Positioning of Diaphragm Electrical Activity Catheter in Premature Infants

Neurally-adjusted ventilatory assist (NAVA) is a mode of ventilation that uses the electrical activity of the diaphragm (EA_di) to synchronize and to control delivered pressure. EA_di is measured with a naso-/orogastric feeding tube, containing an array of sensors. Proper placement of the EA_di catheter is critical for optimal synchronization and support. Positioning the catheter requires (1) predicting the insertion distance and (2) verification using a dedicated positioning window on the ventilator, based on electrocardiogram (ECG) and EA_di signals. In preterm infants, no study has shown that the ventilator method results in proper positioning of the feeding tube tip in the stomach. We aimed to evaluate the position of the EA_di sensors (by the catheter positioning window) with the feeding tube tip position (measured by radiographs).

This was a multi-center (5 sites), prospective study. Eligibility: infants with weight 400-2,000 g and either had or were planning to have an EA_di catheter placed. Screenshots of the positioning window and radiographs were taken.

Sixty-seven infants were included. Median study weight was 1,250 g (interquartile range 1,026-1,448 g). The ventilator's positioning window revealed that all insertions were suitable with respect to the diaphragm/sensors position. Radiographs indicated 92% of insertions had the tip of the catheter appropriately in the body of the stomach. In 5 infants, the catheter tip was either touching the greater curvature of the stomach or near the pylorus.

In our cohort, EA_di catheter insertion using guidance from the ECG/EA_di signals of the electrode array provided a safe method for tube positioning, with regard to both enteral feeding and obtaining appropriate EA_di signals for optimal ventilator support.