Temperature Regulation and Heat Balance in Flying White-necked Ravens, Corvus Cryptoleucus

1981 ◽  
Vol 90 (1) ◽  
pp. 267-281 ◽  
Author(s):  
DENNIS M. HUDSON ◽  
MARVIN H. BERNSTEIN
Keyword(s):  
Steady State ◽  
Body Temperature ◽  
Wind Tunnel ◽  
Body Surface ◽  
Heat Balance ◽  
Metabolic Heat ◽  
Steady State Levels ◽  
Cutaneous Evaporation ◽  
Body Heat ◽  
Respiratory Evaporation

During level flight at 10 m.s−1 in a wind tunnel, white-necked ravens (Corvus cryptoleucus, mass 0·48 kg) exhibited an increase in body temperature to steady-state levels as high as 45°C, exceeding resting levels by nearly 3°C. This reflects the storage of up to half of the metabolic heat produced (Hp) during 5 min of flight. During steady-state flight, body heat was dissipated in part by respiratory evaporation and convection (13–40% of Hp) evoked by increases in ventilation proportional to body temperature. Remaining heat was lost by cutaneous evaporation (10% of Hp) as well as by radiation and convection from the external body surface. The results suggest strategies that might be used by ravens during flight under desert conditions.

Independence of brain and body temperatures in flying American kestrels, Falco sparverius

1979 ◽  
Vol 237 (1) ◽  
pp. R58-R62
Author(s):  
M. H. Bernstein ◽  
M. B. Curtis ◽  
D. M. Hudson
Keyword(s):  
Steady State ◽  
Wind Tunnel ◽  
Air Temperature ◽  
Body Temperatures ◽  
Air Temperatures ◽  
American Kestrels ◽  
Steady State Levels ◽  
Air Speed ◽  
State Difference ◽  
Body Heat

Brain and body temperatures were measured via small thermocouples implanted in the anterior hypothalami and colons, respectively, of five adult American kestrels (F. sparverius, mean mass 119 g) during descending flights in a wind tunnel at angles of 4 and 6 degrees below horizontal, at 10 m.s-1 air speed, and at 23 degrees C air temperature. For comparison, temperatures were recorded from resting birds at 22.5-36.1 degrees C air temperatures. Colonic (Tc) and hypothalamic (Th) temperatures both increased after the onset of flight; steady-state levels were attained after 1 min in the hypothalamus and after 5 or more min in the colon. The steady-state difference (delta T = Tc - Th) averaged 1.2 degrees C, higher by 0.5 degrees C than delta T in resting kestrels. The establishment of delta T during flight may be correlated with increased respiratory and corneal evaporation. The response apparently confines most stored body heat to noncranial regions, thus protecting brain tissue from thermal extremes.

Respiration in exercising fowl. II. Respiratory water loss and heat balance

1981 ◽  
Vol 93 (1) ◽  
pp. 327-332
Author(s):  
J. H. Brackenbury ◽  
M. Gleeson ◽  
P. Avery
Keyword(s):  
Rectal Temperature ◽  
Water Loss ◽  
Heat Balance ◽  
Domestic Fowl ◽  
Metabolic Energy ◽  
Air Temperatures ◽  
Respiratory Heat Loss ◽  
All Speeds ◽  
Body Heat ◽  
Respiratory Evaporation

1. Respiratory water loss and rectal temperature were measured in domestic fowl running for 10 min on a treadmill at speeds of 1.24-4.3 km h-1 in air temperatures of 20 +/− 2 degrees C or 32 +/− 2 degrees C. 2. At given speeds the water loss at 32 +/− 2 degrees C was approximately twice that at 20 +/− 2 degrees C and the end-exercise rectal temperature was 0.5-0.8 degrees C higher. 3. At 20 +/− 2 degrees C, respiratory evaporation accounted for 10–12% of the total metabolic energy used at all speeds. At 32 +/− 2 degrees C, the fractional respiratory heat loss fell from 26.5% at 1.24 km h-1 to 17% at 3.6 km h-1. The fraction of the total metabolic energy stored as body heat rose progressively with air temperature.

Ventilatory and blood acid-base adjustments to a decrease in body temperature from 30 to 10YC in black racer snakes Coluber constrictor

1996 ◽  
Vol 199 (4) ◽  
pp. 815-823
Author(s):  
J Stinner ◽  
M Grguric ◽  
S Beaty
Keyword(s):  
Steady State ◽  
Body Temperature ◽  
Minute Ventilation ◽  
Co2 Production ◽  
Bicarbonate Concentration ◽  
Acid Base ◽  
Slow Increase ◽  
Coluber Constrictor ◽  
Steady State Levels ◽  
Time Required

There is increasing evidence that many amphibian and reptilian species use relatively slow ion-exchange mechanisms in addition to ventilation to adjust pH as body temperature changes. Large changes in blood bicarbonate concentration with changes in temperature have previously been reported for the snake Coluber constrictor. The purpose of the present study was to determine the ventilatory and pH adjustments associated with the increase in CO2 stores when the snakes are cooled. Body temperature was lowered from 30 to 10 °C within 4 h, at which time measurements of inspired minute ventilation (V.air), O2 consumption (VO2) and CO2 production (V.CO2) were started and continued for 56 h. The decrease in temperature produced a transient fall in the respiratory exchange ratio (V.CO2/VO2) to 0.2-0.3 and a steady-state value of 0.65±0.14 (mean ± s.d., N=7) was not achieved until about 35 h. There were concomitant transient reductions in V.air and V.air/V.O2. However, V.air/V.CO2 initially increased, with a corresponding reduction in arterial PCO2 (PaCO2) and increase in arterial pH. By 35 h, V.air/V.CO2 had decreased and PaCO2 had increased to steady-state levels, but pH decreased very little because of a gradual increase in bicarbonate concentration. We conclude that the drop in temperature imposed a metabolic acidosis for approximately 35 h because of the time required to increase bicarbonate concentration, and that the acidosis was compensated for by an elevated V.air/V.CO2. Steady-state breathing and acid-base status were not achieved until the relatively slow increase in CO2 stores had been completed.

Core Cooling by Central Venous Infusion of Ice-cold (4°C and 20°C) Fluid

2000 ◽  
Vol 93 (3) ◽  
pp. 629-637 ◽  
Author(s):  
Angela Rajek ◽  
Robert Greif ◽  
Daniel I. Sessler ◽  
James Baumgardner ◽  
Sonja Laciny ◽  
...  
Keyword(s):  
Therapeutic Hypothermia ◽  
Core Temperature ◽  
Heat Balance ◽  
Heat Content ◽  
Partial Recovery ◽  
Central Venous ◽  
Metabolic Heat ◽  
Cold Fluid ◽  
Venous Infusion ◽  
Body Heat

Background Central venous infusion of cold fluid may be a useful method of inducing therapeutic hypothermia. The aim of this study was to quantify systemic heat balance and regional distribution of body heat during and after central infusion of cold fluid. Methods The authors studied nine volunteers, each on two separate days. Anesthesia was maintained with use of isoflurane, and on each day 40 ml/kg saline was infused centrally over 30 min. On one day, the fluid was 20 degrees C and on the other it was 4 degrees C. By use of a tympanic membrane probe core (trunk and head) temperature and heat content were evaluated. Peripheral compartment (arm and leg) temperature and heat content were estimated with use of fourth-order regressions and integration over volume from 18 intramuscular thermocouples, nine skin temperatures, and "deep" hand and foot temperature. Oxygen consumption and cutaneous heat flux estimated systemic heat balance. Results After 30-min infusion of 4 degrees C or 20 degrees C fluid, core temperature decreased 2.5 +/- 0.4 degrees C and 1.4 +/- 0.2 degrees C, respectively. This reduction in core temperature was 0.8 degrees C and 0.4 degrees C more than would be expected if the change in body heat content were distributed in proportion to body mass. Reduced core temperature resulted from three factors: (1) 10-20% because cutaneous heat loss exceeded metabolic heat production; (2) 50-55% from the systemic effects of the cold fluid per se; and (3) approximately 30% because the reduction in core heat content remained partially constrained to core tissues. The postinfusion period was associated with a rapid and spontaneous recovery of core temperature. This increase in core temperature was not associated with a peripheral-to-core redistribution of body heat because core temperature remained warmer than peripheral tissues even at the end of the infusion. Instead, it resulted from constraint of metabolic heat to the core thermal compartment. Conclusions Central venous infusion of cold fluid decreases core temperature more than would be expected were the reduction in body heat content proportionately distributed. It thus appears to be an effective method of rapidly inducing therapeutic hypothermia. When the infusion is complete, there is a spontaneous partial recovery in core temperature that facilitates rewarming to normothermia.

Thermal balance in infants

1996 ◽  
Vol 80 (6) ◽  
pp. 2234-2242 ◽  
Author(s):  
D. P. Bolton ◽  
E. A. Nelson ◽  
B. J. Taylor ◽  
I. L. Weatherall
Keyword(s):  
Theoretical Model ◽  
Body Surface ◽  
Heat Balance ◽  
Heat Losses ◽  
Thermal Balance ◽  
The Body ◽  
Death Scene ◽  
Metabolic Heat ◽  
Iterative Calculation ◽  
Skin Temperatures

A theoretical model of heat balance is presented that could clarify the matching of babies' wrapping with their environments. Best estimates of metabolic heat input and heat loss by all known routes are defined for 22 parts of the body surface. The variation of these with core temperature, posture, skin vasodilatation, and the onset of sweating are calculated: first, by using presumed skin temperatures and second, by following iterative calculation of the skin temperature and the consequent total heat losses. Calculation of the highest tolerable ambient temperature (HTAT) for a given set of clothes, underbedding, and covers shows that a well-wrapped baby lying face down could have an HTAT 10 degrees C lower than if he/she were lying supine. Representative values for highest and lowest tolerable temperatures (defined in text) are presented for the first 6 mo of life. Retrospective estimation of thermal balance from death-scene data on clothing and bedding can permit assessment of hyperthermia or hypothermia as a contributing cause of death. Recommendations are made on the avoidance of hyperthermia.

Effects of pyrogen administration on temperature regulation in exercising rats

1990 ◽  
Vol 258 (4) ◽  
pp. R842-R847
Author(s):  
H. Tanaka ◽  
K. Kanosue ◽  
M. Yanase ◽  
T. Nakayama
Keyword(s):  
Steady State ◽  
Body Temperature ◽  
Interleukin 1 ◽  
Evaporative Heat Loss ◽  
Saline Injection ◽  
Work Intensity ◽  
Endogenous Pyrogen ◽  
Metabolic Heat ◽  
Series Of Experiments ◽  
The Difference

To study the mechanism of rise in body temperature during exercise, endogenous pyrogen was administered to exercising rats. At rest and at a neutral ambient temperature (Ta) of 24 degrees C, intravenous injection of recombinant human interleukin 1 (IL-1, 40 micrograms/kg) produced a 0.5 degree C rise in rectal temperature (Tre) from 37.4 degrees C. At Ta of 34 degrees C, at which Tre was 38.6 degrees C, Tre rise in response to IL-1 was only 0.2 degree C greater than when saline was used. In the first series of exercise experiments, rats ran on a treadmill after IL-1 or saline injection at two different work intensities (estimated at 40 and 60% of maximal oxygen uptake) at 24 degrees C Ta. At either work intensity, the magnitude of Tre rise after IL-1 injection was approximately 0.5 degree C higher than after saline injection. Threshold Tre for tail vasodilation increased when IL-1 was injected. The difference in the threshold Tre between the IL-1 and saline conditions was 0.5 degree C at either work intensity. Evaporative heat loss was also suppressed and metabolic heat production facilitated when IL-1 was injected. In a second series of experiments, IL-1 was injected after Tre reached a steady state (38.5 degrees C) during exercise. After IL-1 injection Tre increased another 0.5 degrees C, but after saline injection Tre did not change. These results suggest that body temperature rise during exercise is not induced merely by an insufficient capability of dissipating heat and that the thermoregulatory set point is reset during exercise.

Oxygen Fraction Adjustment According to Body Surface Area during Extracorporeal Circulation

2015 ◽  
Vol 18 (3) ◽  
pp. 098
Author(s):  
Cem Arıtürk ◽  
Serpil Ustalar Özgen ◽  
Behiç Danışan ◽  
Hasan Karabulut ◽  
Fevzi Toraman
Keyword(s):  
Body Temperature ◽  
Surface Area ◽  
Body Surface Area ◽  
Body Surface ◽  
Extracorporeal Circulation ◽  
Group Iii ◽  
Oxygen Fraction ◽  
Arterial Blood ◽  
Group I ◽  
Group Ii

<p class="p1"><span class="s1"><strong>Background:</strong> The inspiratory oxygen fraction (FiO<sub>2</sub>) is usually set between 60% and 100% during conventional extracorporeal circulation (ECC). However, this strategy causes partial oxygen pressure (PaO<sub>2</sub>) to reach hyperoxemic levels (&gt;180 mmHg). During anesthetic management of cardiothoracic surgery it is important to keep PaO<sub>2</sub> levels between 80-180 mmHg. The aim of this study was to assess whether adjusting FiO<sub>2</sub> levels in accordance with body temperature and body surface area (BSA) during ECC is an effective method for maintaining normoxemic PaO<sub>2</sub> during cardiac surgery.</span></p><p class="p1"><span class="s1"><strong>Methods:</strong> After approval from the Ethics Committee of the University of Acıbadem, informed consent was given from 60 patients. FiO<sub>2</sub> adjustment strategies applied to the patients in the groups were as follows: FiO<sub>2</sub> levels were set as 0.21 × BSA during hypothermia and 0.21 × BSA + 10 during rewarming in Group I; 0.18 × BSA during hypothermia and 0.18 × BSA + 15 during rewarming in Group II; and 0.18 × BSA during hypothermia and variable with body temperature during rewarming in Group III. Arterial blood gas values and hemodynamic parameters were recorded before ECC (T1); at the 10th minute of cross clamp (T2); when the esophageal temperature (OT) reached 34°C (T3); when OT reached 36°C (T4); and just before the cessation of ECC (T5).</span></p><p class="p1"><span class="s1"><strong>Results:</strong> Mean PaO<sub>2</sub> was significantly higher in Group I than in Group II at T2 and T3 (<em>P</em> = .0001 and <em>P</em> = .0001, respectively); in Group I than in Group III at T1 (<em>P</em> = .02); and in Group II than in Group III at T2, T3, and T4 <br /> (<em>P</em> = .0001 for all). </span></p><p class="p1"><span class="s1"><strong>Conclusion: </strong>Adjustment of FiO<sub>2</sub> according to BSA rather than keeping it at a constant level is more appropriate for keeping PaO<sub>2</sub> between safe level limits. However, since oxygen consumption of cells vary with body temperature, it would be appropriate to set FiO<sub>2</sub> levels in concordance with the body temperature in the <br /> rewarming period.</span></p>

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