Abstract
Mechanical ventilation has been shown to impose work of breathing (WOB) in addition to that associated with spontaneous breathing through endotracheal tubes. Flow-triggered ventilation decreases WOB but data have been limited regarding its use in pediatric patients.
Materials & Methods
We undertook an experiment to compare WOB during flow-triggering (FT) and pressure-triggering (PT) utilizing the Servo Ventilator 300 (SV 300). Thirty experiments, each of 10-minutes duration, were performed in 4 anesthetized, intubated lambs. In each experiment, the animal was randomized either to pressure support (PS) = 5 cm H₂O or continuous positive airway pressure (CPAP) = 0 cm H₂O and studied with both FT and PT. Each animal was used as its own control. WOB was measured with a Bicore monitoring device as WOB of the animal (WOBr) and pressure time product (PTP) for each breath, during the experiment. In addition, oxygen consumption of the animal was measured with a customized metabolic monitoring system with breath-by-breath gas analysis. A Wilcoxon rank sum test was utilized for analysis.
Results
All comparisons between FT and PT for both CPAP and PS showed a statistically significant difference (p < 0.001). WOBr had a 47% reduction in PS and a 19% reduction in CPAP during FT as compared to PT.
Conclusion
We conclude that WOB is significantly lower in animals ventilated with flow-triggering as compared to pressure-triggering with the SV 300. We speculate ventilators with flow-triggering may offer an advantage in ventilating pediatric patients.
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