ALTHOUGH numerous attempts to measure ventilation in early infancy have been reported since that of Eckerlein in 1890,1 reasonable accuracy was not obtained until the body plethysmograph technic2 was introduced. While this eliminated the dead space error of the mask technic, it introduced the difficulty of sealing the apparatus around the infant's neck without unphysiological pressure. Cross3 avoided this by allowing the infant's face to protrude through a head piece of inflatable rubber and connected the recording spirometer to a specially designed integrator.4The first innovation allowed prompter relaxation by the infant and achieved greater freedom from leaks; the latter greatly reduced the labor of record analysis. In the present investigation we used a plethysmograph sealed at the neck but improved both in this regard and in its recording apparatus. These features, plus the additional data secured, are considered worth reporting.
The apparatus used was