Nasogastric (NG) Tube: Irrigation, Uses & Patient Management

1. What Is an NG Tube?

• Has two lumens: the larger lumen connects to wall suction for aspiration; the smaller lumen vents to atmosphere to prevent gastric wall adherence
• Can also deliver medications or feeds when not on suction

• Current Surgical Therapy 14e, p.162

2. Indications for NG Tube Placement

3. Contraindications

• Basilar skull fracture or mid-face fractures (risk of intracranial penetration)
• History of alkali ingestion (risk of esophageal perforation if blind placement)
• Esophageal stricture

• Esophageal varices (though evidence for bleeding risk is limited - one study of 75 hepatic transplant patients found zero bleeding episodes after NG placement)
• Coagulopathy / severe thrombocytopenia
• Roberts and Hedges' Clinical Procedures in Emergency Medicine, p.1725

4. Placement Technique (Step-by-Step)

1. Position: Head of bed elevated to upright
2. Estimate length: Nose-to-earlobe + earlobe-to-xiphoid + 15 cm
3. Select nostril: Ask patient to sniff while occluding each side; choose most patent
4. Anesthesia: Apply lidocaine gel or Cetacaine to nares and nasopharynx
5. Insert tube: Apply gentle pressure through posterior nasopharynx
6. Facilitate passage: Ask patient to sip water; flex neck forward once in nasopharynx to direct tube toward esophagus, not trachea
7. Signs of tracheal misplacement: Excessive coughing, voice changes, condensation in tube - STOP and remove immediately
8. Secure: Commercial adhesive holder on nose

• Current Surgical Therapy 14e, p.163

5. NG Tube Irrigation / Lavage Technique

General Irrigation Principle

• Instill fluid through the tube and aspirate/siphon back
• The Salem-sump's vent port maintains suction without mucosal adherence
• Keep suction mild and intermittent - vigorous suction causes gastric erosions

6. NG Tube in Hematemesis / Upper GI Bleeding

Role of NG Lavage in Upper GI Bleed

• Positive aspirate (bloody, maroon, or coffee-ground material) = strong evidence of upper GI source
• Negative aspirate does NOT exclude upper GI bleeding (only positive in 23% of patients with occult bleeding) - intermittent bleeding or pyloric spasm cause false negatives
• Guaiac testing of aspirate: unreliable - visual inspection is more dependable

Lavage Procedure for Hematemesis

1. Place NG tube and confirm position
2. If bright red blood or clots are present, perform gentle gastric lavage
3. Irrigant: Room-temperature water (preferred) or normal saline, 200-300 mL aliquots
4. Aspirate contents; repeat until return fluid is clear
5. Maintain tube on mild intermittent suction
6. Early lavage is associated with decreased time to endoscopy

Risk Stratification Table (Tintinalli's Emergency Medicine)

Key Management Points

• Avoid varices fear: no proven evidence that NG tube passage provokes variceal bleeding
• Upper endoscopy (EGD) is the gold standard for diagnosis and treatment of upper GI hemorrhage - NG lavage is now primarily used to improve endoscopic visualization in high-risk cases
• Tintinalli's Emergency Medicine, p.538; Current Surgical Therapy 14e, p.318

7. NG Tube in Poisoning / Overdose

A. Gastric Lavage

1. Position patient prone or semi-prone on left side, hips higher than head (Trendelenburg + left lateral decubitus) - prevents aspiration
2. Remove dentures; secure airway; use mouth gag in unconscious patients
3. Use a No. 40 French orogastric tube (adults) or Ryle's tube / No. 8-12 French catheter (children)
4. Lubricate with liquid paraffin or glycerine
5. Insert through mouth (or nose in children) to the 50 cm mark in adults (45 cm = cardia; mark at 50 cm)
6. Confirm position: Insufflate air and auscultate over stomach; bubbling = correct; hissing = trachea
7. First wash: ~250 mL warm water (35°C) - run in by gravity (funnel held above mouth), then lower funnel below stomach to siphon out. Save first wash for chemical/forensic analysis
8. Subsequent washes: 500 mL aliquots, repeated until return fluid is same color and character as lavage fluid
9. Lavage decreases absorption by: ~52% at 5 min, 26% at 30 min, 16% at 60 min
10. After lavage, leave an appropriate antidote or solution in the stomach (e.g., activated charcoal, sodium bicarbonate for aspirin, magnesium sulfate for purgation)
11. Pinch the tube before removal to prevent aspiration of tube contents

• Corrosive (acid/alkali) ingestion - risk of esophageal perforation
• Petroleum distillate (kerosene) ingestion - extreme aspiration risk
• Strychnine poisoning: control convulsions first
• Comatose patients without protected airway - intubate first
• Bowel obstruction

B. Activated Charcoal via NG Tube

• Dose: 1 g/kg body weight (generally; optimum = 10x weight of ingested substance)
• Administer orally or through small-bore NG tube as a suspension in water
• Palatability improved by adding sorbitol, chocolate, or cola syrup
• Reduces absorption by 73% at 5 min, 51% at 30 min, 36% at 60 min

• Heavy metals (iron, lead, arsenic, lithium)
• Mineral acids and alkalis
• Cyanide, fluoride
• Solvents, pesticides

C. Whole Bowel Irrigation (WBI) via NG Tube

1. Place NG tube and confirm position
2. Patient must be in sitting position
3. Administer polyethylene glycol (PEG)-electrolyte solution (GoLytely/Colyte)
   • Adults: 2 L/hour
   • Children: 0.5 L/hour
4. Continue until rectal effluent is clear

• Bowel obstruction or ileus
• Hemodynamic instability
• Unprotected airway
• Gut hypoperfusion
• Harrison's Principles of Internal Medicine 22e, p.3752; Rosen's Emergency Medicine; Tintinalli's Emergency Medicine

Summary Table: GI Decontamination Methods

8. NG Tube for Enteral Nutrition

• Small-bore NG tube for feeding
• For complex/post-surgical patients or pancreatitis, a nasoenteric tube distal to the injury site is preferred
• NG feeds are started with small volumes, titrated up
• The Washington Manual of Medical Therapeutics; Fischer's Mastery of Surgery

9. NG Tube Complications

10. Quick Clinical Scenarios