Publication: The oxygen and volatile anaesthetic delivery characteristics during spontaneous ventilation using a non-rebreathing coaxial anaesthesia system
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Date
2005
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Kathmandu University
Abstract
The gas delivery characteristics during simulated spontaneous ventilation of a non-rebreathing adaptation of the
Bain circuit were examined. Tidal volumes were varied from 200 to 600 ml and respiratory rate from 8 to 20
breaths per minute obtaining characteristics for a minute volume range from 2.4 to 12 litres/minute. The
minimum inspired oxygen concentration with 1 litre/minute 100% oxygen fresh gas flow varied between 86 and
43% over the range of minute volumes. . The minimum inspired Sevoflurane concentration with a 4% vaporiser
setting and a 1 litre/minute fresh gas flow varied between 3.4 and 1.3% over the range of minute volumes.
Increasing minute volume was the primary determinant of decreasing minimum inspired concentrations with
increasing respiratory rate having an independent but smaller effect in reducing concentrations. Thus this
system was shown to be safe and economical for the use in spontaneous ventilation.