Guide — Fundamentals
NG Tube Insertion & Management
A nasogastric tube is a blind bedside procedure that ends millimeters from the airway — which is why verification, not insertion, is the skill exams test hardest. This guide covers tube selection, the NEX measurement, insertion, X-ray-first verification, suction management, and what gastric suction does to electrolytes.
8 min read · Fundamentals
Educational use only. NG tube insertion, verification methods, and suction settings follow provider orders and facility protocol; tube placement in high-risk patients (basilar skull fracture, esophageal varices or surgery) requires specific provider direction. This material supports nursing education and exam review. It is not medical advice and is not a substitute for clinical judgment, institutional policy, or medical direction. Always follow facility protocols and current provider orders.
Overview
NG tubes serve two opposite jobs: putting things in (feeding, medications) and taking things out (decompression of an obstructed or post-operative gut, emptying the stomach after overdose or bleeding). The job determines the tube. A Levin tube is a single lumen — fine for feeding or medication. A Salem sump has a second, smaller lumen ending in a blue pigtail that vents air to the stomach, protecting the mucosa from being sucked against the tube — the standard choice for continuous suction. Small-bore, flexible tubes (Dobhoff-type) are for feeding only and usually pass with a stylet.
Contraindications to blind nasal insertion matter: suspected basilar skull fracture or significant facial trauma (the tube can enter the cranium — use the oral route), and recent esophageal or gastric surgery or known varices without provider involvement.
Key Concepts — Insertion
Measure: NEX
Nose → Earlobe → Xiphoid process. Mark the tube at that length; the mark at the naris becomes your ongoing landmark for migration.
Position and technique
High Fowler’s, towel on the chest, agree on a stop signal. Lubricate (water-soluble only), insert along the floor of the naris aiming back, not up. When the tube reaches the posterior pharynx, have the patient flex the chin to the chest and swallow — sips of water if permitted — advancing with each swallow.
Stop signals
Coughing, choking, cyanosis, or inability to speak means the airway — pull back to the pharynx, let the patient recover, and try again. Resistance is never forced. Curling in the mouth means withdraw and restart.
Secure and document
Tape or a securement device to the nose without pressure on the naris (pressure injuries on the nostril are a real and reportable harm), then document the external length at the naris.
Placement Verification
X-ray is the gold standard and is required before the first use of any blindly placed tube for feeding or medications. At the bedside thereafter: check that the external length matches the documented mark, and test aspirate pH — gastric contents are typically pH 5 or less (acid suppressants raise it). Auscultating an injected air bolus is unreliable and is not an acceptable verification method. Reverify before every intermittent feed or medication and any time displacement is suspected — after vomiting, violent coughing, or a changed external length.
Suction & Decompression Management
Settings
Low suction (typically up to about 80 mmHg) protects gastric mucosa. A single-lumen Levin on suction should run intermittent; a Salem sump tolerates continuous suction because its vent lumen breaks the seal against the stomach wall.
The blue pigtail
Keep the vent above the level of the stomach, never clamped, plugged, or used for irrigation. If gastric contents reflux up the pigtail, flush the main lumen with saline and then clear the vent with air per protocol.
Watch what leaves the body
Measure and describe output every shift. Prolonged gastric suction removes acid, potassium, and volume — the classic result is hypokalemic metabolic alkalosis with dehydration. Trend electrolytes and replace per orders; irrigate with normal saline, not water, to limit electrolyte washout.
Assessment Findings
Each shift: external tube length against the documented mark, securement and naris skin, output volume and character (coffee-ground material suggests bleeding; feculent drainage suggests distal obstruction), bowel sounds and distension for decompression patients, and oral/nasal mucosa (NPO patients on suction need scheduled oral care — thirst and parotitis are real complications). Respiratory changes — new cough, congestion, hypoxia — raise the question every NG nurse must keep asking: is this tube still where it belongs?
Nursing Priorities
Airway before everything
Misplacement into the trachea — or migration there later — is the lethal complication. Verify before anything goes down the tube, every time.
Maintain function
Scheduled saline irrigation per orders for decompression tubes, patent vent lumen, working suction, and an intact securement that isn’t eroding the naris.
Protect comfort and skin
Oral care every 2–4 hours for NPO patients, lubricant for the lips, clean and re-secure the nose daily, and analgesia/throat lozenges per orders for sore throat.
Removal done right
Verify the order, flush per protocol, have the patient take and hold a deep breath (closes the glottis), and withdraw smoothly in one steady motion. Monitor for nausea, distension, or return of symptoms afterward.
Therapeutic Communication Considerations
Insertion is genuinely unpleasant, and anxiety makes the pharynx fight you. Explain each step before it happens, agree on a raised-hand stop signal so the patient keeps some control, and coach breathing and swallowing in real time — “sip, swallow, sip, swallow” gives the patient a job. Afterward, acknowledge the discomfort honestly and explain what the tube is doing for them; patients pull tubes they don’t understand.
Patient Education
Teach the patient and family why the tube is in, why eating and drinking may be off-limits even though the tube is “right there,” and never to pull, reposition, or put anything into the tube. Report nausea, new throat or chest pain, coughing fits, or a tube that suddenly looks longer. For confused patients, involve family in keeping hands busy and away — and use the least restrictive alternatives before any restraint conversation.
NCLEX Pearls
- ✦Measure NEX: nose to earlobe to xiphoid. During insertion, chin to chest plus swallowing directs the tube into the esophagus.
- ✦X-ray before first use; bedside checks are pH (≤5 suggests gastric) plus external length — the air-bolus “whoosh” is always a wrong answer.
- ✦Coughing or cyanosis during insertion = airway: withdraw to the pharynx immediately.
- ✦Salem sump’s blue pigtail stays open, above stomach level, and is never clamped or irrigated; the sump can run continuous suction, a single-lumen Levin runs intermittent.
- ✦Prolonged gastric suction → hypokalemic metabolic alkalosis; irrigate with normal saline, not water.
- ✦Facial trauma or possible basilar skull fracture = no nasal tube; the oral route and the provider decide.
Related Resources
Standards & sources
Fact-checked Jun 21, 2026This page is written to align with American Nurses Association (ANA) Standards of Practice · The Joint Commission. It is an educational summary, not a citation of any single document — always verify specific doses, values, and protocols against current guidelines and your facility policy. How we source content →