Naso-Orogastric Tube Placement

There has been a lot of discussion over the past couple of years regarding the care and maintenance of gastric tubes in neonates.  Many recommendations offered for the adult and pediatric patient may not be appropriate, best practice or effective in the neonate.

For this discussion, I will focus on the issue of measuring the tube for accurate placement.  Traditionally, this has been and often still is done by measuring from the tip of the nose (for nasogastric) or corner of the mouth (for orogastric) to the ear lobe and then to the xiphoid process or mid-umbilicus.  The measurement to the point midway between the xiphoid and umbilicus was established as a more accurate measurement in a small study published in 2004 showing that with measurement to the xiphoid, the tip was frequently noted in the lower esophagus, possibly resulting in aspiration of the feeding that does not go directly into the stomach¹.  With measurement to the umbilicus, the tip of the tube was frequently found too low i.e. through the pylorus resulting in less than optimal digestion due to lack of time in the stomach.  With measurement midway to the umbilicus, the majority (41 of 43) tubes were found to be in the proper location.  Several studies have reported the incidence of tube malposition ranging from 21 to 50%, even when using these measurement techniques, but inaccurate placement is less frequent when utilizing the measurement to midway between the xiphoid and umbilicus^1-5.  Strong evidence exists that the measurement to the xiphoid should no longer be used.

Regardless of the method of measurement, the position of a tube should be confirmed prior to beginning a feeding.  In a 2006 article published in the American Journal of Critical Care, the authors summarize the evidence related to checking for tube placement.  “Radiography remains the gold standard for ruling out respiratory placement of blindly inserted tubes.  For example, testing the pH of a feeding tube aspirate, observing the appearance of the aspirate, and using end-tidal carbon dioxide monitoring are not sufficiently accurate to ensure nonrespiratory placement of blindly inserted tubes in high-risk patients.”⁶ However, repeated x-rays for confirming gastric tube placement in neonates is unrealistic and carries its own risks due to the frequency that these x-rays would be required.  Accurate measurements are important to decrease the risk of tube misplacement although even accurate measurement does not rule out the misdirection of the tube into the airway.

Two recent articles discuss the development of anthropometric measurements for accurate estimation of gastric tube insertion.  Freeman, Saxton and Holberton describe the development of a weight-based formula to estimate tube length insertion⁷.  This formula was determined to be 3 X weight (kg) + 12 for orogastric placement and 3 X weight (kg) + 13 for nasogastric.  Cirgin Ellet et al developed a length-based formula for tube insertion in neonates².  This length-based formula resulted in the same incidence of correct placement as the measurement ending at mid-umbilicus.  This may be related to the fact that accurate length measurements are very difficult in neonates, a problem identified by Freeman’s group.

Accurate placement of gastric tubes is critical in avoiding aspiration and providing optimal nutrition to neonates.  While the research presented in the articles mentioned here contributes to the body of knowledge, there is a need for additional research regarding many aspects of use and care of the neonatal gastric tube, including practical/accurate methods of confirming proper placement, frequency of changing tubes, flushing tubes and more.

Resources:

1. Tedeschi L, Altimier L, Warner B.  Improving the accuracy of indwelling gastric feeding tube placement in the neonatal population.  Neonatal Intensive Care.  2004; 16:16-18.

2. Cirgin Ellett ML, Cohen MD, Perkins SM, Smith CE, Lane KA, Austin JK.  Predicting the insertion length for gastric tube placement in neonates.  J Obstet Gynecol Neonatal Nurs.  2011. 40:412-421.

3. Scalzo AJ, Tominack RL, Thompson MW.  Malposition of pediatric gastric lavage tubes demonstrated radiographically.  J Emerg Med. 1992; 10:581-586.

4. Ellett ML, Maahs J, Forsee S.  Prevalence of feeding tube placement errors & associated risk factors in children.  MCN Am J Matern Child Nurs.  1998; 23:234-239.

5. De Boer J, Smit BJ, Mainous RO.  Nasogastric tube position and intragastric air collection in a neonatal intensive care population.  Adv Neonatal Care.  2009; 9:293-298.

6. Metheny NA.  Preventing respiratory complications of tube feedings: Evidence-based practice.  Am J Crit Care 2006;15:360-369.

7. Freeman D, Saxton V, Holberton J.  A weight-based formula for the estimation of gastric tube insertion length in newborns.  Adv Neonatal Care. 2012; 12:179-182.