ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The presence of two volatile halothane metabolites, 2-chloro-1,1,1-trifluoroethane (CF3CH2Cl) and 2-chloro-1,1-difluoroethylene (CF2CHCl), and a metabolite-decomposition product, 2-bromo-2-chloro-1,1-difluoroethylene (CF2CBrCl), were identified by gas chromatography—maas spectrometry in exhaled gases of 16 patients anesthetized with halothane in nonrebreathing, semiclosed and totally closed anesthesia circuits. No significant differences in concentrations of CF3CH2Cl and CF2CHCl were found relative to the anesthesia circuits used. CF2CBrCl could not be identified in the expired gases of patients anesthetized with a nonrebreathing circuit (Bain), but was present in gases recovered from both semiclosed and totally closed circuits. Under totally closed-circuit rebreathing conditions, the concentration of CF2CBrCl increased to 4–5 ppm, indicating significant breakdown of halothane by the soda lime. Possible pathways for formation of the two metabolites and the metabolite—decomposition product are presented, as well as clinical implications of these findings.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

1,1-Difluoro-2-bromo-2-chloroethylene, a probable metabolite of halothane, was purified by preparative gas chromatography and tested for mutagenicity in theSalmonella/mammalian liver system developed by Ames and colleagues, 1,1,1-Trifluoro-2-chloroethane which had been isolated from the breath of rabbits anesthetized with halothane was also tested for mutagenicity in a similar manner. Both comppounds were found to be nonmutagenic in this bacterial system. Although neither this study nor any other has yet been able to demonstrate that halothane or any of its metabolites is genetically active, nevertheless, unnecessary occupational exposure to the drug should be avoided due to the possibility that future studies could reveal adverse effects secondary to halothane.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Fentanyl is often used as an anesthetic supplement for short procedures because it has a rapid onset and brief duration of action. However, persistence of ventilatory depression several hours following the last dose has been seen. The authors studied the pharmacokinetics of fentanyl in the dog to find an explanation for the occasionally prolonged duration of action.3H-fentanyl citrate, 10 or 100 μg/kg, was injected intravenously is dogs anesthetized with enflurane—O2. Arterial plasma and urine were analyzed for unchanged3H-fentanyl and for total3H radioactivity. Kinetic indices were derived by nonlinear least-squares analysis of log concentration (ng/ml)vs.time relationships. Initially, the elimination of fentanyl from plasma was very rapid, and 98 per cent of the amount administered was removed from plasma in the first 5 min after an intravenous injection. However, the terminal elimination phase was prolonged (t1/2= 199 ± 17 min). The apparent volume of distribution was large (9.8 1/kg) and independent of dose. Repetitive doses produced an accumulation of fentanyl.3H-labelled metabolites of fentanyl were present in the earliest samples of plasma, and accounted for the major portion of the total3H radioactivity in both plasma and urine. Urine collected for six hours contained 36 per cent of the total3H radioactivity administered, but only 4 per cent of fentanyl administered was excreted as unchanged fentanyl. The authors conclude that most of a single dose of fentanyl is rapidly eliminated from plasma (and presumably brain) by biotransformation to inactive metabolites and by uptake of the active drug by body tissues. The high affinity of tissues for fentanyl limits the rate of its ultimate elimination from the body by biotransformation and leads to accumulation of the drug when administered in very large or repeated doses. Under these circumstances the slow release of drug from tissues results in persistent plasma levels of fentanyl and a prolonged duration of action.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Forty patients with chronic pain below the waist level were evaluated in a multidisciplinary pain clinic using a refined differential spinal block (DSB) technique. The refinements consisted of verbal instructions to prevent biasing the patients, coupled with a thorough evaluation of verbal and physiologic responses to the block. When demographic and psychologic data were assessed according to pain mechanisms, a pattern of patient groups emerged along a chronic pain continuum. Stress, anxiety, depression, and hysteria, as well as the neurophysiologic and demographic factors, modified the responses to the DSB. Long-term follow-up of these patients, including repeat DSB procedures and confirmatory anatomic blocks of sympathetic and somatic nerves, validated these impressions. The findings indicate a link between pain mechanisms and psychosocial factors that may directly influence responses to DSB.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Central and peripheral pulmonary mucociliary clearance was assessed by tantalum bronchography and serial chest roentgenograms in dogs. Thiopental, 25 mg/kg, did not change clearance from awake values. Halothane, 1.2 MAC, for six hours, delayed both central and peripheral clearance by at least three hours. After halothane or diethyl ether, 1.2 MAC, for two hours, recovery of mucociliary clearance was delayed for approximately three and a half hours.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Transient hypotension has been observed in patients after rapid intravenous administration of mannitol, 25 per cent, in clinical doses. These studies were conducted to determine the mechanism for the hypotension, to determine dose and rate of injection response curves in rabbits, and to determine which vascular beds were most reactive. Studies in six patients showed mean decreases in blood pressure of 23 ± 6.0 per cent (±SE) and in total peripheral resistance of 38 ± 7 per cent after infusion of mannitol. Studies in 18 patients during cardiopulmonary bypass with mechanically fixed cardiac output demonstrated decreases in mean blood pressure of 30 ± 5 to 40 ± 3 per cent, depending on dose and rate of administration of mannitol. Patients not on bypass compensated for large decreases in total peripheral resistance by increases in cardiac output (3.6 ± .4 at baseline to 4.4 ± .4 1/min) during mannitol-induced hypotension with no change in heart rate. Serum osmolality increased as blood pressure decreased. Significant but clinically unimportant decreases in sodium and potassium ions, hemoglobin,pH, and base excess values were observed. Studies in 18 rabbits showed that the greater the dose or rate of injection of mannitol the greater the decrease in blood pressure. Injection of radiolabeled microspheres in rabbits demonstrated a near doubling of blood flow to skeletal muscle tissue during the hypotension. This occurred with both equiosmotic hypertonic glucose (17 ± 3 to 32 ± 7 per cent) and mannitol (17 ± 1 to 31 ± 5 per cent), but not after isotonic saline solution. Changes in blood flow to other organ beds were variable and unimportant. The results suggest that hypotension following the intravenous administration of hyperosmotic solutions is due primarily to vasodilation in skeletal muscle.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

Hypotension may be expected to produce less perturbation of metabolism in the brain when cerebral metabolic rate is lowered by deep anesthesia. Male Wistar rats having unilateral carotidartery ligation were exposed to mean arterial pressure (MAP) of 40 torr for 20 min by an intravenous infusion of trimethaphan during anesthesia with halothane, 0.6 or 2 per cent, in oxygen. Cortical tissue metabolite levels on the side of the ligated carotid artery were more abnormal in rats receiving halothane, 0.6 per cent, than in those receiving halothane, 2 per cent. Values at halothane, 0.6 per cent, were adenosine triphosphate (ATP), 1.71 ± 0.05 (±SEM) μmol/g, phosphocreatine (PCr) 1.97 ± 0.07 μmol/g, and lactate 16.5 ± 5.1 μmol/g; corresponding values at halothane, 2 per cent, were ATP 2.27 ± 0.02, PCr 4.02 ± 0.23, and lactate 4.75 ± 0.9 μmol/g. ATP and PCr values were significantly lower (P< 0.05) and the lactate value was significantly higher with halothane, 0.6 per cent, than with halothane 2 per cent. Cerebral oxygen consumption decreased 47 percent in rats anesthetized with halothane, 2 per cent. Preservation of cortical metabolite levels in deeply anesthetized animals suggests a protective effect of cerebral metabolic depression.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The potencies of metocurine andd-tubocurarine for neuromuscular and autonomic blockade and histamine release were determined in cats anesthetized with chloralose and pentobarbital. The autonomic margins of safety of these drugs were determined by measuring the ratios of ED50for sympathetic block to ED95for for neuromuscular block; ED50for vagal block to ED95for neuromuscular block; ED50for histamine release to ED95for neuromuscular block. Metocurine is 14 times more potent thand-tubocurarine as a neuromuscular blocking agent in the cat, but its autonomic blocking action is three times weaker than that ofd-tubocurarine and its histamine-releasing action is less than half that ofd-tubocurarine. The combination of higher neuromuscular blocking potency and weaker autonomic effect gives metocurine a much higher autonomic margin of safety thand-tubocurarine in the cat.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID

摘要:

The effects of halothane and enflurane on the polarographic measurement of oxygen with five platinum and three gold micro-electrodes were examined. Oxygen microelectrodes were calibrated in saline solution equilibrated with either nitrogen (N2) or air, then either halothane, 1.0 per cent, or enflurane, 2.0 per cent, was added to the gas mixture. For each electrode, polarographic curves were determined during exposure to five equilibrating gas mixtures: N2, air, N2plus halothane, air plus halothane, and N2plus enflurane. Halothane variably increased the current produced (and therefore the estimated oxygen tension) at all polarizing voltages in saline solution equilibrated with either N2or air. The effect was present in both conical platinum electrodes and recessed-tip gold electrodes and was not prevented by membrane coatings of polystyrol, Rhoplex or collodion. Enflurane did not alter the polarographic measurement of oxygen. It is concluded that tissue oxygen tension measurements, made with these microelectrodes and membranes, may be unreliable in the presence of halothane.

ISSN:0003-3022    

出版商:OVID    

年代:1979

数据来源: OVID