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

Verification of Tube Placement

There is much discussion in the literature related to the best practice for assuring correct placement of a feeding tube.[1,37–39] Unfortunately, much of this discussion does not include the preterm infant population. The gold standard for assessing feeding tube placement in older patients is the radiograph or x-ray, but routine use of this is impractical and potentially dangerous in the neonatal population given the frequency of tube placement.

The injection of air with auscultation is still widely used to assess tube placement in neonates, but is known to be unreliable. The injection of air and auscultation is no longer recommended in adults, as it is not reliable in differentiating correct placement.[39] The most dangerous tube malposition is a tube that has been placed into the pulmonary system. Thankfully, this appears to be a rare complication (see Fig. 2). A review of 15 published case reports of pulmonary placement of nasogastric tubes in children noted that the ausculatory bedside method failed to detect malposition in all seven cases that used it.[40] Capnography and bedside CO2 detectors have been used with some success in the adult patient to assess for pulmonary placement of gastric tubes, but few studies have included neonates. One study successfully used commercially available CO2 detectors (designed for intubation) in pediatric patients in a pediatric intensive care unit;[41] this study included an unknown number of newborns. It is not known if this would be effective in a population of small infants with limited tidal volume. One pilot study has looked at the use of capnography in preterm infants; while the authors found no CO2 detected from the feeding tubes, the number of patients was small and there were no misplaced feeding tubes in their sample.[42] While this technology holds some promise in determining malpositioning into the pulmonary system, there is currently no commercially available product to use for this testing.

Figure 2.

Feeding tube passes down the right main stem bronchus and to the base of the R lung.

There is much discussion in the literature related to the best practice for assuring correct placement of a feeding tube.[1,38,39,43–45] Several techniques suggested to determine correct positioning of a gavage feeding tube include checking the aspirate for pH, trypsin, pepsin, or bilirubin, and assessing color of the gastric aspirate. Unfortunately, in adults only the measurement of pH and bilirubin has been found to be accurate and have a bedside tool available for use.[1] Ellett,[1] in a review of how to accurately assess for correct placement, has recommended pH testing of aspirates to verify correct placement in children. In the one study that examined pH testing in preterm infants, Nyqvist, Sorell and Ewald[46] demonstrated that sufficient volumes of aspirates can be obtained in a high percentage of even preterm infants. Unfortunately, this practice is not universally instituted in NICUs. In a survey of NICUs across the United Kingdom, only 45% of the units were using pH testing to verify placement.[47] In addition, these researchers found that 73% of the NICUs continued to use the auscultation of insufflated air as a method for verification. Freer and Lyon[48] also found that there was a lack of consensus among NICUs as to which pH value was indicative of accurate feeding tube placement. While measurement of pH might hold the most promise, factors associated with physiologic immaturity of the preterm infant including delayed gastric emptying[49] and immature tone of the pyloric sphincter resulting in duodenal-gastric reflux impact gastric pH. In addition, common therapies used with acutely ill preterm infants alter gastric pH including continuous feeding, the administration of supplemental oxygen[50] and medications that inhibit gastric acid production such as H2 blockers and proton pump inhibitors.

While the x-ray is not a practical tool for routine assessment in the neonatal population, it does present the most accurate picture of placement. When x-rays are obtained for other purposes the tube insertion depth should be recorded and the tip location should be noted and tracked.

Currently, the procedure for inserting the feeding tube is frequently a "blind" procedure that leaves the infant at risk for malpositioning. Neonatal nursing is still awaiting the development of a large body of evidence to support the accuracy of methods used for verification at the bedside. Reliance on the injection of air with auscultation as a single test for placement is not reliable and should not be routine practice. A prudent nurse should consider using a variety of tools to assess for correct tube position. Carefully tracking and recording the position of the feeding tube may be helpful in identifying movement of a tube in the active neonate. Aspirating a significant volume of residual may be helpful in reassuring the nurse that a tube is correctly placed. The American Association of Critical-Care Nurses (AACN) has recommended a stepwise progression of assessments to determine feeding tube placement in adult patients.[39] While this policy written for adults might not fully translate to neonates, the use of multiple methods in a standardized progression is a model that should be considered when writing neonatal policies and procedures.

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