Can a BiPAP (Bilevel Positive Airway Pressure) machine cause stomach distension due to excess air inside the stomach?

BiPAP and Stomach Distension

Yes, BiPAP breathing machines can cause stomach distension due to excess air entering the stomach during positive pressure ventilation. This occurs when pressurized air is directed not only into the lungs but also into the esophagus, leading to aerophagia (air swallowing) and gastric insufflation 1.

Mechanism of Stomach Distension with BiPAP

BiPAP (Bilevel Positive Airway Pressure) delivers two levels of pressure:

• Higher inspiratory positive airway pressure (IPAP)
• Lower expiratory positive airway pressure (EPAP) 2

During this process, several factors can contribute to gastric distension:

1. Air leakage into esophagus: Pressurized air can leak into the esophagus instead of only entering the airways
2. Aerophagia: Patients may swallow air during BiPAP use
3. Air trapping: Air can become trapped below the gastroesophageal junction 1

Risk Factors for Gastric Distension

The risk of gastric distension increases with:

• Higher pressure settings
• Longer duration of BiPAP use
• Patient position (particularly supine position)
• Using BiPAP shortly after meals 1
• Multiple consecutive maneuvers or inflations 2

Clinical Evidence

A case report documented severe gastric insufflation in a patient with amyotrophic lateral sclerosis who was receiving BiPAP ventilation 1. The study suggested that the injection of inspiratory flow into the esophagus, aerophagia, and air trapping below the gastroesophageal junction after a meal were likely the major causes.

Prevention Strategies

To minimize the risk of stomach distension during BiPAP use:

1. Proper positioning:

   • Have the patient sit up for about 30 minutes after meals 1
   • Position the neck and/or shoulders in the midline in slight extension 2
   • Use a neck roll or head ring to stabilize position 2

2. Cricoid pressure technique:

   • Some centers use the "Sellick maneuver" (applying cricoid pressure) during lung inflations to minimize aerophagia, though this practice remains controversial 2

3. Timing considerations:

   • Avoid BiPAP use immediately after meals 1
   • Minimize the duration of pressure application

4. Pressure management:

   • Use the lowest effective pressure settings
   • Monitor for signs of gastric distension and adjust accordingly

Clinical Implications

Gastric distension from BiPAP can lead to:

• Abdominal discomfort and bloating
• Decreased functional residual capacity (FRC)
• Decreased forced vital capacity (FVC)
• Reduced flow parameters 2
• In rare cases (1%), symptoms can be severe enough to cause patients to abandon CPAP/BiPAP therapy 3

Monitoring and Management

If gastric distension occurs:

• Consider repositioning the patient
• Evaluate pressure settings
• Terminate BiPAP sessions if there is evidence of sequential reduction in FVC due to distension 2
• Consider alternative ventilation strategies if distension is severe and persistent

While BiPAP therapy is generally safe and effective for respiratory distress 4, clinicians should remain vigilant about this potential complication, especially in patients who are in the supine position or have recently eaten.