Infrared thermography for monitoring severity and treatment of diabetic foot infections

Abstract

Monitoring of diabetic foot infections is largely based on clinical assessment, which is limited by moderate reliability. We conducted a prospective study to explore monitoring of thermal asymmetry (difference between mean plantar temperature of the affected and unaffected foot) for the assessment of severity of diabetic foot infections. In patients with moderate or severe diabetic foot infections (International Working Group on the Diabetic Foot infection-grades 3 or 4) we measured thermal asymmetry with an advanced infrared thermography setup during the first four to five days of in-hospital treatment, in addition to clinical assessments and tests of serum inflammatory markers (white blood cell counts and C-reactive protein levels). We assessed the change in thermal asymmetry from baseline to final assessment, and investigated its association with infection-grades and serum inflammatory markers. In seven included patients, thermal asymmetry decreased from median 1.8°C [range: -0.6-8.4] at baseline to 1.5°C [range: -0.1-5.1] at final assessment (p=0.515). In three patients who improved to infection-grade 2, thermal asymmetry at baseline (median 1.6°C [range: -0.6–1.6]) and final assessment (1.5°C [range: 0.4-5.1]) remained similar (p=0.302). In four patients who did not improve to infection-grade 2, thermal asymmetry decreased from median 4.3°C [range: 1.8–8.4] to 1.9°C [range: -0.1-4.4] (p=0.221). No correlations were found between thermal asymmetry and infection-grades, (r=-0.347; p=0.445), CRP-levels (r=0.321; p=0.482) or WBC (r=-0.250; p=0.589) during the first four to five days of hospitalization. Based on these explorative findings we suggest that infrared thermography is of no value for monitoring diabetic foot infections during in-hospital treatment.

Morphological Foot Model for Temperature Pattern Analysis Proposed for Diabetic Foot Disorders

“…One of the most common limitations in the assessment of diabetic foot disorders is that the contralateral foot analysis is prevented by the existence of partial foot amputations or deformations. In these cases, there is not a straightforward method to perform a comparison if the same deformation is not present on both feet or simply because the severity of the amputation does not allow it [15]. Furthermore, despite the fact that these are common features exhibited by persons affected by diabetic foot disorders, these patients are usually excluded from the assessment studies [15,46].…”

“…In these cases, there is not a straightforward method to perform a comparison if the same deformation is not present on both feet or simply because the severity of the amputation does not allow it [15]. Furthermore, despite the fact that these are common features exhibited by persons affected by diabetic foot disorders, these patients are usually excluded from the assessment studies [15,46].…”

“…Nevertheless, in patients with diabetes, the detection of inflammatory processes is hard to assess objectively when peripheral pathologies are present [14]. Foot temperature asymmetry has been employed to diagnose and monitor the severity of diabetic foot complications [15]. The assessment is based on the difference between the mean plantar temperature of the affected foot and unaffected foot.…”

“…In patients affected by diabetic foot infection, a plantar foot asymmetry of 1.35 • C suffices to seek urgent treatment [16], whereas a threshold of 2.2 • C is usually considered for an inflammatory process and the impending development of a foot ulcer [7,17,18]. In fact, it has been suggested that thermal asymmetry monitoring has no additional value for assessing the severity of diabetic foot infections [15]. Moreover, for patients at a high risk of developing foot ulcers, monthly intervention by thermography did not result in a significant reduction in ulcer recurrence rate or increased ulcer-free survival [19].…”

Medical Infrared Thermography in Odontogenic Facial Cellulitis as a Clinical Decision Support Tool. A Technical Note

“…Thermography as a complementary diagnostic support has been applied in medicine since the mid-1990s to detect various inflammatory diseases, complex regional pain syndrome or even Raynaud's phenomenon [16,17]. This tool also seems to be suitable for diagnoses of infectious processes, e.g., in postoperative wounds after cesarean section, in the feet of diabetics, or in a central venous catheter in children [18][19][20]. In the oral and maxillofacial area, studies have shown its potential for the diagnosis of various diseases such as traumatic fractures, osteomyelitis [21], malignant neoplasms, cervical lymph node metastasis from oral cancer [15], quantification of postsurgical inflammation after removal of wisdom teeth [22] and retained teeth [23], or arthralgia of temporomandibular joints [24].…”