Definition
Doppler ultrasonography evaluates blood flow in the major blood vessels of the arms and legs and in the extracranial cerebrovascular system. A handheld transducer directs high- frequency sound waves to the artery or vein being tested. The sound wave strike moving red blood cells and are reflected back to the transducer at frequencies that corresponds to blood flow velocity through the vessel. The transducer then amplifies the sound waves to permit direct listening and graphic recording of blood flow. Measurement of systolic pressure helps detect the presence, location, and extent of peripheral arterial occlusive disease.
Pulse volume recorder testing may be performed along with Doppler ultrasonography to yield a quantitative recording of changes in blood volume or flow in extremity or organ.
Purpose
- To help diagnose venous insufficiency and superficial and deep vein thrombosis (popliteal, femoral, and iliac).
- To help diagnose peripheral artery disease and arterial occlusion.
- To monitor the patient who has had arterial reconstruction and bypass grafts.
- To detect abnormalities of carotid artery blood flow associated with such conditions as aortic stenosis.
- To evaluate possible arterial trauma.
Procedure
Patient Preparation
- Explain to the patient that Doppler ultrasonography is used to evaluate blood flow in the arms and legs or neck. Tell him who will perform the test and when.
- Reassure the patient that the test doesn’t involve risk or discomfort.
- Inform the patient that he’ll be asked to move his arms to different positions and to perform breathing exercises as measurements are taken.
- Advise him that a small ultrasonic probe resembling a microphone is placed at various sites along veins or arteries, and blood pressure is checked at several sites.
- Check with the vascular laboratory about special equipment or instructions.
Implementation
- Doppler ultrasonography is performed bilaterally.
- The patient is assisted into the supine position on the examination table with his arms at his sides.
Peripheral arterial evaluation
- For peripheral arterial evaluation in the leg, the usual test sites are the common and superficial femoral, popliteal, posterior tibial, and dorsalis pedis arteries.
- For peripheral arterial evaluation in the arm, the usual test sites are the subclavian, brachial, radial, and ulnar arteries.
- Brachial blood pressure is measured, and the transducer is placed at various points along the test arteries.
- The signals are monitored, and the waveforms are recorded for later analysis.
- The blood flow velocity is monitored and recorded over the test artery.
- Segmental limb blood pressures are obtained to localize arterial occlusive disease.
Peripheral venous evaluation
- For peripheral venous evaluation in the leg, the usual test sites are the popliteal, superficial and common femoral veins, and posterior tibial vein.
- For extracranial cerebrovascular evaluation, usual test sites are the supraorbital artery; the common, external, and internal carotid a arteries; the vertebral arteries; and the brachial, axillary, subclavian, and jugular veins.
- The transducer is placed over the appropriate vessel, waveforms are recorded, and respiratory modulations are noted.
- Proximal limb compression maneuvers are performed.
- Augmentation after release of compression is noted to evaluate venous valve competency.
- For test involving the legs and feet, the patient is asked to perform Valsalva’s maneuver, and venous blood flow is recorded.
Nursing Interventions
- Remove the conductive gel from the patient’s skin.
- Assist the patient to a comfortable position.
Interfering Factors
- Unknown
Precautions
- Bradyarrhythmias may occur if the probe is placed near the carotid sinus.
- Make sure that the Doppler probe isn’t placed over an open or draining lesion.
image by: healthline.com, nlm.nih.gov
