Use of Doppler in Wound Care Management’ The Institute of Community Health Nursing 17/05/2017

Theory of ABPI The APBI is the ratio of the systolic B/P measured at the ankle to that measured at the brachial artery (arm)

Theory of ABPI What is an Ankle Brachial Pressure Index? The ankle-brachial pressure index (ABPI) or ankle-brachial index (ABI) is the ratio of the blood pressure at the ankle to the blood pressure in the upper arm (brachium) Compared to the arm, lower blood pressure in the leg is an indication of blocked arteries due to peripheral artery disease (PAD)

Theory of ABPI Systolic B/P in the legs is equal (or slightly greater than) systolic B/P in the arms (= 1) Circulatory system is a closed system When an arterial stenosis (or narrowing) is present, a reduction in pressure(B/P) occurs distally to the lesion. (= 0.9) This can be detected by ABPI or Doppler

Theory of ABPI ABPI is an objective assessment in identifying arterial disease. Ratio of the ankle to the brachial systolic pressure Uses a hand held Doppler ultrasound probe instead of stethoscope to determine the systolic reading. Divide the ankle systolic pressure(highest) by the (highest)brachial systolic pressure

Theory of ABPI Formula Ankle The highest systolic reading in the ankle Brachial The highest systolic reading in the arm

Theory of ABPI Sounds Doppler probe makes audible the pressure at which the systolic pulse return Normal “ triphasic” signal This represents the three phases of arterial flow Three distinct sounds heard during a single cardiac cycle (Donnelly et al 2000)

Theory of ABPI Phases Blood rushes forward Reverses briefly Propels forward again This is echoing the elastic wall of the main artery (Aorta) leaving the heart as it stretches and contracts

Theory of ABPI Sounds Triphasic waveform- all three sounds are present Biphasic- the first two are present Monophasic- first one is observed

Theory of ABPI Sounds Important to understand what the three sounds represent as increasing artery stenosis results in progressive dampening of the waveform and the development of monophasic sound. (Vowden et al 2004)

Assessment Assessment Important to assess the arterial supply to the limbs prior to applying compression therapy Arterial disease can co-exist in approximately 10-20% with lower limb ulceration (Vowden 2001) ABPI should be done at the beginning of treatment and every three months(or as indicated) while compression therapy is used.

Assessment ABPI using a Doppler probe is a reliable way of detecting evidence of arterial insufficiency Also shows if arterial insufficiency is developing ABPI result itself is NOT a diagnostic indicator of venous disease Guides the clinicians decision making towards safe levels of treatment

Danger!! Failure to recognise arterial disease or incorrect interpretation of ABPI results can result in the unsafe application of high compression therapy Pressure damage Exposed tendons Tissue damage Tissue necrosis

Taking a reading Ensure that client is lying flat for 15-20-minutes Semi reclined if patient cannot lie flat due to medical conditions Take the brachial systolic pressure reading on both arms and record the highest. Place the cuff on the lower limb protecting the ulcer site Take the systolic reading using the Dorsalis pedis and posterior tibial artery. Record the higher of the two Calculate the reading by dividing the highest ankle systolic by the highest brachial systolic.

Pedal Pulses Palpation of pulses not a fail safe way to determine arterial sufficiency In one study, lack of pedal pulses had a positive predictive value for significant arterial disease in only 35% of clients. 37% with palpable pedal pulses were found to have significant arterial disease (Moffatt, O Hare 1995)

Pedal Pulses Dorsalis pedis congenitally absent in 12% of population Oedema can make pedal pulses hard to palpate Clients with intermittent claudication can have palpable pulses at rest that disappear on walking Diabetics can have pulses and have significant small vessel disease

Pulse Points Arm… Brachial Artery in both arms Limbs… Dorsalis Pedis, Posterior Tibial pulse

ABPI Readings ABPI between 0.92 and 1.30 = normal Greater than 1.30= calcified artery, false result Greater than 0.8= May be safe for full compression (comprehensive history and physical examination) Between 0.5 and 0.8= reduced compression Mixed ( ABPI < 0.5)- Urgent referral to vascular specialist-NO COMPRESSION

Extrinsic and Intrinsic factors Ambient Temperature Age Ethnicity Height Pulse volume Smoking Medication White coat syndrome

Extrinsic and Intrinsic factors Take into consideration Make reasonable adjustments May have negligible effects on the diagnostic ability of ABPI

Cuff size and position Appropriate to limb size Width should be at least 40% of the limb circumference Standard and large cuff recommended Above the ankle and above the elbow Pulse point accessible May be easier to have cuff upside down so that the tube is away form the pulse point

Equipment Hand held Doppler (or equivalent) Probe.. 8mgHz for lower limb assessment, 5mhHz if there is a lot of oedema Cuff Sphygmomanometer Ultrasound gel Tissues Cling film or equivalent to cover ulcer

Contra Indications Recent DVT ( within 2 weeks ) Sickle cell anaemia (refer) Infection ( should be treated prior to ABPI and application of compression) Caution with Diabetic due to hardening of arteries

Issues to look out for? Cuff repeatedly inflated or inflated for long periods Can cause ankle pressure to fall and affect the reading

Issues to look out for? Cuff not at the ankle Ankle systolic pressure not measured, pressure is usually higher than ankle pressure

Issues to look out for? Pulse is irregular or the cuff is deflated too rapidly True systolic reading may be missed

Issues to look out for? Vessels are calcified, limbs are large, fatty, oedematous, cuff too small or limbs dependant Inappropriately high readings are obtained

Issues to look out for? Central systolic pressure may influence “normal range” for ABPI Has the patient got Hypertension?

Conclusion Once the procedure is followed correctly with proper consideration give to technique, risk factors and data interpretation, ABPI is a safe and reliable method of monitoring arterial disease

Reference http://www.medicinenet.com/peripheral_vascular_disease/article.htm Worboys F, (2006) How to obtain the resting ABPI in leg ulcer Management : Wound Essentials (Technical Guide) VowdenP, Vowden K (2001) Doppler Assessment and ABPI; Interpretation in the management of leg ulceration. World Wide Wounds