Comparison of work of breathing between two neonatal ventilators utilizing a neonatal pig model.
OBJECTIVE: The purpose of this study was to determine whether variations in the delivery systems of continuous positive airway pressure between two ventilators would lead to differences in patient work of breathing (WOBp). DESIGN: Comparison of two neonatal ventilators with a neonatal pig model. SETTING: Animal laboratory. SUBJECTS: Thirty healthy, intubated, sedated, spontaneously breathing neonatal piglets weighing 1.0-2.0 kg. INTERVENTIONS: Patient work of breathing (WOBp) (gm cm/kg) was measured by using measurements based on an esophageal balloon and a flow transducer. Each breath was analyzed for ventilator response times (in msecs) and negative deflection of pressure. Each animal was studied with the Siemens SV300 and Drager Babylog 8000, on continuous positive airway pressure settings of 0, 3, and 5 cm H2O. Data were analyzed by using Wilcoxon's Signed Rank Test with significance of p 1 cm H2O negative pressure before flow was available with the Babylog. CONCLUSIONS: In intubated patients, maximum energy expenditure occurs at the initiation of ventilator breaths. WOBp in neonatal pigs was significantly increased. The response time of the ventilators may explain the differences in initiation of flow times and patient work. These differences may have important implications for energy kinetics, weight gain, and duration of mechanical ventilation in preterm neonates.