No description available.

This study examined the extent to which physiological and psychological concomitants of aerobic terrestrial performance were affected by body cooling of varying degrees induced by cold water immersion (CWI). Thirteen male and 13 female subjects underwent three randomly assigned 30 min treadmill runs: a control run without prior manipulation of the subjects' thermal status and the same exercise after "central" (core temperature 1°C below pre-immersion) and "peripheral" cooling (skin heat loss 100kcal.m⁻².h⁻¹). During treadmill runs core temperature was measured, together with chest, leg, arm and hand temperatures, from which mean skin temperature (T [subscript]s[subscript]k) and mean body temperature (T[subscript]b) were calculated. Heart rate, oxygen consumption (VO₂,), carbon dioxide production (VCO₂), minute ventilation (V₂ (BTPS)), breathing frequency (f), cadence and ratings of perceived exertion (RPE) and thermal sensation (PTS) were also measured. Both central and peripheral cooling resulted in significantly reduced T[subscript]r[subscript]e (males : control 37.9±0. 3°C; central cooling : 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 37.9±0.4°C; central cooling: 37.2±0.5; p<0.05) during subsequent treadmill running, except following peripheral cooling for females (37.9±0.3°C) . For males and females T[subscript]s[subscript]k was lower following peripheral cooling than control values and lowest after central cooling (males: control: 30.0±1.3°C; central cooling: 36.8±0.5°C; peripheral cooling: 37.5±0.4°C; females: control: 30.5±1.2°C; central cooling: 25.9±1.8°C; peripheral cooling: 26.9±1.9°C; p<0.05). Female subjects experienced significantly higher T[subscript]r[subscript]e than males following central and peripheral cooling and a lower T[subscript]s[subscript]k following central cooling. Females experienced less of an increase in heart rate than males during exercise following central and peripheral cooling (control: l57.7±23.7b.min⁻¹; central cooling: 143.5±20.5b.min⁻¹; peripheral cooling 151.7±16.7b.min⁻¹; p<0 .05). Male responses were the same following central cooling but higher for peripheral cooling than control values (control: 139.1±7.3b.min⁻¹; central cooling 134.7±17.5b.min⁻¹; peripheral cooling: 145.0±16.4b.min⁻¹; p<0.05). These data indicate a depression in cardiovascular function for females following peripheral cooling that was not apparent for males. The VO₂ was not different between tests for males; only peripheral cooling resulted in a raised VO₂ of 28.6±3 .3ml.kg⁻¹.min⁻¹ (p<0 .05) for females compared to 27.6±2.6ml.kg⁻¹.min⁻¹ (control). A biphasic response was evident for VO₂ VCO₂ and V[subscript]B (BTPS). For both sexes overall RPE was lower for peripheral cooling (males: 9.4±1.9; females: 8.7±1.3; p<0 .05) than for control and central cooling. Central RPE was only changed for females following peripheral cooling. Changes in cadence and step length together with the effect of low skin and leg temperatures resulted in higher local RPE for females after central cooling (9.6±1.2; p<0.05) than control (9.4±1.9) and peripheral cooling (8.9±1.2 ). Males and females rated the same ambient temperature during the same exercise lower after peripheral cooling (males: 4.6±1.5; females : 5.3±1.3) than control values and lower still after central cooling (males: 3. 8±1.8; females: 2 .7±l. 5) In this study T[subscript]s[subscript]k was the primary determinant of PTS after precooling. / KMBT_363 / Adobe Acrobat 9.54 Paper Capture Plug-in

Patienterna på en intensivvårdsavdelning ligger i riskzonen för oavsiktlig hypotermi. De tidigare identifierade riskgrupperna är bland annat förekomst av kontinuerlig hemodialys, vissa sederande läkemedel, stor mängd intravenös vätska samt kirurgiska ingrepp i generell anestesi. Hypotermi har negativa konsekvenser för patienterna som ökad blödningsrisk, försämrad sårläkning samt kardiologisk påverkan. Syftet med studien var att undersöka förekomsten av hypotermi hos intensivvårdade patienter. En retrospektiv deskriptiv studie på 583 vuxna patienter som vårdades på en intensivvårdsavdelning någon gång under 2009 genomfördes. Resultatet visade att 17 procent av patienterna hade drabbats av oavsiktlig hypotermi. Patienterna med intagningsorsakerna blödning och sepsis hade en ökad förekomst av hypotermi. Patienter med låg kroppsvikt samt äldre patienter hade en ökad förekomst av hypotermi vilket stämmer väl överens med tidigare studier. Däremot att yngre patienter samt kvinnliga patienter hade en högre förekomst av hypotermi är nya fynd. Det förefaller viktigt för intensivvårdssjuksköterskan att tidigt identifiera patienter i riskgrupper för oavsiktlig hypotermi och aktivt förhindra dess uppkomst. / The patients on an intensive care unit are often at risk for inadvertent hypothermia. Previously identified groups at risk include patients receiving continuous renal replacement therapy, some sedative drugs, large amounts of intravenous fluids and surgical procedures during general anesthesia. Hypothermia has negative consequences for patients such as increased risk for hemorrhaging, impaired wound healing and cardiological effects. The purpose of the study was to determine the prevalence of inadvertent hypothermia in patients receiving intensive care. We performed a retrospective descriptive study on 583 adult patients who had been admitted to an intensive care unit. The results showed that 17 percent of the patients had inadvertent hypothermia. The patients admitted under the categories bleeding or septicemia had an increased occurrence of hypothermia. Patients with lower bodyweight and elderly patients had a higher occurrence which concurs with previous research. We also found that younger patients and female patients had a higher occurrence of hypothermia which is new findings. It appears that it is important for the intensive care unit nurse to early identify those patients at risk and to actively prevent its occurrence.

L’arrêt cardiaque (AC) extrahospitalier est un problème majeur de santé publique, malgré la mise en place d’une véritable « chaine de survie ». Les durées de réanimation sont souvent prolongées et aboutissent à des séquelles irréversibles avec un assombrissement dramatique du pronostic. Dans de nombreuses situations, l’AC ne parvient pas à être réanimé avec les soins courants, laissant apparaître un AC « réfractaire » qui nécessite une prise en charge thérapeutique avancée. L’objectif général de ce travail de thèse était d’évaluer de nouvelles approches expérimentales pour la prise en charge de l’AC réfractaire. Nous avons étudié deux stratégies expérimentales chez le porc, consistant à induire une hypothermie ultra-rapide par ventilation liquide ou à mettre en place une assistance circulatoire au cours d’un AC d’origine ischémique.Dans un premier travail, nous avons ainsi évalué la faisabilité d’une hypothermie thérapeutique ultra-rapide par ventilation liquidienne totale (VLT) chez le porc. Cette approche consiste à instiller des perfluorocarbones dans le poumon de façon à induire un refroidissement ultra-rapide. Le poumon est ainsi utilisé comme bio-échangeur thermique, tout en maintenant des échanges gazeux normaux. Dans des travaux préliminaires, le laboratoire a montré que la VLT permettait de réduire la température sanguine jusqu’à 32°C en moins de 10 minutes chez le lapin. Le but de notre étude était de déterminer si la VLT pouvait aussi permettre un refroidissement ultra-rapide chez le porc. L'effet de la VLT a ainsi été évalué dans un premier temps à cœur battant, puis à cœur arrêté sur un modèle d’arrêt cardiaque réfractaire bénéficiant d’une réanimation cardio-pulmonaire prolongée. Dans les conditions physiologiques « à cœur battant », la température de 34°C était atteinte en moins de 10 minutes dans tout l'organisme. Lors de la réanimation prolongée d’un AC réfractaire, le refroidissement corporel était également obtenu rapidement, en moins de 25 minutes, quel que soit le site de mesure de la température. La VLT n’altérait aucunement la qualité du massage cardiaque externe, suggérant un intérêt pour cette approche dans l’induction d‘une hypothermie intra-AC, dans une perspective d’augmentation de l’efficacité des défibrillations ou de préservation d’organe.Dans un deuxième travail, nous nous sommes intéressés à l’AC réfractaire compliquant un syndrome coronaire aigu, traité par assistance circulatoire extracorporelle. Notre but était d’évaluer l'importance de la revascularisation coronaire précoce dans cette situation chez le porc, c’est-à-dire son impact sur le statut hémodynamique et les chances de réanimation. Après anesthésie et instrumentation, les animaux ont ainsi été soumis à une occlusion coronaire, suivie d’un AC par fibrillation ventriculaire non traitée pendant 5 minutes. Ils ont ensuite bénéficié d’une réanimation cardio-pulmonaire de base puis d’une assistance circulatoire extracorporelle. Nous avons comparé les effets d’une revascularisation précoce à ceux d’une revascularisation tardive, c’est-à-dire d’une reperfusion 20 ou 120 min après le début de l'assistance circulatoire. La revascularisation coronaire précoce augmentait significativement les chances de reprise d’activité cardiaque spontanée, limitait l’état de choc, améliorait la perfusion cérébrale et limitait la taille d’infarctus. Cela montre bien l’importance d’une prise en charge rapide du syndrome coronarien en cas d’AC de cause cardiaque présumée, y compris dans une situation d’assistance circulatoire extracorporelle.En conclusion, nous avons montré que la VLT permettait d’induire un refroidissement ultra-rapide dans l’ensemble de l’organisme, tant à cœur battant que pendant une réanimation prolongée. Par ailleurs, la revascularisation précoce d’un AC réfractaire ischémique traité par assistance circulatoire extracorporelle permettait d’améliorer globalement les chances de réanimation et le statut hémodynamique. / Out of hospital cardiac arrest (CA) is a major public health issue, despite the implementation of a “chain of survival”. Resuscitation durations are often extended with irreversible organ damage and poor outcome. Frequently, conventional care does not allow the return of spontaneous circulation, leading to a refractory CA, with the need for advanced therapeutic care. The general objective of this work was to evaluate new therapeutic strategies in the management of refractory cardiac arrest. We studied two experimental strategies in swine, involving ultrafast cooling with total liquid ventilation or extracorporeal cardiopulmonary resuscitation in a CA of ischemic origin.As a first step, we evaluated the feasibility of ultra-fast therapeutic hypothermia using total liquid ventilation (TLV) in swine. This approach involves perfluorocarbon instillation in the lungs to induce ultra-fast cooling. The lungs are thus used as a heat exchanger, while maintaining normal gas exchanges. In previous studies, the laboratory has shown that TLV could reduce blood temperature to 32°C in less than 10 minutes in rabbits. The objective of this study was to determine if TLV could lead to ultra-fast cooling in swine. We first studied the cooling capacity of hypothermic TLV in beating heart pigs, and then during ventricular fibrillation with prolonged chest compressions. In physiological conditions, in “beating heart” animals, the target temperature of 34°C was obtained in less than 10 min in the whole body. In prolonged resuscitation of refractory CA, whole body cooling was also rapidly obtained, within less than 25 min. TLV did not alter the hemodynamic effect of cardiac compressions, suggesting further use of this “intra-resuscitation” cooling in order to increase chances of defibrillation or for organ preservation for the purpose of organ donation.As a second step, we addressed the subject of ischemic refractory CA treated by extracorporeal cardiopulmonary resuscitation (ECPR). Our objective was to evaluate the importance of early coronary reperfusion in this situation, i.e., it’s impact on hemodynamic status and chances of defibrillation. After anesthesia and surgical preparation, animals were submitted to a coronaryocclusion followed by 5 min of CA by ventricular fibrillation. Conventional cardiopulmonary resuscitation was then initiated and followed by extracorporeal cardiopulmonary resuscitation.We compared the effect of early versus late reperfusion, i.e., reperfusion after 20 or 120 min of ECPR. Early reperfusion significantly increased chances of return to spontaneous circulation with limited shock status, increased cerebral perfusion and decreased infarct size. This confirms the need for early treatment of acute coronary syndrome if cardiac cause of CA is suspected, even in the situation of ECPR.In conclusion, we have shown that TLV could provide ultra-fast whole body cooling, both in beating heart swine and during prolonged resuscitation. Secondly, early reperfusion in refractory ischemic CA treated by ECPR globally increases chances of return to spontaneous circulation and improves hemodynamic status.

Purpose: The purpose of this study was to investigate associations between postoperative delirium (POD) and unplanned perioperative hypothermia (UPH) among adults undergoing noncardiac surgery. Design: A retrospective, exploratory design was used. Methods: A retrospective, exploratory study was conducted using electronic medical record data abstracted from a purposive convenience sample of adult patients undergoing noncardiac surgery from January 2014 to June 2017. Findings: The analyzed data set included 22,548 surgeries, of which 9% experienced POD. Logistic regression indicated that American Society of Anesthesiologists (ASA) class was the strongest predictor of POD (χ2 = 1,207.11, df = 4, inclusive of all ASA class terms). A significant relationship between UPH and POD (χ2 = 54.94, df = 4, inclusive of all UPH terms) and a complex relationship among UPH, patient age, ASA class, and POD were also found. Conclusions: Results support a relationship between UPH and POD. Notably, there is also a complex relationship in the noncardiac surgery population among UPH, age, ASA class, and POD. Preliminary understanding of this relationship is based on the pathophysiological response to surgical stress. Further research is indicated.

No description available.

Hypothermia is increasingly being used as a treatment modality for many conditions. Therapeutic hypothermia is any technique in which the body temperature is lowered for reducing oxygen demand and metabolic rate as a means to prevent or minimize organ damage. The purpose of this thesis is to describe current applications of therapeutic hypothermia, including types of cooling techniques, patients who benefit from hypothermia, target temperature, and associated side effects. There are two clinical situations where large randomized studies have demonstrated benefit of therapeutic hypothermia in humans. The first is in treatment of neonates with asphyxia, and the second is for treating survivors of out-of-hospital cardiac arrest. Most cooling research focuses on treatment with mild to moderate hypothermia, 32°C - 34°C. Noninvasive cooling methods include the traditional ice packs, fans, alcohol baths, and cooling blankets not attached to any monitoring device. Invasive cooling techniques consist of the infusion of ice-cold fluids, ice slurries, endovascular, and nasopharyngeal cooling. Patients treated with therapeutic hypothermia require close monitoring due to the increased risk of infections, skin break down, vital sign changes such as bradycardia, and electrolyte balances such as hypokalemia. Optimal depth and duration of hypothermia and optimal rate of re-warming are unknown. Further nursing research is needed for induced hypothermia guidelines as well as education.

Investigations have shown that the hypothalamus and pituitary respond to decreases in body temperature by stimulating the thyroid gland to release T3 and T4 hormones. This study was designed to investigate ultrastructural changes of the thyroid gland induced by hypothermia. The ultrastructural changes produces by stimulation by Thyroid Stimulating Hormone were also examined as an adjunct to the hypothermic stimulation of the gland. There was a significant increase in microvilli on the luminal border of follicle cells along with a remarkable increase in numbers of dense granules. The dense granules also demonstrated a polarity being found near the border of the colloid lumen. The glandular changes induced by Thyroid Stimulating Hormone were very similar to those of hypothermia.

The effects of hypothermia on cultured mammalian (mouse) spinal cord neurons which had been subjected to a defined physical trauma (amputation of a primary dendrite 100μM from the perikaryon) were investigated.

Long-term, repeated exposures to cold might lead to cold adaptation. The study examined, in a small homogeneous group of non-acclimatised men, the inter-individual response to a short-term, high-intensity cold acclimation regimen. In particular, six young (24 - 28 years), healthy men performed 5 daily, whole-body (immersed to the chest for up to 120-min) immersions in 14°C water, during which their thermo-effector responses were evaluated. The study also sought to determine whether, or to what extent, any thermoregulatory modifications induced by the repeated severe cold stress would be transferred to acute moderate cold stress immersions (i.e., “transfer” adaptation). Thus, a few days before and after the acclimation protocol, subjects’ thermoregulatory function was assessed during whole-body immersions in 21°C water. During all immersions, thermal (rectal and skin temperatures), cardiorespiratory (oxygen uptake, mean arterial pressure, heart rate) and perceptual (thermal sensation and comfort, pain, affective valence) responses were monitored. The 5-day cold acclimation regimen caused a hypothermic adaptation, which was characterised by: i) a reduction in the cold-induced elevation of endogenous heat production (i.e., oxygen uptake), which was mainly ascribed to a delay in the activation of shivering, ii) an attenuation in the cold-induced increase of arterial pressure and heart rate, and iii) the alleviation of thermal discomfort. Aside from the blunted pressor response, these thermo-adaptive modifications seemed to be transferrable during exposure to a moderate cold stimulus as well. Still, during both cold provocations, the thermoregulatory adjustments were described by a large inter-individual variability, regarding the direction and the magnitude of the response.