Closed-loop analysis of heart rate variability in obstructive sleep apnea

We have developed a model-based approach for assessing autonomic function in patients with obstructive sleep apnea syndrome (OSA). A closed-loop minimal model of cardiorespiratory control was estimated from RR-interval and respiration measured during a randomized breathing protocol. Application of the algorithm to simulated data confirmed the feasibility of estimating the model parameters under closed-loop conditions. Significant differences in the morphology and magnitude of the impulse response of one of the model components were found in OSA versus normal subjects. The results suggest that this procedure may provide a more sensitive means of detecting and tracking changes in autonomic function in patients before and during therapy for OSA