Rewarming index of the lower leg assessed by infrared thermography in adolescents with type 1 diabetes mellitus

Infrared thermography in paediatrics: a narrative review of clinical use

BACKGROUND

Infrared thermography (IRT) has been used in adult medicine for decades, but recent improvements in quality of imaging and increasing computer processing power have allowed for a diversification of clinical applications. The specific usage of IRT in a paediatric population has not been widely explored, so this article aims to summarise the available literature in this area. IRT involves the non-contact, accurate measurement of skin surface temperature to identify temperature changes suggesting disease. IRT could well have unique applications in paediatric medicine.

METHODS

Electronic searches were performed independently by two authors, using the databases of MEDLINE (via Web of Science), the Cochrane Library, CINAHL (EBSCO) and Scopus, including articles published from 1990 to July 2016. The search strategy that was used aimed to include articles that covered the topics of IRT and children, including studies with participants 18 years old or younger. Articles were screened by title and abstract by two authors. Meta-analysis was not performed due to the marked heterogeneity in applications, study design and outcomes: this is a narrative summary of the available literature.

RESULTS

IRT has been shown to be an effective additional diagnostic tool in a number of different paediatric specialties, namely in fracture screening, burns assessment and neonatal monitoring. Small measurable skin temperature changes can effectively add to the clinical picture, while computer-tracking systems can be reliably used to focus investigations on particular areas of the body.

CONCLUSION

Throughout this review of the available literature, there has been a general consensus that this non-invasive, non-irradiating and relatively inexpensive technology may well have a place in the management of paediatric patients in the future.

Determining peripheral skin temperature: subjective versus objective measurements

AIM

Diseases that affect peripheral vasculature or neurological function can manifest with peripheral skin temperature abnormalities. This pilot study investigates the accuracy of current physical examination techniques and determines whether a hand-held infrared device can be used to estimate peripheral skin temperature and detect temperature disparities.

METHODS

Comparison between traditional physical examination of hands/feet by 30 healthcare professionals and a hand-held infrared device was made in 12 individuals (ages 4-25 years; 5 with disorders affecting peripheral skin temperature). Thermal camera measurements served as the reference temperature for comparison.

RESULTS

A total of 231 extremity examinations by healthcare professionals were analysed. Healthcare professionals correctly identified subjects with colder or warmer than normal peripheral temperature. Hand-held device measurements were significantly different than reference measurements, with the size of the temperature difference diverging significantly between hands (1.20°C) and feet (0.78°C). When analysing temperature disparities, healthcare professionals identified fewer clinically significant disparities (≥3.0°C) than the hand-held device (76% vs. 99%).

CONCLUSION

Although different from reference temperatures, the hand-held infrared device provided a more accurate and objective method than traditional physical exam in identifying peripheral skin temperature asymmetries that may be related to chronic paediatric illness.

An early diagnostic tool for diabetic peripheral neuropathy in rats

The skin’s rewarming rate of diabetic patients is used as a diagnostic tool for early diagnosis of diabetic neuropathy. At present, the relationship between microvascular changes in the skin and diabetic neuropathy is unclear in streptozotocin (STZ) diabetic rats. The aim of this study was to investigate whether the skin rewarming rate in diabetic rats is related to microvascular changes and whether this is accompanied by changes observed in classical diagnostic methods for diabetic peripheral neuropathy. Computer-assisted infrared thermography was used to assess the rewarming rate after cold exposure on the plantar skin of STZ diabetic rats’ hind paws. Peripheral neuropathy was determined by the density of intra-epidermal nerve fibers (IENFs), mechanical sensitivity, and electrophysiological recordings. Data were obtained in diabetic rats at four, six, and eight weeks after the induction of diabetes and in controls. Four weeks after the induction of diabetes, a delayed rewarming rate, decreased skin blood flow and decreased density of IENFs were observed. However, the mechanical hyposensitivity and decreased motor nerve conduction velocity (MNCV) developed 6 and 8 weeks after the induction of diabetes. Our study shows that the skin rewarming rate is related to microvascular changes in diabetic rats. Moreover, the skin rewarming rate is a non-invasive method that provides more information for an earlier diagnosis of peripheral neuropathy than the classical monofilament test and MNCV in STZ induced diabetic rats.

Repeatability of infrared plantar thermography in diabetes patients: a pilot study

OBJECTIVE

Infrared (IR) thermography has been used as a complementary diagnostic method in several pathologies, including distal diabetic neuropathy, by tests that induce thermoregulatory responses, but nothing is known about the repeatability of these tests. This study aimed to assess the repeatability of the rewarming index in subjects with type 2 diabetes mellitus (T2DM) and nondiabetic control subjects.

METHODS

Using an IR camera, plantar IR images were collected at baseline (pre-) and 10 min after (post-) cold stress testing on two different days with 7 days interval. Plantar absolute average temperatures pre- and post-cold stress testing, the difference between them (ΔT), and the rewarming index were obtained and compared between days. Repeatability of the rewarming index after the cold stress test was assessed by Bland-Altman plot limits of agreement.

RESULTS

Ten T2DM subjects and ten nondiabetic subjects had both feet analyzed. Mean age did not differ between groups (p = .080). Absolute average temperatures of plantar region pre- (p = .033) and post-cold stress test (p = .019) differed between days in nondiabetic subjects, whereas they did not differ in T2DM subjects (pretest, p = .329; post-test, p = .540). ΔT and rewarming index did not differ between days for both groups, and the rewarming index presented a 100% agreement of day-to-day measurements from T2DM subjects and 95% with nondiabetic subjects.

CONCLUSIONS

The rewarming index after cold stress testing presented good repeatability between two days a week in both groups. Despite T2DM subjects presenting no differences on absolute temperature values between days, ΔT or rewarming index after cold stress testing remain recommended beside absolute temperature values for clinical use.

Plantar thermography is useful in the early diagnosis of diabetic neuropathy

OBJECTIVES

This study evaluated plantar thermography sensitivity and specificity in diagnosing diabetic polyneuropathy using cardiac tests (heart rate variability) as a reference standard because autonomic small fibers are affected first by this disease.

METHODS

Seventy-nine individuals between the ages of 19 and 79 years old (28 males) were evaluated and divided into three groups: control (n = 37), pre-diabetics (n = 13) and type 2 diabetics (n = 29). The plantar images were recorded at baseline and then minutes after a provocative maneuver (Cold Stress Test) using an infrared camera that is appropriate for clinical use. Two thermographic variables were studied: the thermal recovery index and the interdigital anisothermal technique. Heart rate variability was measured in a seven-test battery that included three spectral indexes (in the frequency domain) and four Ewing tests (the Valsalva maneuver, the orthostatic test, a deep breathing test, and the orthostatic hypotension test). Other classically recommended tests were applied, including electromyography (EMG), Michigan inventory, and a clinical interview that included a neurological physical examination.

RESULTS

Among the diabetic patients, the interdigital anisothermal technique alone performed better than the thermal recovery index alone, with a better sensitivity (81.3%) and specificity (46.2%). For the pre-diabetic patients, the three tests performed equally well. None of the control subjects displayed abnormal interdigital anisothermal readouts or thermal recovery indices, which precluded the sensitivity estimation in this sample of subjects. However, the specificity (70.6%) was higher in this group.

CONCLUSION

In this study, plantar thermography, which predominately considers the small and autonomic fibers that are commonly associated with a sub-clinical condition, proved useful in diagnosing diabetic neuropathy early. The interdigital anisothermal test, when used alone, performed best.

Reduced forearm blood flow in children and adolescents with type 1 diabetes (measured by near-infrared spectroscopy)

OBJECTIVE

The aim of this study was to measure forearm blood flow (FBF) to detect any possible changes that might indicate vascular disorders in children and adolescents with type 1 diabetes.

RESEARCH DESIGN AND METHODS

FBF was measured by near-infrared spectroscopy (NIRS), venous occlusion at rest, and after handgrip exercise. A total of 40 children and adolescents with type 1 diabetes and 40 healthy children and adolescents (6-18 years) were matched for age and sex for comparison.

RESULTS

In the diabetic group (age 12.79 +/- 2.9 years, duration of diabetes 51.5 +/- 36 months), FBF at rest was significantly lower (1.39 +/- 0.76 ml x 100 g muscle(-1) x min(-1)) than in control subjects (age 12.66 +/- 2.9 years, FBF at rest 1.90 +/- 1.19 ml x 100 g muscle(-1) x min(-1)). After exercise, FBF increased significantly less in the diabetic group (0.70 +/- 0.82 ml. 100 g muscle(-1) x min(-1)) compared with the control subjects (1.15 +/- 1.05 ml. 100 g muscle(-1) x min(-1)). FBF at rest decreased with increasing age in both groups. The change in FBF after exercise was independent of age in the diabetic group and increased with increasing age in control subjects. FBF is reduced with impaired hyperemic response after exercise in children and adolescents with type 1 diabetes.

CONCLUSIONS

These data suggest that vascular disorders in childhood are detectable noninvasively by NIRS.