ABG and NIV

NIV use case scenarios

Scenario 1: Retaining CO2 (High pCO2)

• ABG: pCO2 60 mmHg (target < 45), pH 7.28 (acidotic), pO2 85 mmHg.

• Goal: Improve CO2 clearance.

• Adjustment:

  • Increase IPAP: This increases the pressure difference, leading to a larger tidal volume and better CO2 washout. Start with increments of 2 cmH2O.

  • Consider increasing Respiratory Rate (if applicable and patient tolerated): This can also increase minute ventilation.

Scenario 2: Hypoxic (Low pO2)

• ABG: pO2 55 mmHg (target > 60), pCO2 42 mmHg, pH 7.38.

• Goal: Improve oxygenation.

• Adjustment:

  • Increase EPAP: This increases the end-expiratory pressure, which helps to recruit collapsed alveoli and improve oxygen diffusion. Start with increments of 2 cmH2O.

  • Increase FiO2: If the patient is on supplemental oxygen, increase the fraction of inspired oxygen.

Scenario 3: Mixed Picture (High pCO2 and Low pO2)

• ABG: pCO2 55 mmHg, pO2 58 mmHg, pH 7.32.

• Goal: Improve both ventilation and oxygenation.

• Adjustment:

  • Increase IPAP: To improve CO2 clearance.

  • Increase EPAP: To improve oxygenation.

Scenario 4: Patient Tolerating Well, but Mildly Acidotic

• ABG: pCO2 50 mmHg, pH 7.34, pO2 90 mmHg.

• Goal: Optimize ventilation to normalize pH.

• Adjustment:

  • Slightly increase IPAP: A small increase (e.g., 1-2 cmH2O) may be enough to improve CO2 removal without causing discomfort.

General Considerations:

• Monitor Patient: Always assess patient comfort, respiratory effort, and vital signs after any adjustment.

• Small Increments: Make small changes and re-evaluate with repeat ABGs if necessary.

• Respiratory Rate/I:E Ratio: These can also be adjusted, but IPAP and EPAP are primary for initial changes based on ABG.

• Underlying Cause: Always consider and address the underlying cause of respiratory failure.

Feedback