Articles: general-anesthesia.
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Rev Electroencephalogr Neurophysiol Clin · Jan 1977
[An examination of current techniques in anaesthesia (author's transl)].
The techniques of general anaesthesia may be divided into 2 major groups: those used in very brief surgical or diagnostic operations and those used in longer and more pain-producing interventions. The former normally involve a single drug which is very short-acting and allows consciousness to be recovered rapidly and well. The latter are anaesthetics using several drugs together, which allows very precise control of the degree of analgesia, neuro-vegetative protection, muscle relaxation and sleep. ⋯ E. G. remains a technique of choice for studying recovery, and any sequels of hypoxia during the operation. This should, of course, be accompanied by a clinical evaluation which is particularly important in assessing the state of ventilation (residual curarisation, depression by central analgesics).
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Serial invasive and noninvasive (systolic time interval) measurements of left ventricular performance were obtained in six healthy volunteers during general anesthesia employing the following sequence: thiopental induction, succinylcholine (prior to endotracheal intubation), and halothane--100 per cent oxygen at 1.25 and 1.75 MAC. Heart rate (HR), mean pulmonary arterial "wedge" pressure (PAW) and mean systemic arterial pressure (MAP) were measured continuously; cardiac index and systolic time intervals (STI's) were measured during each intervention. At both levels of halothane, MAP and stroke work index decreased (both P less than 0.02), while HR and systemic vascular resistance did not change. ⋯ This intervention resulted in a greater depression of cardiac performance than that observed at 1.75 MAC halothane alone. Although alterations in STI's were directionally similar to changes observed in invasive hemodynamic measurements, STI's were sensitive to acute alternations in loading conditions. It is concluded that the levels of halothane commonly employed for general anesthesia significantly depress left ventricular performance in normal subjects, as evidenced by abnormal responses to alterations in preload and afterload, and that STI's should not be employed for routine measurement of left ventricular performance during anesthesia unless both the afterload and the preload on the myocardium are known.