Performance of neonatal ventilators: the effects of changes in resistance and compliance

The authors tested the ability of 6 neonatal ventilators (Baby bird, Bourns BP-200, Veriflo, Bourns LS, ServoVent, SI-75) to deliver a preset tidal volume with minimal pressures when the compliance and resistance of test lung were altered. The authors also studied the effects of gas leaks from the system and the effects of PEEP. When the ventilator cycling rates exceeded 28-43/min, gas trapping occurred despite compliances and resistance appropriate for a healthy term infant. With a normal compliance and an elevated resistance, gas trapping occurred above rates of 4-6/min. Under these same conditions (normal compliance, elevated resistance), only 24-46% of the preset tidal volume was delivered. The different ventilators caused the pressure within the test lung to exceed 5, 10, and 15 cm H2O for differing amounts of time (sec)/min.