Relationship Between Diaphragmatic Electrical Activity and Esophageal Pressure Monitoring in Children.

Objectives: Mechanical ventilation is an essential life support technology, but it is associated with side effects in case of over or under-assistance. The monitoring of respiratory effort may facilitate titration of the support. The gold standard for respiratory effort measurement is based on esophageal pressure monitoring, a technology not commonly available at bedside. Diaphragmatic electrical activity can be routinely monitored in clinical practice and reflects the output of the respiratory centers. We hypothesized that diaphragmatic electrical activity changes accurately reflect changes in mechanical efforts. The objectives of this study were to characterize the relationship between diaphragmatic electrical activity and esophageal pressure. Design: Prospective crossover study. Setting: Esophageal pressure and diaphragmatic electrical activity were simultaneously recorded using a specific nasogastric tube in three conditions: in pressure support ventilation and in neurally adjusted ventilatory support in a random order, and then after extubation. Patients: Children in the weaning phase of mechanical ventilation. Interventions: The maximal swing in esophageal pressure and esophageal pressure-time product, maximum diaphragmatic electrical activity, and inspiratory diaphragmatic electrical activity integral were calculated from 100 consecutive breaths. Neuroventilatory efficiency was estimated using the ratio of tidal volume/maximum diaphragmatic electrical activity. Measurements and Main Results: Sixteen patients, with a median age of 4 months (interquartile range, 0.5-13 mo), and weight 5.8 kg (interquartile range, 4.1-8 kg) were included. A strong linear correlation between maximum diaphragmatic electrical activity and maximal swing in esophageal pressure (r(2) > 0.95), and inspiratory diaphragmatic electrical activity integral and esophageal pressure-time product (r(2) > 0.71) was observed in all ventilatory conditions. This correlation was not modified by the type of ventilatory support. Conclusions: On a short-term basis, diaphragmatic electrical activity changes are strongly correlated with esophageal pressure changes. In clinical practice, diaphragmatic electrical activity monitoring may help to inform on changes in respiratory efforts.