When a patient is exposed surgical stress, the endocrine system secretes hormones in response to that stress. These hormones further activate the immune system to release cytokines and other acute phase reactions. These processes are supposed to protect the body by upregulating the innate immune system and producing an inflammatory response that acts to protect and heal. However, uncontrolled surgical stress may cause a weaker immune response that may lead to delayed wound healing. The phenomenon of unplanned perioperative hypothermia is known to expose patients to additional surgical stress. The purpose of this preliminary experimental study was to determine the effect of a preoperative warming intervention on the acute phase response of surgical stress in surgical patients. Specifically, the aim of this study was to evaluate the effect of a prewarming intervention using a forced-air warming (FAW) device versus routine care (RC) using warmed cotton blankets on the development of unplanned hypothermia, cytokine production, and endocrine responses. It was hypothesized that 1) the FAW participants would experience less unplanned perioperative hypothermia than the RC participants; 2) the FAW participants would experience lower catecholamine and cortisol levels than the RC participants; and 3) the FAW participants would experience higher proinflammatory cytokine and CRP production intra- and postoperatively than the RC participants. Infrared tympanic temperatures and 4 blood samples were taken at 4 time intervals from each of the 28 (n = 14 each group) randomized participants that underwent routine general anesthesia surgery. Serum concentrations of CRP, cortisol and IL-1beta, IL- 6, TNF-alpha, and IFN-gamma, and plasma concentrations of epinephrine and norepinephrine were measured. To test the hypotheses across time and between groups, a repeated measures ANOVA design was used. Though FAW was not associated with a differential endocrine or inflammatory response in this small, preliminary study, further study of forced air warming as a preoperative nursing intervention is warranted. The finding of higher than expected IL-6 levels in the preoperative period suggests a potential role for anxiety, an important factor in psychoneuroimmunological pathways, that could affect recovery and healing. The relationship between surgical stress, anxiety, and preoperative IL-6 deserves further study.

Die Überlebensrate von Reanimations-Patienten ist seit Jahrzehnten gleichbleibend gering. Die milde therapeutische Hypothermie (MTH) hat als bisher einzige Therapieoption gezeigt, dass das Gesamtüberleben und neurologische Outcome nach Wiedererlangen eines Kreislaufs signifikant verbessert wurde. Eine mögliche Kühlungsmethode ist die Hochvolumengabe 2-4°C kalter Infusionen zur Induktion und Aufrechterhaltung einer Körperkerntemperatur (KKT) von <34°C über 12-24 Stunden. Da nach kardiopulmonaler Reanimation häufig eine myokardiale Dysfunktion sowie eine systemische Entzündungsreaktion (SIRS) mit einhergehender Kreislaufinstabilität im Rahmen des Postreanimationssyndroms (PCAS) auftreten, könnten Bedenken bezüglich der Induktion eines Lungenödems bestehen. In dieser Arbeit wurde daher der Einfluss von kalten Infusionen auf die respiratorische Funktion untersucht. Ebenfalls wurde evaluiert, inwiefern sich die milde therapeutische Hypothermie auf die Katecholamin-Dosierung zur Kreislaufstabilisierung sowie auf Herz-Kreislauf-Parameter auswirkt. Dazu wurden retrospektiv die Daten von 166 Patienten bezüglich respiratorischer Parameter und von 159 Patienten bezüglich kardialer Parameter während des Kühlungszeitraums statistisch analysiert. Respiratorische Daten: Die Ejektionsfraktion (EF) betrug bei Aufnahme 34,8%. Dies entspricht einer mittelgradig eingeschränkten linksventrikulären (LV)-Funktion. Bei Ankunft auf der Intensivstation betrug der Horovitz-Quotient (PaO2/FiO2) als Maß für die Oxygenierungsfunktion der Lunge 210 mmHg bei einem PEEP von 7 mbar. Dies entspricht einem milden bis moderaten akuten Atemnotsyndrom (ARDS). Bis zu einer Zieltemperatur von ≤34°C (4,5 h) wurden 3.279 ml kaltes Volumen infundiert. Der Horovitz-Quotient verblieb dennoch unverändert bei 210 mmHg, der PEEP bei 7 mbar. Es zeigte sich ein schwacher, aber signifikanter, negativer linearer Zusammenhang zwischen Horovitz-Quotient und der Menge an infundiertem kaltem Volumen bei einer infundierten Flüssigkeitsmenge zwischen 0-11.000 ml. Diese Ergebnisse zeigen, dass die Oxygenierungsfunktion der Lunge durch die Volumengabe nicht beeinträchtigt wird. Dennoch sollten aufgrund des schwachen linearen Zusammenhangs von Infusionsmenge und Horovitz-Quotient die respiratorischen Parameter während der Gabe großer Mengen an kaltem Volumen engmaschig überwacht werden. Herz-Kreislauf-Daten: Initial bestand eine mittelgradig eingeschränkte LV-Funktion (EF 34,7%), die sich im Verlauf auf 41,5% verbesserte. Unter MTH konnte die Infusionsrate von Adrenalin signifikant reduziert werden, die Noradrenalin-Dosierung wurde hingegen signifikant erhöht. Die Herzfrequenz sank im gleichen Zeitraum signifikant. Diese Ergebnisse bestätigen vorherige Studien, die zeigen, dass die MTH eine positiv inotrope Wirkung besitzt und die HF senkt. Der zusätzliche Bedarf an Vasokonstriktoren ist wahrscheinlich auf eine im Rahmen des PCAS auftretende Vasodilatation zurückzuführen.

Recent evidence suggests that avian facultative hypothermic responses are more common than previously thought. Traditionally, several categories of avian hypothermic responses have been recognized, and are frequently differentiated on the basis of minimum body temperature (T[b]) The available data suggest that the capacity for shallow hypothermia (rest-phase hypothermia) occurs throughout the avian phylogeny, but that the capacity for pronounced hypothermia (torpor) is restricted to certain taxa. However, there are currently too few data to test hypotheses concerning the evolution of avian hypothermic responses. Facultative hypothermia occurs over most of the avian body mass (M[b]) range, but is most common in small species. Minimum body temperature during hypothermia (T[min]) is continuously distributed from 4.3 °C to ca. 38°C. The continuous T[min] distribution, as well as recent evidence that the T[b] ranges of different avian physiological states may overlap, question the biological reality of specific T[b] limits. Pattens of thermoregulation during avian hypothermic responses are relatively variable, and do not necessarily follow the entry-maintenance-arousal patterns that characterize mammalian responses. Avian hypothermic responses are determined by a suite of ecological and physiological determinants. I investigated normothermic thermoregulation and hypothermic responses to restricted food in the speckled mousebird Colius striatus in the context of the distinction between normothermia, rest-phase hypothermia, and torpor. The lowest T[b] recorded in a bird which was able to arouse spontaneously was 18.2°C. However, I was unable to clearly discern between normothermic, hypothermic and torpor T[b] ranges. Furthermore, hypothermic responses did not accord with the patterns typically observed in birds and mammals. Metabolic suppression normally associated with entry into torpor and the defence of a torpor T[b] setpoint was largely absent. Laboratory data for C. striatus, as well as published data for Colius colius suggest that clustering behavior plays an important thermoregulatory role in mousebirds. Hence, I investigated thermoregulation under semi-natural conditions in C. striatus. In particular, I was interested in the interaction between clustering behavior and hypothermic responses during energy stress (restricted feeding). In contrast to clustering birds, rest-phase thermoregulation in single birds was characterised by linear decreases in T[b] and the birds did not appear to defend a specific T[b] setpoint. During restricted feeding, both clustering and single birds exhibited significant decreases in rest-phase T[b]. The extent of these facultative hypothermic responses was greater in single birds than in clustering birds, supporting the prediction that clustering behavior moderates the use of facultative hypothermia. I also tested the prediction that in free-ranging C. colius, the use of heterothermy should be rare, even at the coldest time of the year. I recorded mid-winter rest-phase body temperatures (T[b]) in a flock of free-ranging C. colius in an arid habitat in the Karoo, South Africa. The mousebirds' rest-phase T[b] was fairly labile, but was maintained above 33°C, despite T[a]s as low as -3.4 °C. The mousebirds showed no evidence of torpor under natural conditions; a facultative hypothermic response, during which T[b] was reduced to 29 - 33°C, was only observed on one occasion. The observed patterns of thermoregulation supported my predictions, and suggest that thermoregulation in clustering C. colius in the wild is significantly different to that of single birds under laboratory conditions. My results also suggest that the pronounced capacity for heterothermy usually associated with mousebirds is not necessarily representative of their patterns of thermoregulation under natural conditions. The capacity for avian torpor appears to be dependent on phylogeny. To investigate phylogenetic constraints on the capacity for torpor, I measured metabolic responses to food deprivation in a small, arid-zone passerine, the red-headed finch (Amadina erythrocephala). I observed significant reductions in rest-phase energy expenditure and body temperature (T[b]) in response to restricted feeding. The maximum extent of T[b] suppression (ca. 5°C) and energy savings (ca. 10%) were consistent with those reported for a number of other passerines. The lowest T[b] I observed in a bird able to arouse spontaneously was 34.8°C. My data support the hypothesis that the capacity for heterothermy in passerines is phylogenetically constrained, and that the majority cannot employ torpor in response to energetic stress. Selection for the capacity for torpor is presumably similar to the selection pressures acting on other avian energetic traits, such as basal metabolic rate (BMR). I tested the generality of a recent model linking the slow-fast mammalian metabolic continuum to global patterns of climatic predictability using BMR data for 219 non-migratory bird species. Avian BMR varied significantly between zoogeographical zones, with Afrotropical, Indomalayan and Australasian species generally exhibiting lower BMR than Holarctic species. In addition, the magnitude of differences between arid and mesic species varied between zones. In the Nearctic, these differences were pronounced, whereas no significant differences were evident for Afrotropical or Australasian species. A slow-fast metabolic continuum similar to that described in mammals appears to exist for birds, with higher BMR associated with predictable, seasonal environments and lower BMR with less predictable environments, in particular those affected by the El Niño Southern Oscillation. I constructed a generalised, conceptual model which attempts to predict the occurrence of torpor using phylogeny, M[b] constraints, a trade-off between energetic benefits and potential ecological costs, and specific ecological factors. A recent hypothesis suggests that endotherm heterothermy is monophyletic, and predicts that torpor should be more widespread in phylogenetically older taxa. Once phylogeny is considered, the most important determinant of avian torpor is M[b]. I used an existing model of endotherm torpor to predict the relationship between M[b] and minimum T[b] during torpor. The available data show that the lower limit of torpor T[b] is determined by the M[b]-dependent costs of rewarming following a torpor bout. Finally, I constructed a model based on the assumption that torpor is adaptive if the energetic benefits exceed the potential ecological costs. The model predicted that torpor should be more prevalent in species near the extremes of the avian metabolic continuum. The available data provide tentative support for this prediction. In addition to generalised factors such as phylogeny and M[b], specific aspects of a particular species' ecology need to be considered when predicting the occurrence of avian torpor. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2001.

Hypotermi, en sänkning av kroppens kärntemperatur under 36°C, är en oönskad men vanlig komplikation under den perioperativa perioden. Det är förenat med en rad negativa konsekvenser som kan orsaka lidande för patienter och innebära ökade vårdkostnader. Svårigheterna med att på ett enkelt och effektivt sätt förhindra hypotermi utgör ett hinder i vården och nya produkter utvecklas därför kontinuerligt. En viktig del i anestesisjuksköterskans arbete är att bevara patientens kroppstemperatur så nära det normala som möjligt. Syftet med föreliggande litteraturstudie var att beskriva olika metoder som är lämpliga för anestesisjuksköterskan att använda för att förhindra hypotermi hos vuxna i det perioperativa förloppet. I de 18 resultatartiklarna testades olika metoder för att bibehålla normal kroppstemperatur: täcka patienten, höjd salstemperatur, värmning med varmluft, elektrisk värmning, värmning av infusionsvätskor, värmning med cirkulerande varmvatten och strålningsvärme. Flera metoder visades effektiva men resultaten var inte entydiga. Inget system visades värma bättre än varmluft. Ytterligare forskning krävs för att fastställa nytta och säkerhet för de övriga aktiva värmesystemen men vissa kan komma att utgöra ett komplement till nuvarande strategier. / Hypothermia, a reduction of the body core temperature below 36°C, is an undesirable but common complication in the perioperative period. It is associated to a series adverse events that can cause discomfort to patients and result in increased health care costs. The difficulties involve a simple and effective way to prevent hypothermia and is an obstacle in the care and new products will develop over time. An important part of nurse anesthetists work is to maintain the patient´s body temperature as close to normal as possible. The aim of the literature study was to describe different methods that is appropriate for the nurse anesthetist to use to prevent hypothermia in adults in the perioperative process. In the results of the 18 articles different forms of methods were tested in order to maintain normal body temperature: cover the patient, raised room temperature, forced air warming, electric heating, fluid warming, warming with circulating hot water and radiant warming. Several methods were shown to be effective but the results were not conclusive. No system was demonstrated to be better than forced air warming. Further research is required to confirm the benefit and safety of the other active warming systems, but some may be in addition to current strategies.

Graduate

Abstract Aim of the study: Aim of the study was to investigate whether there were any connections in time between different parts of care in patients with cardiac arrest and hypothermia treatment and cognitive and physical function six months after cardiac arrest and to investigate neurological outcome related to primary registered cardiac arrest rhythm after six months and if there were any changes in cognitive and physical functions as well as self-related health between discharge from hospital and six months after cardiac arrest. Method: The study included 39 patients admitted to three Swedish hospitals between 2008-2011. Cognitive and physical function was evaluated with Cerebral Performance Cathegory, CPC completed with Mini Mental State Examination, MMSE for cognitive function and Bartels Index, BI for physical function and Euroqol-VAS for evaluating the self-related health. Result:  A significant connection was shown between time to start hypothermia treatment and BI, patients with longer time showed improved physical function after six months. Majority of the participants (66,7 %) had Ventricular fibrillation/Ventricular tachycardia, VF /VT, as primary registered cardiac arrest rhythm and in this group CPC and BI was significant better compared with the asystole /Pulsless Electrical Aktivity, PEA group. CPC, MMSE, BI and Euroqol-VAS were all improved over time. Conclusion: Participants with VF /VT as primary registered cardias arrest rhythm had significant better cognitive and physical function 6 months after hypothermia-treated cardiac arrest compared with participants with asystole/PEA as primary registered rhythm. This shows the importance of access to defibrillators in public places in the society and in hospitals and optimal education of lay people and medical staff. Cognitive and physical function and self-rated health improves over time, which might be a very important reason to convey patients, relatives and medical staff to continue cognitive and physical rehabilitation.   Keywords: Cardiac arrest, hypothermia, cognitive and physical function, wellbeeing

Dissertation (Ph.D.)--University of South Florida, 2007. / Title from PDF of title page. Document formatted into pages; contains 107 pages. Includes vita. Includes bibliographical references.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2005. / Härtill 4 uppsatser.

Thesis--University of Oklahoma. / Includes bibliographical references (leaves 65-69).

Introdução: A hipotermia tópica (HT) e o pré-condicionamento isquêmico (PCI) são métodos utilizados para diminuir a lesão de isquemia/reperfusão (I/R). A eficácia do uso concomitante da HT e PCI (HT+PCI) no fígado em relação à inflamação e à citoproteção antioxidante não está elucidada. Objetivo: Avaliar o processo inflamatório e os mecanismos de segunda linha de defesa antioxidante na lesão de I/R hepática em ratos em relação à utilização das técnicas de HT e PCI de forma isolada ou associada. Métodos: Ratos Wistar (n=32) foram submetidos à isquemia hepática parcial (70%) durante 90 minutos seguida por 120 minutos de reperfusão. Os animais foram alocados nos grupos sham (n=4), isquemia normotérmica (IN, n=7), PCI (n=7), HT (n=7) e HT+PCI (n=7). O PCI consistiu na aplicação consecutiva de 10 minutos de isquemia e reperfusão antes do insulto isquêmico. A HT foi induzida pela superfusão de solução salina a 26°C sobre os lobos isquêmicos. A eutanásia foi realizada ao término do experimento e as amostras foram coletadas para a realização das análises moleculares utilizando as técnicas de ELISA e Western Blot, com o objetivo de comparar os perfis pró-inflamatório, anti-inflamatório e antioxidante. Resultados: O grupo HT comparado ao grupo IN apresentou diminuição da concentração do fator de necrose tumoral (TNF)-α, interleucina (IL)-1β, IL-6 e IL-12 e um aumento dos níveis de IL-10. O grupo HT apresentou menor expressão da óxido nítrico sintase induzível (iNOS) e um aumento da expressão da óxido nítrico sintase endotelial (eNOS). A expressão da NAD(P)H quinone oxidoreductase-1 (NQO1) foi menor no grupo HT. O PCI não demonstrou diferença significativa em relação a esses marcadores quando comparado ao grupo IN. O grupo HT+PCI apresentou menor concentração de IL-12 e menor expressão da iNOS e NQO1, mas em relação a estas moléculas a utilização de HT isolada demonstrou um comportamento semelhante. O grupo HT+PCI apresentou maior expressão da Kelch-like ECH-associated protein (Keap)-1 e menor expressão do nuclear erythroid 2-related factor 2 (Nrf2) nuclear e citoplasmático em relação ao grupo IN. Conclusão: O método de HT foi eficaz na proteção contra a lesão inicial de I/R. O uso de PCI isolado desencadeou a ativação da segunda linha de defesa antioxidante. A aplicação combinada de HT+PCI não confere benefício adicional em relação ao processo inflamatório quando comparado ao grupo HT, mas apresenta a vantagem de evitar a ativação da segunda linha de defesa antioxidante. / Background: Topical hypothermia (TH) and ischemic preconditioning (IPC) are used to decrease ischemia/reperfusion (I/R) injury. The effectiveness of using concomitantly TH and IPC (TH+IPC) in liver, regarding inflammation and antioxidant cytoprotection, is lacking. Aim: To evaluate the process inflammatory and second-line antioxidant defense mechanisms in hepatic I/R injury in rats in relation to the use of techniques TH and IPC isolate or associated. Methods: Wistar rats (n=32) subjected to partial (70%) hepatic ischemia during 90 minutes followed by 120 minutes of reperfusion. Livers from the animals allocated in sham (n=4), normothermic ischemia (NI, n=7), IPC (n=7), TH (n=7) and TH+IPC (n=7) groups. IPC consisted of consecutive 10-minute periods of ischemia and reperfusion before the ischemic insult. TH was induced by the superfusion of cooled saline at 26oC onto the ischemic lobes. Euthanasia was undertaken exactly at the end of the experiment and samples were collected for molecular analyses by ELISA and Western Blot assays, aiming to compare pro-inflammatory, anti-inflammatory and antioxidant profiles. Results: Compared with NI, TH presented decreased tumor necrosis factor (TNF)-α, interleukin (IL)-1β, IL-6 and IL-12 concentrations and increased IL-10 levels. TH displayed lower inducible nitric oxide synthase (iNOS), higher endothelial nitric oxide synthase (eNOS) expressions. NAD(P)H-quinone oxidoreductase-1(NQO1) expression was also lower in TH. Isolate IPC showed no differences regarding all these markers compared to NI. TH+IPC showed decreased IL-12 concentration and reduced iNOS and NQO1 expressions, but regarding these molecules isolate TH behaved similarly. TH+IPC showed higher Kelch-like ECH-associated protein (Keap)-1 and diminished nuclear and cytosolic nuclear erythroid 2-related factor 2 (Nrf2) expressions than NI. Conclusion: TH was the effective method of protection against early I/R injury. Isolated IPC entailed triggering of second-line antioxidant defense enzymes. Combined TH+IPC seemed to confer no additional advantage over isolated TH in relation to the inflammatory process, but had the advantage of avoid activation second-line antioxidant defense enzymes.