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Lung degassing: an evaluation of two methods.

Stengel PW; Frazer DG; Weber KC
J Appl Physiol 1980; 48(2):370-375
The removal of trapped gases from excised lungs by the degassing method or the oxygen absorption process were compared. Lung pressure volume curves were recorded using a lung plethysmograph with capacitance detector and recording device. The design of the experimental apparatus was diagrammed. Male Long-Evans-hooded-rats were endotracheally intubated and ventilated with 100 percent oxygen for 10 minutes to produce oxygen absorption atelectasis. Blood absorption of the oxygen remaining in the lungs after 10 minutes was promoted by clamping the trachea prior to excision. Two episodes of vacuum degassing were performed on the dissected lungs to determine the changes in volume of the atelectatic lungs with a reduction in pressure. The amount of gas remaining in the lungs after vacuum degassing was determined by the output of a capacitance spirometer and a water displacement method. The lungs were reinflated for two to five cycles after the initial degassings, and the trapped gas volumes were determined. Degassing produced no detectable changes in lung volume after oxygen absorption. The amount of trapped gas after artificial inflation cycles was 31 percent of the total lung capacity after two cycles and 55 percent of the total lung capacity after five cycles. The vacuum degassing was most effective at a chamber pressure equivalent to the vaporization pressure of water. The amount of trapped gas removed from the lungs after two degassings in a vacuum chamber was 97 percent at 20 Torr, and this percentage decreased as the pressure increased. The authors conclude that oxygen absorption atelectasis is more effective in removing gas from the lungs than vacuum degassing.
NIOSH-Author; Laboratory-techniques; Oxygen-uptake; Pulmonary-system; Air-pressure; Pulmonary-function; In-vitro-studies; Physiological-response; Laboratory-animals
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Journal of Applied Physiology
Page last reviewed: September 2, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division