Diagnostic Medical Sonography Program Vascular Technology Lecture 6: Doppler Segmental Pressures of the Upper Extremities Holdorf

Capabilities Same as Lower Extremities Assess presence/severity of arterial disease Combined with Doppler velocity or volume pulse waveforms

Limitations Same as Lower Extremities Cannot discriminate between stenosis and occlusion, precisely localize area of obstruction, nor discriminate between CFA and external iliac disease. Calcified vessels (medial calcinosis) render falsely elevated Doppler pressures: e.g., diabetics, end stage renal disease.

Patient Positioning Supine with arms relaxed at the patient’s side Cuffs should be snug, but not tight

Patient Positioning for Doppler Segmental Pressures of the UE Supine with arms relaxed at the patient’s sides. Cuffs should be snug, but not tight.

Patient Position for UE Doppler Segmental Pressures

Physical Principles Same as Doppler Velocity Waveforms Evaluation The DOPPLER effect: When a wave is reflected from a moving target, the frequency of the wave received is different (Doppler shift) from that of the transmitted wave This effect occurs with relative motion between the source and the receiver of the sound Blood is moving target: Transducer is stationary source

Technique 14 x 40 cm cuff placed snugly on the upper arm: 10 x 40 cuff on the forearm bilaterally Brachial artery used to obtain upper are BP; radial and ulnar arteries used to obtain the forearm pressure Pressures are combined with Doppler velocity wave forms from the sites previously described. Digits will be discussed at a later date

ALLEN TEST Performed to evaluate the patency of the palmer arch

Palmar arch

Technique With manual compression of radial Artery by the technologist, patient clenches ipsilateral fist (< 1 minute), inducing pallor, while at the same time increases resistance. With manual compression of the radial artery continuing, patient is asked to relax the hand

Interpretation of the ALLEN TEST Normal: Reappearance of the normal color to indicate the ulnar artery is providing flow to the palmar arch Abnormal: Color does not reappear to indicate: An ulnar artery occlusion or palmar arch obstruction

Limitations of the ALLEN TEST Excessive dorsiflexion of wrist may compress radial and ulnar arteries leading to a false positive test. If hand is open, fingers forcibly extended: the skin over palm can be stretched (could lead to pallor due to compression of small vessels) Documentation of the ALLEN TEST Use a PPG (Photoplethysmograph) on the index finger to document arterial pulsations before and after the “clinched fist” Although more difficult to compress, the ulnar artery can be evaluated similarly to assess radial artery flow.

Interpretation of Doppler Segmental Pressures of the Upper Extremities A 15-20 mm Hg difference from one brachial pressure to the other, suggests a > 50% stenosis of subclavian artery and or the vessel under the cuff. A >15-20 mmHg drop from upper arm to the forearm suggests: A brachial artery obstruction distal to the upper cuff Obstruction in both radial and ulnar arteries Obstruction in single forearm artery which has decreased pressure

A difference of > 20 mm Hg between radial and ulnar pressures suggests obstruction in vessel with lower Pressure The lecture on Digits will provide more information.

Homework Chapter 6 Pages 81 – 87 SDMS assignments