From the Guidelines
For a CO2 level of 90, I would recommend increasing the pressure support (PS) as the patient's arterial PCO2 remains above the goal at the current settings, according to the guidelines for the adjustment of noninvasive positive pressure ventilation (NPPV) 1. This adjustment should be made gradually, monitoring the patient's response for 10-30 minutes before considering further changes. The guidelines suggest increasing the PS every 5 minutes if the tidal volume is low (< 6 to 8 mL/kg) or if the arterial PCO2 remains 10 mm Hg or more above the PCO2 goal at the current settings for 10 minutes or more 1. Additionally, consider increasing the backup respiratory rate by 2-4 breaths per minute if the patient has periods of hypoventilation. This approach works by enhancing alveolar ventilation through increased tidal volume, which helps eliminate more CO2 with each breath. The increased pressure support helps overcome airway resistance and reduces work of breathing. Be vigilant for signs of patient discomfort, mask leaks, or gastric distension with these changes, and ensure oxygen saturation remains adequate throughout the adjustment period. Reassess blood gases after 1-2 hours to evaluate the effectiveness of these changes. It is also important to note that the British Thoracic Society (BTS) guidelines for the ventilatory management of acute hypercapnic respiratory failure in adults suggest allowing permissive hypercapnia, with a pH above 7.2 being well tolerated 2. However, in this case, the primary goal is to reduce the CO2 level, and increasing the pressure support is the most appropriate initial step. The BTS guideline for oxygen use in adults in healthcare and emergency settings also emphasizes the importance of careful monitoring for hypercapnic respiratory failure and avoiding excessive oxygen use in patients with COPD 3. However, the primary focus here is on adjusting the BiPAP settings to address the elevated CO2 level.
From the Research
Adjusting BiPAP Settings for Hypercapnia
To address a CO2 level of 90, adjustments to BiPAP settings may be necessary. The goal is to improve ventilation and reduce hypercapnia.
- Increasing IPAP: Increasing the inspiratory positive airway pressure (IPAP) can help improve ventilation and reduce CO2 levels 4.
- Adjusting Respiratory Rate: Adjusting the respiratory rate on the BiPAP machine can also help improve ventilation and reduce hypercapnia 5.
- Monitoring and Adjusting: Close monitoring of the patient's condition and adjusting the BiPAP settings as needed is crucial in managing hypercapnia 6, 7.
- Targeting Normocapnia: The goal of BiPAP therapy is to achieve normocapnia, or normal CO2 levels, which can improve health-related quality of life, exercise capacity, lung function, and survival 8.
Considerations for BiPAP Adjustment
When adjusting BiPAP settings, consider the following:
- Patient Tolerance: The patient's tolerance to the adjusted settings should be closely monitored 4.
- Clinical Response: The patient's clinical response to the adjusted settings, including improvements in CO2 levels and overall condition, should be closely monitored 5, 7.
- Individualized Care: BiPAP settings should be individualized to each patient's needs and response to therapy 6, 8.