Simulated flying altitude and performance of continuous positive airway pressure devices
2014 (English)In: Aviation, Space and Environmental Medicine, ISSN 0095-6562, E-ISSN 1943-4448, Vol. 85, no 11, 1092-1099 p.Article in journal (Refereed) Published
INTRODUCTION: Continuous positive airway pressure (CPAP) is used in air ambulances to treat patients with impaired oxygenation. Differences in mechanical principles between CPAP devices may affect their performance at different ambient air pressures as will occur in an air ambulance during flight. METHODS: Two different CPAP systems, a threshold resistor device and a flow resistor device, at settings 5 and 10 cm H2O were examined. Static pressure, static airflow and pressure during simulated breathing were measured at ground level and at three different altitudes (2400 m (8 kft), 3000 m (10 kft) and 10700 m (35 kft)). RESULTS: When altitude increased, the performance of the two CPAP systems differed during both static and simulated breathing pressure measurements. With the threshold resistor CPAP, measured pressure levels were close to the preset CPAP level. Static pressure decreased 0.71 ± 0.35 cm H2O, at CPAP 10 cm H2O, comparing ground level and 35 kft. With the flow resistor CPAP, as the altitude increased CPAP produced pressure levels increased. At 35 kft, the increase was 5.13 ± 0.33 cm H2O at CPAP 10 cm H2O. DISCUSSION: The velocity of airflow through the flow resistor CPAP device is strongly influenced by reduced ambient air pressure leading to a higher delivered CPAP effect than the preset CPAP level. Threshold resistor CPAP devices seem to have robust performance regardless of altitude. Thus, the threshold resistor CPAP device is probably more appropriate for CPAP treatment in an air ambulance cabin, where ambient pressure will vary during patient transport.
Place, publisher, year, edition, pages
Aerospace Medical Association , 2014. Vol. 85, no 11, 1092-1099 p.
continuous positive airway pressure, air ambulance, threshold resistor, flow resistor, bench study
Anesthesiology and Intensive Care
IdentifiersURN: urn:nbn:se:umu:diva-93675DOI: 10.3357/ASEM.4013.2014ISI: 000343642500004PubMedID: 25329941OAI: oai:DiVA.org:umu-93675DiVA: diva2:750788