The Application of Medical Thermography to Discriminate Neuroischemic Toe Ulceration in the Diabetic Foot

Clinical value of foot thermometry in patients with acute limb ischemia

OBJECTIVE

We hypothesized that the severity of foot poikilothermy can be used for better differentiation of grades of acute limb ischemia. Thus, the study aim was evaluation of the value of non-contact foot thermometry, performed using a low-cost infrared medical thermometer, as an adjunct for clinical diagnosis of immediately threatened acute limb ischemia.

METHODS

It was a single-center observational prospective study performed over 3 years. Patients with acute limb ischemia of lower limbs grade I-IIB Rutherford treated with urgent revascularization were included. Grade of ischemia was determined independently by two experienced vascular surgeons. Thermometry of the ischemic foot was performed using a medical digital infrared non-contact thermometer (CK-T1501, Cooligg, China) with measuring accuracy of ±0.2°C. Temperature was measured in three points: the dorsal surface of the foot, plantar surface of the foot (both in the metatarsal region), and forehead. The maximal temperature gradient between patient's forehead and foot (∆Tmax F-F) was calculated. Measurements were repeated 6-12 h after revascularization.

RESULTS

A total of 147 patients were included. Only 3 (2%) patients presented rest pain without sensory loss and motor deficit, while the majority were diagnosed with mild (63/147, 42.8%) or moderate (27/147, 18.3%) motor deficit. The temperature of the ischemic foot varied from 20 to 36.1°C, while median value of the temperature was 26.7 [24.5-29.9] °C on the dorsal surface and 26.8 [24.5-29.6] °C on the plantar surface of the foot (p = 0.85). Patients with Grade IIB ischemia had significantly lower dorsal foot temperature, plantar foot temperature, and larger ∆Tmax F-F than the patients with grades I-IIA: 25.1 [23.9-26.8] °C versus 29.9 [27.6-30.8] °C; 25.2 [23.8-27.5] °C versus 29.6 [28-31.1] °C; and 11.6 [9.7-12.8] °C versus 7.2 [6-9] °C (p < 0.0001). Areas under ROC curve for diagnosis of Grade IIB ischemia were similar for dorsal foot temperature (0.82), plantar temperature (0.81), and ∆Tmax F-F (0.82). The best cutoff value by Youden was ≥9.5°C for ∆Tmax F-F, ≤26.8°C for dorsal, and ≤27.7°C for plantar temperature. Criterion ∆Tmax F-F offered the highest specificity of 86% (95%CI 74.2-93.7) and positive predictive value of 89.2% (95%CI 79.5-93.2), while plantar temperature offered sensitivity of 82.5% (95%CI 70.1-91.3) and negative predictive value of 69.1% (95%CI 57.6-83.2). In multivariate analysis including age, gender, and etiology of arterial occlusion, the criterion ∆Tmax F-F of ≥9.5°C was a unique variable significantly associated with risk of amputation (adjusted OR 2.6, 95%CI 1.2-5.9, p = 0.01).

CONCLUSION

Current study demonstrated that patients with immediately threatening ALI have significantly lower foot temperature than those with viable and marginally threatened limbs. Severe foot poikilothermy at admission is associated with poor outcomes of revascularization, mostly with limb loss.

Update on the Use of Infrared Thermography in the Early Detection of Diabetic Foot Complications: A Bibliographic Review

Foot lesions are among the most frequent causes of morbidity and disability in the diabetic population. Thus, the exploration of preventive control measures is vital for detecting early signs and symptoms of this disease. Infrared thermography is one of the complementary diagnostic tools available that has proven to be effective in the control of diabetic foot. The last review on this topic was published in 2015 and so, we conducted a bibliographic review of the main databases (PubMed, the Web of Science, Cochrane library, and Scopus) during the third quarter of 2023. We aimed to identify the effectiveness of infrared thermography as a diagnostic element in pre-ulcerous states in diabetic patients and to detect diabetic foot ulcer complications. We obtained a total of 1199 articles, 26 of which were finally included in the present review and published after 2013. After analyzing the use of infrared thermography in diabetic patients both with and without ulcers, as well as in healthy individuals, we concluded that is an effective tool for detecting early-stage ulcers in diabetic foot patients.

Plantar Thermography in High-Risk Patients With Diabetes Mellitus Compared to Nondiabetic Individuals

Diabetic foot (DF) is one of the most devastating complications of diabetes mellitus (DM). Infrared thermography has been studied for its potential in early diagnosis and preventive measures against DF ulcers, although its role in the management and prevention of DF complications remains uncertain. The objective of this study was to determine the average temperatures of different points of the plantar foot using infrared thermography in patients with DM and history of DF (DFa group, at the highest risk of developing foot ulcers) and compare them to people without DM (NoDM group). One hundred and twenty-three feet were included, 63 of them belonged to DFa Group and the other 60 to NoDM Group. The average temperature in the NoDM Group was 27.4 (26.3-28.5) versus 28.6 (26.8-30.3) in the DFa Group (p = .002). There were differences between both groups in temperatures at the metatarsal heads and heels, but not in the arch. Average foot temperatures did not relate to sex, ankle-brachial index, and age, and had a mild correlation with daily temperature (Spearman 0.51, p < .001). Data provided in our study could be useful in establishing a parameter of normal temperatures for high-risk patients. This could serve as a foundational framework for future research and provide reference values, not only for preventative purposes, as commonly addressed in most studies, but also to assess the applicability of thermography in clinical scenarios particularly when one foot cannot serve as a reference, suspected osteomyelitis of the remaining bone, or instances of increased temperature in specific areas which may necessitate adjustments to the insoles in secondary prevention.

Diabetic Amputations in 2023 are Still More Frightening Than Death-Act Now Before it is Too Late

Despite huge medical and technological advances to date for the diagnosis, monitoring, and management of diabetic foot complications, their prevalence is still alarmingly high. Patients' quality of life may be severely compromised. Patients may fear amputations more than death. An effort to minimize the impact of these complications and to ensure prompt access to care for everyone is still required. Urgent therapeutic measures should become possible when needed. Improved physician training in and management of peripheral arterial disease are also vital. We need to act now before it is too late. This will definitely be one of the greatest challenges for 2023 and the years to come.

The Value of Infrared Thermography to Assess Foot and Limb Perfusion in Relation to Medical, Surgical, Exercise or Pharmacological Interventions in Peripheral Artery Disease: A Systematic Review

Infrared thermography (IRT) is a promising imaging method in patients with peripheral artery disease (PAD). This systematic review aims to provide an up-to-date overview of the employment of IRT as both a diagnostic method and an outcome measure in PAD patients in relation to any kind of intervention. On September 2022, MEDLINE, EMBASE, CENTRAL, Google Scholar, Web of Science, and gray literature were screened. Eligible articles employing IRT in PAD were screened for possible inclusion. The RoB 2.0 tool was used to assess the risk of bias. Twenty-one eligible articles were finally included, recruiting a total of 1078 patients. The IRT was used for PAD diagnosis/monitoring in 11 studies or to assess the effect of interventions (revascularization, pharmacological therapy, or exercise rehabilitation) in 10 studies. The analysis of the included papers raised high concerns about the overall quality of the studies. In conclusion, IRT as a noninvasive technique showed promising results in detecting foot perfusion in PAD patients. However, limits related to devices, points of reference, and measurement conditions need to be overcome by properly designed trials before recommending its implementation in current vascular practice.

The Use of Infrared Thermography to Develop and Assess a Wearable Sock and Monitor Foot Temperature in Diabetic Subjects

One important health problem that could affect diabetics is diabetic foot syndrome, as risk of ulceration, neuropathy, ischemia and infection. Unnoticed minor injuries, subsequent infection and ulceration may end in a foot amputation. Preliminary studies have shown a relationship between increased skin temperature and asymmetries between the same regions of both feet. In the preulceration phase, to develop a smart device able to control the temperature of these types of patients to avoid this risk might be very useful. A statistical analysis has been carried out with a sample of foot temperature data obtained from 93 individuals, of whom 44 are diabetics and 49 nondiabetics and among them 43% are men and 57% are women. Data obtained with a thermographic camera has been successful in providing a set of regions of interest, where the temperature could influence the individual, and the behavior of several variables that could affect these subjects provides a mathematical model. Finally, an in-depth analysis of existing sensors situated in those positions, namely, heel, medial midfoot, first metatarsal head, fifth metatarsal head, and first toe has allowed for the development of a smart sock to store temperatures obtained every few minutes in a mobile device.

Assessing Diabetic Foot Infections With the ThermoScale: A Comparative Thermometry Device Designed as a Patient Self-Screening Tool

Diabetic foot infection (DFI) is an important risk factor for amputation, and late diagnosis or referral is often incriminated for poor outcome. To enable an earlier diagnosis of DFI, comparative foot thermometry has been suggested as a self-screening method for patients in a home setting. We validated the efficacy of the ThermoScale, a weighing scale outfitted with temperature sensors that allows accurate temperature measurement in both feet. Temperature differentials in DFI patients (n = 52) were compared with a control group of similar diabetic patients (n = 45) without any foot wounds. Based on these findings, we drafted a receiver operating characteristic curve to determine an area-under-the-curve of 0.8455. This value suggests that the ThermoScale, as a diagnostic test, is reasonably accurate. A cutoff value of 2.15 °C temperature difference corresponded with a sensitivity of 88.9% and a specificity of 61.5%. As wearables, portable health electronics, and telemedicine become increasingly popular, we think that comparative temperature measurement technology is valuable in improving early diagnosis of DFIs.

Telehealth and telemedicine applications for the diabetic foot: A systematic review

The aim of this systematic review is to assess the peer-reviewed literature on the psychometric properties, feasibility, effectiveness, costs, and current limitations of using telehealth and telemedicine approaches for prevention and management of diabetic foot disease. MEDLINE/PubMed was searched for peer-reviewed studies on telehealth and telemedicine approaches for assessing, monitoring, preventing, or treating diabetic foot disease. Four modalities were formulated: dermal thermography, hyperspectral imaging, digital photographic imaging, and audio/video/online communication. Outcome measures were: validity, reliability, feasibility, effectiveness, and costs. Sixty-one studies were eligible for analysis. Three randomized controlled trials showed that handheld infrared dermal thermography as home-monitoring tool is effective in reducing ulcer recurrence risk, while one small trial showed no effect. Hyperspectral imaging has been tested in clinical settings to assess and monitor foot disease and conflicting results on its diagnostic use show that this method is still in an experimental stage. Digital photography is used to assess and monitor foot ulcers and pre-ulcerative lesions and was found to be a valid, reliable, and feasible method for telehealth purposes. Audio/video/online communication is mainly used for foot ulcer monitoring. Two randomized controlled trials show similar healing efficacy compared with regular outpatient clinic visits, but no benefit in costs. In conclusion, several technologies with good psychometric properties are available that may be of benefit in helping to assess, monitor, prevent, or treat diabetic foot disease, but in most cases, feasibility, effectiveness, and cost savings still need to be demonstrated to become accepted and used modalities in diabetic foot care.