Positioning of EDI Catheter In Premature Infants

Nasogastric (NG) and orogastric (OG) feeding tubes have a high incidence of malpositioning, occurring in up to 59% of preterm infants (Lopes 2019). Ideally, the tip of the feeding tube (including the orifices) should be located within the body of the stomach.

Malpositioning of the feeding tube can be classified as (i) being "too far out" where the tip of the catheter is located in the esophagus above the gastro-esophageal junction, potentially resulting in reflux, aspiration, apnea or (ii) being inserted "too far in" where the tip is located in the pylorus or the duodenum, leading to malabsorption of nutrients, diarrhea, and poor weight gain. Feeding tubes can also be found "curled up" inside the stomach (Quandt 2009) as much as 35% of the time. As well, one cannot ignore the risk of perforation, where the incidence has been reported to be 1.1% in extremely low birth weight (ELBW) infants (<1000g) (n = 7/646) (Thanhaeuser M, 2019); of note: perforations occurred on the third day of life (range days 2-14) not during initial feeding tube placement.

In 2008, a modified feeding tube was introduced to the market (Maquet Critical Care AB), which contains sensors placed in its wall, 13 mm above the feeding orifices, used for measuring the electrical activity of the diaphragm (Edi) during spontaneous breathing. The Edi signal is then used to neurally control mechanical ventilation, or for neural monitoring of the breathing pattern (Sinderby 1999; Beck 2016). The so-called "Edi catheter" comes with the manufacturer's recommended insertion measurements and verification window. In the Servo-I, the insertion distance is provided by a formula on the catheter packaging. In the Servo-U and Servo-n, the calculation for predicted insertion is provided by a tool in the ventilator. There is no available, published data upon which the manufacturer's recommendations were based. It is possible that obtaining appropriate positioning of the Edi catheter - based on a pattern of electrical signals from the sensors - could reduce the incidence of malposition.

This proposed study is observational, and non-interventional. The purpose is to verify the position of a neurally guided, clinically-placed, Edi catheter using radiography (Ellett 2011). The investigators will also record physical measurements and weights of the babies in order to validate previously described methods of predicting insertion length. The x-rays will be taken with "near-simultaneous" screenshots of the Edi catheter positioning window.

The investigators plan on studying a convenience sample of 65 premature babies of varying weights, from 9 sites.