Why are ventilated patients put on orogastric (OG) tube suction?

Why Ventilated Patients Are Put on OG Tube Suction

Ventilated patients are placed on orogastric (OG) tube suction primarily to prevent gastric distension and reduce the risk of aspiration, which can lead to ventilator-associated pneumonia (VAP) and increased mortality.

Mechanism and Rationale

Mechanical ventilation creates several conditions that necessitate gastric decompression:

1. Prevention of Aspiration

   • Intubation impairs normal protective airway reflexes
   • Positive pressure ventilation can force gastric contents upward
   • Gastric distension increases risk of regurgitation and microaspiration 1
   • Aspiration of gastric contents is associated with a 4-fold higher risk of pneumonia 2

2. Reduction of Gastric Volume

   • Mechanical ventilation can cause air to enter the stomach during bag-mask ventilation 1
   • Gastric inflation interferes with effective ventilation 1
   • Excessive gastric volume increases intra-abdominal pressure, which can:
     • Impair diaphragmatic movement
     • Decrease lung compliance
     • Worsen ventilation-perfusion matching

3. Management of Enteral Nutrition Risks

   • Critically ill patients often receive enteral nutrition
   • Gastric emptying is frequently impaired in critical illness
   • OG suction helps manage residual volumes and prevent reflux 3

Evidence-Based Benefits

The American Journal of Respiratory and Critical Care Medicine guidelines recommend:

• "Orotracheal intubation and orogastric tubes are preferred over nasotracheal intubation and nasogastric tubes to prevent nosocomial sinusitis and to reduce the risk of VAP" 1

Research demonstrates that:

• Gastroesophageal reflux (GER) is common in critically ill, mechanically ventilated patients 3
• Reflux can lead to microaspiration through channels formed by folds in endotracheal tube cuffs 4
• Gastric decompression via OG suction reduces the volume of potential aspirate

Best Practices for Implementation

1. Tube Placement and Confirmation

   • Use orogastric rather than nasogastric approach when possible 1
   • Confirm proper placement via X-ray before initiating suction
   • Document insertion depth and check regularly 1

2. Patient Positioning

   • Maintain patients in semi-recumbent position (30-45°) 1, 5
   • Avoid supine positioning which increases aspiration risk 4

3. Suction Parameters

   • Use low intermittent suction rather than continuous high suction
   • Monitor for excessive fluid losses and electrolyte imbalances

4. Special Considerations

   • For patients receiving enteral nutrition, consider:
     • Temporary interruption of suction during feeding periods
     • Post-pyloric feeding tube placement for high-risk patients 6
     • Regular assessment of gastric residual volumes

Potential Complications and Mitigation

• Fluid/Electrolyte Imbalances: Monitor output and replace losses as needed
• Mucosal Damage: Use appropriate suction pressure and intermittent rather than continuous suction
• Tube Displacement: Secure tube properly and confirm position regularly 1
• Sinusitis: Use orogastric rather than nasogastric approach when possible 1

Alternative Approaches

For patients at particularly high risk of aspiration:

• Consider post-pyloric feeding tubes (especially mid-duodenum and beyond) 6
• Research shows aspiration is 13.2% lower when feeding in the second/third portions of the duodenum compared to gastric feeding 6
• Specialized tubes with esophageal balloons have shown promise in reducing GER and aspiration 7

OG tube suction remains a fundamental intervention in ventilated patients to prevent the serious complications of gastric distension and aspiration, which directly impact morbidity and mortality outcomes.