Module 5.1 : Indirect Testing Flashcards
what is an ankle brachial index ABI
- non invasive pathological test that compares systolic blood pressure at the ankle to the systolic pressure of the brachial artery
- CW analog doppler waveforms are recorded to support the pressure information
what does a lumen narrowing to a critical level do to the blood pressure
- distal arterial flow and blood pressure with significantly decrease
how do we calculate the ABI
pedal pressure / highest brachial pressure
what is the average ABI in supine resting patient
1.2
what is the normal ABI
> 0.9
in what patients will ABIs be falsely high
- medial calcification
what should be done with > 1.3
- toe pressures
what is the normal TBI
> 0.75
what does an ABI of > 0.1
normal
what does and ABI or 0.9 - 1.0 mean
- minimal disease
- asymptomatic
what does an ABI of 0.9-0.9 means
- claudication
- single level disease
what does and ABI of < 0.5 means
- rest pain
- severe
- multilevel disease
what does and ABI of < 0.3
- Beverly ischemic leading to gangrene
what is the level of pressure measurement determined by
- cuff postion
- not by doppler interrogation
what are 6 limitations to ABI
- falsely increased pressures from calcified vessels
- significant lesions with developed collateral circulation will result in normal distal pressures and waveforms at rest
- acute DVT in lower extremities should not have pressure cuffs inflated over thrombus
- extensive bandaging
- trauma surgery, ulceration graft no cuffs over
- pressures not permitted on ipsilateral side of mastectomy or AVG/ AVF
what does exercise stress testing determine
- determines functional significance of disease by evaluating the arterial hemodynamics of lower extremities
what is a normal result of exercise testing
- little to no drop in ankle BP after 5 minutes of exercise
- decreased in post exercise BP should be < 20% of the resting pressure and should return to baseline within 3 minutes of exercise
if recovery time after exercise test < 3 minutes mean
- normal
if recovery time after exercise test 2-6 minutes mean
- single level disease
if recovery time after exercise test 6-12 minutes mean
- multilevel disease
if recovery time after exercise test > 15 minutes mean
- severe occlusive disease
what is an abnormal result fo exercise testing
- immediate decrease from baseline in post exercise ankle BP indicates significant arterial obstruction
- severity of the disease is also related to the distance a patient can walk and the absolute pressure drop
