From the Guidelines
For hypercapnic patients, the recommended BiPAP ventilation strategy involves using an inspiratory positive airway pressure (IPAP) of 12-16 cmH2O and an expiratory positive airway pressure (EPAP) of 4-6 cmH2O, with a pressure support of 8-10 cmH2O, as this approach has been shown to improve outcomes in terms of morbidity, mortality, and quality of life 1.
Key Considerations
- The initial settings for BiPAP in hypercapnic patients should aim to achieve a tidal volume of 6-8mls/kg and a respiratory rate of 10-15 breaths per minute, with an I:E ratio of 1.2-1.4, as suggested by the BTS/ICS guideline for the ventilatory management of acute hypercapnic respiratory failure in adults 1.
- In patients with obstructive disease, the goal is to maintain an oxygen saturation (SaO2) of 88-92% and a pH of 7.2-7.4, allowing for permissive hypercapnia if the inspiratory airway pressure exceeds 30 cmH2O 1.
- The use of noninvasive positive pressure ventilation (NIPPV) is recommended as first-line therapy in instances of hypercapnic respiratory failure, as it has been shown to improve oxygenation, pH, and work of breathing, with significant decreases in mortality and intubation rates 1.
Adjusting BiPAP Settings
- The IPAP should be gradually increased by 2-3 cmH2O increments as needed, up to 20-25 cmH2O, while monitoring patient comfort and PCO2 levels.
- The EPAP should be adjusted to prevent alveolar collapse and ensure proper mask fit to prevent leaks that would compromise ventilation effectiveness.
- Arterial blood gases should be monitored after 1-2 hours to assess response and adjust settings accordingly.
Specific Patient Populations
- In patients with ARDS, a low tidal volume strategy improves survival, and permissive hypercapnia may be necessary to avoid ventilator-induced lung injury 1.
- In patients with neuromuscular disease, an adequate tidal volume can be achieved with relatively low inflation pressures, but higher pressures may be needed in patients with chest wall deformity 1.
From the Research
BiPAP Ventilation Strategy for Hypercapnia
- The first-line settings for Non-Invasive Ventilation (NIV) therapy to treat stable hypercapnia are:
- Pressure Support Ventilation Modus
- EPAP 5 cmH2O
- IPAP 15 cmH2O
- Back Up rate 15/Minute 2
- The goal of NIV treatment is to reduce CO2 levels, 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
- Bi-level positive airway pressure spontaneous/timed (BPAP S/T) mode and average volume-assured pressure support (AVAPS) mode are both effective in treating patients with hypercapnic respiratory failure 3, 4
- AVAPS mode delivers a set tidal volume per kg by adjusting the pressure between upper and lower inspiratory positive airway pressures (IPAP), resulting in effective ventilation and CO2 elimination 4
- High-pressure non-invasive positive pressure ventilation (NPPV) is a new strategy targeted at maximally reducing arterial carbon dioxide, but may cause respiratory adverse events 5
- The use of NIV with BiPAP decreases the risk of mortality and need for endotracheal intubation in patients with acute hypercapnic respiratory failure due to exacerbation of chronic obstructive pulmonary disease (COPD) 6