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Query: UMLS:C0020672 (hypothermia)
 17,327 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effect of task complexity on the decrement in mental performance during immersion hypothermia was studied. Psychometric tests of varying length and complexity were administered: 1) prior to cold water immersion (baseline); 2) soon after immersion to the neck in cold (8 degrees C) water but prior to any decrease in core temperature; and 3) after 55 to 80 min of immersion when core temperature had decreased 2-4 degrees C. Results indicated that tests placing relatively minimal cognitive demands on individuals, such as auditory attention, the Benton visual recognition test and forward digit span, were unaffected by either initial cold water immersion or central cooling. On the other hand, tests requiring relatively greater mental manipulation and short term memory (i.e., backward digit span) or processing and analysis (i.e., Stroop test) showed a slight improvement upon cold water immersion (perhaps related to increased arousal and/or learning) but a significant decrement following central cooling of 2-4 degrees C. Thus, relatively simple tasks were unaffected by central cooling, whereas more complex tasks were adversely affected. Cold water immersion itself did not interfere with performance of any tasks. Central nervous system cooling probably interferes with mental processing although discomfort and/or the physiological and physical effects of cold on the neuromuscular aspects of speech, required for responses to some of the tasks, may also affect performance.
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PMID:Effect of task complexity on mental performance during immersion hypothermia. 844 1

Seventy-two healthy dogs required sedation and analgesia for a variety of procedures causing discomfort or pain. They were treated either with the alpha 2-agonist medetomidine at 40 micrograms/kg (15 intravenously and 17 intramuscularly), or 80 micrograms/kg (15 intravenously and 15 intramuscularly) or with xylazine plus l-methadone (1.0 mg)(10 intravenously). The levels of sedation, analgesia and safety were compared clinically and by measurements of the effects on the electrocardiogram (ECG) and blood gases, body temperature, haematology and clinical chemistry. Sedation was achieved reliably with both medetomidine and xylazine plus l-methadone but its onset, depth and duration were influenced by the dose and route of administration. In the medetomidine-treated dogs, intravenous administration resulted in more rapid sedation and the effects of the higher dose were deeper and longer lasting. The small dogs receiving 40 micrograms/kg may have been underdosed. The initial analgesic effects in response to a pin prick to the body surface were sufficient and similar for both drugs, except for the intramuscular dose of 40 micrograms/kg medetomidine. Analgesia for the clinical procedures was less reliable with medetomidine and was not always adequate even at the high dose, but xylazine plus l-methadone assured analgesia in almost every case. Medetomidine resulted in marked bradycardia, lasting as long as the sedation and the ECG revealed a sinus arrhythmia with sinoatrial and atrioventricular blocks grade I and II as a sign of interference with transduction. The bradycardia with xylazine plus l-methadone was less pronounced. A decrease in respiratory rate accompanying sedation had no influence on blood gases and blood acidity in the dogs treated with medetomidine but caused a respiratory acidosis with xylazine plus l-methadone. Body temperature decreased with all treatments for the duration of the period of sedation. Blood glucose concentration increased to a similar extent in all treatment groups, but all other haematological and clinicochemical variables remained unchanged. Treatment with the specific alpha 2 antagonist, atipamezole, reversed the sedation and cardiovascular and pulmonary effects due to medetomidine within minutes.
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PMID:Clinical comparison of medetomidine with xylazine/l-methadone in dogs. 865 Sep 15

Thirty-nine Yucatan miniature swine were used in three fetal surgical experimental protocols. They involved antiarrhythmic administration, pacemaker implantation, and in-utero diagnosis of ventricular septal defect by intraoperative echocardiography. Because of problems encountered with surgical protocols in the initial stages, modifications were made to prevent fetal hypothermia and intraoperative mortality. These modifications included environmental temperature support, staple surgical techniques to reduce operative time, and development of fetal catheters designed to facilitate cannulation of small vessels. Postoperative care protocols were intensive and included antibiotics, analgesics, and supportive care designed to reduce discomfort and prevent abortion and sepsis. Thirty-seven of 39 sows survived the surgical procedures; experiments were performed on 117 fetuses. Twenty-two fetuses died either intraoperatively or postoperatively because of complications related to the experimental protocols. Modification of surgical and postsurgical protocols for these projects demonstrates the feasibility of using miniature swine as a model for fetal surgery, when their use was appropriate for anatomic and physiologic reasons.
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PMID:Fetal surgical protocols in Yucatan miniature swine. 869 29

Simulated conditions of hiking in rain, wind, and cold, without protective rainwear, were used to investigate wet-cold hypothermia in 18 male subjects. Thermal, metabolic, and motor responses were monitored during an attempted 5-h walk (5.1 km/h) at 5 degrees C, with continuous exposure to rain (7.4 cm/h) and wind (8.0 km/h) over the final 4 h. The majority of subjects (11) could not complete the protocol because of intolerance of wet-cold conditions during the last 2 h. Therefore, data from 5 subjects who completed the protocol in rain and control conditions were used to describe the general pattern of response. During the 1st h of walking, core temperature rose 1 degree C to 38.1 degrees C. The subsequent 2 h of rain caused substantial cold stress, indicated by a 40% increase in heat production due to shivering and significant loss of strength and manual dexterity. However, core temperature only decreased to 37.1 degrees C, merely eliminating the initial exercise hyperthermia. Over the last 2 h of rain, core temperature remained relatively stable at 36.8 degrees C, decreasing slightly to 36.4 degrees C by 5 h. Two other subjects developed significant hypothermia (35 degrees C). One demonstrated fatigue of shivering after 2.5 h of rain, confirming the exhaustion hypothesis of wet-cold hypothermia. The older cooled rapidly when he failed to maintain the walking pace. We conclude that if a person can tolerate the intense discomfort of prolonged wet-cold exposure, he or she has the potential to resist significant core hypothermia for at least 4 h of walking under the conditions of this experiment. Exceptions to this generalization occur, making exposure of < 4 h a hypothermia risk for some individuals. Exposures > 4 h would involve increasing probability of rapid decline into hypothermia, associated with exhaustion of shivering and exercise heat production.
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PMID:Wet-cold exposure and hypothermia: thermal and metabolic responses to prolonged exercise in rain. 888 44

It is not uncommon to see an elderly person wearing a sweater on a hot summer day. We know that with advancing age, the efficiency of mechanisms that regulate heat production and loss declines, placing many older people at high risk for cold discomfort and hypothermia, even in warm environments. Whereas healthy elders compensate by turning up the thermostat and adding extra clothing, the frail elders with impaired environmental awareness, physical abilities, and communication may be dependent on caregivers to provide the extra warmth they require. Unfortunately, the thermoregulatory problems of the aged have received insufficient attention in the education of caregivers. As a consequence, some routine procedures in the care of frail elders may inadvertently cause cold discomfort and increase the risk that core temperature will fall. This article provides a brief review of the thermoregulatory system, age-related changes that impair its efficiency, and additional stressors that make it difficult for frail elders to maintain their core temperature at comfortable and safe levels. Nursing interventions to prevent cold discomfort and decrease the risk of hypothermia are emphasized, and changes in some current practices are suggested. Guidelines for assessment and emergency care of elders with hypothermia are provided.
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PMID:Keep frail elders warm! 906 Feb 63

The chief benefits of small skin incisions are reduced patient discomfort, accelerated recovery, and cosmetic satisfaction without compromising the quality of surgery. Since April 1997, the lower ministernotomy approach without femoral cannulation has been performed in 43 patients in the authors' institutions. The indications for this approach were initial single valve surgery and secundum-type atrial septal defect. Cases of aortic valve regurgitation that could be repaired, and aortic stenosis that necessitated annular enlargement were excluded. Among patients with mitral valve disease, those with chronic atrial fibrillation were excluded frpm undergoing the Maze procedure and those reguiring chordal reconstruction for anterior leaflet were also excluded. Mitral valve repair for mitral regurgitation was performed in 8 patients, and open mitral commissurotomy in 2. Mitral valve replacement was performed in 3 patients and aortic valve replacement in 13. Closure of an atrial septal defect was carried out in 18 cases. An approximately 10-cm median skin incision was made, and a ministernotomy with a lower semitransverse division (inverted L-shape) was carried out. Cardiopulmonary bypass was initiated with ascending aortic cannulation and right-angled venous cannulae in the superior and inferior vena cava for mitral valve disease. Single venous cannulae from the right atrial appendage was used for aortic valve disease. Surgery was performed with mild hypothermia and intermittent tepid blood cardioplegia with diltiazem. A rigid 30-degree angle scope held by a videoscope holder with a flexible arm was used for mitral valve surgery. There were one hospital death due to perioperative myocardial infarction and pulmonary embolism. There was one reopening for bleeding which resulted in methicillin-resistant Staphylococcus aureus mediastinitis. However, the patients was discharged after rectal muscle flap repair. There was one reoperation for mitral valve repair due to hemolysis. The improvement of surgical instruments and materials will further facilitate this procedure.
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PMID:[Indications for and limitations of minimally invasive cardiac surgery with the lower ministernotomy approach]. 1006 95

The use of room temperature solutions for body cavity irrigation during surgical procedures can lead to the development of perioperative hypothermia. Hypothermia during this period causes patient discomfort, increases oxygen consumption, interferes with the clotting cascade, and increases the length of hospital stay. Perioperative hypothermia in anesthetized patients also contributes to extended sedation, delayed emergence, and prolonged recovery from neuromuscular blockade. Twenty-four adult American Society of Anesthesiologists (ASA) class I and II patients were randomly assigned to receive warmed arthroscopic irrigation solution or room-temperature irrigation solution in this randomized, prospective study. Tympanic temperatures were monitored every 15 minutes throughout the surgical and postanesthesia recovery periods. P < .05 was considered significant. Statistical comparison of the mean percent temperature decrease from preoperative baseline between the 2 groups did not support the hypothesis that patients receiving warmed irrigation solution would maintain a higher core body temperature than those receiving room temperature solution.
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PMID:The effect of arthroscopic irrigation fluid warming on body temperature. 1123 60

1. The present study tested the hypothesis that motion sickness affects thermoregulatory responses to cooling in humans. 2. Ten healthy male volunteers underwent three separate head-out immersions in 28 degrees C water after different preparatory procedures. In the 'control' procedure immersion was preceded by a rest period. In the 'motion sickness' procedure immersion was preceded by provocation of motion sickness in a human centrifuge. This comprised rapid and repeated alterations of the gravitational (G-) stress in the head-to-foot direction, plus a standardized regimen of head movements at increased G-stress. In the 'G-control' procedure, the subjects were exposed to similar G-stress, but without the motion sickness provocation. 3. During immersion mean skin temperature, rectal temperature, the difference in temperature between the forearm and 3rd digit of the right hand (DeltaT(forearm-fingertip)), oxygen uptake and heart rate were recorded. Subjects provided ratings of temperature perception, thermal comfort and level of motion sickness discomfort at regular intervals. 4. No differences were observed in any of the variables between control and G-control procedures. In the motion sickness procedure, the DeltaT(forearm-fingertip) response was significantly attenuated, indicating a blunted vasoconstrictor response, and rectal temperature decreased at a faster rate. No other differences were observed. 5. Motion sickness attenuates the vasoconstrictor response to skin and core cooling, thereby enhancing heat loss and the magnitude of the fall in deep body temperature. Motion sickness may predispose individuals to hypothermia, and have significant implications for survival time in maritime accidents.
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PMID:Motion sickness potentiates core cooling during immersion in humans. 1153 50

A 15-week-old, male intact, miniature schnauzer presented for signs consistent with persistent right aortic arch (PRAA). Esophagram and esophagoscopy confirmed this diagnosis. Following selective intubation, the constricting ligamentum arteriosum was visualized and completely resected via thoracoscopy. No complications were noted with this procedure. Advantages of thoracoscopy for management of persistent right aortic arch observed in this case were better visualization of the ligamentum arteriosum, minor postoperative discomfort, and minimal intraoperative hypothermia. Therefore, thoracoscopy is a potential alternative to intercostal thoracotomy for correction of PRAA.
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PMID:Thoracoscopic correction of persistent right aortic arch in a dog. 1171 34

Along with nausea and vomiting, postanaesthetic shivering is one of the leading causes of discomfort for patients recovering from general anaesthesia. The distinguishing factor during electromyogram recordings between patients with postanaesthetic shivering and shivering in fully awake patients is the existence of clonus similar to that recorded in patients with spinal cord transection. Clonus coexists with the classic waxing and waning signals associated with cutaneous vasoconstriction (thermoregulatory shivering). The primary cause of postanaesthetic shivering is peroperative hypothermia, which sets in because of anaesthetic-induced inhibition of thermoregulation. However, shivering associated with cutaneous vasodilatation (non-thermoregulatory shivering) also occurs, one of the origins of which is postoperative pain. Apart from causing discomfort and aggravation of pain, postanaesthetic shivering increases metabolic demand proportionally to the solicited muscle mass and the cardiac capacity of the patient. No link has been demonstrated between the occurrence of shivering and an increase in cardiac morbidity, but it is preferable to avoid postanaesthetic shivering because it is oxygen draining. Prevention mainly entails preventing peroperative hypothermia by actively rewarming the patient. Postoperative skin surface rewarming is a rapid way of obtaining the threshold shivering temperature while raising the skin temperature and improving the comfort of the patient. However, it is less efficient than certain drugs such as meperidine, clonidine or tramadol, which act by reducing the shivering threshold temperature.
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PMID:Postanaesthetic shivering: epidemiology, pathophysiology, and approaches to prevention and management. 1177 30


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