The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

EVALUATION OF BRONCHIAL PRESSURES DURING ADULT HIGH FLOW NASAL CANNULA

Keith R. Hirst, David L. Vines; Respiratory Care, Rush University, College of Health Sciences, Chicago, IL

Background: Since the use of High Flow Nasal Cannulas (HFNC) has increased, speculation has been made as to whether or not any kind of CPAP is created in adults. Our hypothesis is that HFNC does create a level of CPAP at flows of 40 LPM or greater. Method: We attached a driver (7200 (Covidien, Boulder CO) to simulate spontaneous breathing to one test lung of a dual test lung system (Dual Adult TTL, Michigan Instruments, Grand Rapids Michigan). The other test lung was attached via tubing to an intubation manikin’s right main stem (Laedral, Wappingers Fall, New York). The left mainstem of the manikin was capped. Monitoring devices were placed In-line at the right main stem. These included a pressure manometer and a flow sensor which was connected to a NICO cardiopulmonary monitor (Philips Electronics, Andover, MA). The intubation manikin was first open to room air, then HFNC therapy (Teleflex Medical, Research Triangle Park, NC) was administered at 40, 50, 60, 70 LPM respectively. The driver was set on CMV, rate-15, sine flow waveform at VT of 400, 600, 800, 1000 mL and peak flows of 30, 40, 60 and 80 LPM. Measurements were taken with the mouth open and closed. Results: See Chart/graph Conclusion: We conclude that bronchial pressures may be increased during HFNC at flows of 40 LPM or higher when the mouth is closed. The elevated airway pressure is relatively low and may have the potential to vary depending on flow rate used and resistance of the upper airway. Sponsored Research - None

Bronchial End Expiratory Pressure in Spontaneously Breathing Lung Model during HFNC

a. Significantly greater than No Flow (p<0.05)
b. Significantly greater than HFNC 40LPM (p<0.05)
c. Significantly greater than HFNC 50 LPM (p<0.05)