Administration of Nitric Oxide via High Flow Nasal Cannula
Nitric oxide can be administered via high flow nasal cannula (HFNC), providing an effective delivery method for spontaneously breathing patients who require supplemental oxygen and positive airway pressure. 1
Mechanism of Delivery and Efficacy
- HFNC delivers high flow rates (up to 60 L/min) of heated and humidified oxygen-air mixture, creating a washout effect in the upper airways, reducing anatomical dead space, and providing a modest positive end-expiratory pressure (PEEP) effect of approximately 2-5 cmH2O 2, 3
- Nitric oxide can be blended with oxygen and delivered through HFNC using standard commercially available NO administration systems connected to the HFNC circuit 1
- Studies have demonstrated that inhaled nitric oxide (iNO) can be effectively delivered through nasal cannula systems, though the delivered dose may vary based on breathing patterns 4
Technical Considerations
- When administering nitric oxide via HFNC, the accuracy of NO delivery may be compromised compared to delivery through endotracheal tubes or other forms of non-invasive ventilation 5
- The actual tracheal concentration of NO may differ from what is measured by the NO delivery system, requiring careful monitoring 5
- Breathing pattern significantly influences inhaled NO concentration, with variations observed between rest, sleep, and exercise states 4
Clinical Applications
- This delivery method is particularly valuable for spontaneously breathing patients who require both nitric oxide therapy and the benefits of HFNC 1
- Long-term administration (up to 24 hours) of nitric oxide with oxygen via nasal cannula has been demonstrated to be safe and effective in reducing pulmonary vascular resistance in patients with COPD 6
- HFNC is generally better tolerated with higher comfort levels compared to mask-based delivery systems due to the heated and humidified oxygen delivery system and less restrictive interface 7
Monitoring and Safety Considerations
- Continuous monitoring of NO and NO₂ levels is essential, as the NO₂ level delivered to the patient could be greater than the value recorded by the NO delivery system 5
- Tracheal NO₂ levels should be maintained below 1.5 ppm to prevent potential toxicity 5
- The mass flow of NO past the trachea may be a more reliable dose metric than concentration for continuous flow delivery via nasal cannula, as it is less sensitive to breathing pattern variations 4
Implementation Protocol
- Begin with standard HFNC setup and establish appropriate flow rates (typically 20-60 L/min) based on the patient's respiratory needs 2
- Connect the NO delivery system to the HFNC circuit before the humidification chamber 1
- Target initial NO dosing based on clinical indication, typically starting at 5-20 ppm 4
- Monitor both the set NO level and the estimated delivered dose, recognizing that they may differ when using HFNC 5
- Adjust settings based on clinical response and measured parameters rather than relying solely on the set values 5