Use of external expiratory resistance in intubated neonates to increase lung volume.

Ten intubated neonates (weights 0.90 to 2.58 kg) recovering from respiratory disease had lung mechanics, respiratory patterns, and functional residual capacity measured at 0 cmH2O continuous positive airways pressure and then after application of serially increasing levels of external expiratory resistance. At an external expiratory resistance greater than 40 cmH2O/1 per second, there was a significant increase in mean functional residual capacity compared with control levels. Immediately after the application of external expiratory resistance, there was a significant decrease in flow which returned to control values after a few breaths. Tidal volume and respiratory rate decreased for a few breaths after the application of the external expiratory resistance, but returned to control values after several seconds. Study age, gestational age, or study weight had no appreciable effect on the relationship between functional residual capacity and external expiratory resistance. Application of external expiratory resistance may be useful for stabilising lung volume in neonates recovering from respiratory disease.