Aim: To investigate the impact of low-dose mannitol on the pulsatility index (PI) and minimum diastolic blood flow velocity (FV-min (-1)) in the middle cerebral artery in cases of traumatic brain injury (TBI).

Study design: A cross-sectional study

Place and duration: From October 2018 to September 2020, the Department of Neurosurgery at Riyadh Care Hospital

Methodology: A total of 80 patients with traumatic brain injury (TBI) were considered in the study. The participants had diffused TBI and their GCS was less than 8. All patients were administered the low-dose mannitol (0.3g kg). PI and FV-min were monitored by Transcranial Doppler (TCD) ultrasonography. The TCD ultrasonography was done before the administration of low-dose mannitol (0.3g kg), immediately after its administration, after 1 hour, 2 hours, and 3 hours.

Result: The values taken before the administration of the low-dose mannitol were pathological (PI>1.5 and FV-min <20cm s (-1)). It was observed that administration of low-dose mannitol brought a significant change in the values of PI (F=8.967, p < 0.001) and FV-min (F=8.642, p <0.0001).

Conclusion: Low-dose mannitol helps to improve the indicators of disturbance of circulation in a patient with TBI. It increased FV-min and decreased the PI. The most improved results in PI were noticed one hour after the administration and it was 11.1%. Similarly, the maximum effect of low-dose mannitol (0.3g kg) on FV-min was also noticed after one hour and it was a 30.2% increase as compared to the values taken in the beginning. The values were significantly different after 2 hours of administration.

Keywords: Traumatic brain injury, low-dose mannitol, pulsatility index, minimum diastolic blood flow velocity