Articles: anesthetics.
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Anesthesia and analgesia · Jul 1982
Pharmacokinetics of inhalation anesthetics: a three-compartment linear model.
The evolution of mathematical models of the uptake of the inhaled anesthetic agents has produced increasingly complex models in which researchers have attempted to incorporate more and more data on the effects of anesthetics on the processes of respiration, circulation, and metabolism. One result of this evolution has been to limit the application of these models due to the large amount of data required by the model and the need for a large digital computer to generate a solution. ⋯ Only a programmable hand calculator is needed for the solution. Due to the simplicity of this model, compared with previously described models, it should prove useful in understanding the kinetics of gas uptake by the body.
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Comparative Study Clinical Trial Controlled Clinical Trial
Control of breathing after fentanyl and Innovar anaesthesia.
Ventilation (VI), end-tidal (PCO2), mixed venous (PvCO2) and the ventilatory response to carbon dioxide were measured before surgery, and during the first 4 h of recovery in 18 adult patients who underwent elective limb surgery under fentanyl or Innovar anaesthesia. End-tidal and mixed venous PCO2 were increased significantly in the first 150 min after the last dose of drug (P less than 0.001, P less than 0.01), but had returned to control values by 4 h. ⋯ This suggests that patients with a low value of VI/PCO2 are not more susceptible to the ventilatory depressed action of narcotic anaesthetics. Recovery of ventilatory responsiveness towards normal during the 4 h after anaesthesia, occurred in a graded and progressive manner, there was no evidence of a biphasic pattern of recovery.
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If the anaesthetic circle system is arranged to increase the humidity of fresh anaesthetic gases by placing the carbon dioxide absorbent canister between the fresh gas inlet and the patient, drying of the soda-lime can occur. Very dry soda-lime adsorbs significant quantities of halothane. Using fresh soda-lime, effluent halothane concentration reached 50% of the input concentration in 35s, but this time increased to 500 s when dry soda-lime was used. The use of dry soda-lime can result in a slow inhalation induction or in the release of absorbed halothane during a subsequent anaesthetic.
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Naunyn Schmiedebergs Arch. Pharmacol. · May 1982
Hydrophobic membrane interaction of etidocaine, bupivacaine and 2-chloroprocaine. A spin and fluorescent probe study.
It has been suggested that local anesthetics may block sodium conductance through nervous membranes also by hydrophobic interaction, e.g., by expanding the membrane. Decreased anisotropy (fluidization) and depressed phase transition temperatures have been shown by relatively high local anesthetic concentrations. We studied the dose dependence of the effect of three clinically used local anesthetics, with different lipid solubility, on lipid fluidity parameters of four different model membranes. ⋯ The effect was most marked with bupivacaine (1-10 mM) when cis-parinaric acid was used. While isolated mammalian nerves are blocked by local anesthetic concentrations below 100 muM, this study shows that the clinically used local anesthetics increase fluidity and depress phase transition temperature only at 10-100 times higher concentrations at physiological pH. This kind of hydrophobic membrane interaction may not be important for the nerve blocking effect.