Methods of Estimating Nasogastric Tube Length: All, Including "NEX," Are Unsafe.

BACKGROUND

Predominance of blind feeding tube placement makes esophageal tube misplacement and aspiration risk commonplace. Accurate estimation of nose-to-stomach length could reduce this risk. Standards for estimating this length were audited against the length measured from guided tube placement.

METHODS

This prospective, single-center observational study used electromagnet-guided tube placement to measure the length from nose to gastric body flexure as part of routine care. This measurement was used to audit standard equations used to estimate this length from external measures: xiphisternum-ear-nose + 10 cm (XEN+10), nose-ear-xiphisternum (NEX), and Hanson_A and Hanson_B.

RESULTS

From April 23, 2015, to March 2, 2020, measurements were obtained from 200 primary tube placements. Median length to the gastric body flexure (61 cm) was significantly different from that to the pre-gastroesophageal junction flexure (48 cm) or lengths predicted by NEX (51 cm) or Hanson_A (50.5 cm) and Hanson_B (56.1 cm) (all P < .00001) but similar to XEN+10 (61 cm). Esophageal placement was a potential risk for all methods (NEX: 96.3%, Hanson_A: 99.5%, Hanson_B: 86.9%, XEN+10: 43.2%) and a definite risk for most (NEX and Hanson_A: 14.9%, Hanson_B: 1%, XEN+10: 0%).

CONCLUSIONS

NEX and Hanson methods of predicting the length from nose to gastric body flexure are too short and risk esophageal misplacement. XEN+10 reduces but does not eliminate this risk. External measurement predictions are clinically unsafe as a guide blind tube placement. Guided placement is recommended.