The Science Journal of the American Association for Respiratory Care

2012 OPEN FORUM Abstracts


Kathleen Deakins, Nancy Johnson, Myers Timothy; Pediatric Respiratory Care, University Hospitals Rainbow Babies & Children’s, Cleveland, OH

Background Non-invasive support via nasal cannula is used in the management of respiratory distress in the Neonatal Intensive Care Unit (NICU). Attaching, securing and managing interfaces during CPAP or non-invasive ventilation can present challenges while maintaining pressure in the presence of leaks. A new nasal cannula interface has created additional opportunities for ventilation. The purpose of this observational study was to determine the effect s of increasing leak on pressure, flow and tidal volume delivered and to determine parameters needed for optimum performance. Methods A newborn size RAM Nasal cannula (Neotech Products, Valencia CA) was attached to two pieces of pressure tubing equivalent to the length of an infant trachea and attached to a stopcock connected to an Ingmar Neonatal Demonstration Lung Model (Ingmar Medical, Pittsburgh, PA) with a set compliance of 2 mL/cmH20. The cannula’s 15 mm adapter was attached to the patient wye of an Airlife neonatal ventilator circuit (Carefusion: Yorba Linda CA) on a GE Engstrom Carestation ventilator (GE, Madison WI). Following ventilator system checkout, it was placed in a non-invasive pediatric mode at the following settings: Pressure support (Psupp) = 14 cmH20, PEEP +5 cmH20, bias flow 8 lpm, rise time 100 msec, trigger 0.25 cmH20 with backup settings of: frequency = 30 bpm, inspiratory time (Ti) 0.5 sec, PEEP +5 cmH20, Psupp 15 cmH20, Time limit for pressure support (T supp) 0.8 sec and end flow 25%. Int he absence of a spontaneous breathing model, backup settings were sole source of ventilation, simulating nasal PCV. Leaks of 0%, 30%, 50%, 70% and 100% were introduced and confirmed by leak% display on ventilator. Flow, pressure and tidal volumes measurements were taken from the ventilator trend screen following 10 snapshots at each leak level. 100% leak was created by disconnecting the circuit from test lung and leaving it open to air. Results: Mean values with standard deviations for pressure, flow and tidal volume at each leak level are found in the table below: The ventilator alarmed for “no breath detected” at > 70% leak. Conclusion Pressure, flow and tidal volumes became increasingly unstable as leak increased. A minimally acceptable flow rate of 12 lpm was maintained with some degree of leak (preferred to reduce expiratory resistance). Alarms generated at high leak percentages created a safety mechanism in the face of a fixed resistance (the cannula). Sponsored Research - None PIP, Vt and Flow Rates at Dfferent Leak %