Impact of Spontaneous Breathing Trial on Work of Breathing Indices Derived From Esophageal Pressure, Electrical Activity of the Diaphragm, and Oxygen Consumption in Children

BACKGROUND: The present study aimed to characterize the behavior of 3 components of respiratory muscle function during mechanical ventilation weaning in children to better understand the respective impact of a spontaneous breathing trial on ventilatory mechanical action (esophageal pressure [P-es], ventilatory demand (electrical activity of the diaphragm [EA(di)]), and oxygen consumption. METHODS: This was a prospective single-center study. All children > 1 months and < 18 y old who were intubated and on mechanical ventilation, and who were hospitalized in the pediatric ICU were eligible. Subjects considered as ready to extubate were included. Simultaneous recordings of oxygen consumption, P-es, and EA(di) were performed during 3 steps: before, during, and after the spontaneous breathing test. RESULTS: Twenty subjects (median age, 5.5 mo) were included. Half of them were admitted for a respiratory cause. The increase in Pes swings and esophageal pressure-time product during the spontaneous breathing trial was not significant (P = .33 and P = .75, respectively), and a similar trend was observed with peak EA(di) (P = .06). Oxygen consumption obtained by indirect calorimetry was stable in the 3 conditions (P = .98). CONCLUSIONS: In these children who were critically ill, a spontaneous breathing trial induced a moderate and nonsignificant increase in work of breathing, as reflected by the respiratory drive with EA(di) and respiratory mechanics with P-es. However, indirect calorimetry did not seem to be a sensitive tool to assess respiratory muscle function during the weaning phase in children who were on mechanical ventilation, especially when work of breathing was slightly increased.