The effect of diabetes on the feet and lower limbs has been well established both in literature and in clinical studies. Changes in the body can ultimately impact both the larger and smaller arteries in the lower limbs. Calcification of arteries as well as formation of thrombi (Blood clots) may lead to further problems that can end in death. As such, ankle systolic blood pressure measurements have been an important process in evaluating and monitoring lower limb arteries for onset of diseases such as peripheral arterial disease and critical limb ischaemia. Currently the most widely accepted method of assessing this is the Ankle Brachial Pressure Index (ABPI). Though this method is effective in identifying blockages in blood flow, recent studies have shown it to be unreliable in elderly patients, those with diabetes or chronic renal failure because the peripheral arteries may be incompressible as a result of calcification or blockages in these smaller arteries.
What does the Systolic Toe Pressure Machine Detect?
The newest technologies look to assess the systolic blood pressure in the toes as well as toe pressure indices. The readings are usually taken at the hallux. The results of these studies can be used to identify or screen for a number of medical conditions including:
- Blockages in large and small blood vessels
- Arterial insufficiency
- Cardiac dysfunction
- Ischaemia/intermittent claudication
- Necrosis and amputation risks.
What Methods are Available to Assess Toe Pressures?
Currently the methods available include standard photophlethymography (PPG) laser dopplers, mercury strain gauges and ultrasound dopplers. Each method varies in its process but all appear to have relatively good reliability in assessing for arterial insufficiency. Readings obtained can indicate the presence and level of vascular abnormality in the feet. The accepted standards are as below:
- 75 mmHg – 130 mmHg : Normal.
- 50 mmHg – 74 mmHg: Mild occlusion/intermittent claudication/asymptomatic arterial disease.
- 30 mmHg – 49 mmHg: moderate occlusion/prominent ischaemia.
- < 30 mmHg: severe occlusion/ischaemia/necrosis may be present.
- Toe/Brachial index 0.65 – 1 : normal.
What are the Benefits of Toe Pressure Assessments?
Assessing toe pressures has many benefits for both health practitioners and patients. As a health practitioner you are able to specifically look for occlusions in smaller vascular structures which may result in much more serious complications if untreated. These are not necessarily covered with the current methods of assessment using the ankle-brachial pressure index assessment. Similarly, toe pressure assessment can be used as a screening tool to identify patients at risk of arterial insufficiency related complications such as ichaemia, necrosis and amputations. Patients can also be at ease knowing they are receiving a fully detailed vascular assessment identifying risks in their feet to better direct an individualised treatment protocol.
Toe Pressure Systems VS Ankle-Brachial Pressure Index systems
When compared to the existing method of ABPI analysis, toe pressure analysis has brought a number of pros that has led it becoming more and more prominent in podiatry treatment rooms. Some advantages of the toe pressure machine systems include:
- The treatment is operator independent
- Most systems are fully automated, thus reducing the chance of operator error or bias.
- Results are obtained fast
- To obtain a pressure reading on average takes no more than a couple of minutes
- The readings obtained are reliable, accurate and reproducible.
- A number of studies looking into the intra and inter reliability of toe pressure analysis has found good reliability and reproducibility when compared to other methods of pressure analysis.
- This fact has led to the push for toe pressure assessments to become a standard in many hospital podiatry appointments for diabetic and renal failure patients.
- The assessment is highly sensitive
- Most PPG toe pressure systems can detect pressures lower than 20 mmHg which is a lot more sensitive than the previously available systems.
Scientific Evidence for Clinical Application
A number of studies have been performed looking at the applicability of toe pressure analysis as a way of determining and screening for lower limb complications particularly in patients with diabetes.
A study by Scanlon et al. 2012 showed excellent interrater and intrarater reliability for measuring toe pressures and good reliability for toe brachial index in patients with diabetes. These findings coincided with those performed by Hoyer et al. 2012 and Perez-Martin et al. 2010 showing that automated portable devices with as PPG’s yielded excellent diagnostic characteristics for detecting peripheral arterial disease when compared to standard methods.
Hoyer C., Sandermann J., Petersen LJ. 2013. Randomised Diagnostic Accuracy Study of a Fully Automated Portable Device for Diagnosing Peripheral Arterial Disease by Measuring the Toe-brachial Index. European Journal of Vascular and Endovascular Surgery. 45(1):57-64
Perez-Martin A., Meyer G., Demattei C., Boge G., Laroche JP., Quere I., Dauzat M. 2010. Validation of a Fully Automatic Photophlethysmographic Device for Toe Blood Pressure Measurement. European Journal of Vascular an Endovascular Surgery. 40(4):515-520.
Scalon C., Park K, Mapletoft D., Begg L., and Burns J. 2012. Interrater and intrarater reliability of photophlethysmography for measuring toe blood pressure and toe-brachial index in people with diabetes mellitus. Journal of Foot and Ankle Research. 5(13):
Dr. Anel Kapur