Staff Scientist Unity Health Toronto Toronto, Ontario, Canada
Background: Feeding tubes may be malpositioned in up to 59% of preterm infants. The tip of the feeding tube should be located within the body of the stomach. In 2007, a modified feeding tube was introduced (Maquet, Sweden), with an embedded electrode array to measure the electrical activity of the diaphragm (Edi). The electrode array should span the diaphragm to receive an appropriate Edi signal. This “Edi catheter” has a two-step insertion method: 1. Initial insertion based on a modified Nose-Ear-Xyphoid (NEX) measurement. 2. Verification of position using a dedicated “catheter positioning window” on the ventilator, based on ECG and Edi signals along the array. There are no data showing that this “ECG/Edi-guided” method results in proper positioning of the feeding tube tip in the stomach. Objective: The aim of the study is to compare the position of the Edi catheter using the dedicated catheter positioning window, with its position using radiography. Design/Methods: This is a multi-center (5 sites), prospective, observational study. Babies were eligible if they weighed between 400-2000g and had an Edi catheter in place. Anatomical measurements, screen shots of the Edi catheter positioning window, and x-rays were performed. We analyzed the position of (i) the tip of the catheter (x-rays) and (ii) the diaphragm along the electrode array (positioning window). Results: Sixty-seven (36 male) babies, ventilated with either Servo-N/U (n=63) or Servo-I, were included. The main diagnosis was RDS or BPD. Babies weighed 1247±346g and were 34±25 days old. Sixty-three babies had the Edi catheter inserted orally (94%). Seventy percent had a second feeding tube inserted. Predicted catheter insertion depth (modified NEX) was different from clinical insertion depth (14±2cm vs 16±1cm, p< 0.001): 94% of the babies had the catheter inserted deeper (by 1.1 cm) than the initial prediction. The clinical insertion depth correlated well to babies’ weight (r=0.85), and to manufacturer’s recommendation (r=0.71). Positioning window based on ECG/Edi revealed all insertions were suitable with respect to the diaphragm/array position (with n=18 at bottom, n=44 in middle, and n=4 at top of the array.). X-rays indicated 91% of insertions had the tip of the catheter appropriately in the body of the stomach. In five babies, the catheter tip was either touching the greater curvature of the stomach (4%) or near the pylorus (3%).
Conclusion(s): Edi catheter insertion – using guidance from the ECG/Edi signals of the electrode array - provides a safe method for tube positioning, with regards to both feeding and obtaining appropriate Edi signals.
