Plethysmography (UE, LE) Flashcards
What does Plethysmography do?
Checks changes in volume PVR
What are the capabilities of plethysmography?
-In combination with Doppler segmental pressures helps differentiate true claudication from non-vascular sources.
- Detect presence/absence of arterial disease while defining tis functional aspects
- Helps localize the level of obstruction
What is PPG mainly used for?
Evaluation of digits and penile vessels
What are the limitations of Plethysmography (UE, LE)?
- Cannot be specific to one vessel
- Cannot discriminate between major arteries and collateral branches
- Difficult to perform on obese patients
How should the patient be positioned?
- Most exams can be done with the limbs in a resting position (supine)
*Patient can be sitting for evaluation of upper limb digits
What are the physical principles of plethysmography?
Volume (air) Plethysmography
** measurement of volume changes
A measured amount of air is sequentially inflated into a cuf to pressure ranging from _____________.
10 - 65, depending on cuff size
A pressure transducer converts the pressure changes into _____.
Analog waveforms that display on strip-charts
Chart paper speed = __________
25 mm/sec
What the amount of cuff pressure in diastole and systole?
Diastole: fixed
Systole: increases as arteries expand
What does a photo-plethysmography consist of?
Transducer, Amplifier, Strip-chart recorder
What does photo-plethysmography detect?
Cutaneous blood flow
What does photocell consist of?
light emitting diode and photo-sensor
What transmits infrared light into subcutaneous tissue with backscattered light reflected back to the adjacent photo sensor?
Diode
What determines the amount of reflection with photo-plethysmography?
cutaneous blood flow