Assessment of alveolar function in neonates on ECMO using the measurement of net CO2 transfer by the artificial lung

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 O2. A capnagraph is used to measure the CO2 concentration of affluent and effluent sweep gas and the Delta Cap is determined by their difference.