Doppler

Doppler

Doppler is a non-invasive technique designed to aid the clinician, by providing a quantitative method to determine the severity of peripheral vascular disease or blockage. There are crystals in the doppler transducer through which an electrical voltage vibrates producing ultrasound waves. When the transducer waves strike moving red blood cells, sound is reflected back to the transducer. The normal arterial pulse produces a pulsating and multiphase signal. Patients undergoing this procedure require

· an explanation of the procedure

· the limb is exposed

· the skin is inspected for colour and warmth

· the presence or absence of peripheral pulses is noted

· application of the conducting gel and placement of the doppler over the site of the artery.

· abnormalities or changes to flow are reported to the surgical registrar on call

· a vascular consult may be requested

Most commonly used for suspected blockage of a lower limb when Intra Aortic Balloon Pump is in use.

Common sites include Posterior Tibial Artery, which is found in the groove behind the medial malleolus of the ankle, one-third the distance from the malleolar prominence to the edge of the tendon. (place fingertips curved behind the medial malleolus and palpate the pulse) The Dorsalis Pedis Artery is found on the dorsal midportion of the foot between the first and second metatarsals. (standing at the foot of the bed using the same hand as the foot being palpated, place three fingers on the dorsum of the foot on an imaginary line drawn between the midpoint between the malleoli and first web space)

Formal doppler studies may be requested by accessing the doppler nurse via the vascular laboratory if requested by the Medical officer on call.

Note: Because of anatomical variations, the Posterior Tibial and Dorsalis Pedis pulse may be absent in about 10% of the population.