Review Article

Transcranial Doppler Ultrasound: A Review of the Physical Principles and Major Applications in Critical Care

Table 5

Cardiopulmonary shunt grading based on microembolic signals [95, 97].

Grade of shuntNumber of microembolic signals (MES)

No shunt0
Low grade shunt1–10
Medium grade shunt11–25
High grade shunt>25 (shower) or uncountable (curtain effect)