Saturday September 09, 2006
Non-radiological tests to confirm naso-gastric tube placement


We use different bedside techniques to confirm NG tube placement before xray is done. The most popular one is air insufflation and auscultation. Another refined version is immersing the end of the tube in water to check for bubbling.

One of the simple quick bedside confirmatory test in talking patient is his ability to continue to phonate. Some studies suggest measurement of bilirubin and enzyme content of the aspirate but naturally it is not feasible at bedside. Also bedside ultrasound has been utilized too.

One other technique whis is very under utilized and found to be more reliable than other bedside tests is to test PH of aspirate. This test is more reliable in NPO patient. Remember, the pitfalls of PH test are feeding formulas, medications like H2 blockers , PPI and patients with GERD (may have higher pH) .

Overall consencus is to combine PH with visual inspection. Here is a quick guideline

• An aspirate from a gastric tube often has a pH of 5 or less and is usually grassy-green or clear.
• An aspirate from a small bowel tube often has a pH of 6 or greater and is usually bile-stained, light to golden yellow or brownish-green in color.
• An aspirate from a tube inadvertently positioned in the tracheobronchial track or the pleural space has a pH of 6 or greater. Obviously, an aspirate from a tube in the tracheobronchial track has the appearance of fluid obtained during tracheal suctioning. An aspirate from a tube in the pleural space is usually straw-colored and watery and mostly tinged with bright-red blood caused by perforation of the pleura.