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Relative effects of flow-resistive and pressure-biased respiratory loading.
Harber P; Luo J; Beck J; Lee J
J Occup Med 1991 Oct; 33(10):1055-1059
The physiologic and subjective effects of pressure biased breathing (PBB) induced by positive pressure respirator simulators were examined. These effects were compared with the effects of dead space and no load. Medical histories of 15 volunteers were acquired and considered along with results derived from testing the subjects in both laboratory and field settings under a variety of respiratory loads. Only two laboratory sessions were summarized in this report. Studies were conducted while the subjects were on exercise bicycles, all performing at the same rate range. Subjects breathed through a mouthpiece and wore a nose clip while determinations of respiratory volumes, respiratory patterns, added work of breathing, and subjective response were made. Experimental periods lasted six minutes; data was collected during the final minute. Visual analog scales were used to determine subjective responses. In opposition to the addition of dead space, PBB decreased inspiration time, increased expiration time and increased ventilatory effort. Subjective discomfort results were similar for both treatments. The authors conclude that PBB (as one would encounter with the use of positive pressure masks designed to ensure an outward net flow in the case of leakage) directly affects resting lung volume and consequently produces significant physiologic and subjective effects.
NIOSH-Publication; NIOSH-Grant; Respirators; Respiratory-rate; Compressed-air-breathing-apparatus; Breathing-atmospheres; Face-masks; Hyperbaric-environments; Humans; Respiratory-equipment
Philip Harber, MD, MPH, Department of Medicine, University of Oallfornla, Los Angeles, Los Angeles, Oallfornla 90024-17
Issue of Publication
Journal of Occupational Medicine
University of California Los Angeles, Los Angeles, California
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division