Testing limits to airflow perturbation device (APD) measurements.

Background: The Airflow Perturbation Device (APD) is a lightweight, portable device that can be used to measure total respiratory resistance as well as inhalation and exhalation resistances. There is a need to determine limits to the accuracy of APD measurements for different conditions likely to occur: leaks around the mouthpiece, use of an oronasal mask, and the addition of resistance in the respiratory system. Also, there is a need for resistance measurements in patients who are ventilated.

How far can one walk wearing a self-contained self rescuer?

Self-contained self rescuers (SCSRs) are used for emergency escapes in oxygen-deficit atmospheres. Certified by NIOSH to last 1 hour, SCSRs generate oxygen by chemical reaction and must meet a minimum oxygen generation time of 60 min when used according to instructions. Wearers must walk or crawl at a controlled rate to conform to the limits of the devices.