Gastric Tube Use and Care in the NICU

Tamara Wallace, DNP, APRN, NNP-BC; Deborah Steward, PhD, RN

Disclosures

NAINR. 2014;14(3):103-108. 

In This Article

Measuring Insertion Depth

The insertion and use of a gavage feeding tube are not without risk; one of the most significant being tube malposition. The safe provision of gavage feedings is contingent upon the accurate positioning of the feeding tube.[28] Malpositioning occurs during insertion of the feeding tube, as well as afterwards with displacement of the tube. Gavage feeding tubes can be malpositioned into the lung, the esophagus, or the intestine. Complications associated with malpositioned tubes include pulmonary compromise, aspiration, and diarrhea.[1,28] Using standard techniques for measurement and verification of feeding tube placement frequently results in tube malpositioning.[11,28–30] Reported rates of malpositioned feeding tubes in children vary greatly in the scientific literature, ranging from 5% to 55.6%.[5]

Thankfully, there is a growing body of evidence to guide determination of the distance a tube is to be inserted. In current practice, distance is externally measured to predict the internal distance to the junction of the esophagus and stomach. There are now enough studies looking at insertion depths to begin to provide some clinical guidance. Historically, one of the most common measurement methods in neonates has been to measure from the nose to ear to xiphoid process (NEX). No validation of this method can be found. A variation on this method includes adding one centimeter to the measure and measuring to midway between the xiphoid and the umbilicus (NEMU). Researchers have now attempted to create several other methods of determining insertion depth including weight based formulas, age and height based formulas, and minimal insertion depths. None of these methods have been found to be accurate at all times for all infants.

Interpretation of the literature is complicated by variation in the definition of ideal placement. The majority of studies use x-ray as the gold standard and consider a feeding tube in good placement if the tip is below the gastro-esophageal junction, within the body of the stomach, and above the pylorus. Other studies have considered the tube not to be in good placement if the tip of the tube hits the greater curvature of the stomach and bent.[11] Tubes with the tip below the level of the disc between the 11th and 12th thoracic vertebra on x-ray should be past the gastro-esophageal junction and in the stomach.[31] The position of the pylorus is more variable and more difficult to define using vertebral bodies as a landmark.[31]

Multiple studies have now demonstrated that the NEX process often results in malpositioning of the feeding tube. The majority of studies have demonstrated that the NEX distance was frequently too short leaving the tube tip and/or orifices in the esophagus. In contrast, Quandt et al.[11] retrospectively looked at feeding tube placement on x-rays of infants in a unit that routinely used NEX to measure for placement, this author found tubes that were frequently placed too deep. This author considered the tube to be malpositioned if the tip touched the greater flexure of the stomach and bent. These variations in the definition of ideal placement complicate their interpretation.

The available research has repeatedly demonstrated that other measures outperform the NEX method. Multiple studies have now demonstrated the superiority of the NEMU method over NEX.[5,32,33] Authors have also had some success using weight based minimal insertion lengths and age related height based measurements. Table 1 provides a summary of the studies available to guide practice. It should be noted that some studies were done on very small subsets of newborns and may not be applicable to all infants. For example: one study looked at only extremely low birth weight infants and achieved an extremely high rate of correct placement using a weight based calculation to modify NEX measurements;[34] this success in a very small defined population suggests that there needs to be further research based on the size of the infant. None of the current studies differentiate the percentage of correct placements based on the size and maturity of the infant.

Given the frequency with which gavage tubes are inserted both orally and nasally in preterm infants, an important question to consider is whether the method for determining the appropriate distance to insert the tube is the same for both oral and nasal insertion. Currently there is only one study that examines differing insertion lengths for oral versus nasal tubes.[35] This study used a weight based formula and was able to achieve accurate placement more frequently by the oral route than by the nasal route, but the concept of variable length may warrant further research.

Some researchers in adults and older children have begun to work on a method for using an electromagnetic device to externally track the position of the tip of the tube.[36] This research has yet to be performed in neonates, but does provide a possible future solution to our concerns about accurate placement. Given the small size of the neonatal patient, extensive research will need to be completed to see if this tool is helpful in improving accurate placement in a neonatal population.

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