What is known about methods of correctly placing gastric tubes in adults and children

Abstract

An abdominal radiograph is considered the "gold standard" for determining the position of flexible small-bore nasogastric/orogastric tubes. However, placement must be checked frequently while a tube is in place, and the summative radiation risk of multiple radiographs, as well as their expense, make the development of adequate bedside placement-locating methods imperative. Several methods of detecting tube placement have been investigated in adults, including: aspirating gastric contents and measuring the pH, bilirubin, pepsin, and trypsin levels; examining the visual characteristics of aspirate; placing the proximal end of the tube under water and observing for bubbles in synchrony with expirations; measuring the carbon dioxide level at the proximal end of the nasogastric/orogastric tube; auscultation for a gurgling sound over the epigastrium or left upper quadrant of the abdomen; and measuring the length from the nose/mouth to the proximal end of the tube. Many researchers have already concluded simple auscultation is not a reliable method to assess tube position because injection of air into the tracheobronchial tree or into the pleural space can produce a sound indistinguishable from that produced by injecting air into the gastrointestinal tract. In adults, only pH and bilirubin of aspirate have been shown both to reliably predict tube position and to have inexpensive simple bedside tests. In children, only pH of aspirate has been shown to be reliable. Research on gastric tube placement in children is relatively new because children are challenging to study in that they are considered a vulnerable population. This review of the literature includes results of both adult and pediatric studies. Tube placement error rates varied from 1.9% to 89.5% in adults and between 20.9% and 43.5% in children.