scholarly journals Temperature Monitoring With Zero Heat Flux Technology in Comparison With Thermocouple Needle Probe During Selective Hypothermia

2018 ◽  
Author(s):  
Mohammad Fazel Bakhsheshi ◽  
Lynn Keenliside ◽  
Ting-Yim Lee
Keyword(s):  
Brain Temperature ◽  
Cardiopulmonary Arrest ◽  
Core Body Temperature ◽  
Head Injuries ◽  
Extended Period ◽  
Accurate Method ◽  
Brain Parenchyma ◽  
Whole Body ◽  
Temperature Management ◽  
Great Promise

Hypothermia (brain temperature < 35°C) shows great promise to minimize neural damage in patients with cardiopulmonary arrest and traumatic head injuries.[1, 2] However, cooling the whole body below 33–34°C can induce severe complications.[3] Arrhythmia, infection and primary coagulopathy are the most commonly noted complications.[3] We have developed a Selective Brain Cooling (SBC) approach which can be initiated early after injury, induces rapid cooling and maintains the target brain temperature over an extended period of time before slowly rewarming without significantly affecting the core body temperature.[4] In our experiments, brain temperature was measured invasively by inserting a thermocouple probe into the brain parenchyma, which measured brain temperature accurately but is invasive, making it unsuitable for most patients. Invasive intracranial probe also can have complications such as intracranial hemorrhage or hematoma and infection.[5] Accordingly, the clinical adaptation of our SBC technique requires a reliable, non-invasive and accurate method for measuring local brain temperature so that cooling and rewarming rate can be controlled during targeted temperature management.

scholarly journals An In Vivo Assessment of Regional Brain Temperature during Whole-Body Cooling for Neonatal Encephalopathy

2020 ◽  
Vol 220 ◽  
pp. 73-79.e3
Author(s):  
Tai-Wei Wu ◽  
Jessica L. Wisnowski ◽  
Robert F. Geisler ◽  
Aaron Reitman ◽  
Eugenia Ho ◽  
...  
Keyword(s):  
Brain Temperature ◽  
Whole Body ◽  
Neonatal Encephalopathy ◽  
Regional Brain ◽  
Body Cooling ◽  
Whole Body Cooling ◽  
In Vivo Assessment

Heat stress protects the perfused rabbit heart from complement-mediated injury

1996 ◽  
Vol 271 (2) ◽  
pp. H571-H578 ◽  
Author(s):  
M. R. Gralinski ◽  
S. C. Black ◽  
L. F. Stancato ◽  
K. S. Kilgore ◽  
P. A. Campau ◽  
...  
Keyword(s):  
Heat Stress ◽  
Human Plasma ◽  
Complement Activation ◽  
Core Body Temperature ◽  
Rabbit Heart ◽  
Whole Body ◽  
Ultrastructural Changes ◽  
Hsp 70 ◽  
Stress Induction ◽  
Xenograft Rejection

We determined if heat stress induction of heat shock protein (HSP) 70 modulates complement activation in an experimental model of xenograft rejection. Male New Zealand White rabbits were heat stressed (core body temperature to 42 degrees C for 15 min; n = 9). Control rabbits (n = 13) were not exposed to heat stress. Hearts were removed 18 h later and perfused by the Langendorff method. After equilibration, human plasma (source of human complement) was added to the perfusion medium. Hemodynamic variables recorded during perfusion with human plasma were improved in hearts from heat-stressed animals compared with control hearts. Assembly of the soluble membrane attack complex was reduced in the interstitial fluid effluent from the heat-stressed hearts. Electron microscopic evidence of ultrastructural changes was attenuated in the hearts from heat-stressed rabbits. Myocardial tissue from heat-stressed animals exhibited an increase in inducible HSP 70 that was virtually absent in the hearts of control rabbits. Previous whole body hyperthermia protects the rabbit heart against the detrimental effects of heterologous plasma, suggesting that heat-stress induction of HSP 70 limits the extent of complement activation by a discordant vascularized tissue (xenograft). Induction of heat stress proteins by the donor organ might be an important mechanism affecting the outcome of xenograft transplants.

Cardiac autonomic function during hypothermia and its measurement repeatability

2019 ◽  
Vol 44 (1) ◽  
pp. 31-36 ◽  
Author(s):  
Gary J. Hodges ◽  
Steven A.H. Ferguson ◽  
Stephen S. Cheung
Keyword(s):  
Heart Rate ◽  
Rectal Temperature ◽  
Mild Hypothermia ◽  
Core Body Temperature ◽  
Intraclass Correlation ◽  
Low Frequency ◽  
Whole Body ◽  
Body Cooling ◽  
Mean Square Difference ◽  
Whole Body Cooling

This study examined the effect of mild hypothermia (a 0.5 °C decrease in rectal temperature) on heart rate variability (HRV), with the identical hypothermia protocol performed twice and compared using intraclass correlation coefficient (r) analysis to study the repeatability. Twelve healthy males each completed 1 neutral (23 °C) and 2 cold (0 °C) trials. In the neutral trial, participants sat quietly for 30 min. In the cold trials, baseline data were obtained from a 5-min sample following 30 min of quiet sitting at 23 °C, followed by passive exposure to 0 °C; hypothermic measures were taken from a 5-min period immediately prior to rectal temperature decreasing by 0.5 °C. HRV was obtained from a 3-lead electrocardiogram. There were no differences (all p > 0.05) in baseline measures between the neutral and the 2 cold trials, suggesting no precooling anxiety related to the cold trials. Heart rate, together with HRV measures (i.e., root mean square difference of successive normal RR intervals, triangular interpolation of NN interval histogram, low-frequency oscillations (LF), and high-frequency oscillations (HF)), increased (all p < 0.05) with mild hypothermia and showed excellent reliability between the 2 cold trials (all r ≥ 0.81). In contrast, the LF/HF ratio decreased (p < 0.05) and had only fair reliability between the 2 cold trials (r = 0.551). In general, hypothermia led to increases in heart rate, together with most measures of HRV. Although it was counterintuitive that both sympathetic and vagal influences would increase simultaneously, these changes likely reflected increased stress from whole-body cooling, together with marked cardiovascular strain and sympathetic nervous system activity from shivering to defend core body temperature. An important methodological consideration for future studies is the consistent and repeatable HRV responses to hypothermia.

Core Temperature and Sweating in Men and Women During a 15-km Race in Cool Conditions

2020 ◽  
Vol 15 (8) ◽  
pp. 1132-1137
Author(s):  
Coen C.W.G. Bongers ◽  
Dominique S.M. ten Haaf ◽  
Nicholas Ravanelli ◽  
Thijs M.H. Eijsvogels ◽  
Maria T.E. Hopman
Keyword(s):  
Body Mass ◽  
Heat Production ◽  
Sweat Rate ◽  
Core Body Temperature ◽  
Whole Body ◽  
Ambient Conditions ◽  
External Work ◽  
Men And Women ◽  
The Impact ◽  
Cool Conditions

Purpose: Studies often assess the impact of sex on the relation between core body temperature (CBT), whole-body sweat rate (WBSR), and heat production during exercise in laboratory settings, but less is known in free-living conditions. Therefore, the authors compared the relation between CBT, WBSR, and heat production between sexes in a 15-km race under cool conditions. Methods: During 3 editions of the Seven Hills Run (Nijmegen, the Netherlands) with similar ambient conditions (8–12°C, 80–95% relative humidity), CBT and WBSR were measured among 375 participants (52% male) before and immediately after the 15-km race. Heat production was estimated using initial body mass and mean running speed, assuming negligible external work. Results: Men finished the race in 76 (12) minutes and women in 83 (13) minutes (P < .001, effect size [ES] = 0.55). Absolute heat production was higher in men than in women (1185 [163] W vs 867 [122] W, respectively, P < .001, ES = 1.47), even after normalizing to body mass (15.0 [2.2] W/kg vs 13.8 [1.9] W/kg, P < .001, ES = 0.56). Finish CBT did not differ between men and women (39.2°C [0.7°C] vs 39.2°C [0.7°C], P = .71, ES = 0.04). Men demonstrated a greater increase in CBT (1.5°C [0.8°C] vs 1.3°C [0.7°C], respectively, P = .013, ES = 0.31); the sex difference remains after correcting for heat production (P = .004). WBSR was larger in men (18.0 [6.9] g/min) than in women (11.4 [4.7] g/min; P < .001, ES = 0.97). A weak correlation between WBSR and heat production was found irrespective of sex (R2 = .395, P < .001). Conclusions: WBSR was associated with heat production, irrespective of sex, during a self-paced 15-km running race in cool environmental conditions. Men had a higher ΔCBT than women.

602 Managing Hypothermia in the Surgical Burn Patient

2020 ◽  
Vol 41 (Supplement_1) ◽  
pp. S144-S144
Author(s):  
Patricia Regojo ◽  
Molly Mohan
Keyword(s):  
Quality Assurance ◽  
Operating Room ◽  
Core Body Temperature ◽  
Temperature Management ◽  
Evidence Based ◽  
Burn Patients ◽  
Estimated Blood Loss ◽  
Increased Risk ◽  
Burn Unit ◽  
Burn Patient

Abstract Introduction It is known, hypothermia, core body temperature at or below 36oC/96.8oF, can lead to dangerous complications for burn patients. Due to loss of their protective thermoregulation, burn patients are at an increased risk of hypothermia during surgery. Findings from a Quality Assurance audit revealed burn patients were returning from surgery hypothermic and hemodynamically unstable. There was little evidence of intra-operative temperature management in the electronic medical record (EMR) or reported to the nurse upon the patients’ return from the operating room (OR). Only 73% of patients had temperatures recorded during their surgery and of those, 40% had a drop of temperature &gt;2 degrees from their baseline. The purpose of this collaborative evidence-based quality assurance project was to improve temperature management in the operating room and prevent hypothermia in the intra and post operative periods. Our aim was to develop warming methods pre-operatively that would establish a goal for keeping the patients’s temperature within 2 degrees of their baseline preoperative temperature during surgery. Methods A literature search obtained from CINAHL, Cochrane, EMBASE, and MEDLINE from 2010–2018, provided current surgical guidelines and evidence-based practices for managing surgical hypothermia in burn patients (levels of evidence I, III, V, & VI). Recommendations from the burn unit staff for preoperative warming initiatives were listed and shared with the OR staff. Hemodynamic documentation, including core temperature, estimated blood loss, and intra-operative warming methods were monitored for twelve months after the Burn Unit Warming Protocol was implemented. Progress was reported quarterly in our Burn and Trauma Quality Committees. Results After implementing the Burn Unit Warming Protocol, temperature management of the burn patient improved. Intra-operative warming methods were initiated. Patients began returning from surgery warmer with improved hemodynamics. 96% of the patients had their temperatures recorded and managed intra-operatively. Of those patients, only 2.6% had a drop in temperature &gt; 2 degrees from their pre-operative baseline. Conclusions Implementing a nurse-driven warming protocol from the pre-operative stage through surgery can aid in reducing post-operative hypothermia in burn patients. Applicability of Research to Practice Managing hypothermia will help reduce complications that can lead to increase morbidity and mortality in burn patients.

Temperature gradients in pigs during whole-body hyperthermia at 42 degrees C

1979 ◽  
Vol 47 (4) ◽  
pp. 712-717 ◽  
Author(s):  
J. A. Dickson ◽  
A. McKenzie ◽  
K. McLeod
Keyword(s):  
Core Temperature ◽  
Brain Temperature ◽  
Heat Content ◽  
Temperature Gradients ◽  
Whole Body ◽  
Induction Phase ◽  
Equilibrium Conditions ◽  
Repeated Heating ◽  
Deep Body ◽  
Body Heat

Temperature was simultaneously measured by thermistors in multiple deep-body and peripheral sites in adult pigs heated continuously at 42 degrees C (rectal) and above for 4–24 h. During hyperthermia, the relations between different body temperatures were maintained and up to 1.0 degrees C separated temperature measurements at sites such as liver and bone marrow. These persistent temperature gradients must be borne in mind when evaluating tumor response in patients subjected to whole-body heating for disseminated cancer. Temperatures recorded by rectal, deep esophageal, or tympanic membrane sensors provided a reliable index of core temperature (including brain temperature) under equilibrium conditions at 42 degrees C, but only esophageal and tympanic sensors could safely be used to monitor the induction phase of hyperthermia and the adjustive changes in body-heat content required to stabilize core temperature during sustained hyperthermia. Pigs withstood repeated heating at 42 degrees C for 6 h, and recovered rapidly, but died after 24 h of hyperthermia. Pigs subjected to unrestrained heating died at 45 degrees C (esophagus).

scholarly journals Canine hyperthermia with cerebral protection

1976 ◽  
Vol 40 (4) ◽  
pp. 543-548 ◽  
Author(s):  
R. W. Carithers ◽  
R. C. Seagrave
Keyword(s):  
Core Temperature ◽  
Cold Water ◽  
Brain Temperature ◽  
Body Core Temperature ◽  
Whole Body ◽  
Similar Time ◽  
Data Points ◽  
Body Core ◽  
Heat Transfer System ◽  
The Brain

Extreme whole-body hyperthermia was achieved without lasting side effects in canines by elevating body core temperature to 42 degrees C, using a warm water bath. Cold water irrigation of the nasal alar fold permitted an additional core temperature elevation of 0.5–1.0 degrees C above brain temperature for periods up to 1.5 h. The brain-core temperature differential was maintained by a physiological arteriovenous heat exchanger located at the base of the brain. The maximum tolerable core temperature for the 21 nonirrigated dogs was 42 degrees C for 60–90 min, whereas that for the 28 irrigated dogs was 42.5–43 degrees C for similar time intervals. A mathematical model of the total heat transfer system described the observed dynamic temperature responses. It was the solution of a differential equation which fit the normalized experimental data points and predicted reasonable values for known and unknown experimental parameters.

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