Page 293 - Libro 2

17 — Venous Valvular Insufficiency Testing
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Diagnostic Criteria
Venous recovery time or refilling time (VRT) is the parameter measured during PPG. VRT is usually measured from the end of flexion/relation period to about 90% to 95% of the distance between the bot- tom of the curve and the baseline tracing. Recovery time is usually greater than 20 seconds.
Venous reflux is suspected if the PPG tracing takes less than 20 seconds to return to baseline. Severe reflux may be suggested if the recovery time is less than 10 seconds.
If results are abnormal, the use of a tourniquet prox- imal to the PPG location may indicate a superficial or deep vein source for reflux. With a tourniquet in place over the GSV in the thigh, if the VRT returns to normal, then GSV incompetence is suspected. If the recovery time remains abnormal with the use of the tourniquet, then a deep vein reflux is suspected. Similar principles are applied to the detection of a small saphenous vein reflux. With a tourniquet placed in the upper third of the calf, if VRT normalizes, then SSV reflux is likely.
AIR PLETHYSMOGRAPHY
APG is a recommended technique for quantification of chronic venous insufficiency.41 Clinically, APG can be used to detect physiologic abnormalities to clearly differentiate a pathophysiologic condition from an apparent aesthetic problem. A comparison between serial APG testing can demonstrate and quantify disease evolution. A comparison between pretreat- ment and posttreatment APG testing can demonstrate immediate quantifiable improvement, particularly in patients in the C4B, C5, and C6 clinical CEAP catego- ries showing skin changes that are not readily modi- fiable. Immediate and long-term posttreatment APG testing can be used to demonstrate either improve- ment due to treatment or disease evolution.
Patient Position
Patient training and performance is paramount to obtaining reliable results. The patient is asked to perform a series of maneuvers requiring the move- ment from supine to standing positions. The specific positions are described in the following section that discusses these particular techniques.
Technique and Required Documentation
An APG examination is conducted as follows with particular care in the use of specific patient position sequencing:
• The subject rests supine to relax while receiv- ing instructions and providing information per- tinent to the test
• The sensing cuff is wrapped around the calf and is inflated to 10 mm Hg
• The leg is elevated to optimize emptying of venous volume
• The leg is brought back to a horizontal position; pressure in sensing cuff is readjusted to 10 mm Hg; in and out 100 mL calibration is performed with syringe
• The patient stands over the nontested leg hold- ing onto a support structure and relaxing the leg being tested (a difficult task in this standing position)
• The patient rests the foot of the leg being tested on the floor and performs one toe raise, then relaxes; this movement is optional in a short protocol
• The patient performs 10 toe raises and relaxes • The patient returns gently to the horizontal
position
The following simplified APG measurements are
recommended:
• Blood venous volume (VV; in milliliters) ac-
cumulated in the veins once the patient moves
from a supine to a standing position
• Filling time (FT) demonstrating how long it takes to accumulate blood in the calf to 90% of
VV once the patient stands
• Volumetric filling rate indicating blood accumu-
lated per unit time (90% VV/FT in mL/s) as
complement to filling time
• Residual volume (RV) measured as a percent-
age of venous volume (100 􏰃 RV/VV in %) indicating how much volume is pumped from the calf after 10 toe raises.
An extensive APG testing would also include:
• Measurement of the ejection fraction as a complement to a “residual volume” testing
following one toe raise
• Total blood volume accumulated in the calf of
a supine patient once a pneumatic cuff placed
around the thigh is inflated to 80 mm Hg
• Volumetric emptying rate measured after the
pneumatic cuff is deflated
• Differentiation of data from superficial and
deep veins by repeating tests with a tourni- quet applied around the knee, for example, to minimize the influence of the superficial veins.
Required documentation for the APG testing includes the tracings obtained during the various maneuvers. The tracing should illustrate the stable baseline at the bottom of the chart; the 100 mL calibration pulse; the exponential filling curve with the estimate of the venous volume VV, FT, and fill- ing rate (90% VV/FT); the one toe raise curve for calculation of the ejection fraction (optional in the