Which method best indicates proper placement of an NG tube in a patient who is NPO?

The most reliable method for confirming proper placement of a nasogastric (NG) tube in a patient who is NPO (nothing by mouth) is the use of X-ray imaging to verify that the tip of the tube is positioned in the gastric fundus. This method provides a direct visual assessment that confirms the tube's location within the stomach, reducing the risk of complications associated with misplacement, such as aspiration.

While other methods may be used in clinical practice, they do not offer the same level of assurance. For instance, assessing respiratory rate may indicate the patient's overall respiratory status but does not specifically confirm the position of the NG tube. Visual inspection of tube length can give a rough estimate but is not definitive without verification of the tube's internal location. Detection of gastric residual volume can suggest that the tube is in the stomach, but it does not confirm correct placement, as the tube could be incorrectly positioned in the esophagus or pharynx.

Therefore, X-ray imaging is the gold standard for ensuring proper NG tube placement, especially in patients who cannot provide input on how they feel, such as those who are NPO.