Plethysmograpy for Venous Testing
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Plethysmography uses what type of sonography?
Uses: 2 crystals- 1 receiving and 1 sending
What is the disadvantage of Plethysmography? (2)
- 1.) display the average of the frequency shifts.
- 2.) any small movement or Bump can cause inaccurate results.
What is the advantage Plethysmography? (2)
Sensitivity to flow are better
What is considered normal venous refill time?
Greater or equal to 20 seconds.
What is considered abnormal venous refill time?
Less than 20 seconds
What are 3 things that can cause abnormal venous refill time?
- 1.) reflux
- 2.) Incompetant valves
- 3.) Venous insufficiency
What are 6 types or what Plethysmography can be used for?
- 1.) arterial testing
- 2.) Venous outflow
- 3.) Impedance plethysmography (IPG)
- 4.) Strain-Gauge (SPG)
- 5.) Air-cuff or Pneumoplethysmography
- 6.) Photo Plethysmograph (PPG)
What are the steps for arterial testing using Plethysmography? (4)
- 1.) PPG probe attacked to the distal medial calf to check for venous reflux.
- 2.) Patient dangles legs to pool venous blood.
- 3.) Dorsiflex the foot 5 times which empties veins by the calf muscles.
- 4.) The patient relaxes allowing blood to pool up again.
What tests do Venous Outflow Plethysmography use?
- 1.) IPG
- 2.) SPG
- 3.) Air cuff or pneumoplethysmography
What does venous Outflow plethysmography test for?
- 1.) the ability of the veins to pool blood will be diminished greatly.
- 2.) The outflow of blood from the lower extremity will be slowed considerably.
What are the steps to venous outflow plethysmography?
Thigh cuff is inflated to 50-60 mmHg to pool blood for a few minutes then emptied quickly to allow blood to rush out.
What is the steps to Impedance Plethysmography? (4)
- 1.) Electrodes are placed about 10 cm apart on the proximal calf
- 2.) A small current is sent through this segment and the changes in impedance to this current are recorded on chart paper.
- 3.) More blood in the segment, makes impedance drop: this is recorded as a rise on the chart to suggest venous filling when the thigh cuff is inflated.
- 4.) When the thigh is deflated and the accumulated blood rushes out of the segment, the impedance goes back up and the tracing drops.
What are the steps of Strain-Gauge (SPG)? (2)
- 1.) A thin tube filled with mercury or some other metal alloy is wrapped around the proximal calf and connected with the instrument.
- 2.) Thigh-cuff inflation and venous filling causes the volume in the calf to increase, which causes the stretching of the strain gauge.
What are the steps of Air-cuff or Pnemoplethysmography? (5)
- 1.) A cuff is wrapped around the proximal calf and connected to a pressure transducer.
- 2.) A small amount of air is put into the cuff to provide a baseline pressure with thigh-cuff inflation and venous pooling.
- 3.) As the calf gets bigger it increases the pressure inside the calf cuff.
- 4.) The pressure transducer records the increase as a rise on the chart paper to suggest venous filling.
- 5.) With outflow, the calf size again decreases, the pressure in the calf cuff drops and the trace drops.
What can Photo Plethysmography be used for?
- To document venous insufficiency/quantitate venous reflux in patients with..
- 1.) chronic swelling
- 2.) venous ulcers
- 3.) varicose veins
When should photo plethysmography NOT BE USED?
- 1.) If patient has acute DVT
- 2.) Improper placement of PPG sensor (over varicose vein)
- 3.) Thickening of skin may present adequate penetration of infrared light.
- 4.) Intact skin required for sensor placement.
What is considered TRUE PLETHYSMOGRAPHY?
measures the volume changes from all vessels under the sensor from both arterial and venous systems.
Is Photo Plethysmography considered true or not true?
Not true Plethysmography
It only detects blood flow in the cutaneous blood vessels.
What does IPG stand for?
What does SPG stand for?
What does PPG stand for?
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