Dynamic modeling of apnea induced concurrent variations in arterial blood pressure and cerebral blood flow velocity.

Obstructive Sleep Apnea (OSA) is characterized by partial (hypopnea) or complete cessation (apnea) of airflow to the lungs during sleep. It has been previously reported that apnea episodes lead to significant rise in instantaneous blood pressure concomitant with a rise in cerebral blood flow velocity, indicating loss of cerebral autoregulation during the episodes. In this study, we have used Auto Regressive Moving Average model (ARMA (na, nb, nk)) to quantify OSA induced dynamic changes in cerebral blood flow velocity (CBFV) with beat to beat blood pressure (BP) as an input. BP and CBFV were recorded from 11 positively diagnosed sleep apnea subjects (6 Males, 5 Females; Age: 54.27±6.23 years, BMI:34.95±7.06kg/m(2), AHI: 57.39±28.43). The results suggest that two separate models, ARMA (5, 9, 1) and ARMA (5, 10, 0) can be used to quantify dynamic CBFV variations during apneas with a duration of less than and greater than 30s respectively with reasonable accuracy (<;6% error).