Thermal Modeling of the Normal Woman’s Breast

1984 ◽  
Vol 106 (2) ◽  
pp. 123-130 ◽  
Author(s):  
M. M. Osman ◽  
E. M. Afify
Keyword(s):  
Venous Blood ◽  
Tissue Perfusion ◽  
3 Dimensional ◽  
Metabolic Heat ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Dimensional Finite Element ◽  
Element Technique ◽  
Arterial Blood Temperature ◽  
Good Agreement

A comprehensive thermal model of the normal woman’s breast is presented. The model is developed taking into consideration metabolic heat production, tissue perfusion with capillary blood, arterial and venous blood thermal interaction and change of arterial blood temperature with position. A series of computer programs are written using a 3-dimensional finite-element technique to evaluate the surface temperature distribution of the breast. Comparison between the results obtained for the model and those from thermograms of a woman’s breast are in good agreement.

Parametric Studies on the Three-Layer Microcirculatory Model for Surface Tissue Energy Exchange

1986 ◽  
Vol 108 (1) ◽  
pp. 89-96 ◽  
Author(s):  
Z. Dagan ◽  
S. Weinbaum ◽  
L. M. Jiji
Keyword(s):  
Venous Blood ◽  
Thermal Characteristics ◽  
Tissue Temperature ◽  
Capillary Perfusion ◽  
Metabolic Heat ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Parametric Studies ◽  
Counter Current ◽  
Cutaneous Blood

The new three-layer microvascular mathematical model for surface tissue heat transfer developed in [1, 2], which is based on detailed vascular casts and tissue temperature measurements in the rabbit thigh, is used to investigate the thermal characteristics of surface tissue under a wide variety of physiological conditions. Studies are carried out to examine the effects of vascular configuration, arterial blood supply rate, distribution of capillary perfusion, cutaneous blood circulation and metabolic heat production on the average tissue temperature profile, the local arterial-venous blood temperature difference in the thermally significant counter-current vessels, and surface heat flux.

Rectal temperature measurement results in artifactual evidence of selective brain cooling

2001 ◽  
Vol 281 (1) ◽  
pp. R108-R114 ◽  
Author(s):  
Shane K. Maloney ◽  
Andrea Fuller ◽  
Graham Mitchell ◽  
Duncan Mitchell
Keyword(s):  
Rectal Temperature ◽  
Brain Temperature ◽  
Brain Cooling ◽  
Selective Brain Cooling ◽  
Blood Temperature ◽  
Arterial Blood ◽  
The Status ◽  
Conscious Sheep ◽  
Surrogate Measures ◽  
Arterial Blood Temperature

Selective brain cooling (SBC) is defined as a brain temperature cooler than the temperature of arterial blood from the trunk. Surrogate measures of arterial blood temperature have been used in many published studies on SBC. The use of a surrogate for arterial blood temperature has the potential to confound proper identification of SBC. We have measured brain, carotid blood, and rectal temperatures in conscious sheep exposed to 40, 22, and 5°C. Rectal temperature was consistently higher than arterial blood temperature. Brain temperature was consistently cooler than rectal temperature during all exposures. Brain temperature only fell below carotid blood temperature during the final few hours of 40°C exposure and not at all during the 5°C exposure. Consequently, using rectal temperature as a surrogate for arterial blood temperature does not provide a reliable indication of the status of the SBC effector. We also show that rapid suppression of SBC can result if the animals are disturbed.

Influence of skin temperature on central thermoregulatory control of leg blood flow

1981 ◽  
Vol 50 (5) ◽  
pp. 974-978 ◽  
Author(s):  
D. W. Proppe
Keyword(s):  
Blood Pressure ◽  
Blood Flow ◽  
Skin Temperature ◽  
Major Influence ◽  
Papio Anubis ◽  
Vascular Conductance ◽  
Leg Blood Flow ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Arterial Blood Temperature

This study examined the influence of elevated skin temperature (Tsk) on the central thermoregulatory control of leg blood flow in five unanesthetized, chronically instrumented, resting baboons (Papio anubis and P. cynocephalus). In each experiment, mean iliac blood flow (MIBF), mean arterial blood pressure, arterial blood temperature (Tbl), and Tsk were measured, and iliac vascular conductance (IVC) was calculated. A heat exchanger was incorporated into a chronic arteriovenous femoral shunt to control Tbl. The protocol consisted of raising Tbl approximately 2.6 degrees C in thermoneutral environment (cool Tsk) an then again after Tsk had been elevated by environmental heating. A major influence of raising Tsk was the lowering of threshold Tbl at which the rise in MIBF and IVC commenced. This threshold Tbl was lowered at least 0.8 degrees C on the average. Also, over the whole range of Tbl studied (37.0-39.6 degrees C), MIBF and IVC were higher at high Tsk than at cool Tsk. Thus an elevation of Tsk significantly influences the control of skin blood flow by central thermoreceptors.

scholarly journals Correlation between Arterial Lactate and Central Venous Lactate in Children with Sepsis

2016 ◽  
Vol 2016 ◽  
pp. 1-5 ◽  
Author(s):  
Jaime Fernández Sarmiento ◽  
Paula Araque ◽  
María Yepes ◽  
Hernando Mulett ◽  
Ximena Tovar ◽  
...  
Keyword(s):  
Septic Shock ◽  
Blood Sample ◽  
Pediatric Patients ◽  
Venous Blood ◽  
Tissue Perfusion ◽  
Central Venous ◽  
Important Indicator ◽  
Arterial Lactate ◽  
Arterial Blood ◽  
Sepsis And Septic Shock

Introduction. Lactate is an important indicator of tissue perfusion. The objective of this study is to evaluate if there are significant differences between the arterial and central venous measurement of lactate in pediatric patients with sepsis and/or septic shock.Methods. Longitudinal retrospective observational study. Forty-two patients were included between the age of 1 month and 17 years, with a diagnosis of sepsis and septic shock, who were admitted to the intensive care unit of a university referral hospital. The lactate value obtained from an arterial blood sample and a central venous blood sample drawn simultaneously, and within 24 hours of admission to the unit, was recorded.Results. The median age was 2.3 years (RIC 0,3–15), with a predominance of males (71.4%), having a 2.5 : 1 ratio to females. Most of the patients had septic shock (78.5%) of pulmonary origin (50.0%), followed by those of gastrointestinal origin (26.1%). Using Spearman’s Rho, a 0.872 (p<0.001) correlation was found between arterial and venous lactate, which did not vary when adjusted for age (p<0.05) and the use of vasoactive drugs (p<0.05).Conclusion. There is a good correlation between arterial and venous lactate in pediatric patients with sepsis and septic shock, which is not affected by demographic variables or type of vasoactive support.

Epinephrine induces tissue perfusion deficit in porcine endotoxin shock: evaluation by regional CO2 content gradients and lactate-to-pyruvate ratios

2005 ◽  
Vol 288 (3) ◽  
pp. G586-G592 ◽  
Author(s):  
Tero J. Martikainen ◽  
Jyrki J. Tenhunen ◽  
Ivo Giovannini ◽  
Ari Uusaro ◽  
Esko Ruokonen
Keyword(s):  
Blood Flow ◽  
Arterial Pressure ◽  
Aerobic Glycolysis ◽  
Venous Blood ◽  
Gastric Wall ◽  
Tissue Perfusion ◽  
Endotoxin Shock ◽  
Perfusion Deficit ◽  
Arterial Blood ◽  
Haldane Effect

Epinephrine is widely used as a vasoconstrictor or inotrope in shock, although it may typically induce or augment lactic acidosis. Ongoing debate addresses the question of whether hyperlactatemia per se is a sign of tissue perfusion deficit or aerobic glycolysis. We wanted to test the hypothesis that epinephrine has selective detrimental effects on visceral perfusion and metabolism. We performed rigorous regional venous blood gas analyses as well as intraperitoneal microdialysis. We used a mathematical model to calculate regional arteriovenous CO2 content gradients and estimated the magnitude of the Haldane effect in a porcine model of prolonged hypotensive shock induced by endotoxin infusion (mean arterial blood pressure < 60 mmHg). Subsequently, vasopressors (epinephrine or norepinephrine) were administered and adjusted to maintain systemic mean arterial pressure > 70 mmHg for 4 h. Epinephrine caused systemic hyperlactatemia and acidosis. Importantly, both systemic and regional venous lactate-to-pyruvate ratios increased. Epinephrine was associated with decreasing portal blood flow despite apparently maintained total splanchnic blood flow. Epinephrine increased gastric venous-to-arterial Pco2 gradients and CO2 content gradients with decreasing magnitude of the Haldane effect, and the regional gastric respiratory quotient remained higher after epinephrine as opposed to norepinephrine infusion. In addition, epinephrine induced intraperitoneal lactate and glycerol release. We did not observe these adverse hemodynamic or metabolic changes related to norepinephrine with the same arterial pressure goal. We conclude that high CO2 content gradients with decreasing magnitude of the Haldane effect pinpoint the most pronounced perfusion deficiency to the gastric wall when epinephrine, as opposed to norepinephrine, is used in experimental endotoxin shock.

Should we rely on nasopharyngeal temperature during cardiopulmonary bypass?

Perfusion ◽  
2002 ◽  
Vol 17 (2) ◽  
pp. 145-151 ◽  
Author(s):  
R Ian Johnson ◽  
Mark A Fox ◽  
Antony Grayson ◽  
Mark Jackson ◽  
Brian M Fabri
Keyword(s):  
Cardiopulmonary Bypass ◽  
Temperature Measurement ◽  
Temperature Control ◽  
Controlled Study ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Normothermic Group ◽  
Control Limits ◽  
Arterial Blood Temperature ◽  
Hypothermic Group

A potential morbidity of incomplete re-warming following hypothermic cardiopulmonary bypass (CPB) is cardiac arrest. In contrast, attempts to fully re-warm the patient can lead to cerebral hyperthermia. Similarly, rigid adherence to 37.0°C during normothermic CPB may also cause cerebral overheating. The literature demonstrates scant information concerning the actual temperatures measured, the sites of temperature measurement and the detailed thermal strategies employed during CPB. A prospective, randomized, controlled study was undertaken to investigate the ability to manage perfusion temperature control in a group of hypothermic patients (28°C) and a group of normothermic patients (37°C). Eighty patients presenting for first-time, elective coronary artery bypass graft surgery (CABG) were randomly allocated to the hypothermic and normothermic groups. All surgery was performed by one surgeon and the anaesthesia managed by one anaesthetist. Temperature measurements were made at the nasopharyngeal (NP) site, as well as in the arterial line of the CPB circuit. The hypothermic group had the arterial blood temperature lowered to 25.0°C to maintain the NP temperature at 28.0-28.5°C. During re-warming, the arterial blood was raised to 38.0°C. Meanwhile, in the normothermic group, the arterial blood temperature was raised to a maximum of 37.0°C to maintain NP temperature at 36.5-37.0°C. Despite strict guidelines, some patients transgressed the temperature control limits. Two patients in the hypothermic group failed to reach an NP temperature of 28.5°C. Twenty-six patients were managed entirely within the control limits. During re-warming in both groups, control of both arterial and NP temperature was well managed with only 25% patients breaching the respective upper control limits. During the re-warming phases of CPB, we were unable to make any correlation between NP temperature and arterial blood temperature, using body weight or body mass index as predictors. Based on the results obtained, we recommend that strict criteria should be implemented for the management of temperature during CPB, in conjunction with more emphasis being placed on monitoring arterial blood temperature as a marker of potential cerebral hyperthermia. We should, therefore, not rely on NP temperature measurement alone during CPB.

Blood and brain temperatures of free-ranging black wildebeest in their natural environment

1994 ◽  
Vol 267 (6) ◽  
pp. R1528-R1536 ◽  
Author(s):  
C. Jessen ◽  
H. P. Laburn ◽  
M. H. Knight ◽  
G. Kuhnen ◽  
K. Goelst ◽  
...  
Keyword(s):  
Brain Temperature ◽  
Natural Habitat ◽  
Radiant Heat ◽  
Brain Cooling ◽  
Selective Brain Cooling ◽  
Blood Temperature ◽  
Arterial Blood ◽  
Data Loggers ◽  
Free Ranging ◽  
Arterial Blood Temperature

Using miniature data loggers, we measured the temperatures of carotid blood and brain in four wildebeest (Connochaetes gnou) every 2 min for 3 wk and every 5 min, in two of the animals, for a further 6 wk. The animals ranged freely in their natural habitat, in which there was no shelter. They were subject to intense radiant heat (maximum approximately 1,000 W/m2) during the day. Arterial blood temperature showed a circadian rhythm with low amplitude (< 1 degree C) and peaked in early evening. Brain temperature was usually within 0.2 degrees C of arterial blood temperature. Above a threshold between 38.8 and 39.2 degrees C, brain temperature tended to plateau so that the animals exhibited selective brain cooling. However, selective brain cooling sometimes was absent even when blood temperature was high and present when it was low. During helicopter chases, selective brain cooling was absent, even though brain temperature was near 42 degrees C. We believe that selective brain cooling is controlled by brain temperature but is modulated by sympathetic nervous system status. In particular, selective brain cooling may be abolished by high sympathetic activity even at high brain temperatures.

A New Open-Circuit Method for Estimating Carbon Dioxide Tension in Mixed Venous Blood

1977 ◽  
Vol 52 (4) ◽  
pp. 377-382 ◽  
Author(s):  
Reiah Al-Dulymi ◽  
R. Hainsworth
Keyword(s):  
Carbon Dioxide ◽  
Venous Blood ◽  
Carbon Dioxide Tension ◽  
Open Circuit ◽  
Mixed Venous Blood ◽  
Arterial Blood ◽  
Venous Pco2 ◽  
Rebreathing Methods ◽  
Mixed Venous ◽  
Good Agreement

1. A new open-circuit respiratory method was developed to estimate mixed venous Pco2 more rapidly and accurately than is possible with rebreathing techniques. 2. The subject breathes a mixture of CO2 in air from an open circuit. Carbon dioxide is added to the air flowing through the circuit at a rate such that the Pco2 in the inspired and expired gases (recorded continuously with a CO2 analyser) are almost identical. 3. Results from respiratory and cardiac patients showed that equilibrium occurred in less than 10 s. There was good agreement between the tensions of CO2 in the respiratory plateaux and in mixed venous and arterial blood withdrawn during equilibrium. 4. During exercise, the tensions of CO2 of the plateaux and arterial blood at equilibrium also showed good agreement. 5. It is suggested that the new method represents an improvement over rebreathing methods as equilibrium is achieved rapidly before the mixed venous tension rises from recirculation.

Sign in / Sign up

Export Citation Format

Share Document