Pathophysiology
Clinical meaning
Nasogastric tubes are inserted through the nares, through the pharynx, down the esophagus, and into the stomach. Verification of placement is critical because misplacement into the respiratory tract (bronchial insertion) can cause aspiration pneumonia, pneumothorax, or death if feedings are inadvertently delivered to the lungs. Gastric aspirate has a pH of 1-5 (acidic due to hydrochloric acid secreted by parietal cells), while respiratory secretions typically have a pH >6 and intestinal fluid has a pH >6. X-ray remains the gold standard for initial placement verification. For gastric decompression (Salem sump tubes), continuous or intermittent suction removes gastric secretions, gas, and swallowed air, preventing nausea, vomiting, and aspiration in patients with gastrointestinal obstruction or postoperative ileus. The blue pigtail port (air vent) on Salem sump tubes prevents the tube from adhering to gastric mucosa by equalizing atmospheric pressure.