Plethysmography Flashcards
T/F
Plethysmography has more to do with volume change then with actual ultrasound
True
With combination of Doppler segmental pressures, plethysmography has these 3 capabilities
- Differentiate true claudication from non-vascular sources
- Detects the presence/absence of arterial disease
- Help localize the level of obstruction
a limitation that plethysmography has is the inability to distinguish between major arteries and ____
Collateral branches
As far as patient position goes for plethysmography, most exams have patients _____ with limbs in resting position, however, patient can be _____ for the upper limb digits
Most patients SUPINE
Upper limbs can have patient SITTING
Measurement of volume change is the key principle for this?
Volume (air) plethysmography
With plethysmography, pneumatic cuffs are placed around specific levels of extremities or digits. Cuffs are inflated by a _______ of air with pressures ranging from ___ to ___ mmHg (depending on cuff size)
Inflated by a MEASURED AMOUNT of air
Pressures rang from 40 to 65 mmHg
As arterial flow moves under the cuff, _______ in the limb segment occur, which is converted to ___________ within the air-filled cuff bladder
Momentary VOLUME CHANGES in the limb occur
Converted to PULSATILE PRESSURE CHANGES
How do we get the pressure changes documented with the plethysmography on the strip for chart record
A pressure transducer CONVERTS the pressure change into ANALOG waveforms
**chart paper speed = 25mm/sec
During a plethysmography exam the cuff can be described with different charectoristics during diastole/systole
During _____ there is a fixed amount of air pressure in the cuff and during _____ the air pressure in the cuff increases as arteries expand
DIASTOLE = fixed amount of air pressure in cuff SYSTOLE = Air pressure in cuff increases as arteries expand
What three things are used in a photo-plethysmography (PPG) study
Transducer
Amplifier
Strip-chart recorder
A PPG uses what kind of light to detect cutaneous blood flow?
Infrared light
With PPG, ____ consists of light emitting diode and photo-sensor
Photocell
____ transmits infrared light into subcutaneous tissue with backscattered light REFLECTED BACK to the adjacent _____
DIODE transmits the infrared light
Light reflected back to the adjacent PHOTO-SENSOR
What determines the amount of reflection with PPG
The cutaneous blood flow
_____ blood flow = ____ attenuation which _____ this reflection
INCREASE blood flow = INCREASE attenuation
This DECREASES reflection
THIS IS A GOOD THING displayed as a positive upstroke of the waveform
With volume PPG, patient is supine with heels slightly elevated on a cushion and appropriate cuffs on extremities, how many pulse cycles should be recorded?
Atleast 3 cycles
Define the following as either NORMAL, MILDLY ABNORMAL, MODERATELY ABNORMAL, and SEVERELY ABNORMAL.
- Flattened systolic peak, upslope and downslope more delayed, reflected wave (notch) absent.
- Fairly rapid upslope, sharp systolic peak with reflected wave
- Low amplitude or absent
- sharp peak, absent reflected wave, downslope bowed away from baseline
NORMAL = fairly rapid upslope, sharp systolic peak with reflected wave
MILDLY ABNORMAL = sharp peak, absent reflected wave, downslope bowed away from baseline
MODERATELY ABNORMAL = Flattened systolic peak, upslope and downslope more delayed, reflected wave (notch) absent.
SEVERELY ABNORMAL = Low amplitude or absent
This is the reflection of the downslope
Dicrotic notch
Abnormal waveforms always reflect hemodynamically significant disease ____ to the level of tracing
PROXIMAL
If there is reduced amplitude with no changes in the contour, it is most likely an insignificant disease unless…….
Unless it is unilateral
What might be the reason for a waveform to be fairly normal (sharp upstroke and narrow peak) but abnormal segmental pressures (absent reflected wave/notch)
Collaterals
**there is good profusion, but the reflection is absent due to the presence of colleratals
Which vascular structure uses AC mode and which one uses DC mode
AC mode is used for arterial
DC mode is used for venous
