Articles: general-anesthesia.
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Comparative Study
EEG Predicts movement response to surgical stimuli during general anesthesia with combinations of isoflurane, 70% N2O, and fentanyl.
Our objective was to evaluate the performance of the EEG as an indicator of anesthetic depth by measuring EEG prediction of movement response to surgical stimuli. ⋯ The EEG, expressed as F95, predicted movement response to surgical stimuli during combinations of isoflurane, 70% N2O, and fentanyl. The F95-response curves shifted upward on the frequency scale for the less intense stimuli and for anesthetic techniques using 70% N2O, fentanyl, or both. F95 prediction of movement response appeared to be related to anesthetic agent doses. Our F95-response curves may provide helpful guidelines for using F95 to titrate the administration of anesthetic agents and for assessing the depth of general anesthesia.
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Clinical Trial Controlled Clinical Trial
Laryngeal mask airway performance: effect of cuff deflation during anaesthesia.
We studied the effect of deflating the laryngeal mask airway (LMA) cuff in situ on recorded respiratory tidal ventilation in 30 spontaneously breathing anaesthetized patients. Another 26 patients were studied in whom the LMA cuff was undisturbed. ⋯ Complete cuff deflation, however, resulted in a 17% decrease in mean tidal ventilation (P < 0.05), with two patients (6%) demonstrating a substantial leak around the cuff and airway obstruction. The practice of complete cuff deflation during the recovery period from anaesthesia cannot be recommended.
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We have compared cardiorespiratory variables in anaesthetized piglets whose lungs were ventilated with oxygen in nitrous oxide (N2O group) or nitrogen (N group) after right ventricular carbon dioxide boluses (0.5 or 1 ml kg-1; n = 12) or slow graded injections (n = 6). Boluses affected all variables studied significantly (P < 0.05) except mean systolic arterial pressure. Significant changes in PE'CO2 (P = 0.012) and PaO2 (P = 0.048) values were observed in the N2O group. ⋯ Volumes and time required to induce a 50% increase in mean pulmonary arterial pressure differed significantly between groups (P < 0.05). We conclude that nitrous oxide worsened the effects of rapid and slow carbon dioxide emboli on cardiopulmonary variables. Rapid carbon dioxide embolism altered respiratory and haemodynamic variables, while slow carbon dioxide embolism changed only respiratory variables.
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To test whether a neural network-based method could differentiate between tracheal and esophageal intubation in anesthetized patients by recognizing breathing circuit pressure and flow waveform patterns. ⋯ A neural network differentiated consistently tracheal from esophageal intubation when the ventilation test mode was used. The ventilation mode employed is feasible in most adult patients undergoing elective procedures under general anesthesia. Further research is required to train neural networks to recognize esophageal intubation in different age groups and when different ventilation modes are applied.
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Mivacurium is a short-acting nondepolarising muscle relaxant of the benzylisoquinoline type undergoing rapid breakdown by plasma cholinesterase. With 2.5 fold ED95, tracheal intubation can be accomplished within 2-3 min following injection. The ensuing DUR 25% (i.e. time from injection to 25% recovery of control twitch tension) is three times as long as with succinylcholine and about half as long as with equipotent doses of atracurium and vecuronium. ⋯ One of them, cis-atracurium, is five times as potent as the chiral mixture while having a similar pharmacodynamic and kinetic profile. It does not cause significant histamine release or clinically relevant cardiovascular effects at doses up to 8 times the ED95. Laudanosine release seems to be less with cis-atracurium than with atracurium.