SOME INFANT VENTILATOR SYSTEMS

The pressure: flow relationships which occur when four infant ventilator systems are attached to model lungs have been investigated. The results show that all four systems were capable of ventilating model lungs with satisfactory values for minute volume but two of the systems had features due to poor expiratory pathway design that were considered unsatisfactory. The expiratory pathway of a T-piece occluder showed considerable advantage and was combined with an improved method of fresh gas flow delivery in a new system. These findings are discussed and in view of the importance of the characteristics of the driving ventilator in interpreting these findings, the time relationships which occur in the cycling of the Newcastle ventilator have been investigated and are included as an appendix.