Comparison of anti-pollution modifications of Mapleson A and D anaesthetic systems

Hafnia A and Hafnia D anaesthetic systems are non-polluting modifications of the Mapleson A and D systems. The excess gas is vented in the Hafnia systems directly and continuously via a calibrated ejector flowmeter. Sixteen adult patients anaesthetized for abdominal surgery were ventilated and either Hafnia A or D systems at six different fresh gas flows. No difference between the Hafnia A and D systems could be demonstrated in the values of arterial carbon dioxide tension measured with the same fresh gas flow, despite gas flows in opposite directions.