Desaturation of exhaled air in camels

1981 ◽  
Vol 211 (1184) ◽  
pp. 305-319 ◽  
Keyword(s):  
Drinking Water ◽  
Heat Exchange ◽  
Body Temperature ◽  
Water Vapour ◽  
Mechanical Model ◽  
Ambient Air ◽  
Body Core Temperature ◽  
Hygroscopic Properties ◽  
Exhaled Air ◽  
Body Core

We have found that camels can reduce the water loss due to evaporation from the respiratory tract in two ways: (1) by decreasing the temperature of the exhaled air and (2) by removal of water vapour from this air, resulting in the exhalation of air at less than 100% relative humidity (r. h.). Camels were kept under desert conditions and deprived of drinking water. In the daytime the exhaled air was at or near body core temperature, while in the cooler night exhaled air was at or near ambient air temperature. In the daytime the exhaled air was fully saturated, but at night its humidity might fall to approximately 75% r. h. The combination of cooling and desaturation can provide a saving of water of 60% relative to exhalation of saturated air at body temperature. The mechanism responsible for cooling of the exhaled air is a simple heat exchange between the respiratory air and the surfaces of the nasal passageways. On inhalation these surfaces are cooled by the air passing over them, and on exhalation heat from the exhaled air is given off to these cooler surfaces. The mechanism responsible for desaturation of the air appears to depend on the hygroscopic properties of the nasal surfaces when the camel is dehydrated. The surfaces give off water vapour during inhalation and take up water from the respiratory air during exhalation. We have used a simple mechanical model to demonstrate the effectiveness of this mechanism.

Impaired memory registration and speed of reasoning caused by low body temperature

1983 ◽  
Vol 55 (1) ◽  
pp. 27-31 ◽  
Author(s):  
S. R. Coleshaw ◽  
R. N. Van Someren ◽  
A. H. Wolff ◽  
H. M. Davis ◽  
W. R. Keatinge
Keyword(s):  
Cognitive Function ◽  
Body Temperature ◽  
Core Temperature ◽  
Body Core Temperature ◽  
Impaired Memory ◽  
Test Speed ◽  
Body Core

Volunteers′ body core temperatures were lowered by immersion in water at 15 degrees C. Aspects of cognitive function were subsequently tested after rewarming had been started in water at 41 degrees C when their skin was warm and they felt comfortable but their body core temperature remained low. Memory registration was found to be impaired progressively when core temperature fell from about 36.7 degrees C; at core temperatures of 34-35 degrees C the impairment caused loss of approximately 70% of data that could normally be retained. However, recall of previously learned data was not impaired at these core temperatures. On a two-digit calculation test, speed of performance was impaired by about 50% at a core temperature of 34-35 degrees C, but provided enough time was available, accuracy of performance was not reduced.

Re-Evaluation of Arteriovenous Cooling of the Blood Supply to Human Brains

1999 ◽  
Author(s):  
Liang Zhu
Keyword(s):  
Heat Conduction ◽  
Heat Exchange ◽  
Carotid Artery ◽  
Body Core Temperature ◽  
Brain Cooling ◽  
Selective Brain Cooling ◽  
Arterial Blood ◽  
Radial Heat ◽  
Body Core ◽  
Vascular Geometry

Abstract The purpose of this work is to evaluate the capacity of the heat loss from the carotid artery in human brain and thus, to provide indirect evidence of the existence of selective brain cooling (SBC) in humans during hyperthermia. A theoretical model is developed to describe the effects of local blood perfusion and vascular geometry on the thermal equilibration in the carotid artery based on the blood flow measurements and the anatomical vascular geometry in the human neck. A theoretical approach is used to estimate the potential for cooling of blood in the carotid artery on its way to the brain by heat exchange with its countercurrent jugular vein and by the radial heat conduction loss to the cool neck surface. It is shown that the cooling of the arterial blood can be as much as 1.3 °C lower than the body core temperature, which is in agreement with previous experimental measurements of the temperature difference between the tympanic and body core temperatures. The model also evaluates the relative contributions of countercurrent heat exchange and radial heat conduction to selective brain cooling. It is found that these mechanisms are comparable with each other. Results of the present study will help provide a better understanding of the thermoregulation during hyperthermia. They can be used to guide the design of future experimental investigations of the mechanism of SBC.

scholarly journals Prevention of Intraoperative Hypothermia in Laparoscopy by the Use of Body-Temperature and Humidified CO2: a Pilot Study

2019 ◽  
Vol 79 (09) ◽  
pp. 969-975
Author(s):  
Julia Wittenborn ◽  
Annika Clausen ◽  
Felix Zeppernick ◽  
Elmar Stickeler ◽  
Ivo Meinhold-Heerlein
Keyword(s):  
Body Temperature ◽  
Temperature Profile ◽  
Room Temperature ◽  
Body Core Temperature ◽  
Control Group ◽  
Study Group ◽  
Treatment And Prevention ◽  
Intraoperative Hypothermia ◽  
Body Core ◽  
Control Study

Abstract Introduction Hypothermia is defined as a decrease in body core temperature to below 36 °C. If intraoperative heat-preserving measures are omitted, a patientʼs temperature will fall by 1 – 2 °C. Even mild forms of intraoperative hypothermia can lead to a marked increase in morbidity and mortality. The temperature of the insufflation gas is usually disregarded in the treatment and prevention of hypothermia. This study was conducted to investigate the effect of body-temperature and humidified CO2 on the intraoperative temperature profile and avoidance of hypothermia in laparoscopic surgery. Material and Methods In this retrospective, non-randomised case control study, 110 patients whose planned operation lasted at least 60 minutes were identified from 376 patients by means of an algorithm. Dry (20% humidity) CO2 at room temperature was insufflated in 51 patients (control group). 59 patients were insufflated with humidified (98% humidity) CO2 at body temperature (37 °C) (study group). These conditions were achieved with the HumiGard MR860 Surgical Humidification System (Fisher & Paykel Healthcare Limited, Auckland, New Zealand). The intraoperative temperature profile was evaluated by measurements every 10 minutes. Statistical analysis was performed with IBM® SPSS® Statistics 23.0.0. Results The intraoperative temperature in the control group fell steadily, while a continuous rise in temperature was observed in the study group. Warming was demonstrated in the study group with a start-end temperature difference of 0.09 °C, which differed significantly from the control group, in which it was − 0.09 °C (p = 0.011). The middle-end difference of 0.11 °C showed even higher significance in favour of the warmed gas (p = 0.003). The rate of hypothermia at the start of the operation fell from 50 to 36% in the study group and increased from 36 to 42% in the control group. Conclusion These results show that the use of body-temperature and humidified insufflation gas for laparoscopy can help to prevent intraoperative hypothermia.

scholarly journals Association of core body temperature and peripheral blood flow of the hands with pain intensity, pressure pain hypersensitivity, central sensitization, and fibromyalgia symptoms

2021 ◽  
Vol 12 ◽  
pp. 204062232199725
Author(s):  
Antonio Casas-Barragán ◽  
Francisco Molina ◽  
Rosa María Tapia-Haro ◽  
María Carmen García-Ríos ◽  
María Correa-Rodríguez ◽  
...  
Keyword(s):  
Body Temperature ◽  
Core Temperature ◽  
Clinical Symptoms ◽  
Core Body Temperature ◽  
Body Core Temperature ◽  
Peripheral Blood Flow ◽  
Greater Trochanter ◽  
Body Core ◽  
Hypothenar Eminence ◽  
Core Body

Our aim was to analyse body core temperature and peripheral vascular microcirculation at skin hypothenar eminence of the hands and its relationship to symptoms in fibromyalgia syndrome (FMS). A total of 80 FMS women and 80 healthy women, matched on weight, were enrolled in this case–control study. Thermography and infrared thermometer were used for evaluating the hypothenar regions and core body temperature, respectively. The main outcome measures were pain pressure thresholds (PPTs) and clinical questionnaires. Significant associations were observed between overall impact [ β = 0.033; 95% confidence interval (95%CI) = 0.003, 0.062; p = 0.030], daytime dysfunction ( β = 0.203; 95%CI = 0.011, 0.395; p = 0.039) and reduced activity ( β = 0.045; 95%CI = 0.005, 0.085; p = 0.029) and core body temperature in FMS women. PPTs including greater trochanter dominant ( β = 0.254; 95%CI = 0.003, 0.504; p = 0.047), greater trochanter non-dominant ( β = 0.650; 95%CI = 0.141, 1.159; p = 0.013), as well as sleeping medication ( β = −0.242; 95%CI = −0.471, −0.013; p = 0.039) were also associated with hypothenar eminence temperature. Data highlighted that FMS women showed correlations among body core temperature and hand temperature with the clinical symptoms.

Effects of Hydration on Febrile Temperature Patterns in Rabbits

2001 ◽  
Vol 2 (4) ◽  
pp. 277-291 ◽  
Author(s):  
Charlotte A. Richmond
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Core Temperature ◽  
Cardiovascular Responses ◽  
Fluid Replacement ◽  
Body Core Temperature ◽  
Hydration Status ◽  
Beneficial Role ◽  
Fluid Supplementation ◽  
Body Core

Patients with fever have a predisposition to experience dehydration, which may alter their thermoregulatory responses to elevated body temperature. In view of the recent discovery of the antipyretic activity of arginine vasopressin (AVP), it is possible that dehydration has a beneficial role during fever. Dehydration may enhance endogenous antipyresis by stimulating AVP release, making aggressive fluid replacement, which may inhibit AVP release, undesirable during fever. This study addressed the effects of manipulation of hydration status on temperature and cardiovascular responses in endotoxin-injected rabbits. Eight unanesthetized chronically instrumented rabbits were exposed to lipopolysaccharide (LPS) while in euhydrated state, after furosemide (5 mg/kg) and 24 hours of water deprivation (dehydrated), after infusion of saline (30 mL/kg) while in euhydrated state (hyperhydrated), and after saline (mL/per overnight body weight loss in grams) while in dehydrated state (rehydrated). Dehydrated rabbits display higher fevers that are biphasic in nature and are accompanied by increased vasoconstriction and duration of mean arterial pressure increases, indicating that activation of antipyretic mechanisms in dehydrated rabbits was not sufficient to reduce body core temperature. In addition, fluid supplementation in euhydrated rabbits did not alter the febrile response; however, a marked decrease in heart rate was noted. Furthermore, fluid supplementation in dehydrated rabbits significantly attenuates the rectal temperature and heart rate response to LPS injection, indicating the possibility that activation of antipyretic mechanisms of AVP in rehydrated rabbits was sufficient to reduce body core temperature. The results suggest that fluid supplementation has a beneficial role in keeping body temperature lower.

Protection Against Cold in Prehospital Care—Thermal Insulation Properties of Blankets and Rescue Bags in Different Wind Conditions

2009 ◽  
Vol 24 (5) ◽  
pp. 408-415 ◽  
Author(s):  
Otto Henriksson ◽  
J. Peter Lundgren ◽  
Kalev Kuklane ◽  
Ingvar Holmér ◽  
Ulf Bjornstig
Keyword(s):  
Thermal Insulation ◽  
Cold Exposure ◽  
Prehospital Care ◽  
Scientific Evidence ◽  
Ambient Air ◽  
Body Core Temperature ◽  
Thermal Manikin ◽  
Wind Condition ◽  
Ambient Temperatures ◽  
Body Core

AbstractIntroduction:In a cold, wet, or windy environment, cold exposure can be considerable for an injured or ill person. The subsequent autonomous stress response initially will increase circulatory and respiratory demands, and as body core temperature declines, the patient's condition might deteriorate. Therefore, the application of adequate insulation to reduce cold exposure and prevent body core cooling is an important part of prehospital primary care, but recommendations for what should be used in the field mostly depend on tradition and experience, not on scientific evidence.Objective:The objective of this study was to evaluate the thermal insulation properties in different wind conditions of 12 different blankets and rescue bags commonly used by prehospital rescue and ambulance services.Methods:The thermal manikin and the selected insulation ensembles were setup inside a climatic chamber in accordance to the modified European Standard for assessing requirements of sleeping bags. Fans were adjusted to provide low (< 0.5 m/s), moderate (2–3 m/s) and high (8–9 m/s) wind condi-tions. During steady state thermal transfer, the total resultant insulation value, Itr (m2 °C/Wclo; where °C = degrees Celcius, and W = watts), was calculated from ambient air temperature (°C), manikin surface temperature (°C), and heat flux (W/m2).Results:In the low wind condition, thermal insulation of the evaluated ensembles correlated to thickness of the ensembles, ranging from 2.0 to 6.0 clo (1 clo = 0.155 m2 °C/W), except for the reflective metallic foil blankets that had higher values than expected. In moderate and high wind conditions, thermal insulation was best preserved for ensembles that were windproof and resistant to the compressive effect of the wind, with insulation reductions down to about 60–80% of the original insulation capacity, whereas wind permeable and/or lighter materials were reduced down to about 30–50% of original insulation capacity.Conclusions:The evaluated insulation ensembles might all be used for prehospital protection against cold, either as single blankets or in multiple layer combinations, depending on ambient temperatures. However, with extended outdoor, on-scene durations, such as during prolonged extrications or in mul-tiple casualty situations, the results of this study emphasize the importance of using a windproof and compression resistant outer ensemble to maintain adequate insulation capacity.

Body temperature lability in sheep and goats during short-term exposures to heat and cold

1971 ◽  
Vol 77 (2) ◽  
pp. 267-272 ◽  
Author(s):  
K. G. Johnson
Keyword(s):  
Thermal Stress ◽  
Body Temperature ◽  
Respiratory Rate ◽  
Air Temperature ◽  
Domestic Animals ◽  
The Body ◽  
Body Core Temperature ◽  
Short Term ◽  
Temperature Changes ◽  
Body Core

SummaryPassive lability of body core temperature during brief exposures to thermal stress is an efficient means of thermoregulation which few species of domestic animals appear to utilize. The body temperature changes of 30 shorn sheep and 10 shorn goats have been measured during standard heat and cold exposures lasting 7 h. During exposures to heat, air temperature was increased from 20 °C to 45 °C then reduced again to 20 °C. Rectal temperatures of goats and Soay, Welsh Mountain, Merino and Clun Forest sheep rose by an average of 1·96 °C, 1·22 °C, 1·04 °C, 0·85 °C and 0·80 °C respectively. All animals had similar increases in respiratory rate. During exposures to cold, air temperature was reduced from 20 °C to about 6 °C then increased again to 20 °C. Rectal temperatures rose by 0·18–0·20 °C in goats and in all sheep except Soays in which they fell by 0·28 °C. All animals showed moderate to vigorous shivering. None of the animals exhibited passive body temperature lability as an adaptation to thermal stress.

scholarly journals Orbital bleeding in rats while under diethylether anaesthesia does not influence telemetrically determined heart rate, body temperature, locomotor and eating activity when compared with anaesthesia alone

1997 ◽  
Vol 31 (3) ◽  
pp. 271-278 ◽  
Author(s):  
H. Van Herck ◽  
S. F. De Boer ◽  
A. P. M. Hesp ◽  
H. A. Van Lith ◽  
A. C. Baumans ◽  
...  
Keyword(s):  
Heart Rate ◽  
Locomotor Activity ◽  
Body Temperature ◽  
Body Core Temperature ◽  
Eating Pattern ◽  
Endocrine Stress Response ◽  
Body Core ◽  
Roman Low Avoidance ◽  
Roman High Avoidance

The question addressed was whether orbital bleeding in rats, while under diethylether anaesthesia, affects their locomotor activity, body core temperature, heart rate rhythm and eating pattern. Roman High Avoidance (RHA) and Roman Low Avoidance (RLA) rats were used to enhance generalization of the results. Orbital bleeding when the rats were under diethylether anaesthesia was compared with diethylether anaesthesia alone. To take into account any effects of handling, the rats were also subjected to sham anaesthesia. The RHA rats urinated more during anaesthesia, needed more time to recover from the anaesthesia and showed a greater endocrine stress response to diethylether anaesthesia when compared with the RLA rats. During anaesthesia, the RHA rats showed a greater fall of body temperature and bradycardia than did the RLA rats. Diethylether anaesthesia reduced locomotor activity in the RHA rats, but had no effect in the RLA rats. In neither RHA nor RLA rats did anaesthesia plus orbital puncture, versus anaesthesia alone, influence body temperature, heart rate rhythm, locomotor and eating activity. The lack of effect of orbital puncture occurred both in the short term (within 2 h) and long term (within 48 hours) and thus this study indicates that orbital puncture had, at least with respect to variables measured in the present study, no effect superimposed on that of diethylether anaesthesia.

Role of neuronal nitric oxide synthase in hypoxia-induced anapyrexia in rats

2000 ◽  
Vol 89 (3) ◽  
pp. 1131-1136 ◽  
Author(s):  
Alexandre A. Steiner ◽  
Evelin C. Carnio ◽  
Luiz G. S. Branco
Keyword(s):  
Nitric Oxide ◽  
Body Temperature ◽  
Nitric Oxide Synthase ◽  
Intraperitoneal Injection ◽  
Neuronal Nitric Oxide Synthase ◽  
Body Core Temperature ◽  
Body Core ◽  
Significant Attenuation ◽  
Oxide Synthase

Anapyrexia (a regulated decrease in body temperature) is a response to hypoxia that occurs in organisms ranging from protozoans to mammals, but very little is known about the mechanisms involved. Recently, it has been shown that the NO pathway plays a major role in hypoxia-induced anapyrexia. However, very little is known about which of the three different nitric oxide synthase isoforms (neuronal, endothelial, or inducible) is involved. The present study was designed to test the hypothesis that neuronal nitric oxide synthase (nNOS) plays a role in hypoxia-induced anapyrexia. Body core temperature (Tc) of awake, unrestrained rats was measured continuously using biotelemetry. Rats were submitted to hypoxia, 7-nitroindazole (7-NI; a selective nNOS inhibitor) injection, or both treatments together. Control animals received vehicle injections of the same volume. We observed a significant ( P < 0.05) reduction in Tc of ∼2.8°C after hypoxia (7% inspired O2), whereas intraperitoneal injection of 7-NI at 25 mg/kg caused no significant change in Tc. 7-NI at 30 mg/kg elicited a reduction in Tc and was abandoned in further experiments. When the two treatments were combined (25 mg/kg of 7-NI and 7% inspired O2), we observed a significant attenuation of hypoxia-induced anapyrexia. The data indicate that nNOS plays a role in hypoxia-induced anapyrexia.

Respiratory water loss in camels

1981 ◽  
Vol 211 (1184) ◽  
pp. 291-303 ◽  
Keyword(s):  
Oxygen Consumption ◽  
Body Temperature ◽  
Relative Humidity ◽  
Metabolic Rate ◽  
Water Vapour ◽  
Water Loss ◽  
Water Deprivation ◽  
Temperature Fluctuations ◽  
Respiratory Frequency ◽  
Exhaled Air

Rates of oxygen consumption and respiratory water loss were studied in camels that were exposed to desert heat and water deprivation. We found that changes in body temperature are accompanied by considerable changes in respiratory water loss. Body temperature fluctuations are greatest in dehydrated camels (up to 7°C), and in these the respiratory water loss might vary from about 0.06 to 1.2 g/min. The respiratory frequency varied from about 4 to 28 min -1 , while the metabolic rate varied by less than twofold. The lowest values for respiratory water loss can be explained by the exhalation of air at temperatures far below body temperature, and, in addition, removal of water vapour from the exhaled air, resulting in exhalation of air at less than 100% relative humidity.

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