Trapped gas at maximum lung volume in intact isolated rat lungs.
Respir Physiol 1979 Jul; 37(2):173-184
The amount and location of gas trapped in excised rat lungs at the maximum lung volume were studied. The lungs of Long-Evans-rats were excised and ventilated with air in a liquid filled plethysmograph. The tracheal pressure was equal to gas pressure inside, which was at ambient pressure (Pamb), Pamb plus 350 Torr, or Pamb minus 350 Torr. The trapped gas was measured for 10 inflation and deflation cycles. When tracheal pressure equaled any one of the three pressures, an equivalent amount of air accumulated in the lungs. The total amount of gas trapped reached an equilibrium value when the lung was inflated and deflated at a constant rate. The maximum amount of trapped gas reached 65 percent of maximum lung volume. Trapped gas spaces contracted or expanded in response to rarefaction or compression of tracheal gas when lungs were inflated and held at maximum lung volume. The authors suggest that the behavior of the trapped gas spaces is due to the physical properties of menisci that occlude the airways or alveoli in the lung.
NIOSH-Author; Laboratory-animals; Respiratory-gas-analysis; Pulmonary-function; Respiratory-gas-transport; Invitro-study; Respiration; Physiological-response;
Author Keywords: Airway closure; Foam formation in lungs; Lung pressure-volume curves; Trapped air
Appalachian Laboratory for Occupational Safety and Health, National Institute for Occupational Safety and Health, Center for Disease Control, Public Health Service, Department of Health, Education, and Welfare, Morgantown, WV 26505