DOPPLER IMAGING – Definition, Indications, Purposes, Advantages, Types, Client Preparation, Equipment, Special Consideration, Procedure and After Care
Ultrasound technology provides information about the flow velocity of blood through cerebral vessels using non-invasive technique. A Doppler is placed externally over the vessel, where ultrasonic waves are generated and blood flow velocities are calculated
DEFINITION
Doppler imaging is a noninvasive diagnostic method to study the flow velocity of blood through cerebral vessels, specifically the circle of Willis
INDICATION
- This procedure is used in the intensive care unit to monitor clients who have experienced cerebrovascular disorders, such as stroke, head trauma or subarachnoid hemorrhage
- It can help detect intracranial stenosis, vasospasm and arteriovenous malfunction as well as assess collateral pathways
PURPOSE
- To detect carotid artery disease such as atherosclerosis arterial occlusion
- To detect vertebral artery disease such as stenosis or reversal of flow
- To detect jugular vein disease such as thrombosis or recanalization
ADVANTAGES
- It is a noninvasive procedure, which causes no pain
- It is a safe procedure
- It is relatively inexpensive
- It has high accuracy
TYPES
- Extracranial Doppler studies: extracranial Doppler studies are used as a routine screening. It is used monitor the intraluminal narrowing of the common and internal carotid arteries as a result of arteriosclerotic plaques or atheromata
- Transcranial Doppler studies: transcranial Doppler studies monitor cerebral blood flow velocity through cranial windows or thinned areas of the skull. One such area, the most popular is the temporal bone
CLIENT PREPARATION
- Prepare the client physiologically and psychologically
- Explain the entire procedure in simple words
- Inform the client not to move during the procedure
EQUIPMENT
- Transcranial Doppler unit
- Transducer with an attachment system
- Terry cloth headband
- Ultrasonic coupling gel
- Tissues
SPECIAL CONSIDERATION
- Velocity changes in the transcranial Doppler signal correlate with changes in cerebral blood flow. Parameter the most clearly reflects this changes in the mean velocity
- Embolus appears as high-intensity transients that occur randomly during the cardiac cycle. Emboli make a distinctive clicking, chirping or plunking sound
- Various screens can be stored on the system’s hard drive and can recall or printed
- Before using the intracranial Doppler system, be sure to remove turban head dressing or thick dressings over the test site
PROCEDURE
- Place the client comfortably on the examination table
- A Doppler probe is placed externally over the vessel, where the ultrasonic waves are generated and blood flow velocities are calculated
- As the diameter of the vessel changes, the velocity of the flow of the blood through the vessel changes
- The Doppler probe represents the velocity of the blood flow
- These data are amplified, a graphic and sound recording of the blood flow are produced
- This procedure takes 15-45 minutes to complete
AFTER CARE
- Check the vital signs
- Document the entire procedure in nurse’s record
