Skin Temperature Fluctuations Research Articles

Application of short-term analysis of skin temperature variability in prediction of survival in patients with cirrhosis.

Background: Liver cirrhosis is a complex disorder, involving several different organ systems and physiological network disruption. Various physiological markers have been developed for survival modelling in patients with cirrhosis. Reduction in heart rate variability and skin temperature variability have been shown to predict mortality in cirrhosis, with the potential to aid clinical prognostication. We have recently reported that short-term skin temperature variability analysis can predict survival independently of the severity of liver failure in cirrhosis. However, in previous reports, 24-h skin temperature recordings were used, which are often not feasible in the context of routine clinical practice. The purpose of this study was to determine the shortest length of time from 24-h proximal temperature recordings that can accurately and independently predict 12-month survival post-recording in patients with cirrhosis. Methods: Forty individuals diagnosed with cirrhosis participated in this study and wireless temperature sensors (iButtons) were used to record patients' proximal skin temperature. From 24-h temperature recordings, different length of recordings (30 min, 1, 2, 3 and 6h) were extracted sequentially for temperature variability analysis using the Extended Poincaré plot to quantify both short-term (SD1) and long-term (SD2) variability. These patients were then subsequently followed for a period of 12 months, during which data was gathered concerning any cases of mortality. Results: Cirrhosis was associated with significantly decreased proximal skin temperature fluctuations among individuals who did not survive, across all durations of daytime temperature recordings lasting 1hour or more. Survival analysis showcased 1-h daytime proximal skin temperature time-series to be significant predictors of survival in cirrhosis, whereby SD2, was found to be independent to the Model for End-Stage Liver Disease (MELD) score and thus, the extent of disease severity. As expected, longer durations of time-series were also predictors of mortality for the majority of the temperature variability indices. Conclusion: Crucially, this study suggests that 1-h proximal skin temperature recordings are sufficient in length to accurately predict 12-month survival in patients with cirrhosis, independent from current prognostic indicators used in the clinic such as MELD.

Determination of Biphasic Menstrual Cycle Based on the Fluctuation of Abdominal Skin Temperature during Sleep

In this study, we focused on the fluctuation of the abdominal skin temperature (AST) during sleep as a second marker for determining the biphasic menstrual cycle, alongside the basal body temperature. The nocturnal AST was measured every 10 min using a wearable device mounted on the abdominal wall. With this system, the AST time-series data were recorded for a total of 1667, 1035, and 1690 days from seven participants for the menstrual/follicular, ovulatory, and luteal phases, respectively. First, the AST fluctuation was evaluated by plotting the cumulative probability distribution (CPD) of changes in AST every 10 min from 0 to 0.7℃. The results showed that the CPD fitted well with an exponential attenuation curve. Second, the mean attenuation coefficients obtained by exponential regression from the CPD data were compared among the three phases. For regular menstrual cycles, the attenuation coefficient was the highest in the menstrual/follicular phase (8.57; 95% confidence interval 8.44–8.70; R2 = 0.983; P < 0.001), followed by the ovulatory phase (7.80; 95% confidence interval 7.65–7.96; R2 = 0.985; P < 0.001) and then the luteal phase (7.24; 95% confidence interval 7.12–7.36; R2 = 0.985; P < 0.001). Finally, we examined whether the attenuation coefficients can be used as an index to classify the three phases by long short-term memory (LSTM)-based deep learning. Consequently, the attenuation coefficient affected the prediction of the menstrual/follicular, ovulatory, and luteal phases with significantly higher F-measures of 0.603, 0.328, and 0.660, respectively. These results suggest that the thermoregulatory system may increase the AST fluctuation in healthy women during the transition from the follicular phase to the ovulatory phase and then to the luteal phase.

Thermal responses of people exhibiting high metabolic rates when exercising in piloti spaces in hot and humid areas

People in hot and humid areas prefer exercising in sheltered spaces, such as pilotis, to avoid direct solar radiation. However, as a piloti space for exercise (PSE) is susceptible to the outdoor environment, it is unclear whether the thermal environment in the PSE satisfies the thermal needs of exercisers exhibiting high metabolic rates. This study investigated the relationship between the thermal environment of PSEs and the thermal response of exercisers. A field survey was conducted in the PSE of a gymnasium in Guangzhou, China, during the summer of 2019. The subjective responses of 28 subjects were collected through questionnaires under various activities, including 3.6 MET shoot (Ex 1), sitting (Post-Ex 1), 5.2 MET layup (Ex 2), sitting (Post-Ex 2), 6.8 MET full-court dribbling shuttle run (Ex 3), and sitting (Post-Ex 3). The environmental and physiological data were recorded using instruments. We documented the fluctuations of mean skin temperature, thermal sensation, thermal acceptability, and sweat feeling index of subjects during the aforementioned activities. The recovery times of thermal acceptability returning to the acceptable state were within 5, 4–22, and 10–39 min during Post-Ex 1, 2, and 3, respectively. The upper limits of the 80% acceptable operative temperatures during Ex 1, 2, and 3 were 32.6, 31.2, and 29.0 °C, respectively. This study contributes to a better understanding of the dynamic changes of exercisers’ thermal responses in the naturally ventilated environment and provides a reference for the evaluation and design of PSEs in hot and humid areas.

High Precision Human Skin Temperature Fluctuations Measuring Instrument.

This paper describes the experimental results of testing a prototype of a high precision human skin rapid temperature fluctuations measuring instrument. Based on the author’s work, an original circuit solution on a miniature semiconductor diode sensor has been designed. The proposed circuitry provides operation in the full voltage range with automatic setting and holding the operating point, as well as the necessary slope of the conversion coefficient (up to 2300 mV/°C), which makes it possible to register fast temperature oscillations from the surface of the human body and other biological objects. Simulation results in the Microcap 12 software and laboratory tests have confirmed all declared design specifications: temperature resolution of 0.01 °C, transducer thermal time constant of 0.05 s. An original thermostat and an experimental setup for the simultaneous registration of the electrocardiogram, pulse wave signals from the Biopac polygraph MP36 and a signal of temperature oscillations from the prototype thermometer have been designed for further investigations. The preliminary test results indicates that using the designed measuring instrument gives a possibility to provide an in-depth study of the relationship between micro- and macro-blood circulations manifested in skin temperature fluctuations.

Effect of nursing procedures on the hand skin temperature of female hospital nurses

Nurses' hand temperature may affect patient comfort but has not been investigated. This study aimed to determine female hospital nurses' hand skin temperature and clarify the effects of measurement site, time, nursing procedures, and environment. An observational study. The middle finger, thenar eminence, hypothenar eminence, and medial forearm skin temperature of 29 female hospital nurses was measured at four time points during a day shift and before and after nursing procedures (hand disinfection, hand washing, taking vital signs, hygiene care, and positioning). Mean hand skin temperature was in the range of 29-32°C with interpersonal variations. Mean skin temperature at the medial forearm was 31.94-32.35°C (SD 0.87-1.52°C) and at the middle finger, 29.73-31.07°C (SD > 3°C). Time-dependent skin temperature fluctuations were confirmed on the middle finger (p = .022), and thenar (p = .005) and hypothenar eminence (p = .001). There were weak correlations between skin temperature and environmental factors, including ambient temperature (ρ = .194-.266), humidity (ρ = -.309 to -.319), and hospital room wind speed (ρ = .253-.314). The skin temperature dropped significantly after hand disinfection and handwashing at all measurement sites (middle finger: -1.30 and -3.56°C, respectively; thenar eminence: -1.19 and -3.32°C; hypothenar eminence: -0.80 and -3.39°C; medial forearm: -0.21 and -1.60°C). These findings may raise nurses' awareness of their skin temperature. Moreover, our study highlights the need to develop countermeasures to ensure optimal nurses' skin temperature and patient comfort.

Endothelial function in metabolic syndrome and its complications: the relationship of functional and structural changes in the cardiovascular system and mechanisms of vascular tone regulation

Endothelial dysfunction is a systemic pathological disorder characterized by weakening of endothelium-dependent vasodilation and vascular remodeling, which is an early manifestation of pathological processes in the cardiovascular system. Vascular endothelial abnormalities in a clinical setting can be diagnosed by biochemical and functional markers. However, there is still no unified optimal method for diagnosing endothelial dysfunction. The aim of the project was to evaluate endothelial dysfunction in patients with metabolic syndrome and to improve the diagnosis and monitoring of treatment effectiveness. Endothelial dysfunction was studied using the method of wavelet analysis of skin temperature fluctuations, and a thermal test was used to assess the properties dynamic state of the endothelium. The obtained data were compared with endothelial dysfunction biochemical markers at baseline and in dynamics after the therapy. The study showed that the wavelet analysis of skin temperature fluctuations technique can be used for diagnosing the endothelial dysfunction. This technique is simple, convenient, reproducible, it has been confirmed by laboratory determination of endothelial dysfunction markers.

The relationship of endothelial dysfunction and metabolic manifestations of obesity

Introduction . Over the past three decades, the prevalence of overweight and obesity in the world has grown by almost 30–50% among adults and children. A number of metabolic and hemodynamic disorders, as well as the pathology of many organs and systems are often associated with obesity. The aim of our study was to compare the functional state of the endothelium in various variants of complicated obesity (СO). Materials and methods . The study included 66 people with СO whose average age was 47.3 ± 9.9 years, from this group 3 groups were formed depending on the complications of obesity (dyslipidemia, hypertension and impaired glucose tolerance). To assess the functional state of endothelium, we used the method of wavelet analysis of skin temperature fluctuations during cooling of the limb; endothelin-1 (ET-1), albuminuria (AC), and vascular endothelial growth factor (VEGF) were determined as markers of endothelial dysfunction. Results . The levels of VEGF, ET-1 and AC in the groups with СO did not differ significantly, however, they were significantly higher than in the comparison group. The results of the cold test revealed the absence of restoration of the amplitudes of fluctuations in skin temperature equally in all groups with CO compared with the control group (post-cold vasodilation indices (IPV) in group 1 – 0.45 (0.38–0.69, in group 2 – 0.59 (0.41–0.83), in group 3 – 0.66 (0.53–0.79), in the Control group – 0.91 (0.86–1.06), p<0.05). Correlations between biochemical and instrumental markers of endothelial dysfunction and insulin resistance indices were obtained: ET-1 correlated with insulin (r=0.49; p=0.02), HOMA index (r=0.55; p=0.01); AU value correlated with glycemia (r=0.70; p=0.02); The IVC vasoconstriction index correlated with the HOMA-IR index (r=0.62; p=0.05); The IPV-1 index decreased with increasing VEGF (r=–0.86; p=0.002) and HOMA-IR (r=–0.86; p=0.002). The IPV-2 index inversely correlated with the level of postprandial glycemia (r=–0.87; p=0.05), systolic blood pressure (r=–0.55; p=0.04), OT (r=–0.57; p=0.04) and ET-1 (r=–0.58; p=0.04). Conclusion . The unified basis of the revealed disorders in СO allows us to conclude that the factors of insulin resistance are complex: hyperglycemia, dyslipidemia, and arterial hypertension, which makes it difficult to identify the leading factor in the formation of endothelial dysfunction.

The Impact of Nonbreaking Waves on Wind‐Driven Ocean Surface Turbulence

AbstractA comprehensive study on the properties of upper ocean turbulence and its response to a variety of wind and wave forcing conditions was conducted at the Surge Structure Atmosphere INteraction (SUSTAIN) facility, University of Miami, RSMAS. The dimensions of SUSTAIN wind‐wave‐current tunnel are 18 m long, 6 m wide, and 2 m high, uniquely allowing for freely forming turbulence unconstrained by side walls. The grid of input parameters covered a range of wave steepness (ak: 0–0.27) within each investigated wind speed (U10: 2–20 m/s), allowing for the isolation of wave effects on the turbulence driven by both wind and waves. The response of turbulence to each pair of wind‐wave parameters was measured in steady‐state conditions (after 20+ min of settling time) by a suite of nonintrusive turbulence visualization techniques, located at 10 m fetch. These included 3‐D visualization of water tracing dye entrainment by turbulence, underwater particle image velocimetry, and passive and active thermal imagery resolving surface skin temperature and velocity fluctuations. The resulting data set includes both qualitative 3‐D view of subsurface turbulent structures and precise quantitative turbulent kinetic energy (TKE) measurements mapped out in response to the grid of input parameters. In lower winds, TKE was found to grow substantially in response to increasing wave steepness, in line with the expected effect of increasing wave forcing. However, in higher winds the effect of increasing wave steepness on TKE was found to be negative. It is hypothesized to be due to the rise of airflow separation, effectively sheltering much of the water surface from turbulence production by wind friction.

Analysis of endothelial dysfunction in the context of pleural effusions of various origins using skin thermometry

To analyze the mechanisms and severity of endothelial dysfunction in patients with pleural effusion of various origins using skin thermometry. We studied microcirculation in 135 patients with pleural effusions of various origins. Local skin thermometry and computer wavelet analysis were performed in 3-5 days after thoracoscopy with pleural biopsy using Microtest-100WF device with a temperature measuring resolution of 0.001°C. We estimated endothelial, myogenic and neurogenic indices using spectral analysis of skin temperature fluctuations in a range 0.0095-2 Hz. The control group comprised 40 healthy participants aged 23-36 years. Three groups of patients were distinguished depending on the cause of effusion: malignant pleural effusions (n=65, 48.1%); inflammatory pleural effusions (para-pneumonic, post-traumatic, pancreatogenic, tuberculous) (n=58, 43%); transudates (hepatogenic, cardiogenic, and nephrogenic) (n=12, 8.9%). There were no significant differences in vascular tone in response to local heating of the second finger of the hand up to 40°C. Measurements were carried out within 10 min in all groups. Patients with diabetes mellitus and cardiovascular diseases (n=48, 35.6%) had significant decrease of thermal vasodilation index in endothelial range up to 2.93±1.77, in the control group - up to 4.21±2.40 (p=0.041). Endothelial dysfunction is a universal non-specific aspect in pathogenesis of various diseases. This process is essential in pleural effusion. Local thermometry and computer wavelet analysis revealed no significant differences between patients with malignant, inflammatory and transudative pleural effusions. Pleural effusions in the context of cardiovascular pathology and/or diabetes mellitus occur due to impaired vasodilatation mechanisms in endothelial range.

Effects of core temperature, skin temperature, and inter-beat interval on resting metabolic rate measurements in thermoneutral conditions.

It is important to identify potential underlying factors that can affect the variability of resting metabolic rate (RMR) measurements. The RMRs of 20 college-aged men were tested twice in stable environmental conditions, with each measurement separated by 40 min. Skin temperature, core temperature, and inter-beat interval were monitored throughout the study as identified factors that could affect RMR measurements. Since environmental conditions in a clinic or laboratory can vary, skin temperature and core temperature can be affected which may affect RMR. Similarly, prior physical activity, stress, sleep, and caffeine intake can affect inter-beat interval and may be a co-variable affecting RMR. Higher RMR measurements were compared to lower RMR measurements. RMR for the higher trial was 2068 ± 66 kcal/day, the lower trial was 1975 ± 65 kcal/day (t = 4.23; p < 0.01). Core temperature for higher trial was 37.1 ± 0.1 °C, the lower trial was 36.8 ± 0.1 °C (s = 105.00; p < 0.01). Skin temperature measurements were significantly different for the anterior bicep site (t = -2.52; p = 0.02), but not for any other site. Inter-beat interval for the higher measurement was 1038 ± 33 ms, the lower measurement was 998 ± 32 ms (t = 3.82; p < 0.01). However, regression analysis found that none of the variables were significant predictors for the higher RMR, lower RMR, or change in RMR. While the factors affecting RMR measurement variability remain unclear, the results suggest that typical fluctuations in core temperature, skin temperature, and inter-beat interval do not effectively predict changes in RMR in a thermoneutral environment.

Enhancing cooling performance via airflow temperature fluctuations

In ventilated and air-conditioned indoor environment, air movement substantially impacts thermal sensation and comfort of occupants from the point of view of whole body and local thermal sensation. Skin temperature and its rate of change are important factors for thermal sensation. Both are affected by the airflow velocity and temperature changes around the body which causes skin temperature fluctuations and changes in convective heat transfer. In this study the impact of temperature fluctuations in airflow on human thermal sensation was examined. For the purposes of the study, an air handling unit was designed for generating airflows with temperature fluctuations and used in a subjective experiment. The experimental study indicates that temperature fluctuations possibly influence the human perception of air movement with a distinct cooling effect.

Vegetative regulation and endothelial dysfunction in patients with metabolic&#x0D; syndrome

Special attention is given to MS bearing in mind its high prevalence in the general population (up to 14-24 %) which is twice the prevalence of diabetes. The study included 50 patients with MS at the age of 25 to 61 years. The group of comparison contained 16 healthy individuals aged 45,3±2,3 years. To evaluate the response of microvascular tone, the wavelet analysis of fluctuations of skin temperature during limb cooling was used. Vascular endothelial growth factor (VEGF) served as a biochemical marker of endothelial dysfunction. Heart rate variability was evaluated in all patients. It was shown that patients with MS were significantly different in terms of all metabolic parameters; their VEGF levels were much higher than in the comparison group. Disturbances of vasodilation identified in the functional cold test in patients with MS confirm the relationship between abnormal vascular reactivity and endothelial dysfunction markers. The cardiointervalographic examination of MS patients revealed typical manifestations of autonomous cardiac neuropathy.

Endothelial dysfunction under body weight loss among women with obesity

The analysis of endothelial dysfunction markers and the results of skin thermometry among women with obesity has been held. The study included 47 postmenopausal women and 21 fertile women, 15 women with normal body weight were studied as the comparison group. To evaluate the response of microvascular tone, the method of wavelet analysis of skin temperature fluctuations was used. The increase of endothelin-1, endothelial vessel growth factor and the amount of endothelial cells testified endothelial dysfunction. The results obtained by the method of skin thermometry showed the stated deviation of vasodilatory mechanisms of vascular tone regulation among women with obesity. Body weight loss and the use of hormone replacement therapy led to the data improvement.

Effect of roost choice on winter torpor patterns of a free-ranging insectivorous bat

Gould’s wattled bat (Chalinolobus gouldii) is one of only three native Australian mammals with an Australia-wide distribution. However, currently no data are available on the thermal physiology of free-ranging C. gouldii. Therefore, we aimed to quantify the effect of roost choice on daily skin temperature fluctuations during winter in C. gouldii living in an agricultural landscape in a temperate region. Ambient conditions consisted of long periods below 0°C and snow. Some individuals roosted high in dead branches whereas one individual roosted in a large cavity located low in a live tree. Torpor was employed on every day of the study period by all bats, with bouts lasting for over five days. The skin temperature of individuals in the dead branches tracked ambient temperature, with skin temperatures below 3°C on 67% of bat-days (lowest recorded –0.2°C). In contrast, the individual in the tree cavity maintained a larger skin-ambient temperature differential, likely influenced by the internal cavity temperature. Our study presents the lowest skin temperature recorded for a free-ranging Australian microbat and reveals that roost choice affects the thermal physiology of C. gouldii, ensuring survival during periods of cold weather and limited food supply.

Skin temperature oscillation model for assessing vasomotion of microcirculation

It has been proved that there exists a certain correlation between fingertip temperature oscillations and blood flow oscillations. In this work, a porous media model of human hand is presented to investigate how the blood flow oscillation in the endothelial frequency band influences fingertip skin temperature oscillations. The porosity which represents the density of micro vessels is assumed to vary periodically and is a function of the skin temperature. Finite element analysis of skin temperature for a contra lateral hand under a cooling test was conducted. Subsequently, wavelet analysis was carried out to extract the temperature oscillations of the data through the numerical analysis and experimental measurements. Furthermore, the oscillations extracted from both numerical analyses and experiments were statistically analyzed to compare the amplitude. The simulation and experimental results show that for the subjects in cardiovascular health, the skin temperature fluctuations in endothelial frequency decrease during the cooling test and increase gradually after cooling, implying that the assumed porosity variation can represent the vasomotion in the endothelial frequency band.

Retrieval of Vertical Distribution of Tropospheric Refractivity through Ground-Based GPS Observation

It has been proved that there exists a certain correlation between fingertip temperature oscillations and blood flow oscillations. In this work, a porous media model of human hand is presented to investigate how the blood flow oscillation in the endothelial frequency band influences fingertip skin temperature oscillations. The porosity which represents the density of micro vessels is assumed to vary periodically and is a function of the skin temperature. Finite element analysis of skin temperature for a contra lateral hand under a cooling test was conducted. Subsequently, wavelet analysis was carried out to extract the temperature oscillations of the data through the numerical analysis and experimental measurements. Furthermore, the oscillations extracted from both numerical analyses and experiments were statistically analyzed to compare the amplitude. The simulation and experimental results show that for the subjects in cardiovascular health, the skin temperature fluctuations in endothelial frequency decrease during the cooling test and increase gradually after cooling, implying that the assumed porosity variation can represent the vasomotion in the endothelial frequency band.

Wavelet-based multifractal analysis of dynamic infrared thermograms to assist in early breast cancer diagnosis.

Breast cancer is the most common type of cancer among women and despite recent advances in the medical field, there are still some inherent limitations in the currently used screening techniques. The radiological interpretation of screening X-ray mammograms often leads to over-diagnosis and, as a consequence, to unnecessary traumatic and painful biopsies. Here we propose a computer-aided multifractal analysis of dynamic infrared (IR) imaging as an efficient method for identifying women with risk of breast cancer. Using a wavelet-based multi-scale method to analyze the temporal fluctuations of breast skin temperature collected from a panel of patients with diagnosed breast cancer and some female volunteers with healthy breasts, we show that the multifractal complexity of temperature fluctuations observed in healthy breasts is lost in mammary glands with malignant tumor. Besides potential clinical impact, these results open new perspectives in the investigation of physiological changes that may precede anatomical alterations in breast cancer development.

Assessment of endothelial dysfunction in patients with impaired glucose tolerance during a cold pressor test

The objective of this study is to explore changes in microvascular tone during a contralateral cold pressor test and to compare the results obtained in healthy subjects and in patients with impaired glucose tolerance (IGT) and type 2 diabetes. Low-amplitude fluctuations of skin temperature in the appropriate frequency ranges were used as a characteristic for the mechanism for vascular tone regulation. In total, 13 adults with type 2 diabetes aged 40-67 years and 18 adults with IGT aged 31-60 years participated in this pilot study. The control group included 12 healthy men and women aged 39-60 years. The response to the cold pressor test in patients with type 2 diabetes and with IGT differs essentially from that of healthy subjects in the endothelial frequency range. Endothelial dysfunction occurs in the preclinical stage of diabetes and manifests, in particular, as a disturbance of the endothelial part of vascular tone regulation.

Determination of ovulation time in sows based on skin temperature and genital electrical resistance changes

Different physical and physiological parameters may be used to determine ovulation time in sows. In the present study, we analysed the ear and vulvar skin temperature fluctuations, and the changes...

Coupling of infraslow fluctuations in autonomic and central vigilance markers: Skin temperature, EEG beta power and ERP P300 latency

Even under thermoneutral conditions, skin temperature fluctuates spontaneously, most prominently at distal parts of the body. These fluctuations were shown to be associated with fluctuations in vigilance: mild manipulation of skin temperature during nocturnal sleep affects sleep depth and the power spectral density of the electroencephalogram (EEG), and fluctuations in skin temperature during daytime wakefulness are related to sleep propensity and task performance. The association of daytime skin temperature fluctuations with EEG markers of vigilance has not previously been investigated. Therefore, the present study aimed to evaluate the association between daytime fluctuations in skin temperature with those in two quantitative EEG measures: the power spectral density of background EEG, and the event related potential (ERP) elicited by visual stimuli.High-density EEG and skin temperature were obtained in eight healthy adults five times a day while they performed a visual sustained-attention task. Assessments were made after a night of normal sleep and after the challenge of a night of total sleep deprivation.Fluctuations in the distal-to-proximal skin temperature gradient measured from the earlobe and mastoid were associated with fluctuations in parieto-occipital high beta band (20–40Hz) power of the pre-stimulus background EEG, but only after sleep deprivation. The temperature fluctuations were moreover associated with fluctuations in the latency of the P300 elicited by the stimulus.The findings demonstrate close association between fluctuations in an autonomic correlate of the vigilance state (i.e. the distal-to-proximal skin temperature gradient), and fluctuations in central nervous system correlates of the vigilance state (i.e. background EEG and ERP). The findings are of theoretical and practical relevance for the assessment and manipulation of vigilance.