Carotid Artery Test: What It Reveals About Blood Oxygenation

A carotid artery duplex ultrasound evaluates blood flow dynamics and structure of the carotid arteries—not blood oxygen levels directly.

What Carotid Ultrasound Measures

• Peak systolic velocity (PSV), end-diastolic velocity (EDV)
• Internal carotid/common carotid velocity ratio
• Plaque presence, morphology, ulceration
• Intima-media thickness (IMT)
• Flow turbulence, direction
• Degree of stenosis (NASCET criteria)

How Oxygenation Is Assessed

• Pulse oximetry: Non-invasive SpO₂ (hemoglobin saturation) via fingertip/earlobe.
• Arterial blood gas (ABG): Direct PaO₂, SaO₂, pH, PaCO₂, bicarbonate from radial artery.
• Co-oximetry: Differentiates oxy-, deoxy-, carboxy-, met-hemoglobin.

Indirect Link

Severe carotid stenosis (>70%) or occlusion can reduce cerebral perfusion, potentially causing hypoxia/ischemia (TIAs, stroke). Ultrasound identifies this vascular compromise, prompting further oxygenation assessment if neurologic symptoms exist.

Carotid ultrasound is for stroke risk stratification, not oxygenation monitoring. Discuss appropriate testing with your physician.