Innovations in Nasal High Flow: The New Asymmetrical Cannula Explained
Published in
Respiratory & Sleep
on April 23, 2025
Flow references the delivery of high flows of humidified air and sometimes oxygen through a comfortable nasal cannula interface. The combination of flow and humidity provides four key mechanisms: airway hydration, comfort, reduction of dead space, and pressure. Heated humidification is integral to nasal high flow (NHF) as it enables comfortable delivery of high flow rates and supports airway hydration. Gas at 37°C and 44 mg per liter of water vapor mimics the lung's natural state and optimizes mucociliary transport so secretions can be managed easily. The combination of dead space clearance and pressure provides respiratory support.
![Asymmetric High Flow]()
During normal breathing, the upper airway is filled with carbon dioxide-rich gas at the end of expiration, which is then rebreathed. In comparison, with NHF, the upper airway is cleared with a continuous flow of fresh gas, reducing the rebreathing of CO2 and improving gas exchange. In addition, exhaling against the continuous flow generates a low level of dynamic positive airway pressure and supports alveolar ventilation. Delivering respiratory support decreases respiratory rate and work of breathing. The key to maximizing these effects is to deliver the highest tolerable flow rate.
![Asymmetric Design]()
To further enhance the effects of NHF, Fisher & Paykel has developed an asymmetric cannula. By using an asymmetric design—with one small prong and one large prong—it provides a dual benefit for both patients and caregivers.
The innovative prong design creates unidirectional flow, optimizing the delivery of nasal high flow. This targeted therapy addresses anatomical dead space, potentially improving CO2 clearance. Additionally, the unique design eliminates sizing issues, offers quieter therapy delivery, and effectively enhances respiratory support. Fisher & Paykel Healthcare remains committed to advancing respiratory care, and the myDuet cannula represents a significant leap forward in this mission.
For more information or connect with a Fisher & Paykel representative, visit the Fisher & Paykel Healthcare website.