Infrared thermography for temperature measurement and non-destructive testing

The intensity of the infrared radiation emitted by objects is mainly a function of their temperature. In infrared thermography, this feature is used for multiple purposes: as a health indicator in medical applications, as a sign of malfunction in mechanical and electrical maintenance or as an indicator of heat loss in buildings. This paper presents a review of infrared thermography especially focused on two applications: temperature measurement and non-destructive testing, two of the main fields where infrared thermography-based sensors are used. A general introduction to infrared thermography and the common procedures for temperature measurement and non-destructive testing are presented. Furthermore, developments in these fields and recent advances are reviewed.

On the importance of telemetric temperature sensor location during intraperitoneal implantation in rats

This study aims to assess the thermal homogeneity of the intraperitoneal (IP) cavity and the relevance of using a fixed telemetric temperature sensor at a given location in studying rodents. Ten rats were intraperitoneally implanted with three Jonah® capsules each; after assessing the accuracy and reliability of the sensors. Two capsules were attached, one to the right iliac fossa (RIF) and the other to the left hypochondrium (LH), and another was placed between the intestines but not attached (Free). In the ex vivo condition, the differences between sensors and reference values remained in the range of ±0.1. In the in vivo condition, each sensor enabled the observation of temperature patterns. However, sensor location affected mean and median temperature values while the rats were moving freely. Indeed, temperature data collected in the LH were 0.1 significantly higher than those collected in the RIF and temperature data collected in the LH were 0.11 significantly higher than those collected with the Free capsules. In in vivo conditions, intra-sensor variability of temperature data was not affected by sensor location. Taking into account sensor accuracy, similar intra-sensor variability, and mean differences observed between the three locations, the impact of sensor location within the IP cavity could be considered negligible. In in vivo conditions, temperature differences between locations regularly exceeded ±0.2 and reached up to 2.5. These extreme values could be explained by behavioral factors such as food or water intake. Finally, considering the good thermal homogeneity of the IP cavity and possible adverse consequences of sensor attachment, it seems better to let sensors range free within the cavity.

Thermometry in children

Accurate measurement of temperature is important for detection of fever and hypothermia in pediatric patients. Ideal temperature-measurement technique should be safe, easy, noninvasive, cost effective, time efficient, and should precisely reflect core body temperature. Pulmonary artery is the closest to hypothalamus and best reflects the core temperature. Other sites used are distal esophagus, urinary bladder and nasopharynx. All these methods are invasive and difficult to use in clinical practice. Amongst the noninvasive methods, rectal thermometry is considered to be the closest to core temperature, but it has its own drawbacks. With the current evidence available, tympanic artery thermometry for children more than 2 years of age and temporal artery thermometry in all age groups are taking precedence over other methods.

History of accidental hypothermia

Death from exposure to cold has been recognised for thousands of years but hypothermia as a clinical condition was not generally recognised until the mid-20th century and then only in extreme conditions such as immersion in cold water or snow. In the UK, hypothermia in less extreme conditions was not generally recognised until the 1960s. Recognition of hypothermia required the temperature to be measured and this did not become a clinical tool until the late 1800s and it was not used routinely until the early 1900s. Although John Hunter and James Curry did some physiological experiments in the 1700s, detailed physiological experiments were not done until the early 20th century and the use of therapeutic hypothermia for malignancy and in anaesthesia in the 1930s and 1940s provided more impetus for investigating the physiology of hypothermia in humans and familiarising the medical profession with measuring core temperatures.

Association between foot temperature and sudomotor dysfunction in type 2 diabetes

BACKGROUND AND AIMS

Increased foot skin temperature has been described as a feature of diabetic neuropathy. The aim of this present study was to investigate the association between foot temperature and sudomotor dysfunction in type 2 diabetes mellitus.

PATIENTS AND METHODS

This study included 51 patients (group A: 25 men, mean age 61.14 +/- 6.11 years) without sudomotor dysfunction and 52 patients (group B: 25 men, mean age 59.54 +/- 6.18 years) with sudomotor dysfunction. Sudomotor dysfunction was defined as time until complete Neuropad color change from blue to pink exceeding 600 s in at least one foot. Time until complete color change of the test was also recorded. Foot skin temperature was measured with a handheld infrared thermometer on the plantar aspect of the foot at the level of the first metatarsal head.

RESULTS

On both feet, temperature was significantly higher in group B than in group A (right foot, group A versus group B, 30.62 +/- 1.13 degrees C versus 32.12 +/- 1.06 degrees C, p < .001; left foot, group A versus group B, 30.65 +/- 1.06 degrees C versus 32.19 +/- 1.10 degrees C, p < .001). There was a significant positive correlation between time to complete Neuropad color change and foot skin temperature (right foot, r = 0.742, p < .001; left foot, r = 0.758, p < .001), which was confirmed in both groups.

CONCLUSIONS

Patients with sudomotor dysfunction have significantly higher foot temperature than those without sudomotor dysfunction. Foot temperature is positively correlated with severity of sudomotor dysfunction, as evaluated by the time to complete Neuropad color change.

Are room temperature and thermal neutral synonymous terms? An investigation of common therapeutic modality control variables

CONTEXT

Therapeutic modality control variables are thought to be thermal neutral, a term sometimes used interchangeably with room temperature. We question this common assumption.

OBJECTIVE

To determine thermal neutrality of common therapeutic modality control variables.

DESIGN

We performed 5 laboratory experiments, including (1) water temperature over 3 weeks in 3 different containers (glass, plastic, and polystyrene); (2) water temperature and volume of 4 beakers (2 insulated, 2 uninsulated) over 4 weeks, with 1 beaker of each type covered by polyethylene; and skin interface temperature of (3) a dry, nonheated hydrocollator pack held against the chest, (4) kitty litter applied to the knee, and (5) room-temperature ultrasound gel to the forearm.

SETTING

Therapeutic modalities laboratory.

PATIENTS OR OTHER PARTICIPANTS

College student volunteers were subjects in experiments 3, 4, and 5.

MAIN OUTCOME MEASURE(S)

We measured temperature and volume change. Data were evaluated using descriptive and interferential statistics.

RESULTS

Water temperature plateaued significantly below room temperature. Temperatures significantly increased in all but the open, insulated container. Open containers plateaued at approximately 2 degrees C below room temperature and lost significant amounts of water; closed containers plateaued at room temperature with negligible water loss. In experiments 3 through 5, skin temperatures rose significantly during hydrocollator pack, kitty litter, and ultrasound gel application.

CONCLUSIONS

Room-temperature water baths, dry hydrocollator packs, kitty litter, and ultrasound gel were not thermally neutral. Room temperature should not be used synonymously with thermal neutral. Care must be taken to ensure that control variables truly are controlled.

Thermometry in paediatric practice

Body temperature is commonly measured to confirm the presence or absence of fever. However, there remains considerable controversy regarding the most appropriate thermometer and the best anatomical site for temperature measurement. Core temperature is generally defined as the temperature measured within the pulmonary artery. Other standard core temperature monitoring sites (distal oesophagus, bladder, and nasopharynx) are accurate to within 0.1-0.2 degrees C of core temperature and are useful surrogates for deep body temperature. However, as deep-tissue measurement sites are clinically inaccessible, physicians have utilised other sites to monitor body temperature including the axilla, skin, under the tongue, rectum, and tympanic membrane. Recent studies have shown that tympanic temperature accurately reflects pulmonary artery temperature, even when body temperature is changing rapidly. Once outstanding issues are addressed, the tympanic site is likely to become the gold standard for measuring temperature in children.