Mortality and Morbidity Associated With Pressure- and Volume-Limited Infant Ventilators

Abstract

\s=b\ The effect of pressure-limited (PL) and volume-limited (VL) ventilation on mortality and morbidity in infants with severe hyaline membrane disease (HMD) was examined in a prospective controlled study. Criteria for mechanical ventilation were Pao2 value of 50 mm Hg or less or a Paco2value of 70 mm Hg or greater, while the infant was receiving nasal continuous positive airway pressure (CPAP) at oxygen concentrations (FIO2) of 0.8 or greater and CPAP of 8 cm H2O or greater; HMD associated with severe perinatal asphyxia requiring mechanical ventilation in the delivery room.Consecutive patients were alternately assigned to receive either PL or VL ventilation. Twenty infants were ventilated with PL machines using low peak inspiratory pressures (mean maximum inspiratory pressure of 28 cm H2O) and prolonged inspiratory times. Twenty other infants were ventilated with VL machines, using essentially unlimited peak inspiratory pressures (mean maximum inspiratory pressure of 62 cm H2O) and prolonged expiratory times.There were no significant differences in survival, incidence of pneumothorax or pulmonary interstitial emphysema, or noteworthy bronchopulmonary dysplasia.(Am J Dis Child 132: [865][866][867][868][869] 1978) The relative merits and shortcom¬ ings of pressure-limited (PL) andvolume-limited (VL) ventilation in infants have been, and continue to be, controversial topics. The simplicity of the PL ventilator, its compact size, and its ability to compensate for air leaks within the system are given attributes. The VL ventilator's versa¬ tility, variable inspiratory flow rate, and ability to compensate for ongoing changes in lung compliance are known advantages. When used strictly as a constant tidal volume machine, the VL ventilator is essentially pressureunlimited.Recent clinical investigations impli¬ cating excessive airway pressure as an important factor in the development of bronchopulmonary dysplasia (BPD) have raised serious questions about the advisability of using VL ventila¬ tors.1·-In an attempt to resolve some of these questions, a controlled venti¬ lator trial was carried out. Neonates with severe hyaline membrane dis¬ ease (HMD) who required mechanical ventilation were alternately assigned From the Children'