Portal de Periódicos da CAPES

Mechanism of pulmonary gas exchange and CO 2 transport during breath holding

1959; American Physiological Society; Volume: 14; Issue: 5 Linguagem: Inglês

10.1152/jappl.1959.14.5.706

8750-7587

John C. Mithoefer,

Cardiac Arrest and Resuscitation

Experiments describe the changes in Pa CO CO2 and lung volume shrinkage during breath holding with O 2 in man and the Pa CO CO2 , pH and CO 2 content of arterial and mixed venous blood during breath holding in the dog. An explanation is offered for the aberrations in CO 2 transport and exchange which occur during apnea. A self-perpetuating cycle is established during breath holding which is initiated by the arrest of the ventilatory output of Co 2 . The arterial Pa CO Co 2 rises rapidly as a result of decreased clearance of Co 2 from venous blood, the concentrating effect of lung volume shrinkage and the Haldane effect from oxygenation of hemoglobin. The venous Pa CO CO2 rises more slowly because of the uptake of Co 2 by the tissues and the Haldane effect from reduction of oxyhemoglobin. By this mechanism the Co 2 output into the lungs progressively falls and eventually stops. The cycle then is reversed and Co 2 moves from lungs to arterial blood. Submitted on March 2, 1959