FIG. 40:  High loop gain may occur because there are frequent arousals during apneic episodes, or it may be that the arousals are related to the PAP itself.^[36]  When patients awaken abruptly, their responsiveness to CO₂ and O₂ changes may be exaggerated, causing an overshoot in response.  An OSA can cause intermittent hypoxemia, and acute hypoxemia itself has been shown to increase chemoreflexive sensitivity, i.e., OSA is really a setup for unstable ventilation. 

Finally, during treatment, since the upper way obstruction is relieved, any ventilatory effort by the patient may result in the super effective ventilations that result in more dramatic PCO₂ and O₂ changes, and this can lead to high loop gain state and unstable breathing.