Current Methods of Treating Diabetic Foot Ulcer

For many years, it has been standard practice to treat diabetic foot ulcers with a combination of any of the following: appropriate wound dressing; offloading; antibiotics; and improving the blood supply. The best way of offloading the foot is, however, uncertain. In addition, whilst there are widely respected guidelines available on treating infection, the choice of antibiotics is also hotly debated, and relies on local sensitivities, the availability of antimicrobial agents and frequently, local microbiologist preferences. Revascularization is dependent on local availability; non-invasive techniques such as angioplasty are often only available in specialist centers, meaning that many units in low-resource environments do not have access to this procedure, let alone a vascular surgeon. Even after effective treatment, relapse probability is 70%, which frequently leads to amputation.

With this background, newer aspects of the care and management of the diabetic foot are emerging. Martha Clokie and Alice Greenway discuss the impact of newer technologies on the identification of the organisms present in an ulcer, as well as novel approaches to treating infections. Keith Harding and Nia Jones also discuss newer technologies, in particular, various uses of remote sensing, that may help in the early detection of tissue damage, thus allowing more timely intervention to prevent ulceration developing. (Jan aw, Khan H; 2016)

Microbiology and current diagnosis of diabetic foot ulcers

The diagnosis of most diabetic foot ulcers is based on the presence of clinical signs and symptoms. Most frequently, tissue biopsy and ulcer fluid aspirates are sent for culture-based identification. Less invasive swabbing from the base of the ulcer is also used to detect surface-associated bacteria but does not detect bacteria associated with deeper structures. The use of non-culture-based molecular microbiological techniques to characterize foot infection microbiota could significantly enhance our understanding of the composition and abundance of the infection and guide effective antimicrobial selection. These techniques have the advantage over culture-based approaches because they are not dependent on the cultivability of the bacteria. This is particularly pertinent for diabetic foot ulcers, which are typically colonized by anaerobes that are notoriously difficult to isolate. (Jan aw, Khan H; 2016)

Bacteriophages

The diagnosis of the infection with deep tissue swabs, selection of the wrong antibiotic can lead to chronic ‘superbug’ infections. Bacteriophages One of the key problems associated with diabetes is peripheral vascular disease and wound ischemia. Poor antibiotic penetration into tissues because of a lack of blood flow is another reason why antibiotics are so unsuccessful. Both the lack of effective penetration of antibiotics and problems with antibiotic resistance means that novel approaches to treating infection are needed. One promising alternative to standard antibiotics is the use of bacteriophages, or phages, which are viruses that target and kill bacteria. (Clokie1, A. L. Greenway, 2017)

Remote sensing in the assessment of diabetic foot disease

It is generally accepted that early diagnosis of risk factors associated with diabetic foot ulcers is a prerequisite for the maintenance of lower limb health. In comparison to current clinical assessment methods, the evolution of innovative technologies provides new opportunities for remotely detecting and monitoring diabetic neuropathy and angiopathy earlier in the disease progression.

Measuring skin temperature is considered one of the most reliable indicators of cutaneous perfusion, and evidence suggests that infrared thermographic monitoring may be an effective method of predicting tissue viability complications in the diabetic foot. Dermal thermography is currently used in routine clinical practice to detect temperature differences between the ipsilateral and contralateral foot in Charcot neuroarthropathy, but emerging evidence suggests that this technology could be adapted to support self-monitoring of diabetic foot disease. (Clokie1, A. L. Greenway, 2017)

Hyperspectral imaging is currently a laboratory-based assessment method used to determine oxygen saturation in human tissue and to detect early microcirculatory changes in the diabetic foot. Hyperspectral imaging technology has also been evaluated as a tool for predicting the healing potential of a foot ulcer with a reported sensitivity and specificity of 80% and 74%, respectively. (Tsai FW, Tulsyan N; 2000)

Skin perfusion pressure, in contrast to hyperspectral imaging, is a portable tool used in routine clinical practice to diagnose small vessel disease in high-risk populations and assess the healing potential of chronic wounds in the lower limb. Skin perfusion pressure is not affected by diffuse vascular calcification and was superior in the diagnosis of peripheral arterial disease in people with diabetes when compared with ankle and toe brachial pressure indices and transcutaneous partial pressure of oxygen (TcPO 2). The one major drawback is that the application of these technologies is driven by the clinician and not the person with diabetes. (Castronuovo JJ, Adera HM; 1997)

Wearable technology is another evolving field in the monitoring and treatment of diabetic foot disease because sensory and motor complications associated with peripheral neuropathy often result in altered proprioception and ataxic gait patterns. Human exoskeleton robots are in early development, but some of these devices have remote body sensors which consist of shoe-embedded force sensors and walking canes to aid with gait difficulties and alert people to the risk of falls when standing from a sitting position (Iqbal MH, Aydin A; 2016). One simple and inexpensive method of adopting wearable technology into practice would be to encourage patients to wear pedometers to monitor their physical activity levels and visually inspect their feet daily for evidence of tissue trauma. This intervention would enable the person to recognize when they need to limit their activity levels and seek advice from their podiatrist. Pulse Flow DFTM is an offloading device which has taken the concept of monitoring physical activity to another level. It has built-in monitoring software that enables the clinician to capture data on the use of the offloading device.