Journal of anesthesia
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Journal of anesthesia · Oct 1990
Effects of intravenous or endotracheal lidocaine on circulatory changes during recovery from general anesthesia.
Intravenous lidocaine (1.5 mg.kg(-1)) was not effective in attenuating the circulatory changes and the cough reflex induced by airway stimulation during recovery from general anesthesia, whereas endotracheal 4% lidocaine (3 ml) was effective. The arterial concentration of the intravenously administered-lidocaine peaked at a level of 9.52 +/- 0.81 microg.ml(-1) 0.5 min later. The arterial concentration of the endotracheally administered-lidocaine peaked at 1.44 +/- 0.13 microg.ml(-1) 15 min later. These findings indicate that the endotracheal administration of lidocaine may be superior to the intravenous administration for attenuating the circulatory changes and the cough reflex during recovery from general anesthesia, and that the arterial concentration of lidocaine did not correlate with the clinical efficacy for this purpose.
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Journal of anesthesia · Oct 1990
Characteristic changes between core and peripheral surface temperature related with postanesthetic shivering following surgical operations.
The relationship between changes in the core and the surface temperature and postanesthetic shivering was studied in 100 patients who underwent general anesthesia. Patients were classified into four groups by the patterns of change in the core and peripheral surface temperature. Type II and type IV groups of patients showed a decrease in surface temperature during the major operation such as gastrectomy and radical mastectomy. ⋯ However, in patients in type I and III, the rate of shivering was low. Evaluation of the difference between core and peripheral surface temperature may be important to manage body temperature at a steady level during the operation. The monitoring of body temperature difference between core and peripheral surface during the operation may be useful for predicting to occurrence of postanesthetic shivering.
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Journal of anesthesia · Jul 1990
Evaluation of conventional weaning criteria in patients with acute respiratory failure.
We evaluated the reliability of conventional weaning criteria from a ventilator during 33 weaning trials on 25 patients with acute respiratory failure (ARF). Of 13 criteria, a ratio of maximal voluntary ventilation to minute ventilation (MV) >2, a vital capacity >12 ml.kg(-1), a spontaneous respiratory rate <25 breaths.min(-1), and a MV <10 l.min(-1) appeared to be useful for predicting successful weaning outcome. ⋯ The present study demonstrates that conventional criteria are frequently inaccurate for predicting weaning outcomes and suggests that the use of some of these criteria may unnecessarily prolong the length of ventilator support. Since ventilation of most patients with poor oxygenation can be successfully discontinued by placing them on a continuous positive airway pressure system, these results suggest that the improvement of oxygenation is not an indispensable prerequisite for weaning from mechanical ventilators.
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We examined the effect of enflurane on diaphragmatic contractility in six anesthetized mechanically ventilated dogs. The diaphragmatic force was assessed from transdiaphragmatic pressure (Pdi) developed at functional residual capacity against an occluded airway during cervical phrenic nerve stimulation. Pdi-stimulus frequency relationship was compared at three levels of anesthesia, namely 1, 1.5, and 2 MAC (minimum alveolar concentration) of enflurane. ⋯ Pdi of 20 Hz stimulation was significantly decreased at 2 MAC as compared to those at 1 and 1.5 MAC. We conclude that enflurane decreases contractility of the diaphragm mainly through impairment of the neuromuscular transmission and/or membrane excitability. Part of its effects is, however, probably related to the impairment of excitation-contraction coupling, as suggested by the depression of Pdi at 2 MAC in response to 20 Hz stimulation.
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Journal of anesthesia · Apr 1990
Airway occlusion pressure (P0.1)-a useful predictor for the weaning outcome in patients with acute respiratory failure-.
Twenty-five patients who required mechanical ventilatory support (MVS) after major surgery or severe burns were studied to determine whether airway occlusion pressure (P(0.1)) is a clinically useful indicator to predict the success or failure of the weaning trial. A total of 33 weaning trials were attempted on these patients. Of the 33 trials, 24 were followed by successful weaning and 9 by failure. ⋯ The alveolar-arterial P(O)(2) gradient, with an F i(O)(2) of 1.0, in weaning success and failure showed no statistical difference. In contrast, all patients in the success group had a P(0.1) of less than 3.5 cmH(2)O and those in the failure group had a P(0.1) of greater than 3.5 cmH(2)O ( P < 0.001). We conclude that P(0.1) is a clinically superior indicator for discontinuing MVS in patients with acute respiratory failure.