Powerpoint 1 Upper/Lower Extremity Indirect Arterial Eval Flashcards
1
Q
Doppler Waveform analysis capabilities: (4)
A
- helps confirm dz (arterial occlusive)
- helps show severity of occlusion pre to post exercise
- obstruction location
- f/u on dz progression/results
2
Q
Doppler waveform analysis limitations
A
- casts/bandages NO
- ambient temp (room temp) can affect waveform
- uncompensated CHF can cause dampened waveforms post exercise
- can’t tell tight stenosis from occlusion
- can’t localize obstruction
- test tech dependent - correct doppler angle impt
3
Q
LEA patient position?
A
- supine, decubitus, or prone
- extremities same level as heart
- hips rotated out
- knee slightly bent
- can use deuce if trying to get PopA
4
Q
UEA patient position?
A
Arms at side and relaxed
5
Q
Doppler Exam what kind of probe (frequency)
A
8-10 MHz
6
Q
PO or CW Doppler utilized … what kind of angle to the skin … why does this angle work?
A
CW… 45 to 60 degrees… most peripheral arteries parallel to skin so it works
7
Q
these two modes usually utilized for doppler exam
A
analog velocimetry or spectral analysis
8
Q
with analog recording, what is used (2)
A
with analog recording, a zero-crossing frequency meter used and strip chart recorder
9
Q
with analog recording, the machine estimates what and counts what
A
estimates the reflected signal frequency and counts how many times the signal crosses the zero baseline
10
Q
with analog recording, the tracings record what over time
A
record the amplitude of Doppler frequencies
11
Q
with analog recording, what are DISADVANTAGES (6)
A
- spectral analysis is more sensitive than analog
- noise
- less sensitivity
- underestimates high velocities
- overestimates low velocities
- most analog systems self calibrate
12
Q
with spectral analysis, this method displays what
A
with spectral analysis, this method displays frequency over time and the amount of backscattered signals at a given frequency and time
13
Q
with spectral analysis, it does not have these drawbacks
A
does not have analog drawbacks
14
Q
with spectral analysis, amplitudes are shown at what frequencies
A
all frequencies
15
Q
with spectral analysis, is it more or less sensitive displaying multiple frequencies
A
more sensitive
16
Q
where should doppler velocity waveforms should be obtained at what levels for LEA (6)
A
common femoral artery (at groin)
femoral artery (mid thigh)
politeal artery
posterior tibial artery
dorsalis pedis artery (top of foot)
peroneal artery (if necessary) @ lateral malleolus
17
Q
where should doppler velocity waveforms be obtained at levels for UEA (5)
A
subclavian artery (supraclavicular)
axillary artery (axilla)
brachial artery (@ elbow)
radial artery (@ wrist)
ulnar artery (@ wrist)
18
Q
some improper sources of error when dopplering arterial
A
improper position of probe, moving probe on accident, wrong angle, not enough gel, too much pressure on probe tip, pt needs more rest before testing
19
Q
qualitative interpretation (normal) waveform is: (what kind of waveform, what kind of peak, what kind of stroke, what kind of waveform below baseline, what kind of resistance)
A
triphasic or multiphase waveform, sharp peak, rapid downstroke, short peak below baseline, high resistance pattern
20
Q
qualitative interpretation (abnormal) waveform is: (what kind of waveform)
A
monophonic, nonpulsatile, absent, a change from triphasic to biphasic or monophasic, no changes should be noted from one level to another
21
Q
can you determine the DEGREE of obstruction on the basis of JUST WAVEFORM?
A
NO
22
Q
Stenosis and occlusion with good collateralization will cause
A
similar waveforms distal to stenosis
23
Q
waveform analysis: monophasic flow occurs
A
can occur proximal AND distal to stenosis
24
Q
waveform analysis: if no other obstructions are present distally, a monophasic waveform may
A
NORMALIZE TO A CERTAIN EXTENT
25
waveform analysis: monophasic can be present anytime there is (2)
there is vasodilation and blood is going to a low resistance vascular bed
26
effect of exercise, normal post exercise waveforms: (2)
postexercise waveforms normally maintain or augment pre exercise waveforms with all waveform components usu depicted above baseline
element of arterial vasodilation does occur even in normal post exercise state
27
effect of exercise, abnormal post exercise waveforms:
slow upstroke w more rounded peak
slow downstroke
no reverse component
28
absence of doppler signals suggests what
OCCLUSION... suggest a preocclusive vessel
29
in the absence of doppler signals... CW Doppler cannot detect flow slower than? In a preclusive vessel this would be known as what
6 cm/sec... known as a string sign
***SOME systems can show these slower flows
30
Upper extremity arterial flow: normal subclavian artery flow:
multiphasic, high resistance flow
31
Upper extremity arterial flow: abnormal subclavian artery flow:
similar to lower extremities w proximal or distal obstructions
32
what causes flow patterns in the hand to vary a lot?
arteriovenous shunts in the skin in the fingertips
33
what kind of waveforms can be seen in relaxed and warm brachial, radial, and ulnar arteries? a cool hand will have what kind of flow
continuous low resistance waveforms
COOL hand will have higher resistance
34
several quantitative methods for arterial flow signals (4)
pulsatility index
inverse damping factor
acceleration time
transit time
35
Pulsatility Index or PI = what to what
Peak to Peak... (mean frequency)
36
Pulsatility Index... from central to peripheral arteries, how does PI change?
it increases
37
what does the increase in PI from central to peripheral arteries help identify
it helps differentiate inflow from outflow dz
Example:
CFA PI >5.5
Popliteal artery PI is approx 8.0
Values decrease w proximal occlusive dz
38
this graph represents what quantitative method for arterial flow signals ?
pulsatility index (PI) = peak-to-peak
39
Inverse Damping Factor define... Also, Damping factor indicates the degree to which...
ratio of distal PI to the proximal PI of an arterial segment
indicates the degree to which wave is dampened as it moves through an arterial segment
40
Ex of damping factor - normal inverse femoral popliteal damping factor
should 0.9 - 1.1
41
Acceleration time helps differentiate what...? It is based on what principle
It helps differentiate inflow from outflow dz... it is based on the principle that arterial obstruction proximal to site of the Doppler probe lengthens the time between onset of systolic flow to the point of max peak in waveforms at the probe site.... BASICALLY... IF PROLONGED THERE IS DZ DISTAL TO THE PROBE
42
Acceleration time is used only with what kind of Doppler?
only spectral analysis
43
Can you have false positives with acceleration time? If so how
Yes... if large angle or poor cardiac output
44
In the CFA, an acceleration time of > or equal to _______ suggests the presence of significant iliac dz
133 msec in CFA
45
Can you use acceleration time value alone to determine dz?
NO, use with waveform eval
46
Transit time... what should happen bilaterally during systole?
systole should be evident simultaneously at the specific site bilaterally
ALWAYS COMPARE SIGNALS BILATERALLY @ SAME SITE
47
With transit time, a delay on one side may indicate
may indicate a more proximal occlusive process... ALWAYS COMPARE SIGNALS BILATERALLY @ SAME SITE
48
Segmental pressures capabilities: identifies what, provides what, evaluates what, results should be COMBINED?
1. identifies if and how bad occlusive arterial dz is
2. provides baseline to follow progression of dz process
3. evaluates treatment plan
4. results should be COMBINED w Doppler analysis or PVRs
49
Segmental pressures limitations: (7) ... can identify type of arterial dz? can it show false reading? post exercise could show what? narrow cuff is a problem? when would it be hard to interpret pressures?
1. can't tell diff between stenosis/occlusion
2. General site only, not specific
Ex. hard to differentiate between external iliac and common femoral dz
3. patients with dz like DIABETES or END STAGE RENAL DZ... it may show falsely elevated Doppler pressures in those pts BC they have calcified vessels.....
4. May show decreased ankle/brachial indices post exercise in pts with uncompensated CHF
5. If cuff is too narrow, may show artifactual elevated high thigh pressures
6. multilevel dz makes it hard to interpret info
50
patient prep: whats most important aspect... just walking into office could do what??? also imps to have patients limbs what if its cold (if taking segmental pressures)
most important aspect is allowing patient to rest for a minimum of 20 mins prior to test ... just the walk into office could cause decreased blood flow... imps to have patients limbs warm if its cold out
51
Segmental pressures technique: one or both sides... where at? how large of bladders? what frequency Doppler?
bilateral BRACHIAL pressures
cuffs with 12 x 40 cm bladders
8-10 MHz Doppler used
52
With segmental pressures... there are two methods used for cuff placement...
Four cuff and. three cuff
53
Segmental pressures: The four cuff method uses how many thigh cuffs?
two thigh cuffs
54
Segmental pressures: explain an advantage and list disadvantages of the four cuff method
advantage: provides proximal and distal thigh pressure measurements
disadvantage: artifactual elevated pressure obtained, high thigh usu 30mmHg HIGHER than brachial, large girth of thigh with TOO NARROW cuff could cause increase
55
What size cuffs and where can you place for the FOUR CUFF METHOD
12 x 40 cm cuffs...
high thigh
above knee
below knee
at ankle
(cuff size may vary according to limb)
56
Segmental pressures : Explain cuff placement...
straight on limb
snug
loose could mean false pressures
widths of cuffs should be 1.2 x greater than limb diameter
57
Segmental pressures : Too narrow cuff size will result in
falsely elevated blood pressure, too wide pressure will be falsely low
58
Segmental pressures : What is the three cuff method
one large thigh cuff placed as high as possible on thigh
size is 19 x 40, which satisfies width-girth relationship
more accurate this way
countoured cuff ideal bc similar shape to thigh
59
Segmental pressures LEA obtained in this order : (4)
obtained bilaterally in this order:
ankle (PTA and DP)
below knee (PTA and DP)
above knee (PTA, DP, or pop there is difficulty)
high thigh (same as above knee)
60
Study this pic
61
Starting from the CFA. and moving down to the ankle with segmental pressures is a big NO NO. Why?
This may cause a pressure drop and cause an underestimation of pressure... this is a reactive hyperemia response
62
Limited Study: ABI may be obtained if a full extremity study
is not required
63
Limited Study: _____ or _____ can be used
PTA or DP... if the other two sites are not available what may be used?
peroneal artery* can be used if other two sites not available
64
Segmental pressure LEA: Arterial signal is completely occluded when cuff is inflated about _________ mmHG over last audible Doppler signal
20-30 mmHg
use higher. brachial pressure as a guide for target cuff inflation
if the pressures need to be repeated, wait ONE MINUTE (at least)
65
with pulsatility index, values _________ with proximal occlusive dz
DECREASE
66
Acceleration time is a prolonging of time between
systolic flow to the point of maximum peak in waveforms when there is arterial obstruction PROXIMAL to site of Doppler probe
*** not prolonged when disease distal to probe
large angle or poor cardiac output can cause false positive
67
what is the acceleration time that suggests the presence of significant iliac dz
> or equal to 133 msec
68
transit time - what should be evident simultaneously at a specific site bilaterally?
SYSTOLE
69
reactive hyperemia is basically what
GYM PUMP... think what happens to blood supply to the tissues
70
with LEA segmental pressure, record the __________ audible Doppler signal
first
71
with LEA segmental pressure, any comments about study should be recorded like...
-can't tell arterial from venous signal
-uncooperative patient
-inability to distinguish signal
-inability to occlude signal
72
ABI stands for
ankle brachial index
ankle blood pressure divided by arm blood pressure
73
what is a normal value for ABI
> 1.0 = normal
74
what are abnormal values for ABI
0.9-1.0 = asymptomatic obstructive dz AKA minimal arterial dz (many consider this still normal)
0.8-0.9 = mild arterial dz
0.5-0.8 = claudication (moderate dz)
<0.5 = rest pain; severe arterial dz
75
PVR stands for what and means what
uses a blood pressure cuff and hand-held Doppler ultrasound device to determine the presence and severity of peripheral artery disease (PAD).
76
Patients with rest pain usu have ABIs that are below what value?
<0.5 or ankle pressure of <50mmHg
> or equal to 0.5 suggests single segment involvement
<0.5 ABI suggests multiple lesions
77
interpreting segmental pressures: a decrease in pressure greater than 30mmHg between 2 consecutive segments suggests
significant obstruction (some say 20 mmHg)
78
interpreting segmental pressures: a horizontal difference between legs of 30mmHg suggests
significant obstruction dz as well, the lower pressure leg being abnormal
79
interpreting segmental pressures: if horizontal difference in pressure that suggests obstruction, the obstruction dz is at what level of the leg ?
it is AT or ABOVE the level with the lower pressure
80
interpreting segmental pressures: as limb girth increases ankle to thigh.... so do
pressures
81
interpreting segmental pressures: four cuff method... how much higher is high thigh than brachial
30mmHg
82
interpreting segmental pressures: four cuff method - above the knee and below the knee are about what compared to brachial
about the same
83
interpreting segmental pressures: thigh indices values are what
normally > 1.2
abnormal thigh indices 0.8 - 1.2 suggests aortoiliac dz
<0.8 proximal occlusion is likely
84
See pic: is this pt normal or abnormal
normal
85
See pic: is this pt normal or abnormal
Abnormal... LLE dz prox to CFA
86
interpreting segmental pressures: three cuff method - thigh cuff pressure is similar to _______ ... no segmental info on thigh?
similar to brachial
no segmental info on thigh is allowed
87
in patients with foot and toe ulcer that fail to heal... what kind of toe pressures?
toe pressures of 30mmHg or less
88
ankle pressures are not always reliable, esp in diabetics... why? use what pressure instead of ankle pressure
because their vessels are calcified and may show falsely elevated Doppler pressures
use toe pressures in these cases... more reliable
89
normal toe pressures are what % of ankle pressure
80%
90
what is claudication again
a condition in which cramping pain in the leg is induced by exercise, typically caused by obstruction of the arteries.
91
what is the preferred method of LEA exercise and reactive hyperemia....what are the capabilities of this test
treadmill
-compare exercise w resting values
-helps differ between true and false claudication
-determines presence/absence of collaterals
92
Contraindications/limiations for exercise testing LEA
SOB, HTN, Cardiac problems, Stroke, walking problems
93
Exercise testing LEA technique for treadmill: first do this. then have pt walk @ what elevation and how fast for how long
obtain resting values FIRST. then pt walks on constant load treadmill @ < or equal to 12% elevation at 1.5 mph for 5 mins max or until symptoms make them stop
94
Exercise testing LEA: get what immediately post exercise
ABIs
95
Exercise testing LEA: which brachial pressure has to be repeated
the higher one
96
Exercise testing LEA: which limb should you do first the symptomatic or asymptomatic one
symptomatic
97
Exercise testing LEA: get ankle pressures every ____ minutes until what is obtained
pre exercise pressures (may take 20 mins)
98
Exercise testing LEA: interpreting based on
length of time to recover
symptoms
duration of exercise
pressure changes from pre to post exercise
99
Exercise testing LEA: pts with signifiant obstructive dz have a pressure drop that is ____________ to severity of dz
proportional
100
Exercise testing LEA: single level obstruction exercise interpretation - ankle pressure drops to
drops to low or unrecordable levels immediately after exercise
2-6 mins back to normal
101
Exercise testing LEA: what is an alternate method for stressing pt
reactive hyperemia
102
Exercise testing LEA: exercise interpretation - multilevel obstruction - ankle. pressure drops to low or unrecordable levels immediately after exercise and then what
they remain that way for 6 mins or more... may have unrecordable pressure for up to 15 minutes
103
Exercise testing LEA: when is reactive hyperemia used
when pt cannot walk long enough
when pt uses cane or walker
when pt has pulmonary problems
when pt has poor cardiac status
104
Exercise testing LEA: reactive hyperemia technique is
thigh cuffs inflated 20-30 mmHg above higher brachial pressure, maintained of 3-5 minutes... this produces ischemia/vasodilation distal to cuff... get pressure when?
after cuff released
105
Exercise testing LEA: interpreting reactive hyperemia... transient ________ ________ from 17-34% does occur at ankles of normal limbs after reactive hyperemia
pressure decrease
106
Exercise testing LEA: reactive hyperemia <50% drop in ankle pressure means
> 50% drop in ankle pressure means
<50% drop in ankle pressure means single level dz
>50% drop in ankle pressure means multilevel dz
107
Exercise testing LEA: other forms of exercise and limitations
-walking the hallway set distance
-toe raises... limitations are you can't tell distance with toe raises, can't tell cardiovascular response of pt stops
108
segmental pressures UEA same capabilities and limitations of LEA?
YES
109
UEA segmental pressures: same cuff requirements as for LEA... use what artery for upper arm and what artery for forearm
brachial for upper arm
radial or ulnar for forearm
110
What is an allen test, when is it performed
Can be performed with UEA exam. Doppler waveforms/segmental pressures
Allen test evaluates patency of wrist arteries and palmar arch
111
When would an allen test be useful
If they were going to use radial artery for bypass graft or for procedures (dialysis/angiography)
112
Limitations of allen test (2)
Excessive dorsiflexion of wrist
Hand open, fingers forcibly extended
113
Limitations of allen test; excessive dorsiflexion would do what and cause what kind of result
Excessive dorsiflexion could compress radial or ulnar artery as they cross the wrist, causing a FALSE - POSITIVE RESULT
114
Limitations of allen test; hands open, fingers forcibly extended would be an issue because
Skin over palm is stretched, and small vessels are compressed; pallor can occur as result
115
Allen test… stand up and act it out (4 steps, if documentation is required… what is needed?(
1. Palpate radial artery at wrist
2. Apply manual compression
3. Have pt clench hand in tight fist
4. Have pt relax hand
***may do with or without PPG, PPG is needed if documentation is required
116
What is this pic
Allen test
117
Allen test using PPG (5 STEPS)
1. Put sensor on digit #2 w double stick tape
2. Use recorder at 5 mm/sec speed
3. Get baseline
4. Do compression
5. Get tracing after pt relaxes hand
118
Allen test interpretation… what’s normal look like
Normal is
Hand coloration goes very pale as hand is clenched in tight fist, normal skin color returns when hand relaxes… what does this mean? Means palmar arch is patent with ulnar artery inflow
119
What’s an ABNORMAL allen test interpretation look like
Hand does not return to normal color when relaxes… obstruction is in where? It is in distal ulnar artery or palmar arch…. This is called “radial artery dependent”
120
With an abnormal allen test interpretation, you can have one of two arteries be “dependent” depending on what technique you use… or what artery you compress.
“Radial artery dependent” if you compress radial artery and there is no blood flow (means there is obstruction in distal ulnary artery or palmar arch
Or
“Ulnar artery dependent” if you compress ulnar artery and there is no blood flow (means ther is obstruction in distal radial artery or palmar arch
121
What does transcutaneous oximetry do
Helps determine wound healing and amputation level… it also reflects tissue oxygen tension…
What does the tissue oxygen tension depend on?
Depends on balance between oxygen supply and consumption
122
With transcutaneous oximetry, what are some limitations (5)
1. Inability to keep electrode flat on skin
2. Skin no intact or is too edematous (edema) for electrode placement
3. Pt can’t lie quietly/still for up to 20 mins
4. Tech depenedent
5. Can be hard to interpret findings
123
Transcutaneous oximetry reflects what
Reflects tissue partial pressure of oxygen, depends between oxygen consumption and supply, skin surface can be used to measure PO2 w/in 1-2%
124
Random facts about transcutaneous oximetry… electrode has what kind of element… what temp… what happens to blood flow… something happens to lipid layer… skin PO2 is usually near what number…. Capillaries do this and affect blood flow and oxygen which allows the whole thing to occur
- electrode has heating element
- heats skin to 44-45 degrees C
- blood flow increases
- lipid layer in fatty tissue melts
- skin PO2 usu near zero
- vasodilation in capillaries increases blood flow, raising oxygen content and allowing measurement at skin surface with sensor in electrode
125
Technique for transcutaneous oximetry
Clean skin site w alcohol/wipe
Self-adhesive molded plastic fixation ring applied to intact skin
Few drops electrolyte solution put inside plastic ring
Electrode sensor put on skin and turned into fixation ring
Manual calibration
PO2 readings taken 15-20 mins after stabilization
Upper left chest (reference reading) obtained first
Readings obtained at specific sites near wound or amputation level
126
For transcutaneous oximetry, don’t put sensor on (4)
1. Edematous skin
2. Ulcers
3. Areas of cellulitis
4. Skin close to bone
127
Oximetry technique… if PO2 is poor, do instead and what should increase
Do with oxygen challenge instead..
Apply electrode to chest and interest site
Oxygen from face mask given to pt
Get values again
Chest electrode should always increase after challenge
128
Interpreting transcutaneous oximetry… what is normal / poor / critical levels
Normal PO2 is >50mmHg on foot
Poor PO2 is <40mmHg… (would impair or prevent wound healing)
Critical limb ischemia <30mmHg or sometimes <20mmHg
This would be seen with rest pain, gangrene or ulcers
129
Transcutaneous oximetry… interpretation for amputation and ulceration level
For amputation level:
If poor level obtained move electrode more proximally (repeat until better level obtained)
For ulceration:
Poor level indicates wound will not heal
130
Transcutaneous oximetry… what are some factors that affect measure tcPO2 (4)
Arterial PO2
Skin blood flow
Skin composition
Capillary temperature
131
Laser Doppler capabilities (2)
Determine healing potential of wound/ulcer
Determine healing potential by amputation level
132
What does laser doppler do? Signal is turned into what and represents what?
Uses optical waves delivered to the skin to illuminate tissue to include both moving and stationary red blood cells
Scattered light from moving cells is collected
Signal turned into PVR to represent microvascular blood volume
