|
Diagnostic Test
|
Description
|
|
Arterial Duplex Scan
|
- Non-invasive ultrasound test that can identify macro- and microvascular changes in the arterial tree.
- Used to diagnose aneurysm and large vessel stenosis >50%.
- Patients with suspected superficial artery stenosis and claudication may undergo duplex scanning to identify a lesion that is amenable to angioplasty, before subjected to angiogram.
- Non-invasive arterial duplex scan as having sensitivity and specificity rates greater than 90%.
|
|
Continuous Wave Doppler
|
- Old technology. It is highly recommended to use in conjunction with duplex imaging to visualize the arteries.
|
|
Plethysmography
|
- Records the “pulse volume recording” – another old tool that can establish diagnosis with limited accuracy.
- May be a initial diagnostic tool for persons with diabetes that do not have compressible arteries but should be used in conjuction with duplex scan.
|
|
Transcutaneous Oxygen (TcpO2)
|
- Measures absolute oxygen partial pressure in the dermis. According to Goldman and Salcido (2002), TcpO2 less than 20 mmHg gives a guarded prognosis for healing.
- 40 mmHg is a good indication for healing.
- TcpO2 should be measured on upper leg and dorsum of the foot for best results.
- Areas of callus, edema or bony prominences produce inaccurate results.
- Valuable for evaluating perfusion and is a good predictor of amputation in the lower limbs.
- TcpO2 < 30 mmHg was an independent predictor of diabetic foot ulceration.
|
|
Toe and Ankle Pressures
|
- Systolic toe and ankle pressures are measured with a fitted occluding cuff placed most often around the base of the first toe and around both ankles.
- Toe pressure of > 45 mmHg is necessary for optimal healing
- Most patients with toe blood pressures > 30mmHg healed with conservative management
- With ankle pressures < 80mmHg, most patients had an amputation or died before healing occurred
- Kalani et al. (1999) suggests a cut-off of 25mmHg for TcpO2and 30mmHg
- for toe blood pressure as predictors of wound healing, with TcpO2being
- the better predictor in patients with diabetes and chronic foot ulcers. Toe pressures, however, may be more technically and economically feasible.
- Toe pressures for persons with diabetes were more reliable than persons with false negative ABPI’s and lower limb neuropathy
|
