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

A delayed effect of fentanyl used for anesthesia may be respiratory distress several hours after surgery. The findings are muscular rigidity, fall in chest wall compliance, hypoventilation, respiratory acidosis, and hypotension. In the past, to our knowledge, this complication was exclusively reported in patients undergoing cardiac surgery, when large fentanyl dosages are employed. This article describes three general surgical patients in whom respiratory distress developed three to five hours following colon surgery when a moderate dose of fentanyl citrate, 55 to 75 micrograms/kg, was used. Initially, all patients had a normal recovery from anesthesia. Later, respiratory distress was successfully treated with a fentanyl antagonist and ventilatory assistance. This delayed toxic phenomenon is thought to be due to the reentry of fentanyl into plasma from deposits in adipose tissue, muscle, and the gastrointestinal tract, leading to a secondary rise in the plasma concentration. It is more likely to be encountered when hypothermia, rewarming, and acidosis are present in the postoperative period. This life-threatening complication is treacherous, since it may occur when the patient has been transferred to the surgical ward and is less closely monitored.
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PMID:Delayed muscular rigidity and respiratory depression following fentanyl anesthesia. 333 59

In 1975 H. Rahn put forward a new concept of hydrogen ions regulation which explains acid-base regulation in relation to body temperature and applies to all animal species. At the root of this concept is the finding that maintenance of intracellular neutrality is governed by water dissociation and regulated by imidazole-rich protein buffers. The pH of the extracellular fluid, which receives acid by-products of cell activity, is kept higher than that of the intracellular fluid (relative alkalinity). The difference between extracellular pH and neutrality is constant for each species and ranges from 0.6 to 0.8 pH units. It is unaffected by changes in temperature, and the total CO2 content of extracellular fluid remains constant. The authors were able to confirm the value of this new concept in man by experimental studies of in vitro and in vivo blood of patients undergoing aorto-coronary bypass under controlled hypothermia. They draw the following practical conclusions: (1) in subjects under moderate or deep hypothermia for surgical purposes, the acid-base status can be controlled and the extracellular pH adjusted by ensuring intracellular neutrality; this is done by keeping PCO 2 at such a level that the arterial blood pH measured at 37 degrees C remains around 7.40; (2) the problem of correcting acid-base values (pH-PCO 2) according to body temperature is solved simply by using pH and PCO 2 values measured at 37 degrees C and interpreting them, as usual, in terms of metabolic or respiratory acidosis or alkalosis.
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PMID:[Relations between acid-base equilibrium and body temperature. Physiological concepts and practical applications]. 622 30

This study was conducted to assess the toxic effects of repeated inhalation exposures to phenyl isocyanate vapor in male Wistar rats. Rats were exposed to design concentrations of 0, 1, 4, 7, or 10 mg/m3 phenyl isocyanate air for 2 weeks (6 hr/day, 5 days/week). The rats were assessed for normal toxicologic parameters, and pulmonary function tests, blood gas measurements, and analysis of bronchoalveolar lavage fluid (BALF) parameters were utilized shortly after exposures as well as 2 months postexposure. The results indicated that rats exposed to 7 and 10 mg/m3 experienced decreased body weights, hypoactivity, hypothermia, signs of respiratory tract irritation, delayed onset of mortality, and changes in organ weights. In addition, pulmonary function tests demonstrated decreased forced expiratory flow rates and quasistatic lung compliance. Arterial blood gases showed an arterial hypoxemia and changes consistent with a pronounced venous-admixture-like perfusion, suggesting severe mismatch of the ventilation/perfusion relationship. Delayed onset of mortality appeared to be associated with respiratory acidosis and hypoxemia. Biochemical and cellular components in BALF complemented the results of the functional alterations. Remarkable changes were indicated by increased activities of the BALF parameters, gamma-GPT, protein, and sialic acid. Histopathological findings provided evidence of increased secretory cell activity and a concentration-dependent increase in goblet cell hyperplasia at concentrations of 4 mg/m3 and above. In rats exposed to 7 mg/m3 further findings consisted of intraluminal inflammation of airways, hypertrophia of bronchial smooth muscle, epithelial desquamation, and eosinophilia of the airways. A complete regression of morphological lesions was not found in the animals exposed to 4 mg/m3 and above at the 2-month postexposure time period. In conclusion, the damage to the airways comprise most of the features characteristic of chronic airway inflammation or asthma.
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PMID:Phenyl isocyanate-induced asthma in rats following a 2-week exposure period. 773 33

Acute hypothermia was surface-induced in unrestrained conscious rats at two different levels, moderate (30 degrees C TB) and severe (20 degrees C TB). Data reflecting the acid/base status were determined. The values obtained for moderate hypothermia were compared with the acid/base pattern observed during hypothermia induced by two different anaesthetics, sodium pentobarbital and urethane, at room temperature. Conscious, hypothermic animals developed an apparent respiratory alkalosis, with an increase in pHa (from 7.476 to 7.546 in moderate hypothermia and from 7.484 to 7.563 in severe hypothermia) correlated with a decrease in arterial bicarbonate levels (from 22.9 to 16.8 mmol l-1 and from 20.7 to 14.9 mmol l-1 respectively). Lactate increased slightly in conscious, severely hypothermic rats (1.02 mmol l-1). This acid/base pattern was clearly different from that seen in sodium pentobarbital (mild respiratory acidosis) and urethane-induced hypothermia (metabolic acidosis). These results suggest that conscious rats follow a pattern closer to that underlying the relative alkalinity shown by many poikilotherms than to that underlying the constant pH shown in hibernating mammals. This latter pattern, nevertheless, approaches that observed during moderate pentobarbital hypothermia and the acid/base pattern during shallow hypothermia in birds. Anaesthesia may interfere with the development of the processes that lead to the acid/base pattern observed in conscious animals.
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PMID:Comparison of acid/base status in conscious and anaesthetized rats during acute hypothermia. 825 25

We investigated the effect of prolonged hypercapnia on human thermoregulation during immersion of seven male subjects in a 15 degrees C water bath until their esophageal temperature dropped to 35 degrees C or until 1 h had elapsed. In the control trial, subjects inspired room air, whereas in the other trial the inhaled gas mixture was a 4% CO2:20% O2:76% N2 gas mixture. Oxygen uptake (VO2, liter.min-1), inspired minute ventilation (VI, liter.min-1), esophageal temperature (Tes, degree C), mean unweighted skin temperature (Tsk, degree C), mean heat flux (Q, W.m-2), and electromyographic (EMG, mV) activity of the trapezius muscle were recorded. VO2 and integrated EMG (IEMG) activity were used as the primary indicators of shivering thermogenesis. There was a tendency for elevated VO2, albeit not significant, in the CO2 trial compared to the air trial. We observed no significant differences in the IEMG between the air and CO2 trials. These results suggest that prolonged inhalation of a gas mixture containing 4% CO2 does not have a significant inhibitory effect on shivering thermogenesis and does not enhance the cooling rate of the body core. The absence of any shivering attenuation is most likely due to the small blood PCO2 increase incurred by inhalation of 4% CO2, compensation of hypercapnic-induced respiratory acidosis, and a strong thermal drive from core and peripheral regions. It is unlikely that elevated PICO2 levels contribute significantly to the etiology of hypothermia in divers.
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PMID:Effects of prolonged CO2 inhalation on shivering thermogenesis during cold-water immersion. 840 Nov 51

Experiments on rats have shown an important role of hypercapnia in the development of condition of artificial hibernation in combination with influence of hypothermia, hypoxia and hypercapnia. It is proved that the joint action of hypothermia, hypoxia and hypercapnia has induced development of respiratory acidosis and hibernation in animals, while removal of the hypercapnia effect has induced development of acute metabolic acidosis and death of animals. It has been found that animals in the state of artificial hibernation have considerable changes in concentrations of main electrolytes (Na+, K+, Ca+, Mg2+, phosphates, Cl-) and metabolites (NH3, glutamine, urea) in blood as well as in activity of enzymes (glutamaldehydrogenase, glutaminase, arginase) in tissues of the liver and kidneys.
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PMID:[Acid-base equilibrium and nitrogen metabolism in rats in a state of artificial hibernation]. 855 76

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

Glucose was infused intravenously into six ponies during halothane anaesthesia, to evaluate its effect on their endocrine response to anaesthesia. The ponies were premedicated with acepromazine, and anaesthesia was induced with thiopentone and maintained with halothane in oxygen for two hours. Glucose was infused to maintain the plasma glucose concentration above 20 mmol/litre. Anaesthesia was associated with hypothermia, a decrease in haematocrit, hypotension, hyperoxaemia, respiratory acidosis and an increase in the plasma concentrations of lactate and arginine vasopressin. The concentration of beta-endorphin in plasma increased transiently after 20 minutes but there were no changes in concentrations of adrenocorticotrophic hormone, dynorphin, cortisol or catecholamines. These data suggest that the glucose infusion attenuated the normal adrenal response of ponies to halothane anaesthesia.
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PMID:Effects of glucose infusion on the endocrine, metabolic and cardiorespiratory responses to halothane anaesthesia of ponies. 1046 34

Snow avalanche case reports have documented the survival of skiers apparently without permanent hypoxic sequelae, after prolonged complete burial despite there being only a small air pocket on extrication. We investigated the underlying pathophysiological changes in a prospective, randomised 2 x 2 crossover study in 12 volunteers (28 tests) breathing into an artificial air pocket (1- or 2-l volume) in snow. Peripheral SpO(2), ETCO(2), arterialised capillary blood variables, air pocket O(2) and CO(2), snow density, and snow conditions at the inner surface of the air pocket were determined. SpO(2) decreased from a median of 99% (93-100%) to 88% (71-94%; P<0.001) within 4 min of breathing into the air pocket; the reduction was greater at 1 l, than 2 l, volume air pocket (P=0.013, intention to treat P=0.003) and correlated to snow density (r=0.50, P=0.021, partial correlation coefficient). ETCO(2) rose simultaneously from median 5.07 kPa (3.47-6.93 kPa) to 6.8 kPa (5.87-8.27 kPa; P<0.001), with consequent respiratory acidosis. Despite premature interruption due to hypoxia (SpO(2)</=75%) in 17 of 28 tests (61%), a respiratory steady state prevailed in five tests until protocol completion (30 min). We conclude that the degree of hypoxia following avalanche burial is dependent on air pocket volume, snow density and unknown individual personal characteristics, yet long-term survival is possible with only a small air pocket. Hence, the definition of an air pocket, "any space surrounding mouth and nose with the proviso of free air passages" is validated as the main criterion for triage and management of avalanche victims. Our experimental model will facilitate evaluating the interrelation between volume and inner surface area of an air pocket for survival of avalanche victims, whilst the present findings have laid the basis for future investigation of possible interactions between hypoxia, hypercapnia, and hypothermia (triple H syndrome) in snow burial.
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PMID:Hypoxia and hypercapnia during respiration into an artificial air pocket in snow: implications for avalanche survival. 1286 13

Maneb, manganese ethylene-bis-dithiocarbamate, is a fungicide pesticide used in the agriculture and bulb flower culture sector. Toxicological effects for humans have been reported in literature and are diverse. They vary from allergic reactions (dermatitis, conjunctivitis, and bronchitis), central nervous system effects (muscarinic, nicotinic, central and extrapyramidal) and renal toxicity (acute renal failure).A 7-year old girl was admitted to the pediatric intensive care unit because of status epilepticus. Physical examination showed respiratory insufficiency, convulsions, and severe hypothermia (32.5 degrees C). The patient was intubated and her convulsions were successfully treated with benzodiazepines. Except for a combined metabolic and respiratory acidosis and hyperglycemia, diagnostic investigations on admission (full blood count, electrolytes, liver and renal functions, cerebrospinal fluid investigation, toxicology screening of blood and urine for barbiturates and benzodiazepines, blood culture, herpes PCR, and a CT scan of the brain) were normal. Within 24 hours, there was a complete recovery of all neurological signs. Within 72 hours, the patient was discharged from the hospital. Liquid chromatography-mass spectrometric investigation of her blood showed amounts of maneb, which can explain all symptoms and signs. However, effects of this magnitude on the central nervous system have not previously been reported in humans.
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PMID:Life threatening central nervous system manifestations and hypothermia due to maneb intoxication in a child: a case report. 1716 99


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