Modeling the interaction between arousal and chemical drive in sleep-disordered breathing.

We have measured the ventilatory response to acoustically induced arousal in normal subjects and patients with obstructive sleep apnea syndrome (OSAS). The arousal responses are similar in magnitude and time-course over the first 3 breaths, but in OSAS the subsequent response declines much more rapidly. Incorporation of these empirical findings into an existing model of sleep-disordered breathing allows an improved characterization of state-chemoreflex interactions. The shorter time-course of the arousal response in OSAS promotes greater ventilatory and state instability at low-to-intermediate levels of CO2 gain.