Fig. 3. Interapnea/hypopnea hyperventilation and carbon dioxide (CO2) excretion. In the first cycle, the interevent hyperpnea is sufficient to excrete the carbon dioxide accumulated during hypopnea. In the second cycle, much more carbon dioxide is accumulated during apnea than is excreted after the event. Multiple cycles of excessive carbon dioxide accumulation during the apneic period lead to hypercapnia. (Adapted from reference 35with permission.)
