Usefulness of Transcranial Doppler‐Derived Cerebral Hemodynamic Parameters in the Noninvasive Assessment of Intracranial Pressure

ABSTRACT BACKGROUND Transcranial Doppler (TCD) ultrasonography is a noninvasive bedside tool that can evaluate cerebral blood flow hemodynamics in major intracranial arteries. TCD‐derived pulsatility index (PI) is believed to be influenced by intracranial pressure (ICP). OBJECTIVE To correlate TCD‐PI with cerebrospinal fluid (CSF) pressure (representing ICP), measured by standard lumbar puncture (LP) manometry. METHODS CSF pressures (CSF‐P) were measured in 78 patients by LP manometry. Stable TCD spectra were obtained 5 minutes before LP from either middle cerebral arteries using Spencer's head frame and 2‐MHz transducer. PI values were calculated from the TCD spectra by an independent neurosonologist. RESULTS Factors displaying a significant relationship with CSF‐P included age ( R = −.426, P < .0005); EDV ( R = −.328, P = .002;) and PI ( R = .650, P < .0005). On analyzing dichotomized data (CSF‐P < 20 vs. ≥ 20 cm H 2 0) TCD‐PI was an independent determinant (OR per .1 increase in PI = 2.437; 95% CI, 1.573‐3.777; P < .0005). PI ≥ 1.26 could reliably predict CSF‐P ≥ 20 cm H 2 0 (sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy were 81.1%, 96.3%, 93.8%, 88.1%, and 90.1% respectively). CONCLUSION TCD‐derived PI could be used to identify patients with CSF‐P ≥ 20 cm H 2 0 and may play an important role as a monitoring tool.