What adjustment to oxygen therapy or NIV settings is recommended for a COPD patient with hypercapnia and normoxemia on current settings?

From the Guidelines

I recommend increasing the NIV pressure settings rather than decreasing oxygen to address the hypercapnia in the COPD patient with normoxemia on current settings. The patient's current ABG shows adequate oxygenation but persistent hypercapnia despite NIV therapy, suggesting ongoing CO2 retention effects. Increasing the pressure gradient will enhance ventilation and CO2 clearance without compromising her oxygen needs. This approach is supported by the American Thoracic Society clinical practice guideline, which suggests NIV with targeted normalization of PaCO2 in patients with hypercapnic COPD on long-term NIV 1.

Key Considerations

• The patient's daytime somnolence suggests ongoing CO2 retention effects, which can be addressed by increasing the NIV pressure settings.
• Reducing oxygen would be counterproductive as she requires supplemental O2 for her severe COPD.
• The BTS guideline for oxygen use in adults in healthcare and emergency settings recommends avoiding excessive oxygen use in patients with COPD and targeting an oxygen saturation of 88-92% 1.
• The BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults recommends starting NIV when pH < 7.35 and pCO2 > 6.5 kPa persist or develop despite optimal medical therapy 1.

Adjustment of NIV Settings

• Increase the inspiratory positive airway pressure (IPAP) from 24 to 26-28 cmH2O while maintaining the expiratory positive airway pressure (EPAP) at 6 cmH2O.
• Monitor the patient's response to the adjusted NIV settings and adjust as needed to achieve targeted normalization of PaCO2.

Follow-up

• Recommend a follow-up ABG in 1-2 weeks to assess the effectiveness of the adjusted NIV settings.
• If hypercapnic symptoms persist despite maximal NIV settings, consideration of adjusting her oxygen prescription might be necessary, but only with close monitoring to prevent worsening hypoxemia 1.

From the Research

Adjustment to Oxygen Therapy or NIV Settings for COPD Patients

To adjust oxygen therapy or Non-Invasive Ventilation (NIV) settings for a COPD patient with hypercapnia and normoxemia on current settings, several factors should be considered:

• The primary goal of NIV treatment is to reduce CO2 levels in the blood, which can be achieved by adjusting the following variables:
  • Increase in IPAP
  • Increase in back-up respiratory rate
  • Use of assisted pressure-controlled ventilation mode (APCV) 2
• First-line settings for NIV therapy to treat "stable hypercapnia" include Pressure Support Ventilation Modus, EPAP 5 cmH2O, IPAP 15 cmH2O, and Back Up rate 15/Minute 2
• High inspiratory positive airway pressures aimed at decreasing CO2 levels can ensure NIV success in stable hypercapnic COPD patients 3
• NIV initiated when patients remain hypercapnic while in a clinically stable state following an acute exacerbation can prolong the time to readmission 3

Key Considerations

• The optimal settings, timing, and target population for NIV utilization in stable hypercapnic COPD patients are crucial to maximize its benefit 3
• Technological advances in NIV algorithms and remote monitoring have the potential to improve use and titration 3
• Long-term NIV is an established treatment for end-stage COPD patients suffering from chronic hypercapnic respiratory failure, with the main target being to augment alveolar hypoventilation by reducing PaCO2 to relieve symptoms 4

Comparison of NIV and Other Therapies

• High-Flow through Nasal Cannula (HFNC) is able to keep PaCO2 unmodified, while oxygenation slightly deteriorates as opposed to NIV, in exacerbated COPD patients 5
• HFNC reduces the work of breathing by a similar extent to NIV, while it increases by 40-50% during conventional oxygen therapy (COT) 5
• HFNC is reported to be more comfortable than COT and NIV, despite limited evidence for improved clinical outcomes 5