Investigations
Ankle/toe Brachial Pressure Index
If venous disease is suspected, the patient should have an ankle/toe brachial pressure index (ABPI) performed to assess the arterial circulation. This involves measuring the blood flow in the arteries of the lower leg compared to that in the upper arm and is recorded as ABPI. Evaluation of peripheral circulation of the lower limb is essential in deciding whether to use compression. Inappropriate high compression bandaging may place the limb at risk of damage. It is generally accepted that ABPI >0.8 allows for compression to be safely applied, however, reduced compression may be applied with ABPI 0.5- 0.8 by an experienced practitioner (Vowden and Vowden 2001).
A toe brachial pressure index (TBPI) requires a different machine than ABPI, it is recommended as essential in all patients with Diabetes Mellitus as the ABPI provides false high readings in this patient group due to calcification of the arteries in the foot. The vessels in the toes do not suffer from the same level of calcification and this is why TBPI is recommended for these patients. It is also helpful for those patients with painful venous leg ucers who cannot tolerate a cuff being inflated over an area where the ulcer may be present.
FORMULA: Highest ankle pressure /highest brachial pressure = ABPI
Ankle – brachial index interpretation:
Above 0.90 – Normal
0.70 - 0.90 – mild obstruction
0.41 – 0.70 – moderate obstruction
0.00 – 0.40 – severe obstruction
Doppler assessment can be performed manually using a hand held Doppler or with an automatic Doppler machine (e.g. DOPPLEX ABILITY)
An on line e-learning masterclass on how to perform a doppler ultrasound assessment can be accessed free of charge at https://www.huntleigh.healthcare/Vascular-Assessment-Academy
BLOOD TESTS
As well as a visual assessment the following investigation will help to assess the individuals current status and potential for healing
- FBC – anaemia may delay healing
- ESR/CRP – markers for inflammation and infection
- U&Es – dehydration may delay healing
- HbA1c – assess for diabetes mellitus and/or control
- Albumin – low albumin may be associated with protein loss which may delay healing