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

A clinical phase 1 study of intravenous anesthetic, propofol, was carried out in 6 male volunteers. Propofol, 1, 2, and 2.5 mg.kg-1, was administered intravenously. Anesthetic effects and effects on vital signs, such as blood pressure, heart rate, respiratory rate and body temperature, were investigated. Any adverse effects or abnormal laboratory findings were also investigated. Venous blood samples were obtained frequently for 12 hours to measure blood propofol concentrations. One volunteer out of 6 lost consciousness with 1 mg.kg-1 and the remaining with 2 mg.kg-1 within 1.5 min. In 2 volunteers the duration of anesthesia was inadequate for clinical practice with 2 mg.kg-1. Therefore, 2.5 mg.kg-1 was given. Rhythmic high voltage slow waves appeared immediately after the loss of consciousness in EEG and then basic activity changed to 11 approximately 16 Hz, 30 approximately 60 microV. Blood pressure decreased and heart rate increased but no profound hypotension was observed. Body temperature decreased. No adverse effect, such as laryngospasm, bronchospasm or hiccough, occurred. Laboratory test showed no abnormal result. Pharmacokinetic analysis was carried out using a 3 compartment open model. The half time of distribution phase, 2.6 min, was short, and total clearance, 1.68 l.min-1, was high. We conclude that the proper induction dose of this agent is 2 approximately 2.5 mg.kg-1, which is similar to the values previously reported in European investigations, and that this agent is safe and useful for induction of anesthesia.
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PMID:[Clinical study of propofol in male volunteers]. 232 55

It is important to know the effects of anaesthetics on cerebral blood flow and cerebral metabolism to enable appropriate selection of agents for the brain injured patient. Thiopental possesses favourable cerebrovascular and metabolic properties but has not been shown to improve outcome in head injured patients. Propofol has properties similar to thiopental. Its rapid metabolism as well as its ability to reduce intracranial pressure and its antiemetic properties render it a very favourable drug. Despite controversies surrounding the effects of short-acting narcotics on intracranial pressure, they continue to be used because they provide stable haemodynamic conditions when used with care. Isoflurane is currently advocated as the best inhalational agent for neuroanaesthesia because of its lesser effects on cerebral blood flow and intracranial pressure. The effects of nitrous oxide on cerebral blood flow and intracranial pressure appear to vary according to the background anaesthetic used. Nitrous oxide is still widely used in most neuroanaesthetic practices, as its effects can be blunted by barbiturates, narcotics and/or hypocapnia. There is no convincing human study on the cerebral protective properties of anaesthetic agents although mild hypothermia has been shown experimentally to offer significant protection against global and focal ischaemia.
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PMID:Cerebrovascular and cerebral metabolic effects of commonly used anaesthetics. 771 Feb 26

Mild intraoperative hypothermia is common. We therefore studied the effects of mild hypothermia on propofol pharmacokinetics, hepatic blood flow, and atracurium duration of action in healthy volunteers. Six young volunteers were studied on two randomly assigned days, at either 34 degrees C or 37 degrees C. Anesthesia was induced with thiopental, 3 mg/kg, and maintained with 70% N2O and 0.6% isoflurane. Core hypothermia was induced by conductive and convective cooling. On the other study day, normothermia was maintained by a Bair Hugger (Augustine Medical, Inc., Eden Prairie, MN) forced-air warmer. Propofol, 1 mg/kg lean body mass (LBM), then was given, followed by a 4-h infusion at 5 mg.kg-1.h-1. After 2 h, atracurium 0.5 mg/kg was administered as an intravenous bolus. Indocyanine green was administered for estimation of hepatic blood flow. Arterial blood was assayed for propofol and indocyanine green concentration. Pharmacokinetic analysis was performed using NONMEM. Results are reported as means +/- SEM. Propofol blood concentrations averaged approximately 28% more at 34 degrees C than at 37 degrees C (P < 0.05). Hepatic blood flow decreased 23% +/- 11% in normothermic volunteers during the propofol infusion, and 33% +/- 11% in hypothermic volunteers (P = not significant). A three-compartment mamillary model fitted the data best. Inclusion of hepatic blood flow change from the prepropofol baseline as a covariate for total body clearance significantly improved the fit. The intercompartmental clearances were decreased in the presence of hypothermia.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Mild hypothermia alters propofol pharmacokinetics and increases the duration of action of atracurium. 856 56

The sighthounds are an ancient group of dog breeds that have been selectively bred for high-speed pursuit of prey by sight. Probably as a consequence of this selection process, these dogs have a number of idiosyncrasies that can potentially adversely affect their anesthetic management. These include (1) nervous demeanor which can lead to stress-induced clinical complications, such as hyperthermia; (2) lean body conformation with high surface-area-to-volume ratio, which predisposes these dogs to hypothermia during anesthesia; (3) hematological differences such as a higher packed cell volume and lower serum protein compared with other dog breeds which may complicate interpretation of preanesthetic blood work; (4) Impaired biotransformation of drugs by the liver resulting in prolonged recovery from certain intravenous anesthetics, especially thiopental; and increased risks of drug interactions. Safe anesthetic management of sighthounds should include sedative premedication and appropriate use of analgesic drugs to minimize perioperative stress. Thiopental, or any other thiobarbiturate, should not be used in these dogs. Propofol, ketamine/diazepam combination, and methohexital are recommended alternative intravenous anesthetics. Avoid coadministration of agents that inhibit drug biotransformation, such as chloramphenicol. Inhalation anesthesia using isoflurane is the preferred anesthetic maintenance technique. Core body temperature should be monitored closely and techniques to minimize hypothermia should be employed both during anesthesia and into the recovery period.
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PMID:Anesthesia of the sighthound. 1019 44

Twelve adult patients for cardiac surgery were divided into 2 groups, normothermia (6 patients) and mild hypothermia (6 patients), based on their body temperature during cardiopulmonary bypass (CPB). Propofol was continuously administered throughout each operation at a dose of 2 mg.kg-1.h-1. Arterial and internal jugular venous bulb blood samples were drawn simultaneously before CPB, at 5, 30, 60, and 90 minutes after the start of CPB, 30 minutes after the end of CPB, and at the conclusion of the operation, to measure propofol concentrations. In the normothermia group, propofol concentration in the arterial blood decreased significantly 5 minutes after the start of CPB, and then recovered immediately to the pre-CPB value. In the mild hypothermia group, however, no significant change in propofol concentration was observed. In both groups, there was no significant difference in propofol concentration between arterial and internal jugular venous bulb blood throughout the study period. Our results suggest that there are no significant differences between the effect of normothermic and that of mild hypothermic CPB on the pharmacokinetics of propofol in the brain.
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PMID:[Blood concentration of propofol during cardiopulmonary bypass--comparison between arterial and internal jugular venous blood]. 1151 60

Propofol is an intravenous anaesthetic agent having anticonvulsant property. We report here a case in which propofol was effective in controlling myoclonus during rewarming in brain hypothermia patient. A 35-year-old male patient was admitted in a comatose state with right-sided hemiparesis, anisocoria and absence of bilateral light reflex. On admission, a head CT showed traumatic subarachnoid hemorrhage, left subdural hematoma, 10 mm midline shift and tentorial herniation with massive brain swelling together with extensive hypodensity in the frontal, temporal and occipital lobes bilaterally. Left decompressive hemicraniectomy, removal of hematoma and brain hypothermia therapy were started immediately. Postoperative head CT showed 15 mm midline shift. The temperature of the jugular bulb was maintained at 34 degrees C for 2 days together with sedation using midazolam under artificial ventilation. The patient was gradually rewarmed at a rate of 0.5 degree C per day from the third hospital day. Myoclonus of sudden onset developed on the patient's head and upper extremities on the third hospital day. An intravenous bolus injection of 10 mg midazolam and continued intravenous infusion of midazolam were given but they did not completely stop myoclonus. A bolus of propofol 60 mg was given intravenously and continuous intravenous infusion of propofol 2 mg.kg-1.hr-1 was started after which the progression of myoclonus disappeared. Myoclonus was kept controlled until the continuous intravenous infusion of midazolam and propofol was discontinued on the sixth hospital day, after which myoclonus occurred again after extubation on the seventh hospital day. The clinical course of this case suggests that propofol might be an alternative effective agent to suppress refractory myoclonus.
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PMID:[Efficacy of propofol in controlling myoclonus during rewarming in a brain hypothermia patient]. 1188 90

The neuroprotective potency of anesthetics such as propofol compared to mild hypothermia remains undefined. Therefore, we determined whether propofol at two clinically relevant concentrations is as effective as mild hypothermia in preventing delayed neuron death in hippocampal slice cultures (HSC). Survival of neurons was assessed 2 and 3 days after 1 h oxygen and glucose deprivation (OGD) either at 37 degrees C (with or without 10 or 100 microM propofol) or at an average temperature of 35 degrees C during OGD (mild hypothermia). Cell death in CA1, CA3, and dentate neurons in each slice was measured with propidium iodide fluorescence. Mild hypothermia eliminated death in CA1, CA3, and dentate neurons but propofol protected dentate neurons only at a concentration of 10 microM; the more ischemia vulnerable CA1 and CA3 neurons were not protected by either 10 microM or 100 microM propofol. In slice cultures, the toxicity of 100 muM N-methyl-D-aspartate (NMDA), 500 microM glutamate, and 20 microM alpha-amino-5-methyl-4-isoxazole propionic acid (AMPA) was not reduced by 100 microM propofol. Because propofol neuroprotection may involve gamma-aminobutyric acid (GABA)-mediated indirect inhibition of glutamate receptors (GluRs), the effects of propofol on GluR activity (calcium influx induced by GluR agonists) were studied in CA1 neurons in HSC, in isolated CA1 neurons, and in cortical brain slices. Propofol (100 and 200 microM, approximate burst suppression concentrations) decreased glutamate-mediated [Ca2+]i increases (Delta[Ca2+]i) responses by 25%-35% in isolated CA1 neurons and reduced glutamate and NMDA Delta[Ca2+]i in acute and cultured hippocampal slices by 35%-50%. In both CA1 neurons and cortical slices, blocking GABAA receptors with picrotoxin reduced the inhibition of GluRs substantially. We conclude that mild hypothermia, but not propofol, protects CA1 and CA3 neurons in hippocampal slice cultures subjected to oxygen and glucose deprivation. Propofol was not neuroprotective at concentrations that reduce glutamate and NMDA receptor responses in cortical and hippocampal neurons.
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PMID:Mild hypothermia, but not propofol, is neuroprotective in organotypic hippocampal cultures. 1561 81

Sedation-analgesia occupies an essential place in the specific therapeutic arsenal of the brain-injured patients. The maintenance of the perfusion of the brain, its relaxation and its protection are the fundamental objectives whose finality is to avoid the extension of the lesions and to preserve the neuronal capital. Sedation is instituted when patients are severely agitated or present a deterioration of their state of consciousness (GCS< or =8). Under cover of mechanical ventilation, sedation is the first line treatment of intracranial hypertension, a common pathway of various acute brain diseases of traumatic, vascular or other origin. The use of the combination of hypnotic and opioids is the rule. The combined action of these two classes reinforces and improves their sedative effects. Midazolam is the 2 benzodiazepine of reference. Propofol is more and more frequently added to the combination of hypnotic and opioids. The "propofol infusion syndrome" is a severe limitation to its long term administration in particular among patients presenting a severe septic or inflammatory state. Propofol will be imperatively stopped in the event of metabolic acidosis, rhabdomyolysis, acute renal insufficiency, hyperkaliemia or increase in the blood triglyceride levels. The use of thiopental is restricted to the most severe cases. Its use as a monotherapy at high doses is abandoned to the profit of a co-administration with midazolam or even with the combination of midazolam and propofol. Thiopental overdose is very frequent in the event of associated hypothermia. Etomidate does not have its place apart from induction in fast sequence. The neuro-protective effects of ketamine require to be demonstrated in man before being recommended routinely. Withdrawal of sedation can be responsible for a state of agitation which can be controlled by neuroleptics.
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PMID:[Sedation and analgesia for the brain-injured patient]. 1861 62

Though propofol requirement is expected to decrease during cardiopulmonary bypass (CPB), a few studies have failed to demonstrate this. The factors affecting pharmacokinetics of propofol and, therefore, the requirement, are different during hypothermic and normothermic CPB. We evaluated and compared the requirement of propofol during hypothermic and normothermic CPB. Fifty adult patients scheduled for elective cardiac surgery on CPB were recruited and randomly allocated into hypothermic CPB (28-30 degrees C) (Group H) and normothermic CPB (35-37 degrees C) (Group N) groups. Patients were induced and maintained with propofol titrated to maintain a target bispectral index (BIS) of 50 +/- 10. Propofol requirement (mean +/- SD) was similar in normothermic and hypothermic groups, both before CPB (4.9 +/- 1.5 mg kg(-1)hr(-1) in Group N, 4.6 +/- 1.5 mg kg(-1)hr(-1) in Group H) and after cessation of bypass (p > 0.05) (4.6 +/- 1.8 mg kg(-1)hr(-1) in Group N and 4.3 +/- 1.7 mg kg(-1)hr(-1) in Group H). CPB significantly reduced (p < 0.001) propofol requirements in both arms of the study (Group N: 2.9 +/- 1.4 mg kg(-1)hr(-1)and Group H: 1.3 +/- 0.7 mg kg(-1)hr(-1)). This reduction was more pronounced in the hypothermic group (p < 0.001). The BIS (median +/- inter quartile range) remained constant during normothermic CPB (50 +/- 8.8), but declined significantly during hypothermic CPB (41 +/- 5.6) despite decreased usage of propofol during hypothermia. No patient had recall of intra-operative events. CPB decreases the magnitude of propofol requirements and the effect of hypothermic CPB is significantly more than that of normothermic CPB.
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PMID:Propofol requirement titrated to bispectral index: a comparison between hypothermic and normothermic cardiopulmonary bypass. 1956 45

Propofol is one of the most commonly used intravenous anesthetic drugs because its distribution, metabolism and excretion are rapid. Recovery from anesthesia using propofol infusion is generally smooth. We have therefore taken this opportunity to report on a case of delayed recovery from anesthesia in a 58-year-old man who underwent removal of a light maxillary sinus mucocele. General anesthesia was performed with propofol 3-7 mg x kg(-1) x hr(-1) associated with intermittent injection of fentanyl, total of 450 microg. He was not obese, and his preoperative liver function was within normal limits. Any intracranial hematomas, brain edema, cerebral infarction, acid-base abnormalities, hypo- and hyperglycemia and hypothermia were not detected in the early postoperative period. The administration of naloxone hydrochloride and flumazenil failed to improve delayed recovery from anesthesia. It was 16 hours after the end of operation and the administration of propofol had been completed before the trachea could be extubated. His plasma concentration of propofol was 4.4 microg x ml(-1), 4.5 hours after administration. In this patient we could not prove a metabolic abnormality with propofol, but it was strongly suspected.
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PMID:[Plasma concentration of propofol was 4.4 microg x ml(-1), 4.5 hours after completion of its administration]. 2122 93


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