Articles: closed-circuit-anesthesia.
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[The effects of fresh gas flow rate on the work of breathing during semi-closed circuit anesthesia].
To evaluate the effects of fresh gas flow rate on the work of breathing during semi-closed circuit anesthesia, we measured respiratory frequency, tidal volume, inspiratory work of breathing, peak inspiratory and expiratory flow rate and fluctuations in airway pressure during breathing with fresh gas flow of 6 l.min-1, 3 l.min-1 and 1.5 l.min-1. There was no significant difference among three flow rates in terms of tidal volume, respiratory frequency, inspiratory work of breathing, peak inspiratory flow rate and fluctuation in airway pressure at inspiration. On the other hand, in the expiratory phase, peak expiratory flow rate was lower and fluctuation in airway pressure at expiration was higher at 6 l.min-1 than those at 3 l.min-1 and 1.5 l.min-1, which may be indicative of increased expiratory work of breathing. The present study shows that low fresh gas flow rate does not increase the inspiratory work of breathing and high fresh gas flow rate may increase the expiratory work of breathing, implying that lowering the fresh gas flow is profitable for the work of breathing during semi-closed circuit anesthesia.
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Randomized Controlled Trial Clinical Trial
Heated breathing tubes affect humidity output of circle absorber systems.
To verify whether the airway climate in circle systems can be improved with heated breathing tubes. ⋯ Low-flow systems need at least 120 minutes to achieve a satisfactory airway climate. Heated breathing tubes effectively reduce this delay.
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The purpose of this investigation was to study the N2 flux between the patient and the breathing circuit, and the excess gas during N2O anesthesia with the low, fresh gas flow technique. ⋯ Regardless of the fresh gas flow used, sampled gas need not be returned during N2O anesthesia.
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We have constructed a simple system for field anaesthesia by using a Farman entrainer and a semi-open circuit to convert a draw-over apparatus to a continuous flow air/O2 system. Compressed O2 was the driving gas for the entrainer; fresh gas (FG) delivered to the semi-open circuit was a mixture of O2, entrained air and anaesthetic vapour. The purpose of this study was to examine FG flow rate and CO2 rebreathing during intermittent positive pressure ventilation (IPPV). ⋯ Thirty-seven adult patients having intra-abdominal or pelvic surgery under general tracheal anaesthesia were studied. Four FG flow rates (5.7, 8.0, 9.3, and 10.4 L.min-1), corresponding to driving gas pressures of 40, 60, 80, and 100 mmHg, were introduced in random order. Although inspired CO2 was detected at FG flow rates of 5.7-9.3 L.min-1, there were no differences in PETCO2 among the four groups.(ABSTRACT TRUNCATED AT 250 WORDS)