The Science Journal of the American Association for Respiratory Care

2011 OPEN FORUM Abstracts


Ankeet Patel, Keith Hirst, David Vines; Respiratory Care, Rush University, Chicago, IL

Background: Although there is a growing body of evidence supporting the use of High Flow Nasal Cannula (HFNC) in adults, little is known about the amount of positive airway pressure created with its use. The goal of our bench study was to determine if there was any Continuous Positive Airway Pressure (CPAP) created. Method: We used a PB 7200 (Covidien, Boulder CO) as our driver 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 transducer and a flow sensor connected to a NICO cardiopulmonary monitor (Philips Electronics, Andover, MA). The driver was set on CMV, rate-15, sine flow waveform at VT's of 400, 600, 800, 1000 mL's and peak flows of 30, 40, 60 and 80 LPM. The manikin was first open to room air with no pressure then with the mouth closed. We then applied CPAP 5, CPAP 5/PSV-5, and CPAP 0/PSV 5 to the manikin via NIPPV through a Drager Evita XL. Finally we applied HFNC therapy through the following devices: Optiflow (Fisher and Paykel, Irvine CA), Comfort Flow (Teleflex Medical, Durham NC), and Precision Flow (Vapotherm, Stevensville MD). We administered HFNC at flows of 30, 40, 60, 70 LPM. Measurements on HFNC were taken with the mouth open and closed. Results: See Table 1. Only CPAP 5, PSV 5, and CPAP 5/PSV 5 had marked difference compared to HFNC (P< 0.05). We did not observe any significant changes in measured tidal volumes between the modes. Conclusion: We concluded that there was no significant CPAP created with any of the HFNC devices with either mouth open or closed. We did find that there was an elevation in Bronchial Inspiratory Pressure with flows of 60 and 70 LPM with the mouth closed.
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