P055 Impact of humidification on bacterial filters and delivered pressures of PAP devices

Abstract Background In typical sleep laboratories, PAP devices are used on multiple patients in short periods of time. Some manufacturers recommend the use of bacterial filters to prevent cross contamination. Bacterial filters are known to increase resistance and reduce delivered pressures, especially at higher flow rates. While bacterial filters are manufactured to specific impedance values, humidification has the potential to increase their impedance in unpredictable ways. We aim to assess the impact of humidification on bacterial filters and delivered CPAP and determine whether pre- and post-study pressure measurements are required in lab-based PAP titration studies. Methods Delivered pressure was measured with a digital manometer at the beginning and end of 20 lab-based CPAP titration studies at four set-pressure points: 5, 10, 15 and 20cmH2O. To avoid tube rainout, humidification was set to 2 out of 5. To assess the impact of maximal humidification, additional measurements were taken before and after 8-hours of bench-testing at 20 cmH2O with humidification set to a 5 out 5. Progress to Date Six of eight studies (75%) have revealed no change (≤0.1cmH2O) in the delivered pressure after a full night of humidification. One study showed a small decrease of 0.3 cmH2O at 20 cmH2O, and one showed a marked decrease of 2.6 cmH2O. Currently, it is unclear what contributed to this marked decrease. Intended outcome and impact This study suggests that pre- and post-study pressure measurements should be taken during routine PAP titration studies when humidification is used in conjunction with bacterial filters.