How to adjust Bi-Level Positive Airway Pressure (BiPAP) parameters in a patient with hypercapnia?

From the Guidelines

To adjust BiPAP parameters for a patient with hypercapnia, increase the pressure support by raising the difference between inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP), with a target IPAP-EPAP difference of 8-12 cmH2O, as this approach has been shown to enhance alveolar ventilation and tidal volume, facilitating CO2 removal 1.

Key Adjustments

• Increase IPAP by 2-4 cmH2O while maintaining EPAP, and reassess with arterial blood gases after 30-60 minutes.
• If hypoxemia is also present, consider increasing EPAP by 1-2 cmH2O increments to improve oxygenation.
• Adjust respiratory rate backup settings to 12-16 breaths per minute if the patient has periods of apnea.
• Increasing inspiratory time to 1.0-1.5 seconds may also help with CO2 clearance.

Considerations

• Monitor the patient closely for signs of discomfort, air leaks, or worsening respiratory status, and ensure the mask fits properly to maximize ventilation efficiency.
• Be aware of the potential for permissive hypercapnia, particularly in patients with ARDS, where a pH above 7.2 is generally well tolerated 1.
• In patients with obstructive disease, prolonging the expiratory time can help reduce dynamic hyperinflation (gas-trapping) 1.

Evidence-Based Recommendations

• The BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults provides evidence-based recommendations for adjusting BiPAP parameters in patients with hypercapnia 1.
• The American Academy of Sleep Medicine has also developed recommendations for the titration of noninvasive positive pressure ventilation (NPPV) in patients with chronic alveolar hypoventilation syndromes 1.

From the Research

Adjusting Bi-Level Positive Airway Pressure (BiPAP) Parameters

To adjust BiPAP parameters in a patient with hypercapnia, several factors should be considered:

• The overall goal of BiPAP treatment is to reduce CO2 levels in the blood 2.
• First-line settings for non-invasive ventilation (NIV) therapy to treat stable hypercapnia include:
  • Pressure Support Ventilation Modus
  • EPAP 5 cmH2O
  • IPAP 15 cmH2O
  • Back Up rate 15/Minute 2
• To achieve a successful reduction in CO2, the following variables can be adjusted:
  • Increase in IPAP
  • Increase in back up respiratory rate
  • Use of assisted pressure controlled ventilation mode (APCV) 2

Ventilator Settings Titration

• An advisory system can be used to recommend NIV ventilator setting titration based on patient respiratory parameters, including oxygenation, ventilation, and patient effort 3.
• The IPAP ventilator setting is often considered in need of changing to target preferred values of partial pressure of oxygen (POB) and tidal volume (VT) 3.
• Increasing expiratory positive airway pressure (EPAP) has theoretical advantages during overnight nasal ventilation, but its effect on nocturnal hypoventilation control varies between patients with different underlying conditions 4.

Treatment of Hypercarbic Respiratory Failure

• Average volume-assured pressure support (AVAPS) mode can be effective in treating critically ill patients with acute hypercarbic respiratory failure, with similar efficiency to bilevel positive airway pressure-spontaneous/timed (BPAP-S/T) mode 5.
• IPAP levels can be titrated up to 30 cmH2O during non-invasive mechanical ventilation (NIMV) with a targeted tidal volume of 6-8 mL/kg 5.
• Airway pressure release ventilation (APRV) and bi-level positive airway pressure (BIPAP) may not be suitable for patients with severe acute lung injury (ALI) due to limitations in controlling patient work of breathing (WOB) and synchrony 6.