The Science Journal of the American Association for Respiratory Care

2010 OPEN FORUM Abstracts

A BENCH STUDY TO COMPARE HUMIDITY OUTPUT OF VARIOUS CPAP MACHINES EQUIPPED WITH INTEGRATED HUMIDIFIERS

Ryan Diesem, Robert McCoy; Valley Inspired Products, Apple Valley, MN

Background: Humidification can be an important factor in a patientÂ’s CPAP compliance. Delivery of cool, dry air can cause significant oro-nasal discomfort. There are numerous models of CPAP devices equipped with integrated heated humidifiers and all have the aim of supplying warm, humidified air to the patient. As with general CPAP performance characteristics, each of these CPAP/humidifier models has unique and sometimes proprietary methods of delivering humidified air. The purpose of this test was to record humidity output, airflow temperature, water loss, and accumulated rainout of three newer models of CPAP machines equipped with integrated heated humidifiers in static use conditions. Method: Three models of CPAP devices equipped with integrated heated humidifiers (Fisher & Paykel Healthcare ICON Auto, ResMed AutoSet S9, Respironics System One REMstar Auto) were tested for various performance characteristics over two separate six hour test periods, one at 74 ?F (23 ?C) ambient temp and the second at 68 ?F (20 ?C). Ambient humidity was not controlled, but averaged 58% RH. Devices were filled with distilled water to the maximum fill line and set to the maximum temperature and humidity settings. Devices were set to deliver static CPAP pressure at 10 cmH2O. Exhaust fittings were created to allow exhaust flow at 40 LPM @ 10 cmH2O and was funnelled out of the test lab. Tube weight, chamber weight and chamber water volume were measured before and after the test. Ambient temperature & humidity and tube-end temperature & humidity readings were taken every five minutes for the first half hour, every half hour up to two hours, and every hour up to six hours. Rainout volume was measured at the end of the test. Results: At both 68 ?F (20 ?C) and 74 ?F (23 ?C) none of the tested devices delivered any rainout. Delivered air temperatures were consistently lower on the SystemOne unit, which did not have a heated tube. The ICON delivered the highest humidity output compared to System One and S9 (Figure 1). The time taken for the ICON to reach its highest output was within 20 minutes while the System One and S9 took 1 hour and 2 hours respectively. Conclusion: No device delivered air temperatures and relative humidity consistent with another device. It is important that clinicians and sleep labs understand the capabilities and limitations of each device before providing this equipment. Sponsored Research - Fisher & Paykel Healthcare paid for this study.