Effects of Ambient Temperature and Forced-air Warming on Intraoperative Core Temperature

2018 ◽  
Vol 128 (5) ◽  
pp. 903-911 ◽  
Author(s):  
Lijian Pei ◽  
Yuguang Huang ◽  
Yiyao Xu ◽  
Yongchang Zheng ◽  
Xinting Sang ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Temperature Change ◽  
Core Temperature ◽  
Negative Slope ◽  
Anesthesia Induction ◽  
Temperature Changes ◽  
Ambient Temperatures ◽  
Forced Air Warming ◽  
Factorial Trial ◽  
Forced Air

Abstract Background The effect of ambient temperature, with and without active warming, on intraoperative core temperature remains poorly characterized. The authors determined the effect of ambient temperature on core temperature changes with and without forced-air warming. Methods In this unblinded three-by-two factorial trial, 292 adults were randomized to ambient temperatures 19°, 21°, or 23°C, and to passive insulation or forced-air warming. The primary outcome was core temperature change between 1 and 3 h after induction. Linear mixed-effects models assessed the effects of ambient temperature, warming method, and their interaction. Results A 1°C increase in ambient temperature attenuated the negative slope of core temperature change 1 to 3 h after anesthesia induction by 0.03 (98.3% CI, 0.01 to 0.06) °Ccore/(h.°Cambient) (P < 0.001), for patients who received passive insulation, but not for those warmed with forced-air (–0.01 [98.3% CI, –0.03 to 0.01] °Ccore/[h.°Cambient]; P = 0.40). Final core temperature at the end of surgery increased 0.13°C (98.3% CI, 0.07 to 0.20; P < 0.01) per degree increase in ambient temperature with passive insulation, but was unaffected by ambient temperature during forced-air warming (0.02 [98.3% CI, –0.04 to 0.09] °Ccore/°Cambient; P = 0.40). After an average of 3.4 h of surgery, core temperature was 36.3° ± 0.5°C in each of the forced-air groups, and ranged from 35.6° to 36.1°C in passively insulated patients. Conclusions Ambient intraoperative temperature has a negligible effect on core temperature when patients are warmed with forced air. The effect is larger when patients are passively insulated, but the magnitude remains small. Ambient temperature can thus be set to comfortable levels for staff in patients who are actively warmed.

scholarly journals Efficacy of forced-air and inhalation rewarming by using a human model for severe hypothermia

1997 ◽  
Vol 83 (5) ◽  
pp. 1635-1640 ◽  
Author(s):  
M. S. L. Goheen ◽  
M. B. Ducharme ◽  
G. P. Kenny ◽  
C. E. Johnston ◽  
John Frim ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Core Temperature ◽  
Cumulative Dose ◽  
Thermal Model ◽  
Human Model ◽  
The Core ◽  
Severe Hypothermia ◽  
Forced Air Warming ◽  
Forced Air

Goheen, M. S. L., M. B. Ducharme, G. P. Kenny, C. E. Johnston, John Frim, Gerald K. Bristow, and Gordon G. Giesbrecht.Efficacy of forced-air and inhalation rewarming by using a human model for severe hypothermia. J. Appl. Physiol. 83(5): 1635–1640, 1997.—We recently developed a nonshivering human model for severe hypothermia by using meperidine to inhibit shivering in mildly hypothermic subjects. This thermal model was used to evaluate warming techniques. On three occasions, eight subjects were immersed for ∼25 min in 9°C water. Meperidine (1.5 mg/kg) was injected before the subjects exited the water. Subjects were then removed, insulated, and rewarmed in an ambient temperature of −20°C with either 1) spontaneous rewarming (control), 2) inhalation rewarming with saturated air at ∼43°C, or 3) forced-air warming. Additional meperidine (to a maximum cumulative dose of 2.5 mg/kg) was given to maintain shivering inhibition. The core temperature afterdrop was 30–40% less during forced-air warming (0.9°C) than during control (1.4°C) and inhalation rewarming (1.2°C) ( P< 0.05). Rewarming rate was 6- to 10-fold greater during forced-air warming (2.40°C/h) than during control (0.41°C/h) and inhalation rewarming (0.23°C/h) ( P< 0.05). In nonshivering hypothermic subjects, forced-air warming provided a rewarming advantage, but inhalation rewarming did not.

Ambient temperature effects on physiological traits of white-tailed deer

1975 ◽  
Vol 53 (6) ◽  
pp. 679-685 ◽  
Author(s):  
J. B. Holter ◽  
W. E. Urban Jr. ◽  
H. H. Hayes ◽  
H. Silver ◽  
H. R. Skutt
Keyword(s):  
Heart Rate ◽  
Body Temperature ◽  
Energy Expenditure ◽  
Ambient Temperature ◽  
Temperature Effects ◽  
Temperature Changes ◽  
Wind Chill ◽  
Ambient Temperatures ◽  
Energy Equilibrium ◽  
Body Energy

Six adult white-tailed deer (Odocoileus virginianus borealis) were exposed to 165 periods of 12 consecutive hours of controlled constant ambient temperature in an indirect respiration calorimeter. Temperatures among periods varied from 38 to 0 (summer) or to −20C (fall, winter, spring). Traits measured were energy expenditure (metabolic rate), proportion of time spent standing, heart rate, and body temperature, the latter two using telemetry. The deer used body posture extensively as a means of maintaining body energy equilibrium. Energy expenditure was increased at low ambient temperature to combat cold and to maintain relatively constant body temperature. Changes in heart rate paralleled changes in energy expenditure. In a limited number of comparisons, slight wind chill was combatted through behavioral means with no effect on energy expenditure. The reaction of deer to varying ambient temperatures was not the same in all seasons of the year.

Efficacy of Two Methods for Reducing Postbypass Afterdrop

2000 ◽  
Vol 92 (2) ◽  
pp. 447-447 ◽  
Author(s):  
Angela Rajek ◽  
Rainer Lenhardt ◽  
Daniel I. Sessler ◽  
Gabriele Brunner ◽  
Markus Haisjackl ◽  
...  
Keyword(s):  
Sodium Nitroprusside ◽  
Core Temperature ◽  
Heat Content ◽  
Tissue Temperature ◽  
Control Group ◽  
Peripheral Tissues ◽  
The Core ◽  
Forced Air Warming ◽  
Forced Air ◽  
Body Heat

Background Afterdrop, defined as the precipitous reduction in core temperature after cardiopulmonary bypass, results from redistribution of body heat to inadequately warmed peripheral tissues. The authors tested two methods of ameliorating afterdrop: (1) forced-air warming of peripheral tissues and (2) nitroprusside-induced vasodilation. Methods Patients were cooled during cardiopulmonary bypass to approximately 32 degrees C and subsequently rewarmed to a nasopharyngeal temperature near 37 degrees C and a rectal temperature near 36 degrees C. Patients in the forced-air protocol (n = 20) were assigned randomly to forced-air warming or passive insulation on the legs. Active heating started with rewarming while undergoing bypass and was continued for the remainder of surgery. Patients in the nitroprusside protocol (n = 30) were assigned randomly to either a control group or sodium nitroprusside administration. Pump flow during rewarming was maintained at 2.5 l x m(-2) x min(-1) in the control patients and at 3.0 l x m(-2) x min(-1) in those assigned to sodium nitroprusside. Sodium nitroprusside was titrated to maintain a mean arterial pressure near 60 mm Hg. In all cases, a nasopharyngeal probe evaluated core (trunk and head) temperature and heat content. Peripheral compartment (arm and leg) temperature and heat content were estimated using fourth-order regressions and integration over volume from 18 intramuscular needle thermocouples, nine skin temperatures, and "deep" hand and foot temperature. Results In patients warmed with forced air, peripheral tissue temperature was higher at the end of warming and remained higher until the end of surgery. The core temperature afterdrop was reduced from 1.2+/-0.2 degrees C to 0.5+/-0.2 degrees C by forced-air warming. The duration of afterdrop also was reduced, from 50+/-11 to 27+/-14 min. In the nitroprusside group, a rectal temperature of 36 degrees C was reached after 30+/-7 min of rewarming. This was only slightly faster than the 40+/-13 min necessary in the control group. The afterdrop was 0.8+/-0.3 degrees C with nitroprusside and lasted 34+/-10 min which was similar to the 1.1+/-0.3 degrees C afterdrop that lasted 44+/-13 min in the control group. Conclusions Cutaneous warming reduced the core temperature afterdrop by 60%. However, heat-balance data indicate that this reduction resulted primarily because forced-air heating prevented the typical decrease in body heat content after discontinuation of bypass, rather than by reducing redistribution. Nitroprusside administration slightly increased peripheral tissue temperature and heat content at the end of rewarming. However, the core-to-peripheral temperature gradient was low in both groups. Consequently, there was little redistribution in either case.

scholarly journals Comparison of Three Warming Devices for the Prevention of Core Hypothermia and Post-Anaesthesia Shivering

2008 ◽  
Vol 36 (5) ◽  
pp. 923-931 ◽  
Author(s):  
CH Ihn ◽  
JD Joo ◽  
HS Chung ◽  
JW Choi ◽  
DW Kim ◽  
...  
Keyword(s):  
Core Temperature ◽  
Total Abdominal Hysterectomy ◽  
Abdominal Hysterectomy ◽  
Upper Body ◽  
Double Blind Study ◽  
Double Blind ◽  
Circulating Water ◽  
Surgical Access ◽  
Forced Air Warming ◽  
Forced Air

The efficacy of forced air warming with a surgical access blanket in preventing a decrease in core temperature during anaesthesia and post-anaesthesia shivering (PAS) was compared with two widely used interventions comprising forced air warming combined with an upper body blanket, and a circulating water mattress, in a prospective, randomized double-blind study. A total of 90 patients undergoing total abdominal hysterectomy were studied, 30 in each group. Core temperature was measured 15, 30, 45, 60, 90 and 120 min after induction of anaesthesia. PAS was evaluated every 5 min after emergence from anaesthesia over a period of 1 h. Core temperature fell in all three groups compared with the baseline, but forced air warming using a surgical access blanket was more effective than the other warming methods in ameliorating the temperature decrease. The surgical access blanket was also superior to the circulating water mattress in reducing PAS.

scholarly journals Effect of ambient temperature during acute aerobic exercise on short-term appetite, energy intake, and plasma acylated ghrelin in recreationally active males

2013 ◽  
Vol 38 (8) ◽  
pp. 905-909 ◽  
Author(s):  
Lucy K. Wasse ◽  
James A. King ◽  
David J. Stensel ◽  
Caroline Sunderland
Keyword(s):  
Ambient Temperature ◽  
Aerobic Exercise ◽  
Energy Intake ◽  
Core Temperature ◽  
Acylated Ghrelin ◽  
Short Term ◽  
Temperature Changes ◽  
Increase Energy Intake ◽  
Ad Libitum ◽  
Intake Regulation

Ambient temperature during exercise may affect energy intake regulation. Compared with a temperate (20 °C) environment, 1 h of running followed by 6 h of rest tended to decrease energy intake from 2 ad libitum meals in a hot (30 °C) environment but increase energy intake in a cool (10 °C) environment (p = 0.08). Core temperature changes did not appear to mediate this trend; whether acylated ghrelin is involved is unclear. Further research is warranted to clarify these findings.

Forced-air warming is no more effective than conventional methods for raising postoperative core temperature after cardiac surgery

1997 ◽  
Vol 11 (6) ◽  
pp. 708-711 ◽  
Author(s):  
Frank J. Villamaria ◽  
Clinton E. Baisden ◽  
Argye Hillis ◽  
M.Hasan Rajab ◽  
Phillip A. Rinaldi
Keyword(s):  
Cardiac Surgery ◽  
Core Temperature ◽  
Forced Air Warming ◽  
Conventional Methods ◽  
Forced Air

Body Morphology and the Speed of Cutaneous Rewarming

2001 ◽  
Vol 95 (1) ◽  
pp. 18-21 ◽  
Author(s):  
Peter Szmuk ◽  
Mary F. Rabb ◽  
James E. Baumgartner ◽  
James M. Berry ◽  
Andrew M. Sessler ◽  
...  
Keyword(s):  
Ambient Temperature ◽  
Surface Area ◽  
Body Mass ◽  
Core Temperature ◽  
Infants And Children ◽  
Metabolic Heat ◽  
Duration Of Surgery ◽  
Forced Air ◽  
Dural Opening ◽  
Full Body

Background Infants and children cool quickly because their surface area (and therefore heat loss) is large compared with their metabolic rate, which is mostly a function of body mass. Rewarming rate is a function of cutaneous heat transfer plus metabolic heat production divided by body mass. Therefore, the authors tested the hypothesis that the rate of forced-air rewarming is inversely related to body size. Methods Isoflurane, nitrous oxide, and fentanyl anesthesia were administered to infants, children, and adults scheduled to undergo hypothermic neurosurgery. All fluids were warmed to 37 degrees C and ambient temperature was maintained near 21 degrees C. Patients were covered with a full-body, forced-air cover of the appropriate size. The heater was set to low or ambient temperature to reduce core temperature to 34 degrees C in time for dural opening. Blower temperature was then adjusted to maintain core temperature at 34 degrees C for 1 h. Subsequently, the forced-air heater temperature was set to high (approximately 43 degrees C). Rewarming continued for the duration of surgery and postoperatively until core temperature exceeded 36.5 degrees C. The rewarming rate in individual patients was determined by linear regression. Results Rewarming rates were highly linear over time, with correlations coefficients (r2) averaging 0.98+/-0.02. There was a linear relation between rewarming rate (degrees C/h) and body surface area (BSA; m2): Rate (degrees C/h) = -0.59 x BSA (m2) + 1.9, r2 = 0.74. Halving BSA thus nearly doubled the rewarming rate. Conclusions Infants and children rewarm two to three times faster than adults, thus rapidly recovering from accidental or therapeutic hypothermia.

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