Authors: Javier A Jo Anna Blasi Edwin M Valladares Ricardo Juarez Ahmet Baydur Michael C K Khoo
Publish Date: 2007/04/06
Volume: 35, Issue: 8, Pages: 1425-1443
Abstract
Using the Volterra–Wiener approach we employed a minimal model to quantitatively characterize the linear and nonlinear effects of respiration RCC and arterial blood pressure ABR on heart rate variability HRV in normal controls and subjects with moderatetosevere obstructive sleep apnea syndrome OSAS Respiration R–R interval RRI blood pressure BP and other polysomnographic variables were recorded in eight normal controls and nine OSAS subjects in wakefulness Stage 2 and rapid eyemovement sleep To increase respiratory and cardiovascular variability a preprogrammed ventilator delivered randomly timed inspiratory pressures that were superimposed on a baseline continuous positive airway pressure Except for lower resting RRI in OSAS subjects summary statistical measures of RRI and BP and their variabilities were similar in controls and OSAS In contrast RCC and ABR gains were significantly lower in OSAS Nonlinear ABR gain and the interaction between respiration and blood pressure in modulating RRI were substantially reduced in OSAS ABR gain increased during sleep in controls but remained unchanged in OSAS These findings suggest that normotensive OSAS subjects have impaired daytime parasympathetic and sympathetic function Nonlinear minimal modeling of HRV provides a useful insightful and comprehensive approach for the detection and assessment of abnormal autonomic function in OSAS
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