Comparison of Four Bedside Indicators Used to Predict Duodenal Feeding Tube Placement With Radiography

Abstract

The validity of four indicators to predict successful duodenal feeding tube placement was evaluated in a prospective trial. Data were collected on each indicator at prepyloric (≤ 65 cm) and postpyloric (≥ 75 cm) feeding tube lengths. Feeding tubes were placed in 106 patients. Eighteen feeding tubes were located in the stomach, and 88 were in the duodenum. Auscultation (progression of loudest sound locations from the left to the right abdomen) had a positive predictive value of 85% (negative predictive value, 31%). The vacuum effect (a change from 40 mL of aspirated air to ≤ 10 mL after 60 mL of air instillation) had a positive predictive value of 86% (negative predictive value, 45%) and was significantly correlated with duodenal placement (p = .02). Aspirate was present at prepyloric and postpyloric lengths in 35 cases. Ten of these 35 cases had the defined change in pH from ≤ 4.0 to ≥ 6.0 (positive predictive value, 100%; negative predictive value, 28%). The positive predictive value of color (a change to yellow) was also 100% (n = 11); the negative predictive value was 29%. The low negative predictive values of the indicators suggest that the absence of defined changes is of no assistance in discriminating between stomach and duodenal placement. A positive auscultation or vacuum effect test is not conclusive for duodenal placement. A positive pH or color change test may obviate the need for a confirmatory radiograph. However, because 40% of the positive pH-test feeding tubes and 36% of the positive color-test feeding tubes were located in the proximal duodenum, we believe refinement of placement techniques and further studies are warranted before elimination of the radiograph is recommended when the pH or color change occurs. (Journal of Parenteral and Enteral Nutrition 18:525-530, 1994)