摘要:

In human volunteers, Forane failed to alter twitch height, but increased average neuromuscular refractory period and prevented a sustained response to stimulation at higher frequencies of tetanus. These effects were dose-related. Surgical patients anesthetized with 1.25 MAC Forane were unable to sustain tetanus at more than 120 Hz. In contrast, patients anesthetized with 1.25 MAC halothane were able to sustain tetanus at 200 Hz. In 15 patients anesthetized with 1.25 MAC Forane, the median effective dose ofd-tubocurarine needed to produce a 50 per cent depression of twitch height (ED50) was 1.70 mg/m2. In contrast, the ED50ofd-tubocurarine in 17 patients anesthetized with 1.25 MAC halothane was 5.69 mg/m2. Thus, 3.3 times as muchd-tubocurarine was needed to produce a 50 per cent depression of twitch height with halothane.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

Hepatic metabolism of halothane, methoxyflurane, cyclopropane, Ēthrane, and Forane was studied in miniature swine, using a modification of a technique which demonstrated that the liver extracts (metabolizes) a greater fraction of halothane from hepatic blood flow at lower than at higher anesthetic partial pressures. Animals were exposed to constant, low subanesthetic concentrations of each anesthetic for periods of 20 hours to one week and measurements of extraction made thereafter. We found considerable hepatic metabolism of halothane and methoxyfiurane, little or none of Ēthrane, and none of cyclopropane or Forane. These results may be related to toxicity since toxic effects of inhalation anesthetics may be due to their metabolites.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The effect of Forane on epinephrine-induced cardiac arrhythmias was tested in dogs by comparing it with halothane and fluroxene. The doses of epinephrine necessary to produce two or more premature ventricular contractions at 1.25 and 2.0 MAC and at Paco2's of 20, 40, and 80 torr were determined. Only 14 to 22 per cent as much epinephrine as in the awake state was needed to produce arrhythmias during halothane anesthesia. The amounts of epinephrine which induced arrhythmias during fluroxene and Forane anesthesia did not differ from the values in awake animals, With Forane, production of arrhythmias required progressively more epinephrine as Paco2increased. With halothane and fluroxene, the same trend was present, but it was not significant. As depth of anesthesia increased, more epinephrine was needed to produce arrhythmias with all agents tested.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The effects of halothane on renal function and consumption of oxygen (&OV0312;o2) have been studied in dogs, with and without diuresis. With diuresis induced by a variety of intravenous solutions and infusion rates, urinary flow rates during halothane anesthesia were relatively low and urine had an osmolality approximately twice that of plasma. Increasing halothane had little effect on this or other aspects of renal function, including glomerular filtration rate, renal blood flow, and the relation between tubular reabsorption of sodium and nonbasal renal &OV0312;o2. Approximately 28 equivalents of sodium were reabsorbed per mole of nonbasal oxygen consumed, which is the value observed by others in a variety of other situations. Conditions of the nondiuresis situation were similar to those under which whole-body, myocardial, cerebral, and skeletal muscle &OV0312;o2previously were demonstrated to be decreased with increased halothane. Renal &OV0312;o2in this situation was 7 to 8 per cent of whole-body &OV0312;o2and was little changed by increasing halothane from 0.1 to 1.5 per cent.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The effects of 0.5 and 1.5 per cent (end-tidal) halothane on the pulmonary circulation in the anesthetized dog were studied by measurement of left atrial pressure, pulmonary arterial pressure, and total pulmonary blood flow. Halothane, 1.5 per cent, decreased pulmonary arterial pressure and flow, while computed pulmonary vascular resistance remained unchanged. In order to establish whether halothane has a direct effect on the pulmonary vascular bed, the left diaphragmatic lobe was isolated from the pulmonary circulation and perfused at a constant rate with blood from an external oxygenating circuit. When halothane was added to the external circuit a sustained decrease in perfusion pressure occurred, indicating that pulmonary vascular resistance had decreased. In the same experiments when halothane was administered to the dog by inhalation no change in perfusion pressure occurred in the lobe. Thus, by a direct action on pulmonary vascular smooth muscle, halothane is capable of producing vasodilatation, which is masked in the intact animal by the decrease in pulmonary arterial pressure and/or the action of a circulating vasoconstrictor substance.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

To obtain further information about the neuronal mechanisms involved in the state of anesthesia, long-term microelectrode recording of activity in the mesencephalic reticular formation in the cat was undertaken. Results were subjected to computer analysis. In most units in the mesencephalic reticular formation (32 of 37 studied) spontaneous firing rates decreased as anesthesia deepened. However, the susceptibility of the spontaneous activity of the units to depression by anesthetic agents varied widely from unit to unit. Two types of changes in spontaneous firing patterns were produced by anesthetics: the “grouping” type and the “tonic” type. The “grouping” pattern was seen more often during sodium thiopental and halothane anesthesia, whereas the “tonic” type was more characteristic of nitrous oxide and diethyl ether anesthesia. In two of 37 units, synchronization between mesencephalic reticular formation unit firings and sharp positive waves of the corticogram was observed during the deep stage of sodium thiopental anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID

摘要:

The differential effects of anesthetics on unitary behavior of the cat's mesencephalic reticular formation in response to repetitive electrical stimulation of the skin were studied by means of longterm microelectrode recording and computer analysis. In most units the anesthetics decreased the total number of firings in response to repetitive electrical stimulation of the skin. However, the ratio of evoked to spontaneous activity varied from unit to unit. Generally, the ratio was highest with sodium thiopental, and lowest during diethyl ether anesthesia. Evoked activity was easily distinguished from background activity during sodium thiopental and halothane anesthesia, but hardly distinguishable during diethyl ether anesthesia. The poststimulus times of short-latency discharges were hardly affected by the anesthetics in most units until the units ceased to respond to stimulation. In contrast, long-latency discharges were easily affected by anesthetics.

ISSN:0003-3022    

出版商:OVID    

年代:1971

数据来源: OVID