No description available.

Thesis (M.S.)--University of Wisconsin. School of Nursing, 1976. / eContent provider-neutral record in process. Description based on print version record.

Non-compensable cold exposure represents a potentially deadly threat to humans, as we lack highly specialized organs and mechanisms necessary to maintain our optimal core temperature of ~37°C. Repeated exposures to cold have been shown to induce protective physiological changes in cold responses through a process known as cold acclimatization (natural) or acclimation (in laboratory). The purpose of this thesis was to determine what physiological changes occur following an intense 7 day, 14°C cold water immersion acclimation protocol, during both non-compensable (Chapter 2) and compensable cold exposures (Chapter 3). This includes identifying changes in the contributions of the shivering (ST) and non-shivering (NST) thermogenic pathways to overall heat production. ST and NST changes were quantified via electromyography and indirect calorimetry, respectively. This 7 day cold water acclimation protocol resulted in a decrease in cooling rate, a significant increase in mean esophageal core temperature, a decrease in peak heart rate following immersion, and increased thermal comfort from day 1 to day 7 of the 1h 14°C cold water immersions. Further to these findings, changes in ST and NST were measured pre- and post-acclimation with a standardized compensable cold protocol using a liquid conditioned suit (LCS) which lowered Tskin to 26°C for 2.5h. The cold acclimation protocol resulted in a ~38% decrease in mean shivering over the 2.5h without any change in thermogenic rate from pre- to post-cold acclimation. In addition, no significant difference in fuel selection was observed. These results indicate that the short, intense cold acclimation protocol did result in a substantial change in the contribution of ST and NST to total heat production which could increase cold tolerance by reducing involuntary muscle contractions during ST.

Human beings have been exposed to different cold conditions throughout time, and have through cold acclimation developed mechanisms to survive in these conditions. Cold acclimation can be elicited through exposure to natural cold climates, or artificially induced in a laboratory to study the body’s response to repeated cold exposures. Several studies looking at the effects of cold acclimation in humans have been conducted during the last 50 years, and have reported that cold acclimation can lead to a change in skin and core temperature, heat production and shivering. An accurate quantification of shivering thermogenesis (ST) during cold acclimation has not been done before, and most previous measurements of shivering during cold acclimation have been inaccurate and inadequate. In this study a Liquid Condition Suits (LCS) was used to elicit cold acclimation (10°C, 2hr daily, for 4 weeks) while an accurate measurement of the effect of cold acclimation on changes in muscle activity was conducted. In CHAPTER 2, results showed that four weeks of cold acclimation at 10°C did not change skin and core temperature, heat production or ST. The effects on shivering pattern and fuel selection were also analysed, but no effects of cold acclimation could be observed. These measurements were a part of a larger study, in which the effects of cold acclimation on changes in BAT were the main outcome measures. These data showed that an increase in BAT volume (45%) and activity (120%) were the only observed effects of cold acclimation. In CHAPTER 3, we set out to assess if changes in shivering from pre to post cold acclimation are associated with changes in BAT volume, and if the amount of BAT a participant possesses prior to cold acclimation can be used to predict changes in shivering intensity during cold acclimation. The interindividual variability in changes in thermal responses, heat production, shivering and BAT volume occurring between subjects during four weeks of cold acclimation was also addressed in this section.

Human beings have been exposed to different cold conditions throughout time, and have through cold acclimation developed mechanisms to survive in these conditions. Cold acclimation can be elicited through exposure to natural cold climates, or artificially induced in a laboratory to study the body’s response to repeated cold exposures. Several studies looking at the effects of cold acclimation in humans have been conducted during the last 50 years, and have reported that cold acclimation can lead to a change in skin and core temperature, heat production and shivering. An accurate quantification of shivering thermogenesis (ST) during cold acclimation has not been done before, and most previous measurements of shivering during cold acclimation have been inaccurate and inadequate. In this study a Liquid Condition Suits (LCS) was used to elicit cold acclimation (10°C, 2hr daily, for 4 weeks) while an accurate measurement of the effect of cold acclimation on changes in muscle activity was conducted. In CHAPTER 2, results showed that four weeks of cold acclimation at 10°C did not change skin and core temperature, heat production or ST. The effects on shivering pattern and fuel selection were also analysed, but no effects of cold acclimation could be observed. These measurements were a part of a larger study, in which the effects of cold acclimation on changes in BAT were the main outcome measures. These data showed that an increase in BAT volume (45%) and activity (120%) were the only observed effects of cold acclimation. In CHAPTER 3, we set out to assess if changes in shivering from pre to post cold acclimation are associated with changes in BAT volume, and if the amount of BAT a participant possesses prior to cold acclimation can be used to predict changes in shivering intensity during cold acclimation. The interindividual variability in changes in thermal responses, heat production, shivering and BAT volume occurring between subjects during four weeks of cold acclimation was also addressed in this section.

Bakgrund: Postoperativ shivering är ett fenomen som uppstår hos patienter efter kirurgi och anestesi, vilket innebär muskeltremor som får patienten att darra eller huttra okontrollerat. Shivering kopplas ofta till hypotermi även om det ensamt inte helt kan förklara uppkomsten. Det har en negativ effekt på läkningsprocessen, men är också obehagligt och gör att patienten lider. En del patienter beskriver upplevelsen som det värsta de har varit med om. Syfte: Att sammanställa anestesisjuksköterskans åtgärder för att förebygga shivering hos den postoperativa patienten. Metod: Vi har antagit induktiv ansats och gjort en systematisk litteraturöversikt, syntetiserat kvantitativ data som sammanställts i en metaanalys och narrativ syntes. Från artiklar som har liknande design och refererar till samma fråga eller intervention. Behandlingar och insatser kallas interventioner, vilket är ett brett begrepp och inkluderar både medicinska och omvårdnadsmässiga behandlingar för att förebygga och behandla postoperativ shivering. Resultat: För att kunna nå syftet att sammanställa åtgärder, behövdes först orsaker identifieras. Två kategorier identifierades, omvårdnadsåtgärder samt farmakologiska åtgärder, med tillhörande koder. Att åtgärda hypotermi, riskbedöma sårbara patientgrupper, ge premedicinering samt analgesi, ha en medvetenhet kring vätskebehandling samt övervakning av anestesidjup ansågs vara åtgärder för att förebygga postoperativ shivering. Olika läkemedel ger olika resultat i det postoperativa måendet. Slutsats: Mycket talar för att nedkylning och smärta måste motverkas för att minska shivering och bör behandlas preventivt. Medvetenheten kring vikten av temperaturövervakning bör ökas. Studien kom även fram till att en begreppsdefinition och standardmetod att behandla postoperativ shivering är önskvärt. / Background: Postoperative shivering is a phenomenon that occurs in patients after surgery and anesthesia, which means muscle tremors that cause the patient to tremble or shake uncontrollably. Shivering is often linked to hypothermia, although it alone cannot fully explain its occurrence. It has a negative effect on the healing process, but is also unpleasant and causes the patient to suffer. Some patients describe the experience as the worst they have been through. Aim: To compile the anesthesia nurse's measures to prevent shivering in the postoperative patient. Method: We have adopted an inductive approach and performed a systematic literature review, synthesized quantitative data compiled in a meta-analysis and narrative synthesis. From articles that have a similar design and refer to the same question or intervention. Treatments and efforts are called interventions, which is a broad term and includes both medical and nursing treatments to prevent and treat postoperative shivering. Results: In order to achieve the aim of compiling measures, causes first needed to be identified. Two categories were identified, nursing measures and pharmacological measures, with associated codes. Correcting hypothermia, risk assessment of vulnerable patient groups, giving premedication and analgesia, having an awareness of fluid treatment and monitoring the depth of anesthesia were considered measures to prevent postoperative shivering. Different drugs give different results in the postoperative mood. Conclusion: Much suggests that cooling and pain must be counteracted to reduce shivering and should be treated preventively. Awareness of the importance of temperature monitoring should be increased. The study also concluded that a conceptual definition and standard method to treat postoperative shivering is desirable.

Shivering är ett fenomen som uppstår hos patienterna postoperativt. Det innebär att patienten har okontrollerbara muskelskälvningar som gör att patienten darrar, skälver eller huttrar i mer än 15 sekunder. Shivering påverkar kroppen negativt, men är också obehagligt och ett onödigt lidande för patienten. I takt med den tekniska utvecklingen utarbetas nya operationstekniker och idag utförs flera operationer med laparoskopisk teknik. Pilotstudiens syfte var att undersöka före-komsten av postoperativ shivering hos patienter som opererats med laparoskopisk teknik. Denna studie har gjorts empirisk med en kvantitativ ansats. En egen konstruerad enkät tillsammans med ett mätinstrument har använts vid datainsamlingen. I pilotstudien deltog 33 patienter i ålders-spannet 23-78 år. Resultatet i pilotstudien visar att det var sex (n=6) av alla (n=33) patienterna i studien shivrade efter genomgången laparoskopisk kirurgi. Då studien är gjord i en liten skala är resultatet inte generaliserbart, men det går ändå att se att vissa påverkande faktorer så som till exempel anestesiläkemedel kan bidra till att patienterna shivrar. / Shivering is a phenomenon that occurs in patients postoperatively. This means that the patient has uncontrollable muscles tremors which allow the patient to tremble or shiver in more than 15 seconds. Previous research shows that shivering have a negative effect on the body, but is also an unpleasant and unnecessary suffering for the patient. In step, with today's rapid development in technology, more and more patients undergo surgery with laparoscopic techniques. The pilot- study aimed to investigate the incidence of postoperative shivering in patients who were surgical operated with laparoscopic technique. This empirical study has been done with a quantitative approach. Self-designed questionnaires, together with an instrument were used in the data col-lection. The pilot study enrolled 33 patients in the age range 23-78 years. The results of the pilot study suggest that the presence of shivering was little in relation to laparoscopic surgery, six (n = 6) of all (n = 33) patients in the study was shivering. When the study is made of a small scale is the result not possible to generalize, but you can still see that certain stressors, such as anesthesia drugs may contribute the patient shivering.

Humans are known as homeothermic endotherms. To ensure thermic balance at rest when exposed to cold, they dispose of two main thermogenic processes: shivering thermogenesis (ST) and non-shivering thermogenesis (NST). ST consists of involuntary muscle contractions and NST represents the component of Hprod that is not ST. While ST is difficult to tolerate, it is not yet known which nutrients and how much are required to stimulate NST and lower ST in the cold. Whether or not food caloric intake has an impact on the relative contribution of ST and NST to total Hprod remains to be determined. Therefore, the purpose of this thesis was 1) to quantify the effects of ingesting two quantities (1507 vs 3015 kJ) of same relative compositions on cold-induced whole-body Hprod and 2) to establish the effects of these two quantities of food on the relative contribution of ST and NST to total Hprod. Five healthy male participants were exposed to a 3h mild cold, using a liquid conditioned suit with water flowing at 15°C (COLD) or 33 °C (CON) for a total of 4 trials. Thermal, metabolic and shivering responses were measured at baseline, before and after shake ingestion. Results demonstrated that Hprod and ST intensity increased in the cold, while no significant differences were found between the ingested shakes at two different caloric equivalents. In addition, ST intensity did not change, which confirmed that NST remained the same between the two conditions. Thus, knowing that the caloric intake will not maximize the thermogenic effects in the cold (i.e. improve the comfort of the individual), is it more advantageous to bring food or additional clothing, for any activity? Clearly, more research on the exact pathways of each processes in the cold with food consumption needs to be made. To that extent, the investigation of the effect of food quality on changes in the thermogenic processes during cold exposure strikes us as a fascinating area for future research.

This study compared head vs. torso warming using a similar source of heat donation. Six subjects were cooled in 8˚C water to either a core temperature of 35˚C or for 60 min. They were then rewarmed by either shivering only, or charcoal heater applied to the head, or torso. There were no significant differences in rewarming rate between the three conditions. Head warming did not inhibit average shivering heat production resulting in greater net heat gain during 35-60 min of rewarming compared to shivering. Head warming is as effective as torso warming for hypothermic victims. Head warming could be a preferred method in some cases: extreme conditions in which removal of the insulation and exposure of the torso to the cold is contraindicated; excessive movement is contraindicated (e.g., severe hypothermia which has a risk of ventricular fibrillation, or potential spinal injury); or if emergency personnel are working on the torso.

This study compared head vs. torso warming using a similar source of heat donation. Six subjects were cooled in 8˚C water to either a core temperature of 35˚C or for 60 min. They were then rewarmed by either shivering only, or charcoal heater applied to the head, or torso. There were no significant differences in rewarming rate between the three conditions. Head warming did not inhibit average shivering heat production resulting in greater net heat gain during 35-60 min of rewarming compared to shivering. Head warming is as effective as torso warming for hypothermic victims. Head warming could be a preferred method in some cases: extreme conditions in which removal of the insulation and exposure of the torso to the cold is contraindicated; excessive movement is contraindicated (e.g., severe hypothermia which has a risk of ventricular fibrillation, or potential spinal injury); or if emergency personnel are working on the torso.