Effects of Varying Respiratory Waveforms on Gas Exchange

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Abstract
Effects of three different respiratory waveforms on magnitude of alveolar-arterial oxygen tension [AaDo2] and physiological dead space were compared during artificial ventilation of healthy anesthetized subjects. Waveforms included two intermittent positive pressure patterns with differing duration of inspiration and one positve-negative pattern. AaDo2 did not vary with use of the different respiratory waveforms with mean pressure during the respiratory cycle or with duration of inspiration. Physiological deadspace likewise did not change with the varying respiratory waveforms or mean pressure. Physiological dead space increased as duration of inspiration decreased but the change, though significant, was not dramatic. It was concluded that any respiratory pattern which provided adequate alveolar ventilation would be efficient in performing the ventilatory functions of oxygenation and carbon dioxide removal. A simple respiratory waveform should be adequate during artificial ventilation of healthy subjects and the provision for using different respiratory waveforms in apparatus seems unnecessary.
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