Skin temperature variations in the cold

Skin temperature plays an important role in human thermoregulation together with core temperature. Skin temperature varies to a large extent across the body and this is especially pronounced in cold environments. The variations of skin temperature are also involved in the generation of regional thermal perceptions that can lead to behavioural adjustments. Whilst the temporal and inter-individual variations of skin temperature have been well studied using contact sensors, the knowledge of spatial variations has received less attention in the literature. Infrared thermography is a specific imaging technique particularly valuable for the exploration of the topography or pattern of skin temperature across the body. Most research using this technique has only been case studies or experiments focused in one specific body region. However, extensive regional skin temperature data over the whole-body can be proven useful for different types of applications including the sport clothing industry in combination with other body-mapping data. The primary aim of this thesis was to develop an original and standardised method using infrared thermography enabling whole-body skin temperature data to be compared for the assessment of spatial, temporal and inter-individual variations. A specific methodology for infrared data collection and data processing was successfully developed in order to combine data from a variety of participants varying in anthropometrical characteristics. The main outcomes were the production of several skin temperature body maps, either absolute maps to show the magnitude of the temporal or inter-individual effects, and normalised maps (relative to mean skin temperature) allowing for topographical comparisons between protocol stages, populations or interventions. The second aim of the thesis was to extend the understanding of the skin temperature patterns and how these could relate with thermal perceptions. The body-mapping method gave the opportunity to investigate a large amount of conditions, where various internal or external determinants of skin temperature were be involved. This was mainly done in cool to cold environments (5°C to 20°C) where skin temperature is not uniform but is associated with local and overall comfort. Studies were firstly performed in semi-nude conditions (Chapter 3, 4, 5) and then in clothed conditions (Chapter 6 and 7). The semi-nude studies were designed to explore the potential sexdifferences in regional skin temperature responses whilst running (Chapter 3) with a special interest in the role of skinfold thickness, this was further extended with a group of males at rest having a large variety of fat content and thickness (Chapter 4). The influence of exercise type and air temperature on skin temperature patterns was studied with a rowing exercise (Chapter 5). Studies were then performed in clothed conditions (Chapter 5, 6). The influence of real-life conditions on skin temperature patterns and associated perceptual responses was observed during a hiking scenario (Chapter 6). Following these descriptive studies, manipulation of skin temperature patterns was performed using clothing in order to determine the presence of any relevant effect on thermal comfort (Chapter 7). Our results demonstrated that the skin temperature pattern over the whole-body is relatively universal with several features being consistently found regardless of the conditions or the populations. The upper body is usually warmer than the lower body and the body creases (orbital, elbow regions etc.) are also warmer than surrounding regions. A Y-shape of colder temperatures has been highlighted over the anterior torso as well as a T- or Y-shape of warmer temperature over the posterior torso. There are yet some specificities that can be displayed due to active muscles during exercise such as the warmer skin overlying the trapezius and biceps muscles in rowing (Chapter 5), the influence of the backpack construction with up to 3°C warmer skin temperature in the lower back (Chapter 6) or the importance of additional clothing insulation minimizing the anterior Y-shape of colder skin temperatures (Chapter 7). Beyond the thermal patterns, absolute skin temperature differences have been observed between sexes with females displaying 2°C colder skin during semi-nude running (Chapter 3) and 1°C colder skin during clothed walking (Chapter 6)compared to males. The skin temperature difference can also be as large as 6°C colder skin for an obese male compared to a very lean male (40% vs 7% body fat). Despite these differences, there were almost no significant differences in overall and regional thermal sensations and comfort between sexes or between males with varying body fat. Our results focused on body fat revealed that overall fat content and sum of skinfolds was inversely associated with the mean skin temperature response during various protocols (Chapter 4, 6, 7). Local skinfold thickness explained the inter-individual variability of local skin temperature for resting (Chapter 4) and exercising males (Chapter 7) in most body regions. In terms of intra-individual variations, the distribution of skinfold thickness across the anterior torso explained the distribution of skin temperature in this segment solely in conditions with strong regional contrasts (Chapter 3, 4 and 7). When the whole-body skin temperature pattern is considered, our body-mapping approach failed to show relationships between skin temperature distribution across the body and regional skinfold thickness distribution neither at rest nor during exercise. The relative contribution of other internal determinants such as local heat production,local blood flow distribution and local anthropometry should be further investigated to fully elucidate the spatial skin temperature variations depending on the climate, clothing and the body thermal state. Lastly, there was a trend towards improved thermal comfort during rest and exercise in the cold through a manipulation of skin temperature patterns targeting the naturally cold body regions with high insulation, therefore obtaining a more homogeneous skin temperature distribution across the body (Chapter 7). The present work will benefit the sport goods industry. The descriptive results of skin temperature variations will be useful in order to validate multi-segmental model of human thermoregulation. Further work can include pattern predictions for exercise types and conditions not covered by the present thesis. The skin temperature maps will mainly feed the general body-mapping approach for clothing design taking into account several other body mapping data such as sweat mapping and the combination of cold, warm and wetness sensitivity mappings. Lastly, the present results have highlighted the interest for targeted solutions and also the need for more evolutive systems in the field of cold weather apparel

A Patient-Specific Approach for Breast Cancer Detection and Tumor Localization Using Infrared Imaging

Breast cancer (BC) is the most common cancer among women in the United States; approximately one out of every 24 women die of related causes. BC screening is a critical factor for improving patient prognosis and survival rate. Infrared (IR) thermography is an accurate, inexpensive and operator independent modality that is not affected by tissue density as it captures surface temperature variations induced by the presence of tumors. A novel patient-specific approach for IR imaging and simulation is proposed. In this work, multi-view IR images of isolated breasts are obtained in the prone position (face down), which allows access to the entire breast surface because the breasts hang freely. The challenge of accurately determining size and location of tumors within the breasts is addressed through numerical simulations of a patient-specific digital breast model. The digital breast models for individual patients are created from clinical images of the breast, such as IR imaging, digital photographs or magnetic resonance images. The numerical simulations of the digital breast model are conducted using ANSYS Fluent, where computed temperature images are generated in the same corresponding views as clinical IRI images. The computed and clinical IRI images are aligned and compared to measure their match. The determination of tumor size and location was conducted through the Levenberg-Marquardt algorithm, which iteratively minimized the mean squared error. The methodology was tested on the breasts of seven patients with biopsy-proven breast cancer with tumor diameters ranging from 8 mm to 27 mm. The method successfully predicted the equivalent tumor diameter within 2 mm and the location was predicted within 6.3 mm in all cases. The time required for the estimation is 48 minutes using a 10-core, 3.41 GHz workstation. The method presented is accurate, fast and has potential to be used as an adjunct modality to mammography in BC screening, especially for dense breasts

Ocular and systemic vascular alterations in overweight and obese individuals undergoing weight-loss interventions

Obesity and its accompanying comorbidities play a crucial role in the pathogenesis of endothelial function which is a pre-cursor to atherosclerosis, subsequently leading to increases in cardiovascular risk. However, amelioration of these risk factors and improvements in endothelial function have never been fully explored in functional assessments of the retinal and peripheral microcirculations.The aim of this thesis was therefore to investigate the presence and impact of weight-loss interventions in overweight and obese individuals and also the relationships between functional measurements of different vascular beds. The principle findings of this work were:1. The relationship between retinal and peripheral vascular function in healthy individuals with low cardiovascular risk• Participants with higher peripheral vascular reactivity indices had a higher amplitude change from maximum to minimum and also showed enhanced reaction times to flicker provocation, which correlated to the degree of peripheral vascular function. 2. The effects of physical training on retinal and systemic microvascular function• Physical exercise positively influenced the retinal microcirculation through improvements in dilation and constriction reaction times to flicker provocation. 3. The long-lasting effects of fasting during the month of Ramadan on retinal and peripheral vascular function• Participants during fasting had a higher capacity to reach maximum dilation and also a greater percentage increase from baseline diameters. The retinal veins were also significantly less variable during baseline corrected measurements. 4. The effect of bariatric surgery on retinal vessels structure and systemic microvascular function• Increases were recorded for the diameter of retinal arteries but also for the veins. Peripheral vascular function was significantly improved and arterial stiffness was decreased. CVD risk was significantly decreased and also correlated with retinal vessel calibre measurements. 5. Is there an improvement in anterior ocular health after bariatric surgery?• Anterior surface health doesn’t necessarily cause ocular health problems in obese individuals nor can it be improved or ameliorated through bariatric surger

Considerations for the measurement of core, skin and mean body temperatures

Despite previous reviews and commentaries, significant misconceptions remain concerning deep-body (core) and skin temperature measurement in humans. Therefore, the authors have assembled the pertinent Laws of Thermodynamics and other first principles that govern physical and physiological heat exchanges. The resulting review is aimed at providing theoretical and empirical justifications for collecting and interpreting these data. The primary emphasis is upon deep-body temperatures, with discussions of intramuscular, subcutaneous, transcutaneous and skin temperatures included. These are all turnover indices resulting from variations in local metabolism, tissue conduction and blood flow. Consequently, inter-site differences and similarities may have no mechanistic relationship unless those sites have similar metabolic rates, are in close proximity and are perfused by the same blood vessels. Therefore, it is proposed that a gold standard deep-body temperature does not exist. Instead, the validity of each measurement must be evaluated relative to one\u27s research objectives, whilst satisfying equilibration and positioning requirements. When using thermometric computations of heat storage, the establishment of steady-state conditions is essential, but for clinically relevant states, targeted temperature monitoring becomes paramount. However, when investigating temperature regulation, the response characteristics of each temperature measurement must match the forcing function applied during experimentation. Thus, during dynamic phases, deep-body temperatures must be measured from sites that track temperature changes in the central blood volume

The effect of work related mechanical stress on the peripheral temperature of the hand

The evolution and developments in modern industry have resulted a wide range of occupational activities, some of which can lead to industrial injuries. Due to the activities of occupational medicine, much progress has been made in transforming the way that operatives perform their tasks. However there are still many occupations where manual tasks have become more repetitive, contributing to the development of conditions that affect the upper limbs. Repetitive Strain Injury is one classification of those conditions which is related to overuse of repetitive movement. Hand Arm Vibration Syndrome is a subtype of this classification directly related to the operation of instruments and machinery which involves vibration. These conditions affect a large number of individuals, and are costly in terms of work absence, loss of income and compensation. While such conditions can be difficult to avoid, they can be monitored and controlled, with prevention usually the least expensive solution. In medico-legal situations it may be difficult to determine the location or the degree of injury, and therefore determining the relevant compensation due is complicated by the absence of objective and quantifiable methods. This research is an investigation into the development of an objective, quantitative and reproducible diagnostic procedure for work related upper limb disorders. A set of objective mechanical provocation tests for the hands have been developed that are associated with vascular challenge. Infrared thermal imaging was used to monitor the temperature changes using a well defined capture protocol. Normal reference values have been measured and a computational tool used to facilitate the process and standardise image processing. These objective tests have demonstrated good discrimination between groups of healthy controls and subjects with work related injuries but not individuals, p<0.05, and are reproducible. A maximum value for thermal symmetry of 0.5±0.3ºC for the whole upper limbs has been established for use as a reference. The tests can be used to monitor occupations at risk, aiming to reduce the impact of these conditions, reducing work related injury costs, and providing early detection. In a medico-legal setting this can also provide important objective information in proof of injury and ultimately in objectively establishing whether or not there is a case for compensation

Physical examination in surgery = Фізикальне обстеження в хірургії : textbook for students, teachers, doctors

У навчальному посібнику всебічно висвітлені фізикальні методи дослідження пацієнтів хірургічного профілю, що викладаються на кафедрі загальної хірургії ДДМУ. Посібник призначається для студентів, лікарів-інтернів, викладачів та практикуючіх лікарів-хірургів