ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Seventeen patients were studied in the supine position during spontaneous ventilation to determine whether the decrease in functional residual capacity (FRC) during general anesthesia was associated with an increase in trapped gas (VTG). Preoperatively, FRC and VTG were measured by modifying the closed-circuit helium technique. Closing volume (CV) was also measured. Measurements of FRC and VTG were then made 20 and 60 minutes after induction of anesthesia. FRC was reduced during anesthesia. Mean VTG was 0.43 per cent of total lung capacity (TLC) before anesthesia, and increased significantly (P<0.001) to 3.03 per cent of TLC 20 minutes after induction. At 60 minutes, VTG decreased to 1.6 per cent TLC. VTG was increased when CV exceeded FRC. The authors conclude that the increase in VTG was a major contributory factor in the alteration of gas exchange during anesthesia.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Effects of maintained airway positive pressures of 5 and 10 cm H2O on standard lung volumes and on closing volume (CV, the lung volume at which airway closure begins) were studied in ten healthy volunteers 24 to 47 years old, in the seated and supine positions. Positive pressures were achieved using a weighted bell spirometer. During breathing with 10 cm H2O pressure FRC's increased 1.78 I (seated) and 1.64 I (supine) above the FRC's at ambient pressure. CV increased with added pressures, but to a lesser extent than FRC In the seated subjects the differences between FRC and CV (FRC— CV) were 1.00 I (ambient), 1.02 I (5 cm H2O) and 2.31 I (10 cm H2O), while in supine subjects they were 0.14 I (ambient), 0.43 I (5 cm H2O), and 1.12 I (10 cm H2O). This relationship of FRC to CV, previously shown to be an important determinant of pulmonary gas exchange, was thus favorably affected by breathing with maintained airway pressures, suggesting one explanation for the observed clinical benefit of such maneuvers.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

In 15 patients anesthetized with Forane and in an additional 15 patients anesthetized with Forane and nitrous oxide, the authors found that surgical stimulation induced increases in ventilation which significantly reduced PaCO2The mean reductions in CO2from control values prior to surgical stimulation ranged from 5 to 13 torr, the magnitudes being similar in the two groups and for all depths of anesthesia. The reductions were sufficient to cause all average CO2values to be less than 50 torr even at deep levels of anesthesia. Prior to operation, the respiratory depression for a given anesthetic concentration appeared to be somewhat greater when Forane was given without nitrous oxide.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The effects of several anesthetics on the responsiveness of thalamic relay nuclei, the nucleus centrum medianum (CM) and the nucleus ventralis posterolateralis (VPL), were studied in gallamine-immobilized cats with electrodes chronically implanted in their brains. Spontaneous activity and activity evoked by stimulation of the skin were monitored by recording multiple-unit activity (MUA). Halothane decreased MUA, cyclopropane enhanced it, and ketamine produced a change in the spontaneous firing pattern. Nitrous oxide and ether produced no consistent change. All agents produced depression of evoked activity. The depression was more profound in the CM than in the VPL. The anatomic basis for this difference is discussed.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

In a series of 21 experiments, 13 large mongrel dogs anesthetized with sodium pentobarbital were ventilated with constant concentrations of ethylene (1.4 per cent), cyclopropane (0.9 per cent), halothane (0.6 per cent) and diethyl ether (0.7 per cent). More than 15,000 measurements of alveolar gas, arterial blood, brain, muscle, and central venous blood concentrations of the anesthetics were made by gas chromatography and compared with concentrations predicted by a relatively simple mathematical model. The model was found to be capable of predicting actual anesthetic concentrations with an average error of ±11.4 per cent. The error did not vary significantly under conditions of increased alveolar ventilation or decreased cardiac output. The average prediction was 5.9 per cent higher than the average actual concentration, suggesting a loss of anesthetic by diffusion or metabolism, or both, which is not accounted for by the model. The demonstrated ability of the model to predict anesthetic uptake and distribution suggests that such a model may eventually be used for predicting and controlling anesthetic uptake during surgery.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Dose-related nephrotoxicity after administration of methoxyflurane was demonstrated in rats of the Fischer 344 strain. This was characterized by Pitressin-resistant polyuria, hypernatremia, serum hyperosmolality, and increased serum urea nitrogen and inorganic fluoride concentrations. Urinary sodium, potassium, osmolality, and urea nitrogen concentrations were decreased in proportion to the dose administered. Light and electron microscopic changes were most prominent in the proximal convoluted tubules and were also dose-related. Injection of inorganic fluoride produced changes in renal function and histology similar to those seen after administration of methoxyflurane. It was concluded that methoxyflurane produced dose-related nephrotoxicity due to increased concentrations of its metabolite, inorganic fluoride.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

The effect of halothane on the ability of human serum albumin to bind the dye, 2-(4' hydroxyazobenzene)benzoic acid, was studied. This test correlates closely with the capacity of albumin to bind bilirubin. The effect of bilirubin on the solubility of halothane in human albumin solutions was also studied. Halothane in a concentration of 15 mg/100 ml caused a small but significant increase in dye-binding by 4 g/100 ml human albumin solutions. Gamma-globulin did not bind dye, with or without halothane present. Bilirubin did not alter the solubility of halothane in albumin solutions.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID

摘要:

Using the frog sartorius muscle preparation,d-tubocurarine in concentrations between 10-12and 10-12g/l was found to increase miniature endplate potential (MEPP) frequency with no effect on MEPP amplitude. The agent at 10-10g/l was able to increase the twitch height of the submaximally stimulated muscle preparation. Between 2.5 X 10-5and 5 X 10-7g/l, it decreased MEPP frequency and twitch height of indirectly-stimulated muscle preparations to 10 per cent of control. At the latter doses, MEPP amplitude and sensitivity to iontophoretically-applied acetylcholine were reduced by only about 40 per cent. At this degree of depression of endplate sensitivity, the ability of postjunctional membrane to generate an action potential is unaltered. It is believed that the primary blocking effect ofd-tubocurarine is presynaptic.

ISSN:0003-3022    

出版商:OVID    

年代:1972

数据来源: OVID