Confirming nasogastric tube position in the emergency department: pH testing is reliable

The aim of this study was to determine whether pH testing is an accurate method of confirming nasogastric tube (NGT) position in children with and without gastroenteritis in the emergency department.

A prospective observational study of NGT insertions was conducted at a tertiary pediatric emergency department, during a 9-month period in 2006. We evaluated methods of NGT position confirmation, pH of nasogastric aspirates from patients with and without gastroenteritis, and adverse events.

A total of 404 patients were enrolled. For 393 patients (97.3%), NGT aspirates could be obtained to assess pH. Of these patients, 294 (74.8%) had a diagnosis of gastroenteritis and 99 (25.2%) did not. There was no difference in median pH between the patients with gastroenteritis (pH, 2; interquartile range, 2-4) and those without gastroenteritis (pH, 2; interquartile range, 2-4; P = 0.09). Overall, 341 patients (86.8%) had a pH of 4 or lower. The patients with gastroenteritis were more likely to have a pH of 4 or lower than the patients without gastroenteritis (P = 0.018). Tube position was confirmed by pH alone in 332 patients (84.5%). Nine (2.6%) of the 341 patients with a pH of 4 or lower also had radiography (7 for causes other than confirmation of NGT position) indicating correct placement of all NGTs. Fifty-two patients (13.2%) had a pH higher than 4, and 18 (34%) of these had the tube position confirmed by radiography, of which 3 had tubes misplaced in the distal esophagus. Irrespective of pH level, there were no respiratory placements clinically or by radiography. Overall, 22 patients (5.6% 95% CI 3.5%-8.3%) required more than 1 attempt for NGT insertion. There were 13 minor adverse events (3.3% 95% CI 1.8%-5.6%) and no major adverse events.

Testing of gastric pH is a reliable way of confirming NGT position when the pH is 4 or lower. When the pH is higher than 4, a radiograph may be necessary.