Sunday, January 17, 2021

detection of tracheal aspiration

 Q: Which of the following is more reliable in detecting tracheal aspiration of gastro-intestinal (GI) contents? (select one)

A) Methylene blue test 

B) Glucose oxidase test

Answer: B

The two most common methods used to detect aspiration in patients especially in post-trach tubes patients beside direct visualization and bronchoscopy are methylene blue test and glucose oxidase test. 

In Methylene blue test, a dye is added to the enteral feedings and then looking for it in tracheal secretions. Unfortunately, this has a very high false negative rate. 

In glucose oxidase testing, the glucose test strips and a glucose meter is used to measure the glucose level in the tracheal secretions. The high glucose level in the tracheal secretions is considered highly suggestive of tracheal aspiration.



1. Belafsky PC, Blumenfeld L, LePage A, Nahrstedt K. The accuracy of the modified Evan's blue dye test in predicting aspiration. Laryngoscope 2003; 113:1969. 

2. Fiorelli A, Ferraro F, Nagar F, et al. A New Modified Evans Blue Dye Test as Screening Test for Aspiration in Tracheostomized Patients. J Cardiothorac Vasc Anesth 2017; 31:441. 

3.  Potts RG, Zaroukian MH, Guerrero PA, Baker CD. Comparison of blue dye visualization and glucose oxidase test strip methods for detecting pulmonary aspiration of enteral feedings in intubated adults. Chest 1993; 103:117.

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