Pulsatility index correlates with opening intraventricular intracranial pressure

Background: Increased intracranial pressure (ICP) is life- threatening complication of a variety of neurologic insult. Various non-invasive methods have been employed to estimate ICP, transcranial Doppler (TCD) is one of them. Increase ICP leads to decrease in diastolic flow velocity (FV) and mean FV in major intracranial vessels resulting in increase in pulsatility index (PI) derived by TCD. Hence, the present study was designed to find a correlation between TCD derived PI with opening intraventricular ICP. Methodology: A prospective, observational, double-blinded study was conducted in Post Graduate Institute of Medical Education and Research, Chandigarh. Thirty-two patients of age 8–60 years with clinical features of raised ICP posted for endoscopic third ventriculostomy or ventriculoperitoneal shunt were enrolled after getting Institute Ethics Committee clearance and written informed consent from patient’s kin. A 2 Mz probe of TCD was insonated through temporal window to measure FV in middle cerebral artery (MCA) pre- operatively, and PI was calculated. A standard anaesthesia protocol was followed in all cases. Opening intraventricular ICP was measured through a ventriculostomy catheter inserted into lateral ventricle and pressure measured without loss of cerebrospinal fluid. Spearman correlation test was used to correlate PI with intraventricular ICP. Receiver operating characteristic curve was drawn at different values of ICP to find out the corresponding PI. Results: MCA FV was measured by TCD in all 32 patients. The systolic and mean velocity varies from 69.3–144 cm/s to 25–89.3 cm/s, respectively. The opening intraventricular ICP values ranged from 9 to 44 mmHg. PI had a strong significant positive correlation with intraventricular ICP. At ICP cut-off value of 20 mmHg, PI was ≥0.92 (70.6% sensitivity and 66.6% specificity; P = 0.009). Discussion: PI correlates well with opening intraventricular ICP, so it can be used to diagnose intracranial hypertension and guide ICP reduction therapy.

No conflict of interest has been declared by the author(s).