Effect of patient-triggered ventilation on respiratory workload in infantsafter cardiac surgery

Background: Patient-triggered ventilation (PTV) is commonly used in adults to avoid dyssynchrony between patient and ventilator. However, few investig ations have examined the effects of PIV in infants. Our objective was to de termine if pressure-control PTV reduces infants' respiratory workloads in p roportion to the level of pressure control. We also explored which level of pressure control provided respiratory workloads similar to those after the extubation of the trachea. Methods: When seven post-cardiac surgery infants, aged 1 to 11 months, were to be weaned with the pressure-control PTV, we randomly applied five level s of pressure control: 0, 4, 8, 12, and 16 cm H2O. All patients were ventil ated with assist-control mode, triggering sensitivity of 1 1/min, and posit ive end-expiratory pressure of 3 cm H2O. After establishing steady state co nditions at each level of pressure control, arterial blood gases were analy zed and esophageal pressure (Pes), ah-way pressure, and airflow were measur ed. inspiratory work of breathing (WOB) was calculated using a Campbell dia gram. A modified pressure-time product (PTPmod) and the negative deflection of Pes were calculated from the Pes tracing below the baseline. The measur ement was repeated after extubation, Results: Pressure-control PTV supported every spontaneous breath. By decrea sing the level of pressure control, respiratory rate Increased, tidal volum e decreased, and as a result, minute ventilation and arterial carbon dioxid e partial pressure were maintained stable. The WOE, PTPmod, and negative de flection of Pes increased as pressure control level was decreased. The WOE and PTPmod at 4 cm H2O pressure control and 0 cm H2O pressure control and a fter extubation were significantly greater than those at the pressure contr ol of 16, 12, and 8 cm H2O (P < 0.05), The WOE and PTPmod were almost equiv alent after extubation and at 4 cm H2O pressure control. Conclusions: Work of breathing and PTPmod were changed according to the pre ssure control level in post-cardiac surgery infants, PTV may be feasible in infants as well as in adults.