Background: The rapid respiratory frequency of children may lead to patient-ventilator asynchrony and increase the work of breathing during mechanical ventilation, and the use of a small endotracheal tube and a demand valve can further increase this work of breathing. Although pressure support ventilation (PSV) is well known to reduce the work of breathing in adults, there are no reports regarding clinical studies of PSV in children. Therefore, the effect of PSV on breathing patterns and the work of breathing in children was studied.
Methods: Six children (3-5 yr of age) were studied in the immediate postoperative period. Three levels of PSV, 0, 5, and 10 cmH2O, were employed. Airway pressure, flow, tidal volume, minute ventilation, and respiratory frequency were measured. To assess the work of breathing, the negative deflection of esophageal pressure (delta Pes) caused by inspiratory effort was measured. The inspiratory work of breathing was also estimated directly by measuring the esophageal pressure-volume loop using the Campbell technique.
Results: Although minute ventilation did not change with PSV, tidal volume increased and respiratory frequency decreased with increasing levels of PSV. The delta Pes decreased markedly from 8.9 cmH2O with PSV of 0 cmH2O to 5.7 cmH2O with PSV of 5 cmH2O and 2.7 cmH2O with PSV of 10 cmH2O. The mechanical work of breathing also decreased from 0.743 Joules/l with PSV of 0 cmH2O to 0.463 Joules/l with PSV of 5 cmH2O and 0.196 Joules/l with PSV of 10 cmH2O.
Conclusions: It was concluded that PSV can effectively augment spontaneous breathing and reduce the work of breathing in children.