TCD

Radiology · 9 cards · 1 labeled figure

Transcranial Doppler (TCD) - Clinical Indications:

SAH[neuro dx]
stroke[neuro dx] to determine possible occlusion esp in the basilar[…] artery or post-IVT[…] or EVT[…] interventions to ensure vessel patency
AMS[neuro symptom - common consult]
Brain Death[…] testing
Patients with liver[organ] dysfunction

TCD - Normal Mean Flow Velocities (MFV) in cm/sec

Anterior Circulation

Posterior Circulation

PI or Pulsatility Index is PSV-EDV/MFV[formula]

Normal values are between 0.8[…]-2.0[…]
Proximal[…] stenosis or occlusion will decrease[…] the PI
Distal[…] stenosis or occlusion will increase[…] the PI
It is important to note that if the vessel is not insonated[…] correctly it will not reflect an accurate PI

TCD - Brain Death Testing

Brain death is defined as irreversible cessation of total brain function (cortical and brain stem)[…]
therefore anterior[…] and posterior[…] circulation must be insonated (bilateral MCA[…]s and the basilar[…] artery)

TCD - Vasospasm in SAH Patients

Can occur early (day 1[…] after initial event)
Will peak between 7[…]-10[…] days
Can occur in a single, focal[…] segment of an artery
Characterized by increased[…] MFV[…]s with a decreased[…] PI[…]
Other factors can effect the MFV[…] such as increasing level of PCO2[…], increasing MAP[…], decreasing level of Hct[…], fever[…], and hyperemia[…]

TCD - Vasospasm Monitoring

Protocol states the when the MFV[…]s are greater than 120[…] cm/s a Lindegaard Ratio[…] must be obtained. This is the MCA[vessel] MFV/extracranial ICA (ipsilateral)[formula]

LR>2.5[…]-3.0[…] is abnormal
MFV>160[…] cm/s is considered significant risk and >200[…] cm/s is considered serious risk
and / or if there is increase in MFV>50[…]%/day or >40[…]cm/s per day