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

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

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

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

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).

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)

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

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.

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

Normal Finger

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

Abnormal Finger

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

Abnormal Peaked Waveform

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

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?

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

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.

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.

Homework Chapter 10 Pages 107 – 114 SDMS assignments