Abstract
BACKGROUND: The RAM cannula (Neotech, Valencia, CA) has become a commonly used interface for CPAP in neonatal intensive care. Performance characteristics of this interface used with a critical care ventilator are not well described.
METHODS: This was a bench study utilizing a lung simulator configured as an actively breathing infant (weights of 800 g, 1.5 kg, and 3 kg) with moderate lung disease and a critical care ventilator in CPAP mode with leak compensation on. Three sizes of the RAM cannulae (preemie, newborn, and infant) were compared to 3 BabyFlow nasal prongs (Dräger Medical, Lübeck, Germany) (medium, large, and extra-large). Fabricated nasal models produced a 70% occlusive fit for the RAM cannula and an occlusive fit with the Dräger prongs. Delivered flow and pressure levels were recorded at 9 CPAP levels between 5 and 20 cm H2O.
RESULTS: The Dräger prongs produced a mean airway pressure (
) within 0.20 cm H2O (range –0.10 to 0.35) of the set CPAP across all evaluated prong sizes and CPAP levels. In contrast, the RAM cannula produced 
values that averaged 8.5 cm H2O (range –15 to –3.5) below the set CPAP levels. The deficit in delivered versus target CPAP level for the RAM cannula increased with greater set CPAP. Set CPAP of 5 cm H2O delivered 
values that ranged from 0.6 to 1.5 cm H2O (difference of 3.5–4.4 cm H2O). Set CPAP of 20 cm H2O delivered 
values that ranged from 5.0 to 8.4 cm H2O (difference of 11.7–15 cm H2O). Inspiratory flow required to achieve set CPAP levels did not differ between interfaces, suggesting high resistance in the RAM cannula device masks the delivered CPAP levels.
CONCLUSIONS: Use of the RAM cannula with a 30% leak on a critical care ventilator delivered 
values lower than set CPAP. This may be clinically meaningful and should be considered when choosing a nasal interface.
- CPAP
- high-flow nasal cannula
- PEEP
- infant
- bench study.
Footnotes
- Correspondence: Natalie Napolitano MPH RRT RRT-NPS, Children’s Hospital of Philadelphia, Respiratory Therapy Department, Room 7NW149, 3401 Civic Center Blvd, Philadelphia, PA 19104. E-mail: napolitanon{at}email.chop.edu
See the Related Editorial on Page 1634
Ms Napolitano presented a version of this paper at AARC Congress 2015, held November 6–9, 2015 in Tampa, Florida, and at the Pediatric Academic Society/Society Pediatric Research, held April 30–May 3, 2016 in Baltimore, Maryland.
Ms Napolitano has disclosed relationships with Aerogen, Dräger Medical, Vero-Biotech, Smiths Medical, and Philips/Respironics. Ms Nickel has disclosed a relationship with Nihon Kohden. The remaining authors have disclosed no conflicts of interest.
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