The Science Journal of the American Association for Respiratory Care

2001 OPEN FORUM Abstracts


JesusOng MD, LiChen Ph.D., Alexander Adams MPH, RRT, Regions Hospital, St. Paul, MN.

Background: Sound of sufficientintensity and duration can affect the mood and concentration of hospitalizedpatients and health care workers. Studies have suggested that hospital noiseand noise producing devices are a potential health hazard. Stand alone CPAPdevices have this potential. The aim of this study is to investigate factorsthat set the noise level generated by 5 CPAP devices.

Method: In a clinical laboratorysetting, the factors tested were: distance from the device (0.5 meter, 1.5 m),tubing type in use (corrugated, smooth), PEEP valve in use (5,10,15 cm H2O),flow setting (maximum flow, flow = 80 L min -1) and filter use (servingas a muffler on 2 devices only). Measurements of the noise levels of the deviceswere taken by an A-weighted sound meter (model 407703, Extech, Taiwan, CHN).Results were analyzed by ANOVA (super ANOVA, SPSS, Chicago, Ill).

Results: The mean decibel(dB) level for all devices under all conditions tested was 59.2 dB. By comparison,the decibel level in the center of our ICU during the day was 45.0 dB. The useof a PEEP valve reduced the noise level by 3.4 dB (no valve vs. PEEP 15 cm H2O).Moving from 0.5 m to 1.5 m from the device reduced the noise level by 3.6 dB.The filter (No.1605, Hudson RCI, Temecula, CA) inserted in the intake port ofthe device reduced noise by 3.5 dB. The flow of 80 L min-1 comparedto maximum flow reduced the noise level by 5.0 dB. The use of smooth tubingreduced the noise level by 1.0 dB. One device (Whisper Flow 2-60, Caradyne,Indianapolis, IN) produced less noise than the other devices.

Conclusion: The EPA noiselimit recommendations for a hospital unit are 45 dB during the day and 35 dBat night. This study clearly indicates that CPAP devices generate noise higherthan EPA recommendations. Noise generated by CPAP devices is set by certainfactors: flow setting, device in use, distance from the device, use of filter,peep valve and tubing type (order of decreasing magnitude). Health care personnelshould set up and maintain CPAP devices with adequate flow, the prescribed FIO2/CPAPlevels and the lowest possible sound exposure.


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