Articles: closed-circuit-anesthesia.
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We have examined, under reproducible conditions, the resistance to airflow of complete anaesthetic breathing systems (Magill, Coaxial Lack, Parallel Lack and Bain systems) and components of these systems. All systems had resistances within the recommended ranges at all flows likely to be experienced in normal clinical practice. The Magill system had the lowest resistance under all conditions. It is concluded that comparisons should be made only between complete breathing systems.
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A new way of saving anaesthetic vapours is described. The method is analogous to the heat-moisture exchanger principle: the vapour is trapped in a filter during expiration and is returned to the patient during the subsequent inspiration. ⋯ In model lung tests, this reduced the isoflurane consumption by 51% at a tidal volume of 300 ml, by 57% at 600 ml and by 51% at 930 ml. Neither isoflurane nor halothane yielded any degradation products when brought in contact with the zeolite.
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The Enclosed Magill anaesthetic breathing system may be used for both spontaneous ventilation and controlled ventilation with similar fresh gas flows. During spontaneous ventilation, a fresh gas flow between estimated alveolar ventilation and minute ventilation is adequate and the system performs as a Mapleson A type breathing system. ⋯ These values are similar to those demonstrated for type D breathing systems. It is suggested from this preliminary study that the breathing system conforms to the requirements of a universal breathing system in as much as similar fresh gas flows are used in both modes of ventilation.
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Ann Fr Anesth Reanim · Jan 1987
Randomized Controlled Trial Comparative Study Clinical Trial[Use of isoflurane in a closed-circuit. Economic advantages].
The present study was designed to assess whether isoflurane requirement was significantly affected by fresh gas flow in a closed-circuit system. Sixty patients scheduled for orthopaedic procedures were randomly assigned into three groups. In group A (n = 20), anaesthesia was conducted with a fresh gas flow of 482.5 +/- 186.6 ml X min-1, corresponding to the patient's metabolic demand. ⋯ Alveolar concentration of isoflurane was set at 0.92 vol. % according to Lowe and Ernst. Statistical analysis was carried out using Student's test for means. Anaesthesia lasted 138 +/- 88.3 min in group A, 125.5 +/- 45.1 min in group B and 146.5 +/- 50 min in group C, no difference being significant.(ABSTRACT TRUNCATED AT 250 WORDS)