Pressure and volume changes during the first breath of human neonates.

The pressure and volume changes associated with the first breath were measured in 17 healthy term babies, using oesophageal balloons and a reverse plethysmograph. 5 babies expanded their lungs with less than --20 cmH2O (--2 kPa). The characteristic opening pressure pattern previously described was seen in only one baby, whose initial volume change was an expiratory one. It is concluded that opening pressures greater than 10 cmH2O (0.96 kPa) are rarely seen in term healthy infants.