Impact of Integrative Cardiopulmonary Exercise Testing (4)
Oxygen uptake (Vo2 by the lungs and carbon dioxide output (VcOg) from the lungs are often considered to be measurements solely of lung function. However, Fick pointed out in 1870 that mass transfer of Oz from air to blood must be dependent on cardiac output and the difference between 02 content of the mixed venous blood and the arterial blood. Thus, Vo2, expressed as quantity per time, must be a function of cardiovascular status because Vo2 is tied to the quantity of deoxygenated blood presented to the lungs (cardiac output) and the degree of deoxygenation (related to the distribution of systemic blood flow relative to local metabolic rate). Buy Advair Diskus Online
For example, Casaburi et al2 and Weissman et al have shown that the increase in Vo2 during exercise is independent of the ventilatory response to exercise whereas Vo2 is greatly affected by changing the cardiac response to exercise. Furthermore, while lung dysfunction can very often lead to abnormal arterial blood gas values, such as hypoxemia, lung disease cannot affect Vo2 unless the lung disease is accompanied by impaired circulatory function. In subjects with normal exercise capacity, Vo2 generally increases with increasing amount of work performed, reflecting the normal increase in cardiovascular function during exercise.