Point-of-care transcranial Doppler by intensivists

Abstract

In the unconscious patient, there is a diagnostic void between the neurologic physical exam, and more invasive, costly and potentially harmful investigations. Transcranial color-coded sonography and two-dimensional transcranial Doppler imaging of the brain have the potential to be a middle ground to bridge this gap for certain diagnoses. With the increasing availability of point-of-care ultrasound devices, coupled with the need for rapid diagnosis of deteriorating neurologic patients, intensivists may be trained to perform point-of-care transcranial Doppler at the bedside. The feasibility and value of this technique in the intensive care unit to help rule-in specific intra-cranial pathologies will form the focus of this article. The proposed scope for point-of-care transcranial Doppler for the intensivist will be put forth and illustrated using four representative cases: presence of midline shift, vasospasm, raised intra-cranial pressure, and progression of cerebral circulatory arrest. We will review the technical details, including methods of image acquisition and interpretation. Common pitfalls and limitations of point-of-care transcranial Doppler will also be reviewed, as they must be understood for accurate diagnoses during interpretation, as well as the drawbacks and inadequacies of the modality in general.Electronic supplementary materialThe online version of this article (doi:10.1186/s13089-017-0077-9) contains supplementary material, which is available to authorized users.

Whole body ultrasound in the operating room and intensive care unit

“…The pulsatility index (PI) is a measure of resistance to blood flow; it is calculated as the difference between the peak systolic flow velocity and end-diastolic flow velocity, divided by the mean velocity. An elevated PI correlates with increased ICP [41]; PI > 2.3 (normal PI value < 1.2) correlates with an ICP > 22 mmHg [34]. Progressive malignant intracranial hypertension leads to diminishing diastolic and then systolic blood flow patterns, and ultimately results in cerebral circulatory arrest ( Fig.…”

“…Point-of-care neurologic ultrasound as a diagnostic tool is an invaluable adjunct to the history, physical exam, and laboratory investigations in the encephalopathic patient, especially in those too unstable to be transported for diagnostic imaging. Several bedside sonographic techniques permit the critical care physician to detect the presence of raised intracranial pressure (ICP) [4,34,35], conditions such as midline shift of the cerebrum [4,36,37], or cerebral vasospasm [4,38]. Ability to detect these pathologies in a timely manner enables rapid institution of appropriate therapy.…”

“…Transcranial colour-coded duplex sonography (TCCS) is a bedside method that can be used to detect intracranial hypertension [34], cerebral artery vasospasm after subarachnoid hemorrhage [4], or ultimately to diagnose brain death [40]. Using the same trans-temporal window described above, a sonographic image of the circle of Willis is obtained; using the principles of Doppler, one can analyse the arterial blood flow pattern in the middle cerebral artery to detect various pathologies.…”

Better With Ultrasound

“…In patients who are unconscious, there is often a diagnostic gap between the yield of the bedside neurologic examination and that of other investigations that may be invasive or require patient transport. 1 In certain clinical scenarios, transcranial Doppler (TCD) may have a role in bridging this gap, effectively augmenting the physical examination and helping the bedside physician decide whether investigations such as CT scan, CT angiography (CTA), or MRI are necessary, or if intracranial pressure (ICP) monitoring or other surgical interventions are required. [2][3][4][5][6] A variety of different ultrasound techniques have been described 1,7,8 ; this paper aims to present a systematic approach for incorporating these techniques into bedside practice.…”

Point-of-Care-Sonografie in der Intensivmedizin

“…Unter den indirekten bettseitigen Verfahren nimmt die transkranielle Doppler-Sonografie eine wichtige Rolle bei der Messung der zerebralen Zirkulation ein. Die Geschwindigkeitsprofile von Blutströmen in verschiedenen intrakraniellen Blutgefäßen erlauben Rückschlüsse auf Vasospasmen, eine Erhöhung des intrakraniellen Drucks, eine Mittellinienverlagerung oder das Fortschreiten eines zerebralen Kreislaufstillstandes [22].…”