Anesthesia and analgesia
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Anesthesia and analgesia · Sep 1989
Randomized Controlled Trial Comparative Study Clinical TrialEffects of thoracic epidural anesthesia on systemic hemodynamic function and systemic oxygen supply-demand relationship.
The effects of thoracic epidural anesthesia (TEA) on total body oxygen supply-demand ratio are complex due to potential influences on both O2 delivery (QO2) and consumption (VO2). One hundred and five patients undergoing abdominal aortic surgery were randomly assigned to one of three groups to compare the cardiovascular and metabolic responses associated with (1) thoracic epidural anesthesia plus light general anesthesia (group TEA); (2) general anesthesia with halothane (group H); and (3) neuroleptanalgesia (group NLA). Values of cardiac index (CI) and QO2 were less intraoperatively in the TEA group than in the H or NLA groups, while VO2 values were similar. ⋯ Heart rate was slowest intraoperatively during TEA, and stroke work was less with TEA than with NLA. As cardiac filling pressure and systemic vascular resistance did not differ among the three groups, reduced adaptation of CI to tissue O2 needs during TEA was attributed to negative inotropic and chronotropic effects of the sympathetic blockade. We conclude that in patients undergoing abdominal aortic surgery, TEA has no apparent advantage over general anesthesia.
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Anesthesia and analgesia · Sep 1989
The effects of airway impedance on work of breathing during halothane anesthesia.
Humidifiers and small diameter endotracheal tubes placed in the airway circuit increase the impedance to breathing. The effect of such impedances on the work of breathing and respiratory patterns was studied in eight healthy adult patients (60-80 kg) anesthetized with 1 and 2 MAC halothane in oxygen. A Cascade Humidifier and Portex Humid-Vent (dry and water saturated) were evaluated while patients breathed through an 8.0-mm endotracheal tube. ⋯ At 1 MAC the Cascade Humidifier and the wet Humid-Vent when used with the 8.0-mm tube increased the work of breathing to 86.8 ml and 76.8 ml, 77% and 70% above baseline levels of 48.1 ml, whereas the 6.0-mm tube without the humidifiers increased work 89% to 78.9 ml. Tidal volume and respiratory frequency were unchanged throughout the study, although inspiratory time was prolonged. Lightly to moderately anesthetized healthy adult patients are able to maintain minute ventilation despite the impedance associated with commonly used humidifiers by significantly increasing work of breathing.
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Around World War I, American novelist Theodore Dreiser wrote several plays, one of which, "Laughing Gas," explores the odd experience of a physician undergoing surgery with nitrous oxide/oxygen anesthesia. The content of this play and its relationship to Dreiser's career are examined.