Transcranial Doppler (TCD) is a bedside, low-cost, and non-invasive technique able to evaluate cerebral hemodynamics [1]; the implementation of transcranial color-coded duplex sonography (TCCS) aids in evaluating the brain anatomy and intracranial lesions [2], real-time monitoring of “basic” (flow velocity (FV) and pulsatility index (PI)) as well as “advanced” TCD-derived parameters (Table 1; Fig. 1). In practice, we use a 2-MHz probe, and most information is obtained by insonating the middle cerebral artery through the temporal window; other windows include the transorbital, occipital, and submandibular windows. TCCD has the advantage to provide a direct visualization of the cerebral anatomy vessels and allow angle correction to assess FV [2]. TCD/TCCD practice is part of the standard training in our institution, and examinations are routinely performed by the medical staff.

Table 1 Common parameters derived from transcranial Doppler Full size table

Fig. 1 Simplified algorithms on the use of TCD to assess intracranial hypertension, brain death, autoregulation, and cerebral vasospasm in clinical practice. PI, pulsatility index; Vd, diastolic flow velocity; Vm, mean flow velocity; Vs, systolic flow velocity; LR, Lindegaard ratio; CCA, cerebral circulatory arrest. *The three reported images represent reverberating flow (top), systolic pikes (middle), and no flow (bottom), respectively Full size image

We discussed herein on how we use TCD in neuro-critically ill patients for hemodynamic indications; some of these proposals could also be used in non-brain injured critically ill patients at a high risk of cerebral complications.