Describing Normative Foot Temperatures in Patients With Diabetes-Related Peripheral Neuropathy

Biomarkers of local inflammation at the skin's surface may predict both pressure and diabetic foot ulcers

This commentary considers the similarities which exist between pressure ulcers (PUs) and diabetic foot ulcers (DFUs). It aims to describe what is known to be shared-both in theory and practice-by these wound types. It goes on to detail the literature surrounding the role of inflammation in both wound types. PUs occur following prolonged exposure to pressure or pressure in conjunction with shear, either due to impaired mobility or medical devices. As a result, inflammation occurs, causing cell damage. While DFUs are not associated with immobility, they are associated with altered mobility occurring as a result of complications of diabetes. The incidence and prevalence of both types of lesions are increased in the presence of multimorbidity. The prediction of either type of ulceration is challenging. Current risk assessment practices are reported to be ineffective at predicting when ulceration will occur. While systemic inflammation is easily measured, the presence of local or subclinical inflammation is harder to discern. In patients at risk of either DFUs or PUs, clinical signs and symptoms of inflammation may be masked, and systemic biomarkers of inflammation may not be elevated sufficiently to predict imminent damage until ulceration appears. The current literature suggests that the use of local biomarkers of inflammation at the skin's surface, namely oedema and temperature, may identify early tissue damage.

Formulation and dermal delivery of a new active pharmaceutical ingredient in an in vitro wound model for the treatment of chronic ulcers

The aim of this study was to investigate dermal delivery of the new active pharmaceutical ingredient (API) TOP-N53 into diabetic foot ulcer using an in vitro wound model consisting of pig ear dermis and elucidate the impact of drug formulation and wound dressing taking into consideration clinical relevance in the home care setting and possible bacterial infection. Different formulation approaches for the poorly water-soluble API including colloidal solubilization, drug micro-suspension and cosolvent addition were investigated; moreover, the effect of (micro-)viscosity of hydrogels used as primary wound dressing on delivery was assessed. Addition of Transcutol® P as cosolvent to water improved solubility and was significantly superior to all other approaches providing a sustained three-day delivery that reached therapeutic drug levels in the tissue. Solubilization in micelles or liposomes, on the contrary, did not boost delivery while micro-suspensions exhibited sedimentation on the tissue surface. Microbial contamination was responsible for considerable metabolism of the drug leading to tissue penetration of metabolites which may be relevant for therapeutic effect. Use of hydrogels under semi-occlusive conditions significantly reduced drug delivery in a viscosity-dependent fashion. Micro-rheologic analysis of the gels using diffusive wave spectroscopy confirmed the restricted diffusion of drug particles in the gel lattice which correlated with the obtained tissue delivery results. Hence, the advantages of hydrogel dressings from the applicatory characteristic point of view must be weighed against their adverse effect on drug delivery. The employed in vitro wound model was useful for the assessment of drug delivery and the development of a drug therapy concept for chronic diabetic foot ulcer. Mechanistic insights about formulation and dressing performance may be applied to drug delivery in other skin conditions such as digital ulcer.

Infrared Thermography Shows That a Temperature Difference of 2.2°C (4°F) or Greater Between Corresponding Sites of Neuropathic Feet Does Not Always Lead to a Diabetic Foot Ulcer

BACKGROUND

There is emerging interest in the application of foot temperature monitoring as means of diabetic foot ulcer (DFU) prevention. However, the variability in temperature readings of neuropathic feet remains unknown. The aim of this study was to analyze the long-term consistency of foot thermograms of diabetic feet at the risk of DFU.

METHODS

A post-hoc analysis of thermal images of 15 participants who remained ulcer-free during a 12-month follow-up were unblinded at the end of the trial. Skin foot temperatures of 12 plantar, 15 dorsal, 3 lateral, and 3 medial regions of interests (ROIs) were derived on monthly thermograms. The temperature differences (∆Ts) of corresponding ROIs of both feet were calculated.

RESULTS

Over the 12-month study period, out of the total 2026 plantar data points, 20.3% ROIs were rated as abnormal (absolute ∆T ≥ 2.2°C). There was a significant between-visit variability in the proportion of plantar ROIs with ∆T ≥ 2.2°C (range 7.6%-30.8%, chi-square test, P = .001). The proportion of patients presenting with hotspots (ROIs with ∆T ≥ 2.2°C), abnormal plantar foot temperature (mean ∆T of 12 plantar ROIs ≥ 2.2°C), and abnormal whole foot temperature (mean ∆T of 33 ROIs ≥ 2.2°C) varied between visits and showed no pattern (P > .05 for all comparisons). This variability was not related to the season of assessment.

CONCLUSIONS

Despite the high rate of hotspots on monthly thermograms, all feet remained intact. This study underscores a significant between-visit inconsistency in thermal images of neuropathic feet which should be considered when planning DFU-prevention programs for self-testing and behavior modification.

Preulcerous Risk Situation in Diabetic Foot Syndrome: Proposal for a Simple Ulcer Prevention Score

BACKGROUND

Preulcerous risk situations in patients with diabetes are often undiagnosed and care administered too late. Even with regular medical check-ups and status documentation, foot examinations have not been given enough attention. Diagnosing an individual patients' risk of developing diabetic foot ulcers may increase vigilance for diabetic foot syndrome (DFS), and the appropriate prevention measures matching the risk involved may prevent the emergence of diabetic ulcers. The classical DFS risk factors are well established and have been extensively covered in the literature; however, there is a lack of efficient screening tools that could be used for a rapid assessment of diabetic foot ulcer risk.

METHODS

A methodical literature search was conducted to assess relevant publications for the preparation of a simple risk score for amputation related to diabetic foot ulcer. We then analyzed the risk factors for predictive value as odds ratios in foot ulcers and/or amputation. We used the available data to deduce a mean value to reflect the authors' consensus.

RESULTS

In view of the current literature on the matter, we have developed a semi-quantitative scoring system using just a few items to allow rapid and visual risk assessment for diabetic foot ulcers alongside recommendations for prevention and a sensible follow-up strategy to match the risk.

CONCLUSION

This relatively simple score enables rapid risk classification for patients that can ease the way for both physicians and patients in gaining an insight into individual risk situations. The score provides more effective preventative measures for high-risk patients against future complications.

Vehicle ergonomics contributing to a diabetic foot ulcer

Background

Diabetes mellitus continues to be a rising concern in the United States. It affects an estimated 9.4% of the population and approximately 1.5 million Americans are diagnosed annually. Approximately 85% of diabetic foot ulcers are associated with diabetic peripheral neuropathy and an infected diabetic foot ulcer is often the first sign of diabetes. There are countless studies within the literature that investigate how insensate feet and the manifestation of a foot ulcer further decrease quality of life and increase risk for mortality. Literature focuses on gait and kinematics that contribute to the formation of a diabetic foot ulcer. While pressure and shear forces are etiologic factors that may lead to the formation of diabetic foot ulcers, the position of the foot while driving an automobile has been ignored as a possible risk factor.

Case presentation

The clinical case will describe the events of healing a neuropathic diabetic foot ulcer beyond the standard of care treatment plan. It is one of the first case reports to describe vehicle ergonomics as an etiologic factor contributing to a diabetic foot ulcer. Once the patient becomes aware of the unnecessary source of pressure, education and care is provided to manage this likely source of daily pressure to the neuropathic foot.

Conclusion

The article emphasizes the importance of a complete assessment, including nontraditional factors, which may lead to diabetic complications.