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Query: UMLS:C0278134 (anesthesia)
 110,339 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Because of reports of fluroxene toxicity in man, the effect of phenobarbital treatment on the toxicity and metabolism of fluroxene was studied in 9 rhesus monkeys. Six monkeys that were exposed to a mean calculated alveolar fluroxene concentration of 5.8% for 4-hr periods up to a total of 16 hr showed no evidence of toxicity. Two animals were sacrificed after a single 4-hr exposure to obtain control measures of fluroxene metabolites in tissues. Four monkeys that had previously survived received exposures to fluroxene and 3 monkeys that had no exposure to fluroxene died during fluroxene anesthesia after treatment with phenobarbital (mean time, 3 hr). Toxicity was manifested by arterial hypotension, pulmonary edema, and arterial hypoxemia. Phenobarbital treatment enhanced production of fluroxene metabolites, including the highly toxic trifluoroethanol. Concentrations of trifluoroethanol in mixed-expired gas, blood, and urine, and of total nonvolatile fluorine in blood, urine, and tissues of animals treated with phenobarbital were 2 to 10 times as in control animals. The results suggest that the rhesus monkey is a valuable model for the study of fluroxene pharmacology and that inclusion of an enzyme-inducing challenge in the evaluation of potential toxicity of other anesthetics seems warranted.
Clin Pharmacol Ther 1975 Dec
PMID:Fluroxene toxicity induced by phenobarbital. 0 Nov 68

Seven healthy men volunteers received 6.6 +/- 1.3 (SD) percent-hours of halothane oxygen anesthesia without surgery. Serum bilirubin, alanine aminotransferase, and aspartate aminotransferase significantly increased after anesthesia, which may indicate subclinical liver-cell damage. Creatine kinase of skeletal muscle origin increased above 90 U/liter in six subjects, indicating subclinical muscle-cell damage. Cortisol, triiodothyronine uptake, thyroxine, and free thyroxine index increased significantly immediately after anesthesia. Serum bromide concentrations had increased by fivefold on the second day after anesthesia, and on the ninth day was still elevated fourfold. Oral temperatures increased 0.7 degrees C 6 h post-anesthesia, possibly because of increased thyroxine activity. Lactate dehydrogenase, hydroxybutyrate dehydrogenase and gamma-glutamyltransferase activities did not change significantly. No drugs administered during the course of this study chemically interfered with any of the test methods used.
Clin Chem 1976 Feb
PMID:Effect of halothane anesthesia on muscle, liver, thyroid, and adrenal-function tests in man. 0 91

This review illustrates current approaches to the study of the disposition in man of the strong analagesics morphine and methadone and the narcotic antagonist naloxone. Morphine administered orally is rapidly absorbed but equally rapidly metabolised to morphine glucuronide. This contributes to the diminished oral efficacy of morphine. Following intramuscular administration morphine is very rapidly absorbed. After intravenous injection, the serum levels of morphine during the first 10 minutes are higher and more variable in older patients. The half-life of morphine between 20 minutes and 6 hours is 2 to 3 hours and this value does not appear to be influenced by the age of the patient. Similar half-lives for morphine have been reported to normal volunteers and in anaethetised patients who received morphine. Thus, surgical anaesthesia may not markedly influence morphine half-life and disposition. Based on urinary excretion data in man, accelerated morphine metabolism and excretion do not contribute to morphine tolerance. Methadone is now widely used in the treatment of narcotic abuse. The half-life of methadone averages 25 hours. The prolonged retention of methadone in the plasma may be related to its extensive binding to plasma proteins. With chronic dosing, studies in both animals and man indicate an increase in the metabolism of methadone. Unlike morphine, the urinary excretion of methadone increases with acidification of the urine. Women may metabolise methadone to a greater extent than do men. With the exception of pupillary effects, the plasma levels of methadone correlate poorly with its pharmacological activity. There is a marked variation in methadone plasma levels between patients and within the same patient. Naloxone rapidly disappears from the serum in man and the initial distribution phase has a half-life of 4 minutes. The half-life of naloxone in serum following distribution is 64 minutes. Based on animal studies, the rapid onset of the narcotic antagonist action of naloxone can be related to its rapid entry into the brain, whereas its potency stems in part from its high lipid solubility which allows a high brain concentration to be achieved. The short duration of action of naloxone may result from its rapid egress from the brain.
Clin Pharmacokinet 1976
PMID:The relationship of pharmacokinetics to pharmacological activity: morphine, methadone and naloxone. 1 57

The anesthesiologist uses a wide spectrum of drugs, including inhalational general anesthetics, barbiturates, benzodiazepines, narcotics analgesics and their antagonists, and neuromuscular blocking drugs. All of these drugs in sufficient dose impair the ventilatory response to chemical stimuli, and may cause inadequate gas exchange. The effect of depression of ventilatory control depends on the magnitude of depression and the coexistence of functional abnormalities in the respiratory system. The functional abnormalities are the result of preexistent pulmonary disease or other disease processes that impair respiratory function, the anticipated effects of major surgery (e.g., pulmonary resection), and the complications of anesthesia and surgery. From a functional viewpoint, the mechanisms of the effects of these disease processes on ventilatory control are: (1) interference with the neurophysiological control of automatic ventilation; (2) impairment of peripheral or central chemoreceptor function; (3) impairment of respiratory muscle function; (4) increase in the mechanical load to breathing as a result of increased resistance or decreased compliance of the respiratory system; and (5) increase in the ventilatory requirements as a result of ventilation/blood flow maldistribution, metabolic acidosis, or increased metabolic rate. As a result of current trends in the use of multiple drugs and controlled ventilation during anesthesia, the patient is at greatest risk during the early postoperative period in the recovery room. In addition to the functional abnormalities described above, the probability of impaired gas exchange and respiratory failure is increased as a result of impaired metabolism and elimination of drugs as a result of hepatic and renal insufficiency, and acute changes in acidbase status, which alter the ionization and distribution of drugs.
Int Anesthesiol Clin 1977
PMID:The effects of anesthetic drugs and disease on the chemical regulation of ventilation. 1 49

The cardiovascular effects of total hip placement were evaluated in 10 surgical patients, aged 55 to 82, while receiving fluroxene-N2O-O2 anesthesia. The anesthetic regimen caused mild cardiovascular depression. The placement of the acrylic cement into the acetabulum and femoral shaft also induced mild cardiovascular depression, but these changes were not significant at p less than 0.05. In one 67-yr-old woman, there were significant reductions of cardiac output and stroke volume 2 min after the insertion of acrylic into the femoral shaft, despite careful replacement of intravascular loss and careful anesthetic management. Methylmethacrylate (1 X 10(-6) to 1 X 10(-4), v/v) was administered to 24 isolated perfused rabbits hearts. These concentrations of methylmetacrylate are of the same order as measurable blood levels in surgical patients. There was a dose-dependent depression of left ventricular dP/dt correlated with a depression of the spontaneous heart rate. When the bradycardia was prevented by electrically pacing the hearts or the administration of atropine, the depressed dP/dt rose to control levels. Reduction in myocardial temperature and heart rate by means of reduction in perfusate temperature of the isolated hearts reduced the myocardial depressant effect of methylmethacrylate.
Clin Pharmacol Ther 1977 Jun
PMID:Cardiovascular effects of total hip placement in man. With observations on the effects of methylmethacrylate on the isolated rabbit heart. 1 17

After four decades of intense and competitive research, three hypothalamic releasing hormones (formerly factors) have recently been isolated and characterized. These are the decapeptide gonadotrophin releasing hormone (GnRH), tripeptide thyrotrophin releasing hormone (TRH), and the tetradecapeptide somatostatin. Some aspects of these hormones are discussed, and GnRH is considered in greater detail to demonstrate the difficulties involved in fulfilling completely the criteria which determine whether a substance can be accepted as a physiological releasing hormone. A substance immunologically similar to GnRH is present in rat hypophysial portal vessel blood, but, while the amount of this substance released into the portal circulation can be increased significantly by electrical stimulation of the preoptic area, no significant changes occur during the oestrous cycle or after long-term castration. This may be due to interference with the normal secretion of GnRH by the trauma and anaesthesia which necessarily accompany exposure of the pituitary stalk. However, the possibility exists that our preconceived notions regarding the changes in plasma levels of releasing hormones under physiological conditions may be incorrect. Thus it seems likely that changes in the rate of secretion of thyrotrophin is effected by throid hormones modulating the responsiveness of the thyrotrophs to a steady input of TRH. Evidence is presented for the existence of a similar mechanism for gonadotrophin secretion, and the role of steroid hormones and the priming effect of GnRH in modulating the responsiveness of the gonadotrophs is considered. The intrinsic connexions of the hypothalamus, the role of the hypothalamic aminergic systems and the autonomy of the hypothalamus with respect to anterior pituitary control present many problems which will prove difficult to solve.
Clin Endocrinol (Oxf) 1976
PMID:The development of the releasing factor concept. 2 35

1. Pentobarbitone anaesthesia, in rabbits, produces (i) hypokalaemia, (ii) increased intracellular potassium and reduced intracellular sodium in cardiac and skeletal muscle. 2. These changes suggest that the hypokalaemia which accompanies anaesthesia results from movement of potassium between the extracellular and intracellular compartments.
Clin Sci (Lond) 1979 Dec
PMID:The effect of pentobarbitone on plasma and intracellular sodium, potassium and pH in rabbit cardiac and skeletal muscle. 4 7

Visually evoked response (VER) and EEG from the motor cortex (precruciate gyrus) and the visual cortex (marginal gyrus) of cats were recorded from 4 to 7 h after the injection of anesthetic doses of alpha-chloralose. During the recording period the VER from the precruciat gyrus showed a 200-300% increase in amplitude while the VER from the marginal gyrus rarely varied more than 50% in amplitude, and did so independent of the changes in the VER from the precruciate gyrus. The number of large amplitude spikes in the EEG from the precruciate gyrus also increased dramatically during the recording period, but no definite correlation between changes in VER amplitude and in the number of spikes in the EEG could be demonstrated. These observations suggest a functional separation between specific and nonspecific sensory pathways, with the latter showing a considerably greater sensitivity to level of anesthesia.
Electroencephalogr Clin Neurophysiol 1975 Aug
PMID:Chloralose induced alteration of visually evoked response from specific and non-specific regions of cat neocortex. 5 Feb 18

The effects of taurine on the direct cortical response have been studied in immobilized cats (with local analgesia). The primary negative component of the response was inverted in polarity by the topical application of 25 mM taurine while the later slow negative component was considerably augmented. These effects are identical to those observed with 25 mM GABA. Pentobarbital anesthesia produced little qualitative change in the effects of taurine. With stronger stimuli in the presence of taurine, rhythmic waves followed each stimulus both at the cortical surface and at a depth of 1000 mum. An increase in the EEG amplitude following topical taurine was generally localized to the cortical surface but in certain experiments, could be recorded at cortical depths up to 1000 mum.
Electroencephalogr Clin Neurophysiol 1975 Sep
PMID:Modification of the direct cortical response by taurine. 5 Feb 28

The effect of "task relevance" on early and late components of cortical and subcortical somatic evoked potentials (SEPs) was studied in a group of Parkinsonian patients operated on under local anesthesia for treatment of prominent unilateral tremor. 1. SEPs produced by median nerve stimulation were found at contralateral cortical (ss), thalamic (vcpci, vcai), lemniscal (Lm), postilemniscal (PoLm), prelemniscal (Raprl) and reticular (Ttc) regions. No SEPs were found in other contiguous thalamic (M,Pf, ce) and subthalamic (Q) regions. 2. Subcortical early SEP components consisted of two monophasic positive potentials distributed within a circumscribed thalamo-lemniscal region where electrical stimulation elicited consistent sensory responses circumscribed to contralateral hand and face. In contrast, subcortical late SEP components consisted of monophasic or polyphasic, positive or negative potentials distributed in a widespread, thalamic, lemniscal, prelemniscal and reticular region where elecrical stimulation elecited sensory or motor responses of various types. Subcortical early and late SEP components appeared together in lemniscal, thalamic and cortical regions but they wers separated at postlemniscal (only early) and prelemniscal and reticular ones (only late). 3. Significant amplitude changes in cortical and subcortical late SEP componets were found concomitant to variations in "task relevance": they decreased when patients shifted from novelty to habituation, they increased when patients shifted from habituation to attention and they decreased when patients shifted from attention to distraction. In contrast, no significant ampiltude changes in cortical and subcortical early components were found when patients shifted through these various "task relevance" conditions.
Electroencephalogr Clin Neurophysiol 1975 Oct
PMID:Differential effect of task relevance on early and late components of cortical and subcortical somatic evoked potentials in man. 5 18


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