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Hypothermia is commonly found in injured victims who suffer from central nervous system injury, hypovolemic shock, exposure to environment, administration of anesthetic drugs and cold intravenous fluid. All these factors decrease the abilities of trauma victims to maintain normothermia and conserve body heat. Hypothermia in injured victim is a significant contributor to a well known cycle—triad of death and associated with increased mortality, morbidity and length of hospital stay. Hypothermia is one of the preventable complications in trauma patients. Therefore nurse plays a vital role to evaluate the methods of preventing hypothermia. However, there is no systematic review of effectiveness of different warming methods in local setting. The purpose of this dissertation is to develop an evidence-based guideline to prevent hypothermia in trauma patients by reviewing existing evidence, to assess the feasibility and transferability of implementing the guideline and to develop its implementation and evaluation plan. Five articles meeting the inclusion and exclusion criteria are identified after a systematic research of six electronic databases. Among these articles, four of them are randomized controlled trials while the remaining one is quasi-experimental design with prospective randomized assignment. The quality of these identified articles is evaluated with the methodology checklist for randomized controlled trials which is developed by Scottish Intercollegiate Guideline Network (SIGN). All studies of medium and high quality would be considered as sufficient evidence to support the proposed innovation in preventing hypothermia for trauma patients in Accident & Emergency Department. After assessing the implementation potential, an evidence-based guideline in preventing hypothermia for adult trauma patients is established. The proposed innovation is necessary and beneficial for adult trauma patients to prevent hypothermia. The grade of recommendation in the guideline is rated based on the SIGN grading system from A to D. Communication plans with stakeholders and 3-month pilot study on 20 patients are conducted before implementing the innovation into clinical setting. Evaluation is made to assess the effectiveness of the proposed guideline after the end of pilot study and the end of implementation of guideline. The effectiveness of the proposed innovation is determined by change of core temperature as + 1.1 °C/hr and at least 90% reduction in shivering and thermal discomfort which are reported in the reviewed articles. The guideline is considered as clinical effective when similar outcome is obtained. / published_or_final_version / Nursing Studies / Master / Master of Nursing

In the homeotherm, core body temperature (T(bc)) is considered one of the vital signs by which physiologic normality can be assessed. In persons who are unable to self-regulate T(bc), hypothermia (HT) can result. Recognition of HT as a potential physiologic problem especially in the adult postsurgical patient who is recovering from anesthesia has been acknowledged. Recovery room (RR) nurses daily manage the shivering patient who not only experiences increased oxygen demand, but who may also exhibit airway obstruction and increased somnolence as a result of HT. Thus, a primary nursing activity in the RR is to assist the patient in recovery from anesthesia and to facilitate his return toward normothermia. No study has delineated the frequency, temperature range, or duration of HT in adult RR postsurgical patients. Additionally, no data exist to support the effectiveness of current nursing heat treatments directed against mild to moderate degrees of HT. The present study addresses both of these issues. Hypothermia is defined as T(bc) of less than 36.0 degrees centigrade (°C). One hundred ninety-eight patients were randomly assigned to one of four treatment groups. Three groups received a form of external heat while the final group did not. Heat was applied with radiant heat lamps, thermal with bath blanket (warmed), and bath blankets (warmed) with change. The control group had one bath blanket at room temperature. The purposive, nonrandom sample consisted of consenting adults scheduled for various operative procedures. Previous approval for the protocol had been received from the Human Subjects Committee. In all patients requiring RR care, identifying and descriptive characteristics were recorded. Disposable tympanic membrane probes were used to assess T(bc) with measurements taken on RR admission and every 15 minutes thereafter until discharge. Descriptive statistical analyses demonstrated that 60 percent of the subjects (n = 118) were hypothermic on RR admission. Mean RR admission T(bc) and discharge T(bc) (mean ± standard error [range]) were 35.6°C ± 0.06 [32.5-37.5°C] and 36.3 ± 0.05 [33.5-38.0°C] respectively. Duration of HT averaged 47 ± 4 minutes. Eighteen percent of all subjects were discharged from the RR with T(bc) of less than 36.0°C. Among heat transfer treatment groups, one-way analysis of variance or group t-tests demonstrated no significant difference in the rate of T(bc) rise in the first hour of RR stay, T(bc) change every 15 minutes, change in T(bc) divided by RR time, or discharge T(bc). Statistical significance was set at p < .05). Aged subjects (≥ 60 years) compared to nonaged subjects (< 60 years) demonstrated significantly lower T(bc)'s on admission and throughout the mean RR stay (admission to +90 minutes; p < .05). Rate of T(bc) rise for aged subjects was not significantly different from nonaged subjects. In conclusion, RR nurses should be alert for HT in a significant number of adult postsurgical patients. Accurate monitoring of T(bc) is necessary particularly early during the RR stay. Application of the heat transfer treatments does not significantly affect T(bc). However, anesthetic type and age can significantly affect T(bc) and therefore prescribe alterations in nursing activities.

Hyperglycaemia is prevalent in critical care and increases the risks of further complications and mortality. Glycaemic control has shown benefits in reducing mortality. However, due in parts to excessive metabolic variability, many studies have found it difficult to reproduce these results. Out-of-Hospital Cardiac Arrest (OHCA) patients have low survival rates and often experience hyperglycaemia. However, these patients belongs to one group who has shown benefit from accurate glycaemic control (AGC), but can be highly insulin resistant and variable, particularly on the first two days of stay. Hypothermia is often used to treat post-cardiac arrest patients or out of hospital cardiac arrest (OHCA) and these same patients often simultaneously receive insulin. In general, it leads to a lowering of metabolic rate that induces changes in energy metabolism. However, its impact on metabolism and insulin resistance in critical illness is unknown, although one of the adverse events associated with hypothermic therapy is a decrease in insulin sensitivity and insulin secretion. However, this decrease may not be notable in the cohort that is already highly resistant and variable. Hence, understanding metabolic evolution and variability would enable safer and more accurate glycaemic control using insulin in this cohort. OHCA patients were undergone preliminary analysis during cool and warm, which includes insulin sensitivity (SI), blood glucose (BG), and exogenous insulin and dextrose. Patients were analysed based on overall cohort, sub-cohorts, and 6 and 12 hour time block. Generally, the results show that OHCA patients had very low metabolic activity during cool period but significantly increased over time. In contrast, BG is higher during cool period and decreased over time. The analysis is equally important as the controller development since it provides scientific evidence and understanding of patients’ physiology and metabolic evolution especially during cool and warm. Model-based methods can deliver control that is patient-specific and adaptive to handle highly dynamic patients. A physiological ICING-2 model of the glucose-insulin regulatory system is presented in this thesis. This model has three compartments for glucose utilisation, effective interstitial insulin and its transport, and insulin kinetics in blood plasma, with emphasis on clinical applicability. The predictive control for the model is driven by the patient-specific and time-varying insulin sensitivity parameter. A novel integral-based parameter identification enables fast and accurate real-time model adaptation to individual patients and patient condition. Stochastic models and time-series methods for forecasting future insulin sensitivity are presented in this thesis. These methods can deliver probability intervals to support clinical control interventions. The risk of adverse glycaemic outcomes given observed variability from cohort-specific and patient-specific forecasting methods can be quantified to inform clinical staff. Hypoglycaemia can thus be further avoided with the probability interval guided intervention assessments. Simulation studies of STAR-OHCA control trials on ‘virtual patients’ derived from retrospective clinical data provided a framework to optimise control protocol design in-silico. Comparisons with retrospective control showed substantial improvements in glycaemia within the target 4 - 7 mmol/L range by optimising the infusions of insulin. The simulation environment allowed experimentation with controller parameters to arrive at a protocol that operates within the constraints found earlier during patient analysis. Overall, the research presented takes model-based OHCA glycaemic control from concept to proof-of-concept virtual trials. The thesis employs the full range of models, tools and methods to optimise the protocol design and problem solution.

Zugl.: Habil'schr. Bern.

Thesis (Ph. D.)--University of Wisconsin, 1967. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.

Core temperature (Tc) regulation is fundamental to mammalian survival, since hypothermia (Tc ≤ 35°C) and hyperthermia (Tc ≥ 40°C) are major risk factors for health and wellbeing. The purpose of this thesis was to determine if acetaminophen, an analgesic and antipyretic drug, increased the onset of hypothermia or hyperthermia during passive cold and heat stress, respectively. It was later investigated if acetaminophen induced inhibition of cyclooxygenase mediated these side-effects. In Study 1a, the plasma acetaminophen response to a dose of 20 mg·kg-1 of lean body mass was determined through enzyme linked immunosorbent assay. In Study 1b, the effect of acetaminophen administration on internal temperature (rectal; Tre) during a passive 2-hour mild cold (20°C, 40% relative humidity) exposure was examined. Study 1a showed that the plasma response was homogenous between subjects, reaching peak concentrations between 80-100 minutes (14 ± 4 μg·ml-1). In Study 1b, acetaminophen reduced Tre in all participants compared with baseline, and the average peak reduction was 0.19 ± 0.09°C. In contrast, Tre remained stable when participants ingested a sugar placebo. Study 1 is the first experiment which confirms a hypothermic side-effect of acetaminophen in healthy humans. Study 2 investigated whether acetaminophen augmented the rate of Tre rise during exposure to passive dry (45°C, 30% r.h.) and humid (45°C, 70% r.h.) heat stress for 2-hours and 45-minutes, respectively. This study showed that the rate of Tre rise in the dry (0.005 vs 0.006°C∙min-1) and humid (0.023 vs 0.021 °C∙min-1) conditions were similar between the acetaminophen and placebo trials (p > 0.05). Study 2 is the first experiment which confirms acetaminophen has no meaningful effect on thermoregulation during passive dry or humid heat exposure. Study 3 determined how the hypothermic effect of acetaminophen changes during exposure to a thermoneutral (25°C, 40% r.h.) and cold (10°C, 40% r.h.) environment for 2-hours. In summary, there was no hypothermic effect of acetaminophen in a thermoneutral environment (p > 0.05), whereas Tre fell by 0.40 ± 0.15°C compared with baseline during cold stress (p < 0.05). Compared with the placebo, Tre was ~0.35°C lower at 120 minutes, but was significantly lower from 70-minutes. Study 3 confirmed that there is a relationship between the level of cold stress and magnitude of the hypothermic effect of acetaminophen. Study 4 determined whether ibuprofen (400 mg), a cyclooxygenase inhibitor, reduced Tre during 2-hour passive cold stress (10°C, 40% r.h.) to a level comparable with acetaminophen. Ibuprofen administration did not influence Tre, vastus medialis shivering, or energy expenditure compared with a placebo throughout the cold exposure (p > 0.05). Taken together, this renders it unlikely that cyclooxygenase activity is required for thermogenesis induced by skin cooling. Study 4 provides evidence that acetaminophen induced hypothermia is not exclusively mediated by cyclooxygenase inhibition. In Summary, this series of experiments has shown that acetaminophen has a hypothermic side effect in healthy humans, which is amplified during acute cold stress. Ibuprofen had no such effect on thermoregulation during cold exposure, so it is unlikely that cyclooxygenase inhibition mediates the hypothermic side-effect of acetaminophen.

Made available in DSpace on 2014-06-11T19:35:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-16Bitstream added on 2014-06-13T19:24:22Z : No. of bitstreams: 1 fernandes_la_dr_botfm.pdf: 1359001 bytes, checksum: a5448cd95987f70f2201ed53f0d8f36a (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / O obeso tem menor incidência de hipotermia intraoperatória em relação ao não obeso por apresentar limiar de vasoconstrição termorregulatória mais elevado. A combinação de métodos de aquecimento no intraoperatório parece ser melhor do que o uso isolado na prevenção de hipotermia. O objetivo da pesquisa foi avaliar se a combinação de permutador de calor e umidade (PCU) no circuito inspiratório com ar forçado aquecido ou aquecimento das soluções parenterais previne a ocorrência de hipotermia no período intraoperatório em obesas (OB) e não obesas (NOB) submetidas à anestesia venosa total. Quarenta pacientes submetidas à cirurgia abdominal ginecológica foram anestesiadas com propofol e remifentanil em infusão alvocontrolada. Todas as pacientes tinham um PCU acoplado no circuito inspiratório. As pacientes foram distribuídas aleatoriamente em 4 grupos de acordo com o índice de massa corporal (IMC) e com o manejo termal. Em 10 obesas (IMC de 30 a 34,9 kg.m-2) e 10 não obesas (IMC de 18,5 a 24,9 kg.m-2), utilizou-se ar forçado aquecido nos membros inferiores (WB). Dez obesas e 10 não obesas receberam aquecimento das soluções infundidas (HF). A temperatura central foi registrada nos momentos controle (0) e 15, 30, 60 90 e 120 minutos após instalação do circuito respiratório, e no final da cirurgia. Na Sala de Recuperação Pós-Anestésica (SRPA), a temperatura central das pacientes foi registrada durante o período de 1 hora. O IMC e a temperatura central foram correlacionados nos grupos que receberam o mesmo tratamento termal da hipotermia. O grupo OB/WB apresentou temperatura central intraoperatória mais alta em relação aos outros grupos (p<0,001). A proporção de pacientes normotérmicos no final da cirurgia e na admissão da SRPA foi mais alta em OB/WB do que nos outros grupos (p<0,05). Houve correlação positiva entre o IMC e a temperatura central no... / Obese individuals show less intraoperative (IOP) hypothermia than non-obese ones due to higher vasoconstriction threshold. A combination of warming methods may be better than an isolated one in preventing IOP hypothermia. Our aim was to evaluate whether the combination of a heat and moisture exchanger (HME) on inhaled gas with IOP forced air warming blanket (WB) or warming intravenous (IV) fluids (HF) prevents IOP hypothermia in obese (OB) and non-obese (NOB) women under intravenous anesthesia. Forty patients scheduled for gynecological abdominal surgery were anesthetized with propofol and remifentanil in a target controlled infusion. All patients had a HME on the inhaled gas. Patients were randomly distributed into 4 groups according to body mass index (BMI) and IOP thermal management. Ten OB grade I (BMI between 30 and 34.9 kg.m-2) and 10 NOB (BMI between 18.5 and 24.9 kg.m-2) had WB on the lower limbs. Ten OB and 10 NOB patients received IV HF. Core temperatures were recorded at baseline, after 15, 30, 60, 90, and 120 minutes of ventilatory system installation, and at the end of surgery. Core temperature was also followed for 60 minutes in the Post Anesthetic Care Unit (PACU). Core temperature and BMI were correlated in the groups with the same hypothermia treatment method. OB/WB group presented a higher IOP core temperature higher than the other groups (P<0.001). The proportion of normothermic patients at end of surgery and in PACU admission was higher in OB/WB than the other groups (P<0.05). There was a positive correlation between BMI and core temperature in the skin-surface warming groups (P<0.001). The combination of IOP skin-surface warming with HME on the inhaled gas in female obese patients, but not in non-obese ones, minimizes hypothermia. The combination of warming IV fluids and HME does not avoid IOP hypothermia in female obese or non-obese patients

Hypothermia is potently neuroprotective, but the molecular basis of this effect remains obscure and the practical challenges of cooling have restricted its clinical use. This thesis was borne on the premise that considerable therapeutic potential may lie in a deeper understanding of the neuronal physiology of cooling. Rodent studies indicate that hypothermia can elicit preconditioning wherein a subtoxic stress confers resistance to an otherwise lethal injury. This cooling-induced tolerance requires de novo protein synthesis – a fundamental arm of the cold-shock response, for which data in human neurons is lacking. Since cooling protects the human neonatal brain, experiments herein address the molecular effects of clinicallyrelevant cooling using functional, maturationally-comparable cortical neurons differentiated from human pluripotent stem cells (hCNs). Several core hypothermic phenomena are explored, with particular scrutiny of neuronal tau, since this protein is modified extensively in brains that are resistant to injury. Mild-to-moderate hypothermia produces an archetypal cold-shock response in hCNs and protects them from oxidative and excitotoxic stress. Principal features of human cortical tau development are recapitulated during hCN differentiation, and subsequently reversed by cooling, returning tau transcriptionally and post-translationally to an earlier foetallike state. These findings provide the first evidence of cold-stress-mediated ontogenic reversal in human neurons. Furthermore, neuroprotective hypothermia induces mild endoplasmic reticulum (ER) stress in hCNs, with subsequent activation of the unfolded protein response (UPR). Reciprocal modulation of both tau phosphorylation and the ER-UPR cascade suggests that cold-induced hyperphosphorylation of tau and ER-hormesis (preconditioning) represent significant components of hypothermic neuroprotection. Cooling thus modifies proteostatic pathways in a manner that supports neuronal viability. Historically, hypothermic preconditioning has been limited to the acute injury setting, and tau hyperphosphorylation is an established hallmark of chronic neural demise. More recently however, preconditioning has been proposed as a target for neurodegenerative disease and neuroprotective roles of phospho-tau have emerged. To date, hypothermia has protected hCNs against oxidative, excitotoxic and ER stress, all of which have been implicated in traumatic as well as degenerative processes. This ‘cross-tolerance’ effect places exponential value on the molecular neurobiology of cooling, with the potential to extract multiple therapeutic targets for an unmet need.