Transcranial Doppler Ultrasonography Cerebral Blood Flow Dynamics Study of Neurosurgical Patients in Peri-Agonal Period with Fixed Dilated or Non-Reacting Pupils.

Introduction: Fixed dilated and unreactive pupils are a harbinger of imminent death in neurosurgical patients, signifying that the brainstem is not functioning. Transcranial Doppler (TCD) ultrasonography is a noninvasive, bedside method of determining the flow velocities in the basal cerebral arteries, used extensively in various neurosurgical conditions. Aims and Objectives: To study the cerebral blood flow dynamics of neurosurgical patients in peri-agonal period with fixed dilated or non reacting pupils using TCD. Materials and Methods: Repeated TCD studies were done in patients with fixed dilated or unreactive pupils in a tertiary care, neurosurgical hospital over a year, recording the various waveforms and indices as Pulsatility Index (PI), Resistivity Index, Peak systolic flow velocity (PSV), End diastolic flow velocity (EDV), Mean cerebral blood flow velocity (MCBFV) of their middle cerebral artery in their peri-agonal period. The subsequent change in the indices as the patients died or improved was analyzed. Results: A total of 104 TCD studies were done on 57 patients. Mean initial PI and MCBFV in the patients that died were 1.52 +/- 0.76 and 28.55 +/- 14.92 cm/sec respectively; and in the patients that showed neurosurgical recovery was 1.11 +/- 0.28 and 36.52 +/- 8.56 cm/sec respectively. Four out of 57 patients showed neurosurgical recovery and all of them had an initial PI less than 1.4 and they showed decrement in PI and increment in MCBFV on subsequent TCD study. The specificity and positive predictive value of the TCD waveform in predicting death was 100%, however, it had low sensitivity (47.17%) and negative predictive value (12.5%). Conclusion: The various indices and waveforms of TCD can be useful in assessing the cerebral blood flow dynamics in patients with various traumatic and non-traumatic ailments in the peri-agonal period; and hence help in their management as well as in the confirmation of brainstem death.