LAUSR

BACKGROUND Bronchiolitis is the most common cause of admission in children under 2 years of age in the United States. The standard of care involves supportive measures, including non-invasive interventions such as CPAP. CPAP is traditionally delivered through a full facemask; however, pediatric intensive care units have been exploring the use of the RAM cannula by Neotech as a mode of CPAP delivery, but the level of CPAP delivered is uncertain. We, therefore, completed an in vitro study to determine the level of CPAP delivered via the RAM cannula utilizing a pediatric lung model. METHODS 3D-printed models of seven sizes of pediatric upper airways were connected to an ASL 5000 Breathing Simulator. We applied each size of RAM cannula to weight-appropriate airway and lung compliance parameters, delivering pressures of 5, 7 and 10 cmH2O using a ventilator in the CPAP mode. Leaks of 0%, 20%, 40% and 60% were generated to emulate a complete seal or poor fit and/or open-mouth breathing. The outcome measure was the difference in CPAP, referred to as '%leak effect', measured by the lung simulator relative to the CPAP set on the ventilator. RESULTS We found that set CPAP of 5 through 10 cmH2O generated measured CPAP ranging from 2.6 to 9.7 cmH2O. For set CPAP of 5, 7 and 10 cmH2O the mean '%leak effect' of measured CPAP from the set CPAP was: -25%, -26% and -25.7%, respectively. For each specific cannula-airway combination, increasing the set pressure and decreasing the air leak resulted in higher levels of CPAP delivered. CONCLUSION RAM cannula delivers varying amounts of CPAP, with a percent loss of approximately -25% depending on the level of leak in the system. With minimal leak, it is conceivable that the RAM cannula can be used to deliver clinically meaningful CPAP.