Chapter 41 - Lung volumes in full-term neonates during active and quiet sleep

Abstract

This chapter describes a study to evaluate the lung volumes in full-term neonates during active and quiet sleep. A purpose built 48 l, cylindrical, total body plethysmograph was used to measure thoracic gas volume (TGVs) in a group of nine full-term normal babies. Measurements were made in both quiet and active sleep at end expiration and on end inspiration. Sleep state was scored purely by observation. It is found that if eye or body movements were present in any degree the state was scored as active sleep. It is found that if no body or eye movements had been visible for at least 30 s, the baby was considered to be in quiet sleep. The mean gestation of the babies was 39. 8 weeks, the average birthweight 3. 34 kg and the age at time of testing were 6. 37 h. Recordings of 41 transitions from active to quiet sleep were made and on no occasion was any change in end-tidal baseline demonstrated. Similarly, in 14 of 43 changes from quiet to active sleep, there was no alteration in the baseline. A transient rise in functional residual capacity accompanied 12 changes from quiet to active sleep. These rises average approximately 7 ml and were often associated with sighs, respiratory pauses, or movement.