Tissue Heat Content and Distribution during and after Cardiopulmonary Bypass at 31 [degree sign]C and 27 [degree sign]C 

1998 ◽  
Vol 88 (6) ◽  
pp. 1511-1518 ◽  
Author(s):  
Angela Rajek ◽  
Rainer Lenhardt ◽  
Daniel I. Sessler ◽  
Andrea Kurz ◽  
Gunther Laufer ◽  
...  
Keyword(s):  
Cardiopulmonary Bypass ◽  
Temperature Gradient ◽  
Heat Content ◽  
Peripheral Tissue ◽  
Tissue Temperature ◽  
Peripheral Compartment ◽  
Peripheral Tissues ◽  
The Core ◽  
Total Body ◽  
Body Heat

Background Afterdrop following cardiopulmonary bypass results from redistribution of body heat to inadequately warmed peripheral tissues. However, the distribution of heat between the thermal compartments and the extent to which core-to-peripheral redistribution contributes to post-bypass hypothermia remains unknown. Methods Patients were cooled during cardiopulmonary bypass to nasopharyngeal temperatures near 31 degrees C (n=8) or 27 degrees C (n=8) and subsequently rewarmed by the bypass heat exchanger to approximately 37.5 degrees C. 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 19 intramuscular needle thermocouples, 10 skin temperatures, and "deep" foot temperature. Results In the 31 degrees C group, the average peripheral tissue temperature decreased to 31.9+/-1.4 degrees C (means+/-SD) and subsequently increased to 34+/-1.4 degrees C at the end of bypass. The core-to-peripheral tissue temperature gradient was 3.5+/-1.8 degrees C at the end of rewarming, and the afterdrop was 1.5+/-0.4 degrees C. Total body heat content decreased 231+/-93 kcal. During pump rewarming, the peripheral heat content increased to 7+/-27 kcal below precooling values, whereas the core heat content increased to 94+/-33 kcal above precooling values. Body heat content at the end of rewarming was thus 87+/-42 kcal more than at the onset of cooling. In the 27 degrees C group, the average peripheral tissue temperature decreased to a minimum of 29.8 +/-1.7 degrees C and subsequently increased to 32.8+/-2.1 degrees C at the end of bypass. The core-to-peripheral tissue temperature gradient was 4.6+/-1.9 degrees C at the end of rewarming, and the afterdrop was 2.3+/-0.9 degrees C. Total body heat content decreased 419+/-49 kcal. During pump rewarming, core heat content increased to 66+/-23 kcal above precooling values, whereas peripheral heat content remained 70+/-42 kcal below precooling values. Body heat content at the end of rewarming was thus 4+/-52 kcal less than at the onset of cooling. Conclusions Peripheral tissues failed to fully rewarm by the end of bypass in the patients in the 27 degrees C group, and the afterdrop was 2.3+/-0.9 degrees C. Peripheral tissues rewarmed better in the patients in the 31 degrees C group, and the afterdrop was only 1.5+/-0.4 degrees C.

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.

Perioperative Heat Balance

2000 ◽  
Vol 92 (2) ◽  
pp. 578-578 ◽  
Author(s):  
Daniel I. Sessler ◽  
Michael M. Todd
Keyword(s):  
Temperature Gradient ◽  
General Anesthesia ◽  
Heat Loss ◽  
Core Temperature ◽  
Neuraxial Anesthesia ◽  
Tissue Temperature ◽  
Large Core ◽  
Peripheral Tissues ◽  
Peripheral Temperature ◽  
Body Heat

Hypothermia during general anesthesia develops with a characteristic three-phase pattern. The initial rapid reduction in core temperature after induction of anesthesia results from an internal redistribution of body heat. Redistribution results because anesthetics inhibit the tonic vasoconstriction that normally maintains a large core-to-peripheral temperature gradient. Core temperature then decreases linearly at a rate determined by the difference between heat loss and production. However, when surgical patients become sufficiently hypothermic, they again trigger thermoregulatory vasoconstriction, which restricts core-to-peripheral flow of heat. Constraint of metabolic heat, in turn, maintains a core temperature plateau (despite continued systemic heat loss) and eventually reestablishes the normal core-to-peripheral temperature gradient. Together, these mechanisms indicate that alterations in the distribution of body heat contribute more to changes in core temperature than to systemic heat imbalance in most patients. Just as with general anesthesia, redistribution of body heat is the major initial cause of hypothermia in patients administered spinal or epidural anesthesia. However, redistribution during neuraxial anesthesia is typically restricted to the legs. Consequently, redistribution decreases core temperature about half as much during major conduction anesthesia. As during general anesthesia, core temperature subsequently decreases linearly at a rate determined by the inequality between heat loss and production. The major difference, however, is that the linear hypothermia phase is not discontinued by reemergence of thermoregulatory vasoconstriction because constriction in the legs is blocked peripherally. As a result, in patients undergoing large operations with neuraxial anesthesia, there is the potential of development of serious hypothermia. Hypothermic cardiopulmonary bypass is associated with enormous changes in body heat content. Furthermore, rapid cooling and rewarming produces large core-to-peripheral, longitudinal, and radial tissue temperature gradients. Inadequate rewarming of peripheral tissues typically produces a considerable core-to-peripheral gradient at the end of bypass. Subsequently, redistribution of heat from the core to the cooler arms and legs produces an afterdrop. Afterdrop magnitude can be reduced by prolonging rewarming, pharmacologic vasodilation, or peripheral warming. Postoperative return to normothermia occurs when brain anesthetic concentration decreases sufficiently to again trigger normal thermoregulatory defenses. However, residual anesthesia and opioids given for treatment of postoperative pain decreases the effectiveness of these responses. Consequently, return to normothermia often needs 2-5 h, depending on the degree of hypothermia and the age of the patient.

Prewarming: Preventing Intraoperative Hypothermia

2005 ◽  
Vol 15 (10) ◽  
pp. 444-451 ◽  
Author(s):  
Panagiotis Kiekkas ◽  
Maria Karga
Keyword(s):  
Temperature Gradient ◽  
Core Temperature ◽  
Peripheral Tissue ◽  
Tissue Temperature ◽  
Temperature Decrease ◽  
Perioperative Hypothermia ◽  
Normal Limits ◽  
Normal Core ◽  
Short Period ◽  
Peripheral Temperature

Perioperative hypothermia can be followed by severe complications. The greatest proportion of temperature decrease is attributed to heat redistribution, which mainly occurs during the first hour of anaesthesia and is difficult to treat intraoperatively. Prewarming, based on active warming techniques, has been proposed. Even a short period of prewarming may significantly increase peripheral tissue temperature, minimise normal core-to-peripheral temperature gradient, and keep core temperature within normal limits.

scholarly journals Effects of a Circulating-water Garment and Forced-air Warming on Body Heat Content and Core Temperature

2004 ◽  
Vol 100 (5) ◽  
pp. 1058-1064 ◽  
Author(s):  
Akiko Taguchi ◽  
Jebadurai Ratnaraj ◽  
Barbara Kabon ◽  
Neeru Sharma ◽  
Rainer Lenhardt ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Core Temperature ◽  
Thermal Flux ◽  
Heat Content ◽  
Skin Surface ◽  
Peripheral Tissue ◽  
Tissue Temperature ◽  
Circulating Water ◽  
Forced Air Warming ◽  
Forced Air

Background Forced-air warming is sometimes unable to maintain perioperative normothermia. Therefore, the authors compared heat transfer, regional heat distribution, and core rewarming of forced-air warming with a novel circulating-water garment. Methods Nine volunteers were each evaluated on two randomly ordered study days. They were anesthetized and cooled to a core temperature near 34 degrees C. The volunteers were subsequently warmed for 2.5 h with either a circulating-water garment or a forced-air cover. Overall, heat balance was determined from the difference between cutaneous heat loss (thermal flux transducers) and metabolic heat production (oxygen consumption). Average arm and leg (peripheral) tissue temperatures were determined from 18 intramuscular needle thermocouples, 15 skin thermal flux transducers, and "deep" hand and foot thermometers. Results Heat production (approximately 60 kcal/h) and loss (approximately 45 kcal/h) were similar with each treatment before warming. The increases in heat transfer across anterior portions of the skin surface were similar with each warming system (approximately 65 kcal/h). Forced-air warming had no effect on posterior heat transfer, whereas circulating-water transferred 21+/-9 kcal/h through the posterior skin surface after a half hour of warming. Over 2.5 h, circulating water thus increased body heat content 56% more than forced air. Core temperatures thus increased faster than with circulating water than forced air, especially during the first hour, with the result that core temperature was 1.1 degrees +/- 0.7 degrees C greater after 2.5 h (P < 0.001). Peripheral tissue heat content increased twice as much as core heat content with each device, but the core-to-peripheral tissue temperature gradient remained positive throughout the study. Conclusions The circulating-water system transferred more heat than forced air, with the difference resulting largely from posterior heating. Circulating water rewarmed patients 0.4 degrees C/h faster than forced air. A substantial peripheral-to-core tissue temperature gradient with each device indicated that peripheral tissues insulated the core, thus slowing heat transfer.

Metabolic actions of morphine in conscious chronically instrumented pigs

1991 ◽  
Vol 260 (6) ◽  
pp. R1051-R1057
Author(s):  
C. A. Bossone ◽  
J. P. Hannon
Keyword(s):  
Energy Metabolism ◽  
Plasma Concentrations ◽  
Potassium Phosphate ◽  
Heat Content ◽  
Co2 Production ◽  
Morphine Injection ◽  
Thermal Status ◽  
Intravenous Morphine ◽  
Total Body ◽  
Body Heat

Effects of a modest dose of morphine sulfate (1 mg/kg) on total body energy metabolism, body thermal status, and the plasma concentrations of certain electrolytes and metabolites were investigated in conscious chronically instrumented pigs (n = 8). Control pigs (n = 8) received an equivalent volume of normal saline. Intravenous morphine injection led to an excitatory state associated with significant (P less than or equal to 0.05) immediate increases in O2 consumption. CO2 production, respiratory exchange ratio, and plasma concentrations of lactate, glucose, potassium, phosphate, epinephrine, and norepinephrine. Significant more gradual increases were observed in rectal and skin temperatures, body heat content, and the plasma concentrations of adrenocorticotropic hormone, cortisol, and phosphate. The hypermetabolic state persisted for approximately 1 h. Thereafter, most functional variables regressed toward, but did not reach, control levels. Increased muscle activity appeared to be the major factor underlying the rise in energy metabolism. Body heat storage after morphine injection appeared to be attributable to increased heat production coupled with an inadequate rise in heat loss.

scholarly journals Estimation of Mean Body Temperature from Mean Skin and Core Temperature

2006 ◽  
Vol 105 (6) ◽  
pp. 1117-1121 ◽  
Author(s):  
Rainer Lenhardt ◽  
Daniel I. Sessler
Keyword(s):  
Body Temperature ◽  
Core Temperature ◽  
Weighted Average ◽  
Perioperative Period ◽  
Peripheral Tissue ◽  
Tissue Temperature ◽  
Peripheral Compartment ◽  
Mean Body Temperature ◽  
Body Tissues ◽  
Skin Temperatures

Background Mean body temperature (MBT) is the mass-weighted average temperature of body tissues. Core temperature is easy to measure, but direct measurement of peripheral tissue temperature is painful and risky and requires complex calculations. Alternatively MBT can be estimated from core and mean skin temperatures with a formula proposed by Burton in 1935: MBT = 0.64 x TCore + 0.36 x TSkin. This formula remains widely used, but has not been validated in the perioperative period and seems unlikely to remain accurate in dynamic perioperative conditions such as cardiopulmonary bypass. Therefore, the authors tested the hypothesis that MBT, as estimated with Burton's formula, poorly estimates measured MBT at a temperature range between 18 degrees and 36.5 degrees C. Methods The authors reevaluated four of their previously published studies in which core and mass-weighted mean peripheral tissue temperatures were measured in patients undergoing substantial thermal perturbations. Peripheral compartment temperatures were estimated using fourth-order regression and integration over volume from 18 intramuscular needle thermocouples, 9 skin temperatures, and "deep" hand and foot temperature. MBT was determined from mass-weighted average of core and peripheral tissue temperatures and estimated from core temperature and mean skin temperature (15 area-weighted sites) using Burton's formula. Results Nine hundred thirteen data pairs from 44 study subjects were included in the analysis. Measured MBT ranged from 18 degrees to 36.5 degrees C. There was a remarkably good relation between measured and estimated MBT: MBTmeasured = 0.94 x MBTestimated + 2.15, r = 0.98. Differences between the estimated and measured values averaged -0.09 degrees +/- 0.42 degrees C. Conclusions The authors concluded that estimation of MBT from mean skin and core temperatures is generally accurate and precise.

scholarly journals Effect of polyaspartic acid on pharmacokinetics of gentamicin after single intravenous dose in the dog.

1996 ◽  
Vol 40 (5) ◽  
pp. 1237-1241 ◽  
Author(s):  
T Whittem ◽  
K Parton ◽  
K Turner
Keyword(s):  
Aspartic Acid ◽  
Elimination Rate ◽  
Volume Of Distribution ◽  
Intravenous Dose ◽  
Pharmacokinetic Parameters ◽  
Therapeutic Drug ◽  
Peripheral Compartment ◽  
Single Intravenous Dose ◽  
Polyaspartic Acid ◽  
Peripheral Tissues

The effects of poly-L-aspartic acid on the pharmacokinetics of gentamicin were examined by using a randomized crossover trial design with the dog. When analyzed according to a three-compartment open model, poly-L-aspartic acid reduced some first-order rate equation constants (A3, lambda 1, and lambda 3), the deep peripheral compartment exit microconstant (k31), the elimination rate constant (k(el)), and the area under the concentration-time curve from 0 to 480 h (AUC0-480) (0.21-, 0.60-, 0.26-, 0.27-, 0.72-, and 0.76-fold, respectively; P < 0.05) but increased the volume of distribution at steady state (Vss), the volume of distribution calculated by the area method (V(area)), the apparent volume of the peripheral compartment (Vp), and all mean time parameters. These results suggested that poly-L-aspartic acid increased the distribution of gentamicin to or binding within the deep peripheral compartment and that poly-L-aspartic acid may have delayed gentamicin transit through the peripheral tissues. In contrast, poly-L-aspartic acid did not alter pharmacokinetic parameters relevant to the central or shallow peripheral compartments to a clinically significant extent. Although gentamicin's pharmacokinetic parameters of relevance to therapeutic drug monitoring were not directly altered, this study has provided pharmacokinetic evidence that poly-L-aspartic acid alters the peripheral distribution of gentamicin. This pharmacokinetic interaction occurred after a single intravenous dose of each drug. Therefore, this interaction should be investigated further, before polyaspartic acid can be considered for use as a clinical nephroprotectant.

scholarly journals Temperature Monitoring and Perioperative Thermoregulation

2008 ◽  
Vol 109 (2) ◽  
pp. 318-338 ◽  
Author(s):  
Daniel I. Sessler ◽  
David S. Warner ◽  
Mark A. Warner
Keyword(s):  
Body Temperature ◽  
General Anesthesia ◽  
Core Temperature ◽  
Core Body Temperature ◽  
Neuraxial Anesthesia ◽  
General Anesthetics ◽  
The Core ◽  
Core Body ◽  
Dose Dependent ◽  
Body Heat

Most clinically available thermometers accurately report the temperature of whatever tissue is being measured. The difficulty is that no reliably core-temperature-measuring sites are completely noninvasive and easy to use-especially in patients not undergoing general anesthesia. Nonetheless, temperature can be reliably measured in most patients. Body temperature should be measured in patients undergoing general anesthesia exceeding 30 min in duration and in patients undergoing major operations during neuraxial anesthesia. Core body temperature is normally tightly regulated. All general anesthetics produce a profound dose-dependent reduction in the core temperature, triggering cold defenses, including arteriovenous shunt vasoconstriction and shivering. Anesthetic-induced impairment of normal thermoregulatory control, with the resulting core-to-peripheral redistribution of body heat, is the primary cause of hypothermia in most patients. Neuraxial anesthesia also impairs thermoregulatory control, although to a lesser extent than does general anesthesia. Prolonged epidural analgesia is associated with hyperthermia whose cause remains unknown.

Heat balance precedes stabilization of body temperatures during cold water immersion

2003 ◽  
Vol 95 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Peter Tikuisis
Keyword(s):  
Heat Balance ◽  
Cold Water ◽  
Water Immersion ◽  
Heat Content ◽  
Cold Water Immersion ◽  
The Body ◽  
Body Temperatures ◽  
Mean Body Temperature ◽  
The Core ◽  
Region Temperature

Certain previous studies suggest, as hypothesized herein, that heat balance (i.e., when heat loss is matched by heat production) is attained before stabilization of body temperatures during cold exposure. This phenomenon is explained through a theoretical analysis of heat distribution in the body applied to an experiment involving cold water immersion. Six healthy and fit men (mean ± SD of age = 37.5 ± 6.5 yr, height = 1.79 ± 0.07 m, mass = 81.8 ± 9.5 kg, body fat = 17.3 ± 4.2%, maximal O2 uptake = 46.9 ± 5.5 l/min) were immersed in water ranging from 16.4 to 24.1°C for up to 10 h. Core temperature (Tco) underwent an insignificant transient rise during the first hour of immersion, then declined steadily for several hours, although no subject's Tco reached 35°C. Despite the continued decrease in Tco, shivering had reached a steady state of ∼2 × resting metabolism. Heat debt peaked at 932 ± 334 kJ after 2 h of immersion, indicating the attainment of heat balance, but unexpectedly proceeded to decline at ∼48 kJ/h, indicating a recovery of mean body temperature. These observations were rationalized by introducing a third compartment of the body, comprising fat, connective tissue, muscle, and bone, between the core (viscera and vessels) and skin. Temperature change in this “mid region” can account for the incongruity between the body's heat debt and the changes in only the core and skin temperatures. The mid region temperature decreased by 3.7 ± 1.1°C at maximal heat debt and increased slowly thereafter. The reversal in heat debt might help explain why shivering drive failed to respond to a continued decrease in Tco, as shivering drive might be modulated by changes in body heat content.

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