Can a nasal cannula be used to deliver supplemental oxygen in a patient who is already on Bilevel Positive Airway Pressure (BiPAP) therapy?

Can Nasal Cannula Be Used Simultaneously with BiPAP?

Yes, nasal cannula can be placed underneath a BiPAP mask to deliver supplemental oxygen when BiPAP alone fails to maintain adequate oxygenation, and this "dual oxygen therapy" approach may prevent the need for intubation. 1

Clinical Evidence for Dual Oxygen Therapy

The practice of adding nasal cannula oxygen while a patient is on BiPAP has been specifically studied and reported as effective:

• Dual oxygen therapy using nasal cannula underneath the BiPAP mask with an additional flow meter can increase oxygen saturation and improve patient comfort when BiPAP with high oxygen flow through the mask alone is insufficient. 1
• This approach is particularly useful when noninvasive ventilation is required but the patient cannot maintain adequate oxygen saturation despite high BiPAP settings and high oxygen flow through the BiPAP circuit. 1
• Case reports demonstrate that this technique prevented the need for invasive mechanical ventilation in patients who were failing BiPAP therapy alone. 1

Physiological Rationale

The effectiveness of adding nasal cannula to BiPAP is supported by oxygen delivery principles:

• Nasal cannula delivers oxygen continuously into the nose at 1-6 L/min, providing approximately 24-50% FiO2, and this oxygen delivery continues to function even when placed under a BiPAP mask. 2, 3
• The British Thoracic Society guidelines specifically recommend that nasal oxygen can be applied throughout airway management procedures, including during use of positive pressure devices. 4
• Standard nasal cannulae at 5 L/min during preoxygenation, increased to 15 L/min when consciousness is lost, is recommended even when CPAP or other positive pressure is being used. 4

Practical Implementation Algorithm

When a patient on BiPAP has inadequate oxygenation:

1. First, optimize BiPAP settings (increase IPAP/EPAP as tolerated, ensure proper mask fit to minimize leak). 4
2. Maximize oxygen flow through the BiPAP circuit (typically 10-15 L/min depending on the device). 4
3. If oxygen saturation remains inadequate, add nasal cannula at 2-6 L/min underneath the BiPAP mask using a separate oxygen source and flow meter. 1
4. Monitor for improvement in oxygen saturation and patient comfort. 1
5. If dual oxygen therapy fails, prepare for intubation as this indicates BiPAP failure. 4

Important Caveats

• The effective FiO2 delivered through the BiPAP circuit decreases as IPAP or EPAP increases due to higher intentional leak rates, so adding nasal cannula helps compensate for this phenomenon. 4
• Ensure the nasal cannula tubing does not interfere with the BiPAP mask seal, as significant unintentional leak will compromise BiPAP effectiveness. 4
• This is a temporizing measure; patients requiring dual oxygen therapy are at high risk for BiPAP failure and should be monitored closely for signs of respiratory deterioration requiring intubation. 4, 1
• For patients with COPD at risk of hypercapnic respiratory failure, target oxygen saturation of 88-92% even when using dual oxygen therapy, as excessive oxygen can worsen hypercapnia. 4, 5

Alternative Consideration

High-flow nasal cannula (HFNC) at 30-70 L/min provides more predictable FiO2 and modest CPAP effect, and may be considered as an alternative to BiPAP in some patients with hypoxemic respiratory failure, though it does not provide the same level of ventilatory support as BiPAP. 2, 6