Technique

Assessment of Alveolar Function in Neonates on ECMO Using the Measurement of Net CO₂ Transfer by the Artificial Lung

The Children’s Mercy Hospital Kansas City, Missouri

^* Address correspondence to: Gary Grist, RN, Operating Room, The Children’s Mercy Hospital, 24th & Gillham Road, Kansas City, MO 64108

Abstract

The measurement of the net transfer of the CO₂ by the artificial lung (Delta Cap) during ECMO indicates the rate at which the alveoli are becoming functional and allows the prediction of when weaning can best begin. Usually, an infant with lung disease placed on ECMO will need to excrete most of his CO₂ production via the artificial lung. But as the alveoli heal, CO₂ will be removed in increasing amounts by the infant’s own lungs. When the Delta Cap reaches zero, all of the infant’s CO₂ production is being removed by his own lungs, an indication that he has adequate alveolar function to exchange O_2· A capnagraph is used to measure the CO₂ concentration of affluent and effluent sweep gas and the Delta Cap is determined by their difference.