Class 11: LEA Physiological Testing Methods Flashcards
what is the purpose of indirect physiological testing?
to detect arterial disease in LEA that is hemodynamically significant
what % stenosis is considered hemodynamically significant?
60%
indirect physiological testing is often used as a screening process to ____
differentiate between true claudicators & pseudoclaudication
indirect physiological testing is used to assess graft ____
patency
5 limitations of indirect physiological testing
- can’t differentiate bw stenosis & occlusion
- only detects hemodynamically significant stenosis
- can’t precisely locate occlusive disease (no images!)
- hard to differentiate CIA & CFA stenosis
- may show falsely elevated pressures in diabetics
another name for ankle brachial index
ankle arm index
what is ABI used for?
screening process to differentiate true claudicators from pseudoclaudicators
ABI results are usually combined with ___
doppler waveform analysis
steps to take the ABI
- put patient in supine
- take BP of both arms; use the higher brachial BP
- take BP of both ankles (PTA or DPA)
- calculate both ABI ratios: LT ABI = LT ankle BP/highest brachial BP; RT ABI = RT ankle BP/highest brachial BP
what does an ABI ratio of 1.0-1.10 suggest
normal findings
what does an ABI ratio of 0.9-1 suggest?
minimal ischemia with minimal symptoms
what does an ABI ratio of 0.5-0.9 suggest?
mild to moderate ischemia with mild to moderate claudication
what does an ABI ratio of 0.3-0.5 suggest?
moderate to severe ischemia with severe claudication or rest pain
what does an ABI ratio of 0.3 or below suggest?
severe ischemia with rest pain or gangrene
what do doppler segmental surveys provide more information on?
location of disease
2 limitations of doppler segmental surveys
- can’t distinguish stenosis from occlusion
- still not location specific
2 techniques for doppler segmental surveys
- 3 cuff method
- 4 cuff method
which is preferred? 3 cuff or 4 cuff method?
3 cuff
why is 3 cuff method preferred over 4 cuff method with doppler segmental surveys?
the 4 cuff method can give falsely elevated pressures on the upper thigh
how do you inflate the cuffs with doppler segmental surveys?
start from ankle & go up to the thigh
what size should the blood pressure cuff be for doppler segmental surveys?
BP bladder should be 20% wider than the limb diameter
a ___ mmHg pressure gradient is significant in the presence of an ____ ABI
20+ mmHg; abnormal
if there is a pressure drop at the level of the high thigh, the disease level is at the ___
aortoiliac level
if there is a pressure drop at the level of the low thigh, this indicates ___ disease
iliofemoral
if there is a pressure drop at the level of the high calf, this indicates ___ disease
femoropopliteal
if there is a pressure drop at the level of the low calf, this indicates ___ disease
tibioperoneal
how long does a patient need to rest prior to doing a segmental limb survey?
20 minutes
what patients’ segmental pressures may be unobtainable or too high?
- diabetics
- chronic steroid therapy
- renal dialysis patients
what ABI is considered too high for segmental limb surveys?
> 1.4
what causes some patients’ segmental pressures to be too high?
calcified arteries
digit vessels are affected by calcific medial sclerosis. T/F?
false
what is a normal toe brachial index (TBI)?
> 0.75
what is an abnormal TBI?
< 0.66
what is exercise stress testing used for?
to induce reactive hyperemia in patients who may be well-collateralized
what is hyperemia?
increased blood flow to a part of the body
how to perform exercise stress testing?
- perform ABI
- put patient on treadmill for max 5 min
- recalculate ABI
pressures should ___ after exercise stress testing
increase
what settings should the treadmill be at for exercise stress testing?
1.5-2 mph
10% grade
5 min
what are 2 substitutes for exercise stress testing when there are contraindications present for patients?
- post-occlusive reactive hyperemia (PORH)
- toe raises
what is post-occlusive reactive hyperemia?
when the distal thigh is occluded for 3 minutes with a blood pressure cuff
how long should toe raises be done before recording post-exercise pressures?
1 minute
what are two types of arterial plethysmography?
- air (pneumo) plethysmography
- photo-plethysmography
pulse volume recordings are a type of ___ plethysmography
air/pneumo plethysmography
for PVRs, limb volume changes with ____ & air is ____ within the cuff
systole; displaced
instantaneous ___ ___ is recorded with PVR
pressure change
PVR is unaffected by calcified arteries. T/F?
true
an advantage for PVR includes ___ evaluation
metatarsal & toe
an advantage for PVR includes assessment for global ___ ___
limb perfusion
a disadvantage of PVR includes atrial fibrillation. T/F?
true
how does photo-plethysmography work?
infrared light is transmitted into the tissue & reflected light is processed for cutaneous blood flow
