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274 PART 4 — PERIPHERAL VENOUS
limited protocol); the 10 toe raise curve with the estimate of the RV; and the return to the baseline showing a posttest baseline curve deviating from the pretest baseline curve by no more than 5% to 10% of the VV.
Diagnostic Criteria
Normal values for VV are variable and will be de- pendent on gender, age, and other characteristics. Normal FT should be longer than 25 seconds. The venous filling rate (FR) should be less than 2 mL/s. The RV is normally less than 20% to 35%.
Abnormal findings include a very low VV, which may indicate a calf venous thrombosis or chronic obstruction. A high venous volume greater than for example, 100 mL should indicate abnormally high venous pooling due to large veins or numerous veins. An FT shorter than 10 seconds indicates se- vere reflux, whereas an FT shorter than 25 seconds suggests mild-to-moderate reflux. An FR greater than 2 mL/s indicates venous insufficiency, and ranges of this variable have been coarsely related to severity of venous diseases. An RV greater than 20% to 35% has been associated with increased ambulatory venous pressures, suggesting severity of disease according to the inability to empty the calf veins. Pathology Box 17-2 summarizes CVVI findings with PPG and APG.
Extensive APG evaluation may give parameters suggesting (1) proximal venous obstruction in the pelvic and abdominal regions, (2) differentiation between superficial and deep venous patholo- gies, (3) a nonfunctional calf muscle pump, (4) the
SUMMARY
effectiveness of elastic compression, and (5) venous versus nonvenous edematous changes.41,42
NEAR-INFRARED IMAGING43,44
Several imaging technologies are being developed to show superficial veins on the skin. These are not commonly employed, but some centers are using this technology to aid in venous imaging in this pa- tient population. Imaging in the near-infrared range (880 to 930 nm) demonstrates subcutaneous veins with a diameter of 0.5 to 2 mm at a depth of 1 to 3 mm. This technology may help with guidance of venous access, phlebotomy, injection sclerotherapy, and control of laser interstitial therapy.
A highly processed method detects veins as deep as 8 mm from the skin. The vein is detected with near-infrared technology and is projected on the skin with green light.44 The green light does not affect the infrared signal. Appropriate projection is the key to localizing veins that are going to be treated.
PATHOLOGY BOX 17-2
APG and PPG Results with CVVI
PPG VRT 􏰀20 seconds
APG FT 􏰀25 seconds FR 􏰁2 mL/s
RV 􏰁20%–35%
VRT, venous refilling time (recovery time); FT, filling time; FR, filling rate; RV, residual volume.
Chronic venous valvular insufficiency is one of the most prevalent diseases. Proper clinical, etiological, anatomical, and pathophysiological descriptions of the patient being studied and/or treated are recommended. Color flow duplex ultrasonography has become the most useful technology for definitive diagnosis, pretreatment and peritreatment imaging, and procedure/patient follow-up.
Critical Thinking Questions
1. What is an anatomic feature that differentiates an anterior accessory saphe- nous vein (AASV) from the great saphenous vein (GSV)?
2. A patient is old and reports episodes of dizziness in the past. Your examination table cannot be put into a reverse Trendelenburg position. What can you do to accurately complete your CVVI examination?
3. You are having difficulty demonstrating retrograde flow in a patient with exten- sive varicose veins. What equipment settings should you check and why?