Mean Body Temperature Research Articles

An optimal condition for the evaluation of human brown adipose tissue by infrared thermography

Brown adipose tissue (BAT) is responsible for non-shivering thermogenesis and is an attractive therapeutic target for combating obesity and related diseases. Human BAT activity has been evaluated by 18F-fluorodeoxyglucose-positron emission tomography/computed tomography (18FDG-PET/CT) under acute cold exposure, but the method has some serious limitations, including radiation exposure. Infrared thermography (IRT) may be a simple and less-invasive alternative to evaluate BAT activity. In the present study, to establish an optimal condition for IRT, using a thermal imaging camera, skin temperature was measured in the supraclavicular region close to BAT depots (Tscv) and the control chest region (Tc) in 24 young healthy volunteers. Their BAT activity was assessed as the maximal standardized uptake value (SUVmax) by 18FDG-PET/CT. Under a warm condition at 24–27°C, no significant correlation was found between the IRT parameters (Tscv, Tc,, and the difference between Tscv and Tc,, Δtemp) and SUVmax, but 30–120 min after cold exposure at 19°C, Tscv and Δtemp were significantly correlated with SUVmax (r = 0.40–0.48 and r = 0.68–0.76). Δtemp after cold exposure was not affected by mean body temperature, body fatness, and skin blood flow. A lower correlation (r = 0.43) of Δtemp with SUVmax was also obtained when the participant’s hands were immersed in water at 18°C for 5 min. Receiver operating characteristic analysis revealed that Δtemp after 30–60 min cold exposure can be used as an index for BAT evaluation with 74% sensitivity, 92% specificity, and 79% diagnostic accuracy. Thus, IRT may be useful as a simple and less-invasive method for evaluating BAT, particularly for large-scale screening and longitudinal repeat studies.

Clinical Efficacy of Amoxicillin versus Cefodoxime Proxetil for the Treatment of Pneumonia

Background: Pneumonia is one of the leading cause of death of under 5 children in Bangladesh. WHO recommended Amoxicillin and Co-trimoxazole as first line drugs for the treatment of pneumonia. But emergence of antimicrobial resistance against the common pathogens prompted WHO panel to find out evidence based recommendations for treating pneumonia.
 Objectives: The purpose of the present study was to compare the effect of oral Amoxicillin and Cefpodoxime proxetil in children with pneumonia.
 Methodology: This prospective randomized study was conducted in outpatient department of Pediatrics at Mymensingh Medical College Hospital, Mymensingh, Bangladesh from March 2010 to March 2012 for a period of two (02) years. Baseline data were collected from 197 patients, thereafter 85 patients from Amoxicillin group and 89 patients from Cefpodoxime proxetil group completed the trial.
 Results: Among the enrolled (197) children, majority (53%) were boys. The baseline clinical characteristics before therapy were not significantly different in both the Amoxicillin and Cefpodoxime proxetil groups. Changes in duration of cough, duration of dyspnea, duration of fast breathing, mean heart rate, temperature and respiratory rate were observed. After treatment with Amoxicillin and Cefpodoxime proxetil similar significant improvement in mean body temperature, respiratory rate and wheeze were observed which were almost similar in both the groups (p <0.001). While comparing the efficacy, treatment outcome did not differ significantly in both the groups (p >0.127). Chi-square test revealed no statistically significant difference between patients treated with Amoxicillin and those treated with Cefpodoxime proxetil (p =0.171).
 Conclusion: Response to therapy in both Amoxicillin and Cefpodoxime Proxetil groups was nearly similar and the difference was statistically insignificant.
 Bangladesh Journal of Infectious Diseases, June 2019;6(1):22-25

Fan cooling after cardiovascular drift does not reverse decrements in maximal oxygen uptake during heat stress

ABSTRACTCardiovascular (CV) drift, the progressive increase in heart rate (HR) and decrease in stroke volume (SV) during constant rate, moderate intensity exercise, is related to reduced maximal oxygen uptake (V̇O2max) during heat stress. Once it has already occurred, it is unknown whether the detrimental effects of CV drift on V̇O2max can be reversed. This study tested the hypothesis that fan cooling after CV drift has occurred attenuates decrements in V̇O2max associated with CV drift. Eight men completed a control graded exercise test (GXT) in 22°C to measure V̇O2max. Then on separate, counterbalanced occasions, they completed one 15-min (15MIN) and two 45-min bouts (45NF and 45FAN) of cycling in 35°C, 40% RH at 60% V̇O2max, each immediately followed by a GXT to measure V̇O2max. For one of the 45-min trials (45FAN), fan airflow (4.5 m/s) was directed at participants beginning ~5 min before the GXT and continuing throughout the remainder of exercise. The purpose of the separate 15- and 45-min trials was to measure V̇O2max during the same time interval that CV drift occurred. HR increased (13.8% and 11.4%) and SV decreased (14.4% and 14.1%) for 45NF and 45FAN, respectively; trials were not different (all P > 0.05). Despite a decrease in mean skin temperature of ~1°C with fan use, V̇O2max decreased similarly between conditions (17% vs. 15% for 45NF and 45FAN, P = 0.54). Fan cooling after CV drift was insufficient to reverse the negative consequences of CV drift on V̇O2max after prolonged exercise in a hot environment.Abbreviations: 15MIN: 15-min trial; 45FAN: 45-min, fan trial; 45NF: 45-min, no fan trial; ANOVA: Analysis of variance; CV: Cardiovascular; GXT: Graded exercise test; HR: Heart rate; SV: Stroke volume; T̅b: Mean body temperature; Tre: Rectal temperature; T̅sk: Mean skin temperature; V̇O2max: Maximal oxygen uptake

Impacts of "supermoon" events on the physiology of a wild bird.

The position of the Moon in relation to the Earth and the Sun gives rise to several predictable cycles, and natural changes in nighttime light intensity are known to cause alterations to physiological processes and behaviors in many animals. The limited research undertaken to date on the physiological responses of animals to the lunar illumination has exclusively focused on the synodic lunar cycle (full moon to full moon, or moon phase) but the moon's orbit—its distance from the Earth—may also be relevant. Every month, the moon moves from apogee, its most distant point from Earth—and then to perigee, its closest point to Earth. Here, we studied wild barnacle geese (Branta leucopsis) to investigate the influence of multiple interacting lunar cycles on the physiology of diurnally active animals. Our study, which uses biologging technology to continually monitor body temperature and heart rate for an entire annual cycle, asks whether there is evidence for a physiological response to natural cycles in lunar brightness in wild birds, particularly “supermoon” phenomena, where perigee coincides with a full moon. There was a three‐way interaction between lunar phase, lunar distance, and cloud cover as predictors of nighttime mean body temperature, such that body temperature was highest on clear nights when the full moon coincided with perigee moon. Our study is the first to report the physiological responses of wild birds to “supermoon” events; the wild geese responded to the combination of two independent lunar cycles, by significantly increasing their body temperature at night. That wild birds respond to natural fluctuations in nighttime ambient light levels support the documented responses of many species to anthropogenic sources of artificial light, that birds seem unable to override. As most biological systems are arguably organized foremost by light, this suggests that any interactions between lunar cycles and local weather conditions could have significant impacts on the energy budgets of birds.

Diurnal and Circannual Variation in Body Temperature: Implications for Heat Illness Protocols

As warm-season temperatures continue to rise, the incidence of heat illness is likely to increase. Although preventive protocols currently consider environmental risk factors, there may be reason to emphasize diurnal and seasonal influences. Data supporting seasonal fluctuation in body temperature are abundant in animals but limited in humans. PURPOSE: To examine circannual and diurnal patterns of body temperature in a patient population. METHODS: We analyzed 2,184 men and women admitted to a major hospital in Indiana over 3 years. Demographic, anthropometric, and cardiometabolic variables were collected along with season, month, and time of admission. The National Centers for Environmental Information’s National Climate Report was used to generate month-by-month ambient temperature data; there were clearly defined cold (October through April) and warm (May through September) periods. All patients received oral temperatures. We used t-tests and ANOVAs to detect differences in body temperature by time conditions; we used linear regression to test the effect of chronological variables on body temperature, holding all measured confounders constant. RESULTS: Mean body temperature was 98.16 ± 0.73°F. The warmest period of the day was 6:00 to 10:00pm (98.27°F). The coldest period was 2:00 to 6:00am (98.05°F; p < 0.001). ANOVA revealed differences in body temperature by month (F = 2.525; p = 0.004) and by season (F = 3.656; p = 0.012). The strongest comparison was the cold vs. warm period (T = -3.835; p < 0.001). Patients admitted during the cold period (N = 1,139) had a temperature of 98.10 ± 0.81°F while patients admitted during the warm period (N = 1,045) had a temperature of 98.22 ± 0.63°F (p < 0.001). Lower temperatures were also found among patients ≥ 65 years (p < 0.001) and those with a positive blood alcohol test (p = 0.004). Holding all measured confounders constant, being admitted during the warmer months predicted an elevation in body temperature of 0.13°F (p < 0.001). CONCLUSION: These findings support diurnal and circannual variations in humans. Coaches and athletic trainers may consider this when designing and monitoring practice conditions. Athletes will likely require closer observation along with updated prevention protocols when practicing outdoors to minimize the risk of a heat-related event.

Comparison of argon and air as thermal insulating gases in drysuit dives during military Arctic diving equipment development tests

Introduction: It is vital to protect divers from the cold, particularly in Arctic conditions. The insulating gas layer within the drysuit is crucial for reducing heat loss. The technical diving community has long claimed the superiority of argon over air as an insulating gas. Although argon is widely used, previous studies have shown no significant differences between the two gases. Owing to its lower heat conductivity, argon should be a better thermal insulating gas than air. Methods: The study aimed to determine whether argon is beneficial for reducing heat loss in divers during development of military drysuit diving equipment in Arctic water temperatures. Four divers completed 14 dives, each lasting 45 minutes: seven dives used air insulation and seven used argon insulation. Rectal and eight skin temperatures were measured from which changes in calculated mean body temperature (MBT) were assessed. Results: There was a significant reduction in area weighted skin temperature over time (0-45 minute) on air dives (ΔTskin = -4.16ÅãC, SE = 0.445, P &lt; 0.001). On argon dives the reduction was significantly smaller compared to air dives (difference between groups = 2.26ÅãC, SE = 0.358, P&lt;0.001). There were no significant changes in rectal temperatures, nor was a significant difference seen between groups. Conclusion: Compared to air, argon may be superior as a drysuit insulating gas in Arctic water temperatures for some divers. Argon used as insulating gas can make diving safer and may diminish the risks of fatal diving accidents and occupational hazard risks in professional diving.

BOVINE WELLFARE HANDLED IN ADAPTED CORRAL WITH UNCONVENTIONAL MATERIALS

ABSTRACT This study aimed at evaluating bovine behavioral parameters managed in crowding pens built with modular panel of reforestation wood and homogeneous particle sheets of sugarcane bagasse and in conventional wooden crowding pens. The animals treated had their body surface temperature measured by the infrared thermography method and the behavior evaluated through the flight time parameters and the behavior score in the crowding pens. The results indicated that the animals managed in these buildings showed no difference in the behavioral parameters, but the mean and maximum superficial body temperatures were lower in the animals managed in the crowding pens of modular panel.

Comparison of Effectiveness of Two Polyethylene Covers on Body Temperature and Oxygen Saturation of Neonates Transferring to NICUs

Background: The sudden exposure of premature newborns to a cold and dry environment can lead to hypothermia. This study aimed at comparing the effectiveness of two polyethylene covers on the body temperature and oxygen saturation of premature neonates. Methods: This experimental study was conducted on 72 premature newborns in the neonatal intensive care unit (NICU) of Shahid Sadoughi Hospital in Yazd, Iran. The study subjects were randomly assigned into three groups, including the neonates with polyethylene head cap, polyethylene body bag, and routine care. The data were collected using a thermometer and a pulse oximeter. The data analysis was performed through descriptive statistics, Chi-square test, analysis of variance (ANOVA), repeated measures ANOVA, and Tukey test using SPSS (version 18) software. Results: There was a significant difference in the mean body temperature of control and intervention groups immediately after their NICU admission and 1 h later. Other significant differences were found in the mean of oxygen saturation belonging to the control group and the hat group upon admission and 1 h later. Also, the mean scores of oxygen saturation belonging to the control group were compared with those of the bag group, and the differences were significantly different 1 h after the admission. Conclusion: In the light of these findings, the application of both polyethylene head cap and body bag can maintain the body temperature and oxygen saturation in the premature neonates transferring to the NICU. In particular, the head cap seems to better improve than oxygen saturation.

Suhu Tubuh Bayi Prematur di Inkubator Dinding Tunggal dengan Inkubator Dinding Tunggal Disertai Sungkup

This study aims to compare the average change in body temperature in a single wall incubator with a single wall incubator with hood in preterm infants with hypothermia. The design of this study uses a comparative descriptive method. The results of the study in the group of preterm infants with hypothermia in a single wall incubator with a lid significantly increased mean body temperature changes with a mean value of 36.09 variance 0.152 while for preterm infants with hypothermia in a single wall incubator a mean value of 35.35 variance values 0.859 and obtained t count from the two study groups namely 2.551 and 1.717 t table. In conclusion, a single wall incubator with a lid increases body temperature in premature infants with hypothermia compared to a single wall incubator.&#x0D; &#x0D; Keywords: Hypothermia, Incubator, Premature

Interleukin-10 and interleukin-1 receptor antagonist distinguish between patients with sepsis and the systemic inflammatory response syndrome (SIRS)

The current study evaluated the potential of clinical parameters and circulating biomarkers to distinguish sepsis from SIRS in patients admitted with systemic inflammation. Clinical parameters, leukocyte counts and platelets were measured on admission. Circulating C-reactive protein (CRP), procalcitonin (PCT) and cytokine concentrations were quantified using laser immunonephelometry, immunoluminescence and a Bio-Plex suspension bead array system respectively. Blood, sputum, urine, peritoneal and cerebrospinal fluid were sent for microscopy and culture. Based on clinical information and the results of microbiological testing, 62 patients were classified retrospectively into 2 groups, those with sepsis (n = 37) or SIRS (n = 25). Mean body temperature was higher and blood pressure lower in the sepsis patients. Circulating concentrations of CRP, PCT, interleukin (IL)-10 and IL-1 receptor antagonist (IL-1Ra) were significantly higher in patients with sepsis, with IL-10 identified as the best biomarker in differentiating sepsis from SIRS. The biomarkers that best predicted overall mortality were platelet counts >PCT ≥ CRP > IL-6 > IL-1Ra. These findings demonstrate that patients with sepsis have significantly increased levels of the immunosuppressive/anti-inflammatory cytokines, IL-1Ra and IL-10, compared to those with SIRS, consistent with a more intense counteracting anti-inflammatory response, while a biomarker profile including platelets, PCT, CRP, IL-6 and IL-1Ra may be useful to predict mortality.

Therapeutic efficacy of chloroquine for treatment of Plasmodium vivax malaria cases in Guragae zone southern Central Ethiopia

BackgroundMalaria continues to be a public health problem and important cause of morbidity and mortality in Ethiopia. Due to continuous interventions to combat malaria in endemic regions, a decline in malaria related deaths and morbidity has been registered. These gains, however, are threatened with the emergency of antimalarial drugs resistant strains of plasmodium parasites. This study aimed to determine therapeutic efficacy of chloroquine for treatment of Plasmodium vivax malaria cases in Guragae zone, southern central Ethiopia.MethodsA one arm prospective study with recurrence of parasitaemia and clinical conditions of patients were evaluated on days 0, 1, 2, 3, 7, 14, and 28. Patients with Plasmodium vivax malaria mono infection and eligible for study inclusion criteria were recruited. SPSS-21 used for data analysis and management. Kaplan-Meier survival probability analysis was estimated. Mean geometric parasitaemia and average haemoglobin concentration were calculated.ResultsAmong 87 total recruited subjects, 81 of them completed the 28 days follow up. More than half of (57.5%) the study participants had a history of fever and 42.5% of them had fever at the time of enrollment. The mean body temperature on day of recruitment was 38.2 °C and 36.8 °C on day 28. Geometric mean parasitaemia calculated on day of enrollment was 2270 parasites/μl of blood. Recurrence of parasitaemia was registered from two subjects during entire follow up. The mean haemoglobin concentration of study participants on day of enrolment was 11.8 g/ dl and 13.8 g/dl on day 28.ConclusionThis study registered a high chloroquine efficacy rate among the study participants. Therefore, chloroquine remains efficacious for the treatment of Plasmodium vivax malaria in the study area. However, there is a need to monitor chloroquine resistance by employing molecular tools for better evaluation of treatment outcome.

Light affects heart rate's 24-h rhythmicity in intensive care unit patients: an observational study.

Intensive care unit (ICU) patients experience two affronts to normal 24-h rhythms: largely internal events such as medication and external factors such as light, noise and nursing interventions. We investigated the impact of light variance within an ICU on 24-h rhythmicity of three key physiological parameters: heart rate (HR), mean arterial blood pressure (MAP) and body temperature (BT) in this patient population. Patients were assigned to beds either in the 'light' or 'dark' side within a single ICU. An actigraph continuously recorded light intensity for a 24-72-h period. Measurements of HR, MAP and BT were recorded every 30 min. HR, MAP and BT did not follow 24-h rhythmicity in all patients. Higher light exposure in the Light Side of the ICU (122·3 versus 50·6lx) was related to higher HR (89·4 versus 79·8 bpm), which may translate to clinically relevant outcomes in a larger sample. Duration of stay, the one clinical outcome measured in this study, showed no significant variation between the groups (p = 0·147). ICU patients are exposed to varying light intensities depending on bed positioning relative to natural sunlight, affecting the 24-h rhythm of HR. Larger, well-controlled studies also investigating the effect of relevant light intensity are indicated. Light is a variable that can be manipulated in the constrained environment of an ICU, thus offering an avenue for relatively unobtrusive interventions.

Physiologic Stress of Ear Punch Identification Compared with Restraint Only in Mice.

Social housing of laboratory rodents is recommended whenever possible to encourage natural behavior and social dynamics. Several identification methods are used to distinguish rodents from one another. One of the most common means of identifying mice is ear punching. The effect of ear punching for identification or genotyping on the welfare of mice remains a concern, because this method negatively affects welfare in other species. To assess the influence of ear punching on the welfare of mice, we implanted telemetry units in 6 female Swiss-Webster mice and monitored heart rate, body temperature, and activity after various routine procedures. The physiologic and behavioral responses to restraint (by scruffing) only, restraint and ear punching, and routine handling for husbandry were evaluated. The mean heart rate of mice after receiving an ear punch was significantly higher than baseline values at 30 min after the procedure, and the mean body temperature was significantly increased over baseline for at least 1 h. The heart rate, body temperature, and activity levels of mice after scruffing only and routine handling did not differ from baseline values. The proportion of time mice spent head grooming, a potentially nocifensive behavior, was increased immediately after ear punching and began to decline by 60 min. We show that the physiologic stress of mice receiving an ear punch was greater than that from restraint (scruffing) alone, whereas behavioral indices of pain were unchanged, suggesting that ear punching causes a transient response in mice.

Thermoeffector threshold plasticity: The impact of thermal pre-conditioning on sudomotor, cutaneous vasomotor and thermogenic thresholds.

To better understand the relationships between changes in body temperature and displacements of the thermoeffector thresholds (critical temperatures), the passive cooling (and heating) of pre-heated (and pre-cooled) individuals was investigated. Such experiments are necessary to understand the inter-dependence of those thresholds, and may possibly yield human evidence for the existence of separate central controllers. Eight males participated in four trials; two when normothermic, one following pre-experimental heating and the fourth following pre-cooling. Subjects were exposed to passive, whole-body cooling and heating when normothermic (the control trials), and again following pre-heating and pre-cooling (respectively). Cutaneous vasomotor, thermogenic, as well as precursor and discharged sudomotor thresholds from different body segments were compared across those dynamic thermal states. Following pre-heating, the critical mean body temperatures for vasoconstriction (0.37 °C ± 0.10) and thermogenesis (0.67 °C ± 0.20) were significantly elevated during passive cooling, relative to the corresponding control trial (both P < 0.05). When passive heating followed pre-cooling, the thresholds for vasodilatation were reduced (0.37 °C ± 0.07; P < 0.05). Conversely, but with the exception of forehead precursor sweating, the sudomotor thresholds were elevated (averaging 0.16 °C ± 0.02; P < 0.05). Most thermoeffectors revealed unique and adjustable activation thresholds, with the threshold displacements for thermogenesis and vasomotion appearing to be linked to the change in mean body temperature. Following pre-cooling, the critical temperatures for vasodilatation and sudomotor activation varied independently, with the exception of forehead precursor sweating. Collectively, those observations are consistent with the presence of independent central controllers for thermally dependent vasomotor and sudomotor responses, and perhaps also for shivering thermogenesis.

Minimally invasive surfactant therapy failure: risk factors and outcome

ObjectiveTo evaluate incidence of minimally invasive surfactant therapy (MIST) failure, identify risk factors and assess the impact of MIST failure on neonatal outcome.DesignRetrospective cohort study. MIST failure was defined as...

Thermogenic and psychogenic sweating in humans: Identifying eccrine glandular recruitment patterns from glabrous and non-glabrous skin surfaces.

In this experiment, psychogenic (mental arithmetic), thermogenic (mean body temperature elevation of 0.6 °C) and combined thermo-psychogenic treatments were used to explore eccrine sweat-gland recruitment from glabrous (volar hand and forehead) and non-glabrous skin surfaces (chest). It was hypothesised that each treatment would activate the same glands, and that glandular activity would be intermittent. Nine individuals participated in a single trial with normothermic and mildly hyperthermic phases. When normothermic, a 10-min arithmetical challenge was administered, during which sudomotor activity was recorded. Following passive heating and thermal clamping, sweating responses were again evaluated (10 min). A second arithmetical challenge (10 min) was administered during clamped hyperthermia, with its sudorific impact recorded. The activity of individual sweat glands was recorded at 60-s intervals, using precisely positioned, and uniformly applied, starch-iodide papers. Those imprints were digitised and analysed. Peak activity typically occurred during the thermo-psychogenic treatment, revealing physiologically active densities of 128 (volar hand), 165 (forehead) and 77 glands.cm-2 (chest). Except for the hand (46%), glands uniquely activated by one treatment were consistently <10% of the total glands identified. Glandular activations were most commonly of an intermittent nature, particularly during the thermogenic treatment. Accordingly, we accepted the hypothesis that psychogenic, thermogenic and thermo-psychogenic stimuli activate the same sweat glands in both the glabrous and non-glabrous regions. In addition, this investigation has provided detailed descriptions of the intermittent nature of sweat-gland activity, revealing that a consistent proportion of the physiologically active glands are recruited during these thermal and non-thermal stimuli.

Effect of change in ambient temperature on core temperature of female subjects during the daytime and its sex differences.

Tympanic temperature (Tty), skin temperature, and regional dry heat loss were measured continuously in eight female subjects under three conditions: (1) stepwise increases in ambient temperature (Ta) from 26°C at 09:00 to 30°C at 18:00, (2) steady Ta at 28°C from 09:00 to 18:00, and (3) stepwise decreases in Ta from 30°C at 09:00 to 26°C at 18:00. Oxygen consumption, body weight loss, thermal sensation, and comfort levels were periodically recorded. The Tty increased significantly (p < 0.01) from 36.1 ± 0.36°C to 36.6 ± 0.23°C at 18:00 under condition 1 but remained virtually unchanged under conditions 2 and 3. Thermal comfort was observed at 15:00 and 17:00 under condition 3, whereas subjects reported that they felt slightly cool at 15:00. The rate of body heat storage (S), changes in Tty, mean skin temperature ([Formula: see text]sk), and mean body temperature during each period were calculated, and confirmed that changes in [Formula: see text]sk was correlated with S. Diurnal changes in core temperature (Tc) appeared to be more dependent on diurnal rhythm than on changes in Ta, except when Ta increased continuously. Thus, it may be difficult to predict diurnal changes in women's Tc using a body-heat-balance equation during thermal transient.

An Evaluation of Personal Cooling Systems for Reducing Thermal Strain Whilst Working in Chemical/Biological Protective Clothing.

ObjectiveThe use of personal cooling systems to mitigate heat strain on first-responders achieves two potential performance benefits relative to the absence of such cooling: (1) the completion of a workload with less effort; and/or (2) the completion of a greater workload for the same effort. Currently, claims made by manufacturers regarding the capability of their products for use in conjunction with chemical/biological protective clothing remain largely unsubstantiated. The purpose of this investigation was to evaluate the means by which heat strain can be alleviated during uncompensable heat stress in chemical/biological clothing, using the ASTM F2300-10 methodology.MethodsEight healthy males completed five trials of continuous walking (4.5 km h−1; 35°C; 49% RH) for up to 120 min while wearing one of four cooling systems and/or a National Fire and Protection Association 1994 Class-3 chemical/biological ensemble. The four cooling methods (ice vest [IV], phase-change vest [PCM], water-perfused suit [WS], and combination ice slurry/ice vest [SLIV]) and no cooling (CON).ResultsWe observed significant improvements in trial times for IV (18 ± 10 min), PCM (20 ± 10 min) and SLIV (22 ± 10 min), but no differences for WS (4 ± 7 min). Heart rate, rectal, mean skin, and body temperatures were significantly lower in all cooling conditions relative to control at various matched time points in the first 60 min of exercise. Thermal sensation, comfort and perceived exertion all had significant main effects for condition, and time, there were no differences in their respective interactions.ConclusionThe IV, PCM, and SLIV produced lower heart rate, mean skin, rectal and mean body temperatures in addition to improved work times compared to control. The WS did not improve work times possibly as a result of the cooling capacity of the suit abating, and magnifying thermal insulation. Considering the added time and resources required to implement combination cooling in the form of ice slurry and ice vest (SLIV), there was no significant additive effect for perception, cardiovascular strain, rectal temperature and total trial time relative to the phase change vest or ice vest alone. This may be a product of a “ceiling” effect for work limit set to 120 min as part of ASTM F2300-10.

Anesthetic quality and cardiovascular and respiratory effects of continuous intravenous infusion of tiletamine-zolazepam in bitches

ABSTRACT: The objective of this study was to evaluate the quality and recovery from anesthesia promoted by the tiletamine-zolazepam (TZ) combination administered intravenously (IV) continuously in bitches pre-medicated with acepromazine. Eight cross-bred, clinically healthy bitches weighing 13.7 ±1.9kg on average were used in this study. After a food fast of 12 h and a water fast of four hours, the animals were treated with acepromazine (0.1mg/kg, intramuscular) and, after 15 minutes, anesthesia was induced with a combination of tiletamine-zolazepam (2mg/kg, IV) immediately followed by continuous IV infusion thereof at a dose of 2mg/kg/h for 60 min. The following parameters were measured in all animals immediately before administration of acepromazine (M15), immediately before anesthetic induction (M0), and at 5, 10, 20, 30, 40, 50, and 60 min after initiation of continuous infusion (M5, M10, M20, M30, M40, M50, and M60): electrocardiography (ECG), heart rate (HR), mean arterial pressure (MAP), respiratory rate (RR), body temperature (BT), and arterial hemogasometry, with the last performed only at experimental times M15, M0, M30, and M60. A subcutaneous electrical stimulator was used to evaluate the degree of analgesia. Myorelaxation and quality of anesthetic recovery were also assessed, classifying these parameters as excellent, good, and poor. Anesthetic recovery time was recorded in minutes. HR increased significantly at time M10 in relation to that at M-15, and at times M5, M10, M40, and M50 in relation to that at M0. MAP decreased significantly at M20 and M30 compared with the baseline. BT decreased significantly at M50 compared with that at M0, but no hypothermia was observed. RR showed significant reduction at M5, M10, and M20 in relation to that at M-15, and at M5 and M10 in relation to that at M0, and bradypnoea was observed during the first 20 min after anesthetic induction. Significant decreases in the PR interval at times M10, M40, and M50 were observed in relation to that at M15. Amplitude of the R wave showed significant decrease at M20 compared with that at M-15. In the other ECG parameters, no significant difference was observed between the times evaluated. Hemogasometric parameters and analgesia did not show significant alterations. Myorelaxation and quality of anesthetic recovery were considered excellent. Recovery time was 15.1±7.7 min for positioning of sternal decubitus and 45.5±23.1 minutes for return of ambulation. Continuous IV administration of TZ combination does not produce satisfactory analgesia and does not cause severe cardiorespiratory and hemogasometric effects in bitches pre-medicated with acepromazine.

Distal skin vasodilation in sleep preparedness, and its impact on thermal status in preterm neonates

ObjectivePrior to sleep onset in human adults, distal body temperatures change progressively from wakefulness levels (low skin temperatures and a high core temperature) to sleep levels (high skin temperatures and a low core temperature) due to distal skin vasodilation and greater body cooling. It is not known whether this sleep preparedness exists in preterm neonates, even though sleep has a key role in neonatal health and neurodevelopment. The present study's objectives were to determine whether sleep preparedness (as observed in adults) can be evidenced in preterm neonates, and to assess repercussions on thermal stress. MethodsDuring a 12-h night-time polysomnography session, skin temperatures (recorded with an infrared camera), sleep, and wakefulness episodes were measured in 18 nine-day-old preterm neonates. ResultsFifteen wakefulness episodes were considered. Our results highlighted significant pre-sleep distal skin vasodilation (mainly at the foot: an increase of 0.38 °C in the 20 min preceding sleep onset) for the first time in preterm neonates. This vasodilation occurred even though (1) most factors known to influence pre-sleep vasodilation in adults were not present in these neonates, and (2) the neonates were nursed in a nearly constant thermal environment. The vasodilatation-related increase in body heat loss corresponded to a 0.15°C/h fall in mean body temperature (calculated using partitional calorimetry). ConclusionCompensation for this body heat loss and the maintenance of body homeothermia would require a 4% increase in metabolic heat production. In neonates, this type of energy expenditure cannot be maintained for a long period of time.