Role of Transcranial Doppler Ultrasound Pulsatility Index as a Predictor of Outcome in Moderate to Severe Brain Injury

Abstract

Background: Elevated intracranial pressure (ICP) is a critical determinant of outcome in patients with moderate to severe brain injury. While invasive monitoring remains the gold standard, Transcranial Doppler (TCD) ultrasound offers a promising non-invasive alternative. This study investigates the prognostic utility of TCD-derived Pulsatility Index (PI) alongside other neuro-monitoring parameters in predicting outcomes in brain-injured patients.

Methods: In this prospective observational study, 50 adult patients admitted to intensive care units with moderate to severe traumatic or spontaneous brain injury (GCS ≤13) were enrolled. TCD assessments were performed serially up to day 7, measuring PI, estimated ICP (eICP), and resistive index (RI). Invasive ICP monitoring was also conducted. The primary outcome was the Glasgow Outcome Scale-Extended (GOS-E) at 28 days, dichotomized into favorable (5–8) and unfavorable (1–4) outcomes. Secondary outcomes included ICU stay, MV duration, and mortality.

Results: PI showed significant associations with outcomes. On day 3, PI correlated negatively with GOS-E (r = –0.288, P = 0.045), while on day 7, it correlated positively with ICU stay (r = 0.536, P < 0.001) and ventilation duration (r = 0.435, P = 0.004). Mortality was significantly associated with elevated PI on days 1, 3, and 5 (P < 0.01). ROC analysis revealed day 7 RI had the highest prognostic accuracy (AUC = 0.769), followed by eICP (AUC = 0.754) and PI (AUC = 0.747). Multivariate regression identified Marshall score as the sole independent predictor of GOS-E (P = 0.001).

Conclusions: TCD-derived PI is a valuable non-invasive marker that correlates with clinical outcomes in brain-injured patients. Its integration with standard monitoring may enhance prognostication, especially when invasive methods are contraindicated.