The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts


John R. Meyers1, David L. Vines2, Steven B. Powell1; 1Pediatrics/Neonatology, Rush University Medical Center, Chicago, IL; 2Respiratory Care, Rush University Medical Center, Chicago, IL

BACKGROUND High Frequency Ventilation by Endotracheal Tube (ETT) has been used to treat various forms of lung disease in the newborn. Several types of High Frequency devices have been studied, all by ETT. Some proponents of Bubble Nasal Continuous Positive Airway Pressure (Bubble-CPAP) have suggested that the bubbling and its corresponding high frequency oscillatory effect on flow is clinically beneficial. Heated, Humidified, High Flow Nasal Cannulas (HFNC) are now widely used and have been shown to generate positive hypopharyngeal pressures consistent with therapeutic range of traditional CPAP devices. We previously tested two devices that induced flow oscillations mechanically. Four new devices using a fluidic oscillator in conjunction with a High Flow Nasal Cannula were evaluated at flow rates used in the clinical setting. METHODS A standard infant nasal cannula was used with the nose tips inserted into a balloon model of the nares and nasopharyngeal airway. A pressure sensor in the pharyngeal model captured continuous pressure readings. The first three devices were inserted into the nasal cannula circuit and evaluated at flow rates of 4-8 L/MIN. The fourth device was evaluated at flow rates of 2-7 L/MIN. For each device, waves of the hypopharyngeal pressure were generated and plotted. Frequency, Amplitude, and Mean Airway Pressure (MAP) were measured for each device at each flow rate. RESULTS For all devices, the MAP was directly proportional to the flow rate. There was a direct relationship between amplitude and flow for all devices. Devices #1 and #2 showed an inverse relationship between flow and frequency. Device #3 had a frequency that increased, and then decreased with rising flow. Device #4 had a frequency that decreased, and then increased as flow values rose. These last two frequency anomalies are likely due to complex turbulence patterns within the device. See table for absolute values. CONCLUSIONS An oscillatory device in-line within the circuit of a HFNC may enhance gas exchange, decrease apnea/bradycardia, and/or prevent intubation and mechanical ventilation in newborns with mild to moderate lung disease. Additional clinical studies are needed to evaluate this new ventilation modality. Sponsored Research - Supervising author has contractual royalty agreement with manufacturer.