[Value of transcranial Doppler ultrasonography in the management of severe head injuries].

Transcranial doppler ultrasonography (TCD) is a non invasive technique for the assessment of cerebral blood flow (CBF). The aim of this prospective study was to evaluate the benefit of TCD for the monitoring of major head trauma patients. Therefore 10 of such patients, aged 17 to 37 years, had a TCD at admission and subsequently at least twice a day. Following data were measured simultaneously at the site of the right and the left middle cerebral arteries: the systolic (SV), diastolic (DV) and mean (MV) blood velocity, the resistance index (RI) of Pourcelot (RI = SV-DV/SV) and the pulsatility index (PI) of Gosling (PI = SV-DV/MV). Simultaneously, the mean intracranial pressure (ICP) obtained with a subarachnoid probe, the PaCO2 and the mean arterial pressure (Pa) were measured. The cerebral perfusion pressure (CPP) was calculated with the formula: CPP = Pa-ICP. A total of 132 measures were analysed. There was a linear relation between RI and CPP (r = 0.566; p < 0.001), between RI and ICP (r = 0.822; p < 0.001), as well as between PI and CPP (r = 0.563; p < 0.001) and between PI and ICP (r = 0.837; p < 0.001). In the opposite there was no statistically significant relation between ICP and MV (r = 0.18) nor between CPP and MV (r = 0.23). However, a MV over 100 cm.s-1 was regularly associated with a ICP over 60 mmHg. The close correlation between RI, PI and ICP allows to use RI or PI to estimate ICP.(ABSTRACT TRUNCATED AT 250 WORDS)