chapter 11: indirect assessment of arterial disease

PAOD

peripheral arterial occlusive disease

PAOD symptoms

• intermittent claudication

  • pain in large muscle groups caused by activity

  • pain may be described as fatigue, cramping, aching, or tiredness

  • usually occurs in calf, thigh, or buttocks

distal

site of PAOD symptoms occurs — to site of disease

true claudication

• relieved with quiet standing

• easily reproducible with the same amount of activity

diseases that may mimic claudication

• spinal stenosis

• herniated disk

• osteoarthritis

PAOD symptoms #2

• rest pain

  • pain in foot while patient is lying down

  • represents increasing severity of disease

advanced PAOD symptoms

• thickening of toenails and loss of toe hair

• skin discoloration and scaliness

• elevation pallor/dependent rubor

• ulceration/gangrene

• blue toes may indicate aneurysmal disease

10 to 15

let patient rest for — minutes before beginning exam

• ensures TRUE resting levels of blood flow

20%

width of cuff size should be — wider than the diameter of underlying limb

elevated

if cuff is too narrow = falsely — pressure

lower

if cuff is too wide = falsely — pressure

for ankle brachial indexes (ABIs)

cuffs are placed at the upper arm and ankle

20; 3

once doppler signal is obtained, cuff is inflated to register systolic pressure

• cuff should be inflated — mm Hg above point where signal disappears

• cuff should be deflated at a rate of about — mm Hg/s

severity

ratio of Doppler systolic pressures at the brachial level to those at the ankle indicate the — of PAOD

ABI is calculated by

dividing highest systolic ankle pressure by the higher of the 2 brachial systolic pressures

incompressible (severity of PAOD)

ABI >1.30

normal (severity of PAOD)

ABI 0.90-1.30

mild (severity of PAOD)

ABI 0.75-0.89

moderate (severity of PAOD)

ABI 0.50-0.74

severe (severity of PAOD)

ABI <50

tissue threatening (severity of PAOD)

ABI <0.35

1.0

normal ABI is about —

0.15

a change of — between repeat studies is considered significant

lower

— ABI values correspond to worsening PAOD

calcified arteries

excessively high ABI values typically correspond to —

• systolic pressure is invalid when the underlying artery is calcified and not compressible

• interpretation relies on the waveform

site

ABI indicates overall severity of PAOD, but not necessarily the —

segmental pressures

can add additional information about disease LOCATION

• pressures are taken at multiple sites down the leg

• pressure differences are noted between locations and can indicate specific level of disease

volume plethysmographic waveforms

can also be obtained to aid in interpretation

segmental pressure 3 cuff method

one large cuff on thigh, one cuff around calf just below the knee, and one at the ankle

segmental pressure 4 cuff method

• two smaller cuff on thigh (high thigh and above knee), one at calf, and one at ankle

• allows the ability to further define level of disease separating iliofemoral disease from superficial femoral artery disease

increase

systolic pressures usually — as blood flows distally in the lower extremity

30

(segmental limb systolic pressures) any reduction in distal pressure should be — mm Hg between adjacent segments

proximal obstruction

pressure drop > 30 mm Hg indicates presence of —

exercise testing

primarily used in patients with intermittent claudication with normal or near normal ABIs at rest

typical treadmill settings

• 10% grade

• 1 to 2 mph

• maximum walking time of 5 minutes

contraindications for treadmill testing

• chest pain

• arrhythmias

• postmyocardial infarction (MI) or cardiac procedure

• unsteadiness

• hypertension (>180 mm Hg)

restinf pressure

treadmill testing is performed following — measurements

postexercise ABI calculation

postexercise ankle and brachial pressures are obtained immediately for —

• pressures are typically repeated every 1 to 2 minutes until they return to normal

lowest value

— of post activity ABI categorizes functional severity of limb

recovery time

suggests whether PAOD is single or multilevel

5 minutes

ABI that returns to pre-exercise level within — associated with single-level disease

>10 minutes

ABI that returns to pre-exercise level — associated with multilevel disease

phasicity

waveform — now described as either multiphasic or monophasic

multiphasic

— includes waveforms previously characterized as tri- or bi-phasic

normal doppler waveforms

are multiphasic

• flow reversal relates to greater resistance to flow

PAOD reduces flow energy distal to lesion

• results in reduction of peripheral resistance

• reduces amount of flow reversal

• volume flow is maintained in this way until PAOD reaches critical stage

• arteriolar bed can no longer dilate to increase blood flow

• patient experiences rest pain

plethysmography

aka air plethysmography, pulse volume recording (PVR), or volume pulse recording (VPR)

• cuff is used to measure volume changes in limb

• reflects the total perfusion in the underlying arterial segments (does not identify specific arteries)

• can be used in patients with calcified arteries

55 to 65

plethysmography technique

each cuff is inflated to — mmHg

• venous outflow is restricted

• changes occuring under cuff are from arterial inflow

• volume in limb changes with the cardiac cycle

• pressure chnage is converted to a waveform

normal PVR waveforms

• rapid upstroke with well-defined peak

• notch on downstroke in early diastole (dicrotic notch)

  • result of the reflected wave in healthy high-resistance vessels

• return to baseline through the remainder of diastole (bends toward baseline)

plethysmography waveform ; moderate to severe disease

• delayed onset to peak

• round peak

• diastolic phase becomes convex (bows out rather than toward the baseline)

2.0-2.5

digital evaluation technique

digital cuff are used, diameter of about — cm

normal digital waveform

demonstrates brisk systolic upstroke, well-defined peak, and concave shape on return to baseline during diastole

• used to determine systolic pressure

toe brachial index (TBI)

• normal >0.8

• — is useful when ankle vessels are incompressible

• toe pressure of 50 mmHg indicates

<5%

PAOD in the upper extremity is encountered in — of all cases

PAOD in the upper extremity occurs as

• positional extrinsic compression (TOS syndrome)

• cold-related vasospasm (Raynaud’s disease or phenomenon)

thoracic outlet syndrome

• numbness, aching, or tiredness with positional changes of the shoulder

• results in compression of

  • nerve (95%)

  • vein (3%-4%)

  • artery (1%-2%)

segmental limb systolic pressures in teh UE

radial and ulnar arteries are used for wrist pressures

• the higher of the 2 is then used for forearm and upper arm

• if no signal is present at the wrist, brachial artery can be used for upper arm

subclavian

if PAOD is found in the UE, it is most likely to occur in the — and proximal axillary arteries

> 20

— mm Hg difference in brachial systolic pressures indicates presence of subclavian artery stenosis

• also indicated disease

normal DBI (digital brachial index)

>0.9

10 minutes

cold sensitivity

normal digital tracings or temperatures should return to pre-immersion levels within —

digita