1. Diagnostic Medical Sonography Program
Vascular Technology
Lecture 9: Digital Pressures and Plethysmography
Holdorf

2. Digit Plethysmography and Pressures
Capabilities
Help detect presence of arterial disease
Differentiate fixed arterial obstruction from vasospasm
Assess effects of treatment

3. Limitations
Quality of tracings greatly affected by the vasoconstricted state of arteries before testing begins. (Has patient: Come in from cold weather? Been Smoking? Nervous?)
With Volume Plethysmography, cuffs applied too tightly can obliterate or diminish the pulse wave forms
With Photo Plethysmography improper contact with skin surface will cause poor results
Bandages that can’t be removed; ulcerations and or gangrene may prevent placement of cuff or photocell
Patient with extremity tremor

4. Patient positioning Physical principles
Toe evaluation: Supine with some elevation of head
Finger evaluation: Sitting with arms resting on pillow placed on patient’s lap
Physical principles
Volume and photo plethysmography principles

5. Technique - Toes Patient should be kept as warm as possible
The study is done in combination with a complete LE arterial exam, or a limited version as an ABI
An appropriately sized cuff the width at last 1.2 times that of the toe (2.5 – 3 cm) is applied to base of great toe
Equipment does a self calibration when activated
Plethysmographic waveforms are recorded for all toes. ( If poor waveforms, warm the toes
Usual method of obtaining great toe pressures is PPG; (Photocell as end point detector).

6. Great toe pressures method
Digit cuff placed at base of great toe
Photocell securely attached to plantar side of toe using double-stick tape or Velcro strap
Pulses recorded: paper speed slowed to 5mm/sec (A)
While pulsations are recorded, cuff is inflated to 20-30mmHg above highest brachial pressure
No pulsations should be seen (B)
Cuff is slowly deflated, watching for return of first pulse to define the pressure level (C)

8. Technique: Fingers without cold stress
Upper extremity arterial study is completed initially
Evaluate Doppler signals (triphasic, biphasic, monophasic) and obtain pressures
Doppler exam of the palmer arch to verify patency
Apply finger cuffs (sized: 2 – 2.5 cm)
Pressures and waveforms obtained, using similar method described for toes

9. Technique: Fingers with cold stress
Performed in cases of symptoms occurring due to cold sensitivity (Toes can also be evaluated).
After resting stud is performed , hands are immersed in ice cold water for 3 minutes if possible.
Following cold stress, waveforms and pressures are obtained: immediately after and five minutes after
Document patient symptoms, skin color observations and other pertinent findings on the report form.

10. Interpretation Normal waveform qualities: Sharp upstroke peak systole
Prolonged down-stroke with notch (reflected wave) approximately half way down
Amplitude is usually greater than toe tracings

11. Normal Finger

12. Abnormal Obstructive waveform qualities
Occlusion located anywhere proximal to the tip of finger causes the pulse to assume an “obstructive” form
Slow upslope to rounded peak
Downslope that bows away from baseline

13. Abnormal Finger

14. Abnormal peaked waveform qualities:
Upslope is slower than normal
Sharp (anacrotic) notch is present
Reflected wave located high on the downslope
Has characteristics of both normal and obstructive waveforms

15. Abnormal Peaked Waveform

16. Following cold immersion, abnormal cold sensitivity is likely if the amplitude fails to return to baseline levels within 5 minutes.

17. Lecture 9 additional notes Digit Plethysmography and Pressures
Quality of tracings greatly affected by the vaso-constricted state of arteries before testing begins.
Has the patient come in from cold weather?
Been smoking?

18. You want to increase the volume of blood
Again, records volume changes .
Example:
Inflate cuff
Increase the volume of blood
Release air
When the pulse begins, that is the systolic pressure
In the example it is about 70

19. Technique: Fingers with cold stress
Following cold stress, waveforms and pressures are obtained: immediately after and five Minutes after.
MOST IMPORTANT.
With Raynaud’s will not stabilize. Do not do
Do a waveform immediately after. Wait 5 minutes. If ok, then ok. If Raynaud’s, then will
Not be ok after 5 minutes.
Pressures immediately after are useless.

20. Abnormal PEAKED waveform qualities.
If the waveform is PEAKED, then this is positive for a vasospastic problem. 100% Raynaud’s.
No need to put the patient’s hands in the cold water to test.
This Peaked waveform is taken with a PPG sensor.
Digit pressure measurements
Fingers are different than toes.

21. Homework
Chapter 10
Pages 107 – 114
SDMS assignments