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Thermal Physiology and Thermoregulation
Published in James Stewart Campbell, M. Nathaniel Mead, Human Medical Thermography, 2023
James Stewart Campbell, M. Nathaniel Mead
Skin temperature is normally a reliable indicator of the heat exchange activity of the body. The average temperature of the skin is about 32.5°C (90.5°F) or 4°C (7.2°F) lower than the body's core temperature under thermoneutral conditions.12 At a room temperature of 25°C (77°F), local skin temperatures may vary within a range of 4–5°C (7.2–9°F) depending on physiologic, anatomic, and pathologic factors.13 In a warmer environment, the temperature of the skin increases toward core temperature as blood flow through the skin increases. The human body is generally warmer than the ambient temperature, allowing a flow of heat from the core to the environment. Even with clothing for insulation, heat is steadily lost from the body. During cold stress, blood flow through exposed skin is reduced, leading to a decrease in skin temperature and conservation of core body heat. Skin temperature in the periphery may approach the ambient temperature during cooling, with the nose, ear, finger, and toe temperatures becoming about 17°C (30.6°F) lower than normal core temperature when the body is equilibrated to an air temperature of 20°C (68°F).
Protocol for Standardized Data Collection in Humans
Published in U. Snekhalatha, K. Palani Thanaraj, Kurt Ammer, Artificial Intelligence-Based Infrared Thermal Image Processing and Its Applications, 2023
U. Snekhalatha, K. Palani Thanaraj, Kurt Ammer
There is a long history of the cold-provocation test to detect a suspected Raynaud’s phenomenon by thermal imaging. However, the idea to detect finger color changes following cold exposure goes back to the British cardiologist Sir Thomas Lewis. Francis Ring proposed in 1980, a combined thermal gradient by summing up the distal–dorsal temperature difference prior and 10 (15 or 20) minutes after the cold challenge for assisting the diagnosis of Raynaud’s phenomenon (Ring, 1980). He also reported the consensus of a panel of thermal imaging experts on the thermographic assessment of patients with Raynaud’s phenomenon in 1988 (Ring et al., 1988). Ammer tried to extract from the thermographic literature, procedures which address patient’s preparation, temperature of the examination room, temperature and duration of the immersion bath, position of hands, time of follow-up after the cold challenge, and method of evaluation. The review article reported a wide variation in water temperature of the immersion bath, also of the duration of immersion. More than 20 different methods for evaluation of hand temperatures were published (Ammer, 2009). Applying a mild cold stress with the hands covered with plastic gloves being immersed in water of 20°C for 1 minute is in the author’s experience, an easily performed provocation test for Raynaud’s phenomenon. After emersion, thermal images recorded for 20 minutes at 5-minute intervals allow to determine combined thermal gradients. This kind of analysis can be performed semi-automatically with dedicated software (Plassmann and Jones, 2003).
Age-Related Changes in the Autonomic Nervous System
Published in David Robertson, Italo Biaggioni, Disorders of the Autonomic Nervous System, 2019
Sheila M. Ryan, Lewis A. Lipsitz
Elderly hospitalized patients are also at risk of hypothermia. In Israel, despite a warm climate, 50% of patients identified as hypothermic developed it while in hospital (Kramer, Vandijk and Rosin, 1989). Medical conditions which impair thermoregulation in the elderly predispose them to the development of hypothermia even under relatively mild cold stress. Diseases such as Parkinson’s disease and severe arthritis can immobilize the older person and thereby impair heat production. Malnutrition - by itself or in association with dementia, poor living conditions, cancer or other conditions - can result in a lowered basal metabolic rate and reduced heat production. Neuroleptic medications impair central heat regulation and can also immobilize an elderly person. Sepsis is frequently observed among elderly patients admitted with hypothermia (Kramer, Vandijk and Rosin, 1989). It appears that underlying medical conditions predisposing to hypothermia are more common that autonomic dysfunction per se (Besdine, 1979). Mortality in elderly persons with hypothermia is high and ranges from 30-80%. Mortality from hypothermia in association with myxoedema is particularly high.
Drug discovery and development for fibromyalgia using practical biomarkers throughout the process from relevant animal models to patients
Published in Expert Opinion on Drug Discovery, 2023
Yukinori Nagakura, Hidetoshi Tozaki-Saitoh, Hiroshi Takeda
The Sluka model was constructed based on the hypothesis that the continued primary afferent input from the muscle leads to chronic FM-like widespread pain, which is unrelated to tissue damage [76]. Two injections of acidic saline into the gastrocnemius muscle induce contralaterally spreading (widespread) hyperalgesia via spinal hyperexcitability with several comorbidities, including depression and sleep disturbances [79,80]. The RIM model was constructed based on the hypothesis that a chronic decrease in brain biogenic amines triggers FM-like chronic widespread pain and comorbid symptoms. Biogenic amine reduction in the brain by repeated reserpine injection causes chronic spontaneous pain detected as an elevation of the grimace score [81], widespread musculoskeletal pain, and comorbid symptoms, including depression, fatigue, and sleep disturbance [77,79]. The ICS model was developed based on the hypothesis that exposure to physical and mental stress triggers FM-like chronic pain conditions. Intermittent cold stress (alteration of temperatures between −3°C to −4°C and 22°C to 24°C), but not constant cold stress, induces long-lasting bilateral allodynia and thermal hyperalgesia [78]. Comorbid symptoms, including sleep disturbances, depression, and fatigue, commonly observed in patients with FM, have also been expressed in this model [79].
Stationed in Alaska: Subjective Winter Stress and Mental Health
Published in Military Behavioral Health, 2019
Lynn Alkhalil, Maria E. St. Pierre, Walter J. Sowden, Amy B. Adler
Results also showed that the effect of subjective cold stress appears to outweigh the effect of stress caused by winter darkness for mental health and sleep outcomes. This difference may be attributed to the fact that subjective cold stress is a more salient experience characterized by significant physical discomfort (Roth-Isigkeit, 2005; Coghill, 2010), whereas prolonged darkness is not as readily felt by the individual. Thus, subjective stress from the cold may place more of a strain on soldiers, and this strain may account for the stronger correlation between cold stress and with physical and psychological problems. Another explanation for the cold stress finding may be related to differences in how individuals manage the cold. Soldiers may choose to manage the cold by social hibernation (e.g., avoiding exposure to the outside). This isolation may result in loneliness. Not only is loneliness associated with greater risk for mental health problems (Losada et al., 2012), but it also exacerbates feelings of coldness (Ijzerman et al., 2012; Zhong & Leonardelli, 2008), thus increasing the risk for physical and psychological strain.
Identification of complex regional pain syndrome in the upper limb: Skin temperature asymmetry after cold pressor test
Published in Canadian Journal of Pain, 2018
Tara Packham, Joy MacDermid, James Bain, Norm Buckley
Cooke et al.22 studied responses to mild cold stress in the symptomatic (ipsilateral) hand on mean hand temperature measured using IR thermography in 20 persons with CRPS I, also tracking rewarming and then repeating cold stress on the unaffected (contralateral) hand. Some participants saw rewarming temperatures increase from baseline, whereas others failed to return to baseline; these responses also varied between cold stress to the ipsilateral or contralateral hand.22 At baseline, they reported a mean temperature asymmetry of 0.3°C in healthy controls and mean SkTA of 0.6°C in participants with CRPS I. We also observed a variety of responses in our patient groups after exposure to a strong cold stress on the foot: though skin surface temperatures generally decreased in both hands in response to cold (suggesting vasoconstriction), the affected hand would drop to a greater extent. However, we did have several cases where the affected hand increased in temperature after cold stress and asymmetry disappeared. Given the heterogeneity of responses seen relative to cold pressor testing,18,22,24 we posit that this may represent elements of fear or threat anticipation that modulate the peripheral vasomotor responses measured relative to activity and environmental stimuli.7,23