Related Experiment Video

Updated: Jul 16, 2026

Functional Transcranial Doppler Ultrasound for Monitoring Cerebral Blood Flow
09:41

Functional Transcranial Doppler Ultrasound for Monitoring Cerebral Blood Flow

Published on: March 15, 2021

Transcranial Doppler findings in patients with COVID-19: a prospective observational study

Marcella Barreto Santos1, Ana Flávia Silveira2, João Brainer Clares de Andrade1,3

  • 1Universidade Federal de São Paulo, Escola Paulista de Medicina, Departamento de Neurologia e Neurocirurgia, São Paulo SP, Brazil.

Arquivos De Neuro-Psiquiatria
|July 14, 2026
PubMed

Insights

This study found no microembolic signals (MESs) in COVID-19 patients using Transcranial Doppler (TCD). However, elevated inflammatory markers like C-reactive protein (CRP) and D-dimer were linked to lower estimated cerebral perfusion pressure (eCPP).

Area of Science:

  • Neuroscience
  • Critical Care Medicine
  • Infectious Diseases

Background:

  • Transcranial Doppler (TCD) detects microembolic signals (MESs) in intracranial circulation.
  • Critically-ill COVID-19 patients may have increased MESs due to inflammation and hypercoagulability.

Purpose of the Study:

  • To assess MESs and TCD parameters (cerebral blood flow velocity, pulsatility, resistance indices) in COVID-19 patients.
  • To calculate estimated cerebral perfusion pressure (eCPP) in patients with and without COVID-19.

Main Methods:

  • One-hour TCD monitoring in middle cerebral arteries (MCAs) of ICU patients with confirmed COVID-19.
  • Calculation of eCPP using mean arterial pressure (MAP) and CBFV parameters.
  • Comparison of TCD parameters and eCPP between COVID-19 and non-COVID-19 groups.

Main Results:

  • No MESs were detected in any patient group.
  • A positive correlation was observed between MCA resistance index and D-dimer.
  • Negative correlations were found between direct bilirubin, CRP, aPTT, D-dimer, and eCPP.

Conclusions:

  • No spontaneous cerebral microemboli were observed in this cohort.
  • Higher levels of direct bilirubin, CRP, aPTT, and D-dimer were associated with lower eCPP in patients.
Abstract

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