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Effect of patient-triggered ventilation on respiratory workload in infants after cardiac surgery
M Takeuchi1, H Imanaka, H Miyano
1Surgical Intensive Care Unit, National Cardiovascular Center and Intensive Care Unit, Osaka University Hospital, Osaka, Japan.
Insights
Patient-triggered ventilation (PTV) in infants reduces respiratory workload with higher pressure control levels. Lower pressure control settings increased work of breathing, similar to post-extubation levels.
Area of Science:
- Pediatric critical care medicine
- Respiratory physiology
- Mechanical ventilation
Background:
- Patient-triggered ventilation (PTV) is standard for adult ventilator dyssynchrony.
- Limited research exists on PTV's effects in infants.
- This study investigates PTV's impact on infant respiratory workload.
Purpose of the Study:
- To assess if pressure-control PTV reduces infant respiratory workload proportionally to the pressure control level.
- To identify pressure control levels yielding workloads similar to post-extubation conditions.
Main Methods:
- Seven post-cardiac surgery infants (1-11 months) received pressure-control PTV at five levels (0-16 cm H2O).
- Ventilator settings included assist-control mode, 1 l/min triggering sensitivity, and 3 cm H2O PEEP.
- Measurements included arterial blood gases, esophageal pressure, airway pressure, airflow, work of breathing (WOB), and modified pressure-time product (PTPmod).
- Measurements were repeated post-extubation.
Main Results:
- Decreasing pressure control increased respiratory rate and decreased tidal volume, maintaining stable minute ventilation and PaCO2.
- Work of breathing (WOB), PTPmod, and esophageal pressure deflection increased as pressure control decreased.
- WOB and PTPmod were significantly higher at 4 cm H2O and 0 cm H2O pressure control compared to 16, 12, and 8 cm H2O.
- Work of breathing and PTPmod were comparable between 4 cm H2O pressure control and post-extubation.
Conclusions:
- Infant respiratory workload and PTPmod varied with pressure control levels.
- Patient-triggered ventilation appears feasible for infants, similar to adults.
Background:
Patient-triggered ventilation (PTV) is commonly used in adults to avoid dyssynchrony between patient and ventilator. However, few investigations have examined the effects of PTV in infants. Our objective was to determine if pressure-control PTV reduces infants' respiratory workloads in proportion 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 levels of pressure control: 0, 4, 8, 12, and 16 cm H2O. All patients were ventilated with assist-control mode, triggering sensitivity of 1 l/min, and positive end-expiratory pressure of 3 cm H2O. After establishing steady state conditions at each level of pressure control, arterial blood gases were analyzed and esophageal pressure (Pes), airway pressure, and airflow were measured. Inspiratory work of breathing (WOB) was calculated using a Campbell diagram. A modified pressure-time product (PTPmod) and the negative deflection of Pes were calculated from the Pes tracing below the baseline. The measurement was repeated after extubation.
Results:
Pressure-control PTV supported every spontaneous breath. By decreasing the level of pressure control, respiratory rate increased, tidal volume decreased, and as a result, minute ventilation and arterial carbon dioxide partial pressure were maintained stable. The WOB, PTPmod, and negative deflection of Pes increased as pressure control level was decreased. The WOB and PTPmod at 4 cm H2O pressure control and 0 cm H2O pressure control and after extubation were significantly greater than those at the pressure control of 16, 12, and 8 cm H2O (P < 0.05). The WOB and PTPmod were almost equivalent after extubation and at 4 cm H2O pressure control.
Conclusions:
Work of breathing and PTPmod were changed according to the pressure control level in post-cardiac surgery infants. PTV may be feasible in infants as well as in adults.