Modulation of Respiratory Sinus Arrhythmia by Breathing Pattern

Respiratory sinus arrhythmia (RSA) of healthy humans is dependent on multiple factors like heart rate itself, blood pressure, stroke volume and sympatho-vagal tone. Respiration is a dominant factor causing an extended variability of heart rate, and is frequently used for testing the status of autonomic nervous system [I]. If heart rate variability (€IRV) is abnormally rcduced, this could be caused by ischaemic heart disease. [2], diabetes ml l i tus [3], dysfunction of CNS [4]. It is also well known that anaesthesia can cause an major reduction of RSA [S]. In thc 60's and ~ O ' S , several investigations were made to find a rclationship between the amplitude of respiratory sinus arrhythmia and breathing parameters like tidal volume, breathing frcqucncy and brcathhold in an actively breathing volunteer [6,7]. In thc SO'S, spectral analysis was performed and HRV was thc objcct o f many cardiological investigations. In the 90's. spcctral analysis of 1IRV was incrcasingly used in anesthesia and ICU patients in ordcr to find a sedation score [S]. The aim of this study is to dcmonstratc thc effect of mechanical passivc vcntilation on healthy volunteer's RSA.