Manipulation of ventilator settings to prevent active expiration against positive pressure inflation.

Recent publications have suggested that in infants receiving artificial ventilatory support a particular pattern of interaction between spontaneous breaths and ventilator inflations (active expiration against each ventilator inflation) may be important in the production of pneumothoraces. We have looked at patterns of interaction from 47 preterm infants studied on 51 occasions. We found that active expiration against the ventilator occurred on a total of 16 occasions. This pattern was prevented on 14 occasions by altering the ventilator settings. In two other babies, the pattern persisted but neither baby developed a pneumothorax.