Non-Invasive Ventilation (NIV): Refers to methods that support breathing without the need for intubation.
Non-Invasive Positive Pressure Ventilation (NIPPV): Provides positive pressure to aid in breathing.
BiPAP and CPAP: Both are types of NIPPV but serve different functions.
BiPAP (Bi-Level Positive Airway Pressure)
Function: Supports both ventilation and oxygenation.
Key Components:
IPAP (Inspiratory Positive Airway Pressure): Pressure applied during inhalation.
EPAP (Expiratory Positive Airway Pressure): Pressure applied during exhalation.
Pressure Support: The differential between IPAP and EPAP, augments tidal volume and improves CO2 removal.
Use Case: Considered when a patient has issues with ventilation and oxygenation.
CPAP (Continuous Positive Airway Pressure)
Function: Supports oxygenation only.
Key Component: One continuous baseline pressure.
Use Case: Suitable for patients with pure oxygenation issues.
Clinical Application
Ventilation vs. Oxygenation:
Ventilation: Removal of CO2
Oxygenation: Involves adequate oxygen intake.
Graphical Representation
BiPAP: Shows two levels of pressure (IPAP and EPAP), useful for supporting both ventilation and oxygenation.
CPAP: Displays a continuous pressure, primarily aids in increasing functional residual capacity (FRC) and thus improving oxygenation.
Functional Residual Capacity (FRC)
Definition: The volume in the lungs at the end of passive expiration.
Clinical Relevance:
CPAP and PEEP: Both increase FRC and aid in oxygenation.
EPAP in BiPAP: Acts similarly to CPAP in improving oxygenation.
Adjusting Settings Based on Blood Gases
Blood Gas Interpretation:
Ventilation Problems: High CO2, low pH
Oxygenation Problems: Low PO2
Scenario Adjustments:
If no ventilation problem but an oxygenation problem (eg. PO2 low), use CPAP.
If ventilation and oxygenation issues coexist, adjust both IPAP and EPAP in BiPAP.
Practical Case Scenarios
Scenario 1
Patient on Non-Rebreather: PH 7.39, CO2 41, PO2 52
Interpretation: Normal ventilation, oxygenation issue
Solution: Initiate CPAP to improve oxygenation.
Scenario 2
Patient on BiPAP (10 over 5, 30% O2): PH 7.28, CO2 55, PO2 82
Interpretation: Ventilation issue
Solution: Increase IPAP to increase pressure support and assist with ventilation.
Scenario 3
Patient on BiPAP (15 over 5, 50% O2): PH normal, CO2 44, PO2 59
Interpretation: Oxygenation issue
Solution: Increase EPAP to improve oxygenation, adjust IPAP to maintain pressure support.
Scenario 4
Patient on BiPAP (10 over 5, 50% O2): PH 7.25, CO2 58, PO2 60
Interpretation: Both ventilation and oxygenation issues
Solution: Increase both IPAP and EPAP.
Summary
IPAP vs EPAP: It's not only about IPAP alone; it's about the relation between IPAP and EPAP, which defines pressure support crucial for ventilation.
Ventilation and Oxygenation Management: Adjust settings based on patient-specific scenarios, focusing on the relationship between pressures for effective treatment.