (TCD) ultrasound. The blood mean flow velocity in the middle cerebral artery (MCA-FV) and pulsatility index (PI) was recorded using TCD ultrasound (TC2-64, EME) as in the clinical study. Acute intracranial hypertension was produced to determine the correlation of MCA-FV with intracranial pressure (ICP) and cerebral perfusion pressure (CPP) in 11 monkeys, and the correlation of PI with ICP and CPP in 7 monkeys. ICP was elevated by infusing 0.1-0.2 ml/min of saline into the balloon using infusion pump. ICP was raised until maximum level. Changes of MCA-FV, PI, ICP and CPP were evaluated until the CPP of 0mmHg. There was a significant correlation between MCA-FV and ICP (p < 0.01) as well as between MCA-FV and CPP (p < 0.01) in all 11 monkeys. There was also a significant correlation between PI and ICP (p < 0.01) and between PI and CPP (p < 0.01) in 7 monkeys. PI increased markedly when ICP was 80mmHg or greater or when CPP was 60mmHg or less. ICP was always above 80mmHg when PI was above 1.2. All PI values were above 1.0 when CPP was 40mmHg or less. Thus, we could not estimate the absolute values of ICP or CPP from MCA-FV and PI. It seems possible, however, to follow changes in intracranial hemodynamics at the time of increased ICP if MCA-FV and PI are measured continuously while paying attention to factors influencing MCA-FV.(ABSTRACT TRUNCATED AT 250 WORDS)