To characterize the incidence of airway misplacement of nasogastric tubes in anesthetized intubated patients by using a manometer technique.

This study characterized the incidence of airway misplacement of nasogastric (NG) tubes in surgical patients, and the benefit of using a manometer to discriminate gastric placement from airway placement of NG tubes. Subjects included adult patients scheduled for abdominal surgery. After tracheal intubation, a 16 Fr. NG tube was inserted blindly through the nostril, and its position was assessed using the auscultation (10-ml air insufflation) or manometer (attached to NG tubes) techniques. Briefly, a biphasic pressure change synchronous with airway pressure during mechanical ventilation indicated airway misplacement. The presence of a notable pressure change while compressing the epigastric area indicated a gastric placement. A surgeon made the final confirmation of NG tube placement within the stomach using manual palpation of the tube immediately after laparotomy. The first-attempt success rate was 82.7 % in 104 patients. There were 29 misplacements of 130 attempted insertions (oral cavity, n = 23; trachea, n = 3; distal esophagus, n = 3). The incidence of airway misplacement was 2.9 % (3 of 104 cases). For confirmation of gastric placement, the auscultation technique had a sensitivity of 100.0 % and a specificity of 79.3 %. In contrast, the manometer technique had a sensitivity of 100.0 % and a specificity of 100.0 % in the discrimination of gastric placement from airway placement of NG tubes. Airway misplacement of NG tubes is not uncommon in surgical patients, and the manometer technique may be a reliable and safe method to discriminate gastric placement from airway placement of NG tubes.