URR Segmental Pressures and Plethysmography Flashcards
how is the probe?
-8-10 MHz pencil probe
-zero crossing detector - counts each time the reflected signal crosses through the baseline over time
-does NOT display a range of frequency shifts, displays average shift as single line
waveforms?
normal are triphasic with rapid upslope, sharp peak, rapid downstroke, a small peak below baseline representing diastolic flow reversal, followed by small peak of flow above baseline
-change in waveform to biphasic or monophasic flow between two segments indicates disease between the 2 sites
what happens to waveforms during exercise?
normal = no change
abnormal= change in arterial phasicity, delayed uplope, delayed downslope, lower amplitude
limitations?
-bandages, casts, wounds
-room temp affects resistance
-cant precisly localize area of obstruction
-improper angels can degrade waveforms
-underestimates high velocities and overestimates low velocities
-cant detect flow velocities less than 6 cm/s
for LE segmental pressures patient should do what before?
should rest on back for 10-15 mins to produce accurate pressures
the cuff width should be how?
20% greater than diameter of the part
-if too wide, pressure underestimates
-if too small, pressure overestimates
Most common cuff method?
4 cuff method
-2 cuffs below knee and 2 above
-allows eval of prox and distal thigh pressures
-causes overestimation of thigh pressures due to using smaller cuffs for 2 thigh pressures
size of cuffs?
-brachial, ankle, and calf normally can use the same blood pressure cuff. usually 10-12cm
-12 cm of larger cuffs usually used for thighs or other areas in larger patients
-7 cm cuff used for wrist and 2.5 used for digits
what offers more accurate measurement of mid thigh?
3 cuff method by using larger cuff, but cannot differentiate distal femoral from pop disease
the below the knee or upper calf cuff should be placed where?
just distal to the tibial tubercle or pressure readings will be falsely elevatedq
the lower calf cuff should be placed where?
distal edge 2-3 cm above the medial malleolus
what arteries area examined in the calf by CW?
ATA and PTA
sometimes people use the branch of the ATA otherwise known as?
dorsalis pedis (DPA)
brachial blood pressures are prohibited on the ipsilateral arm of a what patient?
mastectomy
-if bilateral, neither brachial pressure should be taken
normal pressures for 4 cuff method?
-12 cm cuff for upper thigh, lower thigh, calf, 10 or 12 cm cuff for ankle or arm
-high thigh pressure > brachial pressure by 30-40 mmHg which indicates a thigh brachial index of >1.2
-distal thigh and calf pressures should be the same as brachial
-<30 mmHg difference between 2 adjacent levels in same leg
-< 20 mmHg difference between same level in both legs
normal pressures for 3 cuff method?
-18-20 cm for the thigh, 12 cm cuff for calf, 10 or 12 cm cuff for ankle or arm
-thigh pressure very similar to brachial
-most accurate method of thigh pressure assessment
-<30 mmHg difference between 2 adjacent levels in same leg
-< 20 mmHg difference between same level in both legs
if both thigh pressures are below the highest brachial what should be suspected
aortoiliac disease
rest pain is seen in patients with an ankle pressure of:
< 50 mmHg
falsely elevated ankle pressures means what?
medial calcification, cuff too loose, cuff too small, patient not supine
ABI over 1.3, ankle pressures that are > 200mmHG or 30% higher than the brachial pressure indicates
noncompressibility of the lower extrem vessel under the cuff, usually due to medial calcification
falsely reduced ankle pressures means what?
cuff too large, congestive heart failure, coarctation
reduction in cardiac output with CHF and reduced cardiac EF% will cause what
decrease in ABI bilat
