The use of transcranial Doppler ultrasonography (TCD) in the diagnosis of intracranial hypertension

Introduction

In patients with severe head injury the main complication is cerebral edema and intracranial hypertension. TCD is a noninvasive, bedside technique, which detects the blood flow velocities in the great intracranial arteries. The aim of our study was to investigate whether TCD is a useful technique for the diagnosis of intracranial hypertension.

Materials and methods

Fifty-nine patients with severe head injury (Glasgow Coma Scale < 8) were included in our study. From these 59 patients, 49 were males and 10 females. Their mean age was 36.8 years, with a range from 12 to 71 years. In all patients, we performed and compared concomitant intracranial pressure (ICP) measurement with an intracranial catheter and a TCD examination. In each TCD examination we measured the maximum, mean and the end diastolic velocity (Vmax, Vmean and Vmin, respectively), and we calculated the pulsatility index (PI). The mean cerebral artery through the temporal acoustic window was used for the TCD examinations. A total of 120 TCD examinations and ICP measurements were recorded. We performed correlations between Vmax, Vmean, Vmin and PI with ICP and cerebral perfusion pressure (CPP).

Results

There was no statistically significant linear correlation between TCD velocities and ICP and between the PI index and ICP. There was a significant correlation between Vmax and CPP and between Vmean and CPP. The best correlation found was between Vmin and CPP and between the PI index and CPP. Linear correlation and regression between TCD findings and ICP and CPP are presented in Table 1.

Table 1

Conclusions

TCD examination cannot be used as reliable noninvasive method to determine a concrete number of ICP. The PI index is more reliable than the TCD blood flow velocities to target therapeutic strategies in patients with severe head injury, but we must keep in mind that the PI estimates the changes of CPP over time and not an absolute value of CPP.