How to modify a volume-cycled home ventilator to satisfy a child's need for pressure-limiting and continuous positive airway pressure during spontaneous breathing.

Piston driven volume-cycled home ventilators increase work of breathing in the synchronized intermittent mandatory ventilation mode. A 2-year-old trisomy 21 patient with chronic lung disease due to recurrent aspiration pneumonia required a ventilator rate of 6-8 breaths per minute awake and 15 asleep, with peak pressure of 32 cm H2O and positive end-expiratory pressure (PEEP) of 10 cm H2O. Two circuits were designed to facilitate breathing and respiratory mechanics of his spontaneous breaths on both were compared. A spring valve on the inspiratory line pressure-limited ventilation and at the end of the expiratory line provided PEEP in both systems. The reservoir system had a 2-liter bag on the inspiratory limb of the circuit, and two one-way valves at the patient connector to direct inspiratory and expiratory flow. The continuous positive airway pressure (CPAP) system provided continuous flow with a CPAP device set to deliver a pressure 2 cmH2O higher than the PEEP valve. On the CPAP system, compared to the reservoir system, dynamic compliance was greater [1.52 (0.14 SD) ml/cm H2O/kg vs. 0.39 (0.02), p < 0.001] and resistance less [8.15 (1.26) cm H2O/l/s vs. 45.86 (0.87), p < 0.001] as measured with a PeDS machine. This is an innovative use of a CPAP device.