Evaluation of two-way valves for resting level respiratory testing.
NIOSH 1977 Mayl :1-33
Ten two-way respiratory valves were compared for the influence of their dead space and resistance to air flow characteristics on the accuracy of measurement of eight ventilation variables and oxygen consumption in normal male human subjects under resting conditions, to identify the best single respiratory valve for resting pulmonary function measurements. The data showed a greater effect due to added dead space (hyperventilation) than to increased breathing resistance (hypoventilation) under the study conditions and within the range of valve characteristics encountered. The James valve, Von Dobeln valve and modified Douglas valve, appeared to offer the least deviation in response variables under the resting test conditions, attributed to low dead space and low breathing resistance. Although the first 2 valves have minimal effective dead space, other problems suggest selection of the Von Dobeln valve as the best choice for general resting level studies of both patients and normals.
NIOSH-Author; Respiratory-function-tests; Diagnostic-tests; Physiological-tests; Physiological-effects; Physiological-functions; Respiratory-gases; Respiratory-mechanics; Airway-resistance; Control-devices
NTIS Accession No.
DHEW (NIOSH) Publication No. 77-212
National Institute for Occupational Safety and Health