30: Non-Invasive Arterial Exam - Mahoney Flashcards
____of BK amputations and ____ of AK amputations die in the hospital
5-10%
15-20%
5-year mortality rates:
PVD ___
Critical Limb Ischemia-___
Non-healing diabetic ulcer___
30%
64%
48%
describe segmental blood pressures
- Multiple cuffs along lower limb (mid thigh, above knee, below knee, above ankle)
- Measure systolic blood pressure at each cuff
- Pressure will decrease normally from mid thigh to ankle
signs of obstruction in segmental blood pressures
> 20-30mmHg difference between adjacent cuffs **
> 30 mmHg change along leg from thigh to ankle
> 20mmHg or more difference between opposite leg, same level
ABI =
Ankle Systolic Blood Pressure / Brachial Systolic Blood Pressure
successful healing ABI values
normal = 0.9 -1.3
successful values for foot surgery:
- Above 0.35 in arteriosclerosis
- Above 0.45 in diabetes (due to arterial calcification, diabetics often have falsely elevated values)
which arteries are measured in ABI?
- Measures arterial flow only to the ankle
- Perform it for both the dorsalis pedis artery and the posterior tibial artery
- Take the higher of the 2 readings
ABI normal intermittent claudication rest pain skin loss
- 9-1.3
- 7
- 5
- 3
If you are unable to occlude the vessel at ___ mm Hg, your pressure readings will be unreliable and the test is invalid.
200
stop the exam
A patient complains of pain in the right calf after walking 2 blocks, as well as calf pain at night while in bed. The ABI is most likely:
0.5
what do pitch and loudness tell you from doppler ultrasound?
Pitch – function of how fast blood cells moving – faster the cells move, the higher the pitch
Loudness – function of how many blood cells the waves hit – the more cells hit, the louder the sound
look at the doppler waveform picture. what does each peak mean?
Pressure and
flow velocity are directly
proportional to each other
A Ventricles contract, aortic valve opens
B Peak aortic pressure corresponds to peak flow velocity of vessels
C Ventricles relax, aortic valve is still open which decreases pressure in ventricle and blood flows backwards in large arteries
D Aortic valve closes, pressure increases in large vessels
E Return to diastolic baseline
Normal doppler waveform =
- triphasic (3 sounds and 3 peaks)
- Bidirectional
- Rapid upstroke/ downstroke
- Flow reversal
- Arterial wall rebound
mild obstruction doppler waveform
- biphasic (2 sounds and 2 peaks)
- Bidirectional
- Decreased peak height
- Partial loss of flow reversal
- Loss of arterial rebound due to calcification of artery
moderate and severe doppler ultrasound waveforms
Moderate obstruction
- Monophasic (1 sound and 1 peak)
- Rounding of upstroke/downstroke
- Decreased peak height
- Absent flow reversal
- Absent elastic rebound
Severe obstruction – (no sound)
- Loss of peak height
- Absent flow reversal
- Absent elastic rebound
Over the obstruction, the _____ is higher and the _______ is lower
pitch; loudness
– Number of cells passing through decreases, but those that pass through are moving faster
On either side of the obstruction, the ___ is lower and ____ is higher
pitch; loudness
- There is a greater number of cells collecting here, but there velocity is lower
- blood pooling here
absolute pressure for toe blood pressure for healing should be …
above 45 mmHg
toe-brachial index High healing potential Moderate potential Low potential Won’t heal
High healing potential = Above 0.6
Moderate potential = Above 0.4
Low potential = Above 0.2
Won’t heal = Below 0.2
Measuring and recording changes in volume over a short period of time
plethysmography
two ways of measuring:
- Infrared light and photocells: Photoplethysmography (PPG)
- Pressure cuffs: Pnuemoplethysmography or pulse volume recording (PVR) or pressure cuff recording (PCR) [not inflating, just sitting there as a measuring device]
describe how PPG works
- Infrared light source attached to pulp of toe
- Light is reflected from the skin as it changes color due to hemoglobin
- The greater the volume of blood, the more red cells, the more color change and the more defined the peaks
- Has a steeply rising upslope and sharp peak and distinct dicrotic notch
- Normal is 2 distinct peaks ***
Normal PVR ***
- Steep Upslope
- 1 Rounded Peak
- Dicrotic notch usually not present like it is in the arm and on PPG
Mild obstruction = Less steep upslope; Less distinct peak; Loss of dicrotic notch
Severe Obstruction = Delayed upslope; Rounded peak; Reduced peak height
how do you perform skin perfusion pressue?
Place the photosensor over the area of skin to be tested. Slowly deflate a tourniquet (toe, midfoot, ankle, calf) and note the pressure when the pulsatile flow returns
what skin perfusion pressure indicates PAD?
LESS THAN 30 mm Hg suggests critical limb ischemia and wound won’t heal
30-50 mm Hg indicates PAD
GREATER THAN 50 mm Hg indicates adequate perfusion to heal wounds
what does transcutaenous oxygen pressure TcPO2 measure?
- Measures partial oxygen tension on skin surface
- The more red blood cells to the skin, the more O2
- must be done with skin heated to 45 degrees C
- TcPO2 = arterial PO2
what TcPO2 is the best standard to use?
greater than 40 mmHg for good healing potential
most common site of arterial occlusion
mid-low thigh at hunter’s canal/ adductor canal
