What are the effects of BiPAP (Bilevel Positive Airway Pressure) settings on oxygenation?

From the Guidelines

BiPAP settings have a significant impact on oxygenation, and adjusting these settings can enhance breathing and gas exchange, ultimately improving patient outcomes in terms of morbidity, mortality, and quality of life. The effects of BiPAP settings on oxygenation can be understood by considering the roles of inspiratory positive airway pressure (IPAP) and expiratory positive airway pressure (EPAP). IPAP helps increase tidal volume and alveolar ventilation, while EPAP prevents alveolar collapse and maintains functional residual capacity 1. Typically, IPAP ranges from 8-25 cmH2O and EPAP from 4-10 cmH2O, with the pressure difference (PS = IPAP - EPAP) determining ventilatory support.

Key Considerations for BiPAP Settings

• Higher EPAP settings can improve oxygenation by recruiting collapsed alveoli and preventing atelectasis, which is particularly beneficial in conditions like COPD, heart failure, and sleep apnea 1.
• Oxygen supplementation can be added to BiPAP to further increase FiO2, and the effective inspired oxygen concentration can be affected by machine flow and intentional leak 1.
• The respiratory rate backup (usually 10-16 breaths/minute) and inspiratory time (typically 0.8-1.5 seconds) also influence gas exchange, and adjusting these parameters can help optimize oxygenation while avoiding complications like barotrauma or patient-ventilator asynchrony.

Recommendations for Adjusting BiPAP Settings

• Clinicians should monitor oxygen saturation, arterial blood gases, and patient comfort when adjusting BiPAP settings, making incremental changes to optimize oxygenation 1.
• A slightly higher goal than 88% (90%-94%) for oxygen saturation might be prudent in some circumstances to account for potential overestimation by oximetry 1.
• The location of supplemental oxygen connection to the NPPV circuit can affect the effective fraction of oxygen in the inspired air, and a 3-orifice “T” shaped connector attached between the NPPV device outlet and the hose can allow for optimal addition of supplemental oxygen into the circuit 1.

From the Research

Effects of BiPAP Settings on Oxygenation

The effects of BiPAP settings on oxygenation can be understood through various studies that have examined the impact of different BiPAP settings on patient outcomes.

• BiPAP has been shown to improve oxygenation in patients with respiratory failure, with studies demonstrating an increase in oxygen saturation and a decrease in oxygen requirements 2, 3.
• The use of dual oxygen therapy with BiPAP has also been shown to improve oxygenation and prevent the need for invasive mechanical ventilation in some patients 4.
• However, the optimal BiPAP settings for improving oxygenation are not well established and may vary depending on the individual patient and their underlying condition.
• Some studies have examined the effects of different BiPAP modes, such as biphasic positive airway pressure, on oxygenation in patients with chronic obstructive pulmonary disease (COPD) 5.
• The use of continuous flow biphasic positive airway pressure by helmet has also been shown to improve oxygenation in patients with acute hypoxic respiratory failure 6.

Key Findings

• BiPAP can improve oxygenation in patients with respiratory failure, with an increase in oxygen saturation and a decrease in oxygen requirements.
• Dual oxygen therapy with BiPAP may improve oxygenation and prevent the need for invasive mechanical ventilation in some patients.
• The optimal BiPAP settings for improving oxygenation are not well established and may vary depending on the individual patient and their underlying condition.
• Different BiPAP modes, such as biphasic positive airway pressure, may have varying effects on oxygenation in patients with COPD.
• Continuous flow biphasic positive airway pressure by helmet may improve oxygenation in patients with acute hypoxic respiratory failure.

BiPAP Settings and Oxygenation

• The initial BiPAP settings used in one study were an inspiratory positive airway pressure (IPAP) of 8 cm H2O and an expiratory positive airway pressure (EPAP) of 4 cm H2O, with adjustments made as needed to achieve respiratory comfort and improve oxygenation 2.
• Other studies have used different BiPAP settings, such as an IPAP of 15 cm H2O and an EPAP of 5 cm H2O, to improve oxygenation in patients with COPD 5.
• The use of higher IPAP and EPAP settings may be necessary to achieve optimal oxygenation in some patients, but the optimal settings will depend on the individual patient and their underlying condition.