Anesthesia and analgesia
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Anesthesia and analgesia · Jan 1979
Nitrous oxide increases enflurane concentrations delivered by Ethrane vaporizers.
Delivered enflurane concentrations from two calibrated Ethrane vaporizers were determined with total gas flows of 3,5 and 8 L/min. Regardless of total gas flow the presence of 60% nitrous oxide increased enflurane concentrations by 20 to 40% above those concentrations present when only oxygen was flowing through the vaporizer. This nitrous oxide effect was present at all dial settings studied except the lowest engraved (0.25) concentration. ⋯ A similar mechanism has been proposed to explain increased halothane concentrations delivered by Fluotec Mark 2 vaporizers in the presence of nitrous oxide. Clinically, central system stimulation and anesthetic overdose may occur from increased enflurane concentrations delivered when nitrous oxide is added to the gases flowing through the Ethrane vaporizer. The ability to deliver low enflurane concentrations is limited since the measured concentration at the lowest dial setting was nearly 0.4%.
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Anesthesia and analgesia · Jan 1979
Case ReportsHypotension and respiratory distress caused by rapid infusion of mannitol or hypertonic saline.
Following a case of mannitol-induced respiratory and circulatory collapse, the effects of hyperosmolar injections on pulmonary arterial pressure, systemic blood pressure, and cardiac output were studied in dogs. The injection of 20 ml of 10% NaCl into the pulmonary artery increased pulmonary arterial pressure and decreased systemic blood pressure by approximately 50% of control values. Injections of solutions of equal hyperosmolar strength, 50 ml of 25% mannitol or 50 ml of 4% NaCl into the pulmonary artery produced no significant elevation of pulmonary arterial pressure, but were associated with comparable decreases in systemic blood pressure. ⋯ After five to 10 injections, the decreases in system blood pressure with any of the solutions and the increases in pulmonary arterial pressure with 10% NaCl disappeared and further injections were without effect. It is concluded that adminstration of mannitol probably does not cause pulmonary edema due to fluid overload, nor does it cause heart failure as evidenced by increases in pulmonary arterial pressure. However, rapid injection may cause a fall in blood pressure and may on occasion be accompanied by bronchospasm, especially in sensitive subjects.
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Anesthesia and analgesia · Jan 1979
Historical ArticleAnesthesia and the development of surgery (1846-1896).
The hypothesis that the introduction of anesthesia in 1846 accelerated the development of surgery was tested by compiling statistics on the types of operations performed in this country and abroad in the absence of anesthesia (prior to 1846) and over the 50-year period after 1846. Prior to 1846, surgery involved the extremities and superficial parts of the body almost exclusively. ⋯ The introduction of anesthesia was necessary before surgery could advance, but control of infection, establishment of the sciences of pathology and physiology, and development of professionalism in clinical medicine and surgery based on research and teaching were also required. Almost a half-century lapsed after the introduction of anesthesia before surgery advanced significantly beyond the stage it was at prior to the introduction of anesthesia in 1846.