Chapter 20 - Vascular lab - arterial physiologic

Question 1

Transmitting frequency of pocket doppler

Answer 1

5-10 MHz

Question 2

Tip of the probe of a doppler

Answer 2

Piezoelectric crystal - converts electrical energy into ultrasound waves - detects reflected ultrasound waves

Question 3

Impedance mismatch in duplex

Answer 3

Difference in density causing significant reflection of ultrasound waves - prevent further tissue penetration

Question 4

Doppler equation

Answer 4

ABOVE FIGURE 20.1 delta f = frequency shift V = blood velocity f0 = transmitted frequency theta = angle between velocity and path of beam C = velocity of sound through blood

Question 5

Loudness/amplitude is proportional to

Answer 5

Volume of RBC

Question 6

Earliest change at site of stenosis on doppler waveform

Answer 6

Widening of waveform (spectral broadening) in early diastole

Question 7

Name of the analysis to turn frequency into picture

Answer 7

Fourier analysis

Question 8

Indirect measures of waveform from doppler

Answer 8

Peak to peak pulsatility index = (Vmax - Vmin) / Vmean

Question 9

Frequency most sensitive to stenosis

Answer 9

Higher frequency components decrease in systolic pressure more sensitive

Question 10

What type of energy loss is caused by turbulence

Answer 10

Kinetic energy loss

Question 11

When does turbulence occur

Answer 11

Reynold number > 2500 Re = Vd/viscosity V = velocity d = diameter vessel

Question 12

ABI measurement interpretation

Answer 12

> 1.3 = noncompressible 1-1.29 = normal 0.91-0.99 = borderline (equivocal) 0.41-0.9 = mild to moderate PAD 0-0.4 = severe PAD

Question 13

Percentage higher pressure in normal ankle compared to arm

Answer 13

10%

Question 14

Causes of normal person to have higher pressure in ankle

Answer 14

1) increased intraluminal pressure from gravity 2) thickened arterial wall and stiffness

Question 15

Sen and SPE of ABI to detect PAD PPV/NPV

Answer 15

Sen 80-95% Spe 95-100% ppv and npv 90%

Question 16

How does automated BP cuff work

Answer 16

Detects oscillations of pressure caused by changes in volume in extremity

Question 17

Using oscillometry to detect ankle pressure

Answer 17

Overestimate pressure when there is moderate disease and cannot detect severe disease

Question 18

Positive test for popliteal entrapment

Answer 18

ABI change > 0.5 with dorsi or plantar flexion flattening of plethysmography

Question 19

Ankle pressure in relation to height difference from right atrium to cuff

Answer 19

0.74 x increase with every cm

Question 20

cuff bladder length requirements to be used

Answer 20

length 80% of circumference width 40% of circumference

Question 21

Signs of a falsely elevated ABI

Answer 21

1) quality of doppler waveform 2) nonpalpable pulse when one expected 3) clinical picture does not fit 4) doppler diminish with ankle elevation

Question 22

Typical segmental systolic arterial pressure

Answer 22

TABLE 20.1

Question 23

Profundapopliteal collateral index (PPCI) interpretation

Answer 23

Difference between above knee and below knee pressure divided by above knee low index = good collateral < 0.25 = good result from profundaplasty > 0.5 = no improvement with profundaplasty alone

Question 24

Normal toe pressure

Answer 24

20-40 mmHg less than ankle pressure TBI > 0.7 normal

Question 25

Exercise test protocol

Answer 25

1) super 20 min 2) ABI measured 3) walk 2 mile/ehr on treadmill at 12 degree for 5 min 4) note time of symp, nature and time until stop 5) lie down and remeasure ABI q2min for 10 min

Question 26

Cut off for potential benefit of revascularization in mmHg drop from exercise test

Answer 26

20 mmHg

Question 27

Why is exercise not good for detecting infra popliteal disease

Answer 27

Sural branches to gastrocnemius come off proximally

Question 28

Reactive hyperemia

Answer 28

Occlusion of blood flow to extremity by tourniquet with BP cuff x 3-5 min Release and monitor ankle pressure q2-3min for 6 min Normal = returns to half within seconds then doubles compared to baseline PAD = half of resting value delayed; does not go above baseline drops like in exercise but comes back faster - less oxygen debt

Question 29

Which penile artery is for erectile function

Answer 29

Cavernosal artery proximal occlusion responsible for vasculogenic impotence

Question 30

Penile-brachial index for normal erectile function

Answer 30

0.75-0.8 \< 0.6 = diagnostic vasculogenic impotence

Question 31

Brachial-penil pressure gradient thats normal

Answer 31

20-40 \> 60 is arterial insufficiency

Question 32

Plethysmography

Answer 32

Measurement of change in volume of extremity caused by cyclic nature of arterial inflow

Question 33

Impedance plethysmography

Answer 33

Monitors electrical impedance = inversely proportional to volume

Question 34

Air plethysmography

Answer 34

monitors pressure in cuff placed around extremity and inflated to 65 mmhg

Question 35

Pulse volume recording normal appearance

Answer 35

1) rapid upslope 2) sharp systolic peak 3) dicrotic notch 4) downslope bows towards baseline

Question 36

Definition of pulse volume recorder categories at different levels

Answer 36

TABLE 20.2

Question 37

Photo plethysmography how it works

Answer 37

1) infrared light into tissue 2) detector for backscattered light 3) corresponds to variation of blood volume over time

Question 38

Pulse reappearance time after release of arterial occlusion based on location of lesion

Answer 38

TABLE 20.3

Question 39

Reactive hyperemia is a good test for what

Answer 39

Predicting response to sympathectomy since it requires sympathetic tone

Question 40

Other way to test if sympathetic innervation is intact

Answer 40

Decrease in pulse volume in response to a deep breath

Question 41

Transcutaneous oxygen tension key points

Answer 41

1) TcPO2 2) electrode at dorsal foot, AM aspect calf below and above patella, supraclavicular chest as reference 3) requires O2 sat to drop 80% before detection

Question 42

Factors affecting TcPO2

Answer 42

1) temperature 2) sympathetic tone 3) cellulitis 4) hyperkeratosis 5) obesity 6) edema 7) metabolic activity 8) oxygen diffusion through tissue 9) oxyhemoglobin curve 10) increased venous pressure 11) vertical position of site of measurement relative to heart 12) age

Question 43

Cut off for wound healing in TcPO2

Answer 43

\> 40 mmHg same for skin pressure pressure

Question 44

Laser doppler key points

Answer 44

1) monochromatic light to detect RBC 2) depth 1.5 mm from skin