The mechanics of breathing in newly born babies.

Little is known about the mechanics of breathing in newborn babies. The difficulties encountered in obtaining spirometric tracings in infants have largely been surmounted by the use of a body plethysmograph (Shaw and Hopkins, 1931; Murphy and Thorpe, 1931; Cross, 1949; Boutourline-Young and Smith, 1950), and in the past 20 years the normal range of infants' tidal volume has been established. Up to now, however, no measurements of the intrathoracic pressure have been reported and no attempt has been made to measure the work required to ventilate the lungs. This paper reports a study of the mechanics of breathing in newly born babies in whom the mechanical work of breathing has been measured from simultaneous tracings of the intraoesophageal pressure and air flow in a manner similar to that already reported in adults by Mcllroy, Marshall, and Christie (1954).