HR and BP variabilities
HR variability (HRV) was measured as a reliable quantitative marker to assess the activity of the sympathetic and parasympathetic branches of the autonomic nervous system using HRV analysis module (MLS 310, AD Instruments, New South Wales, Australia). In the time domain, the root mean square of the squared differences of successive RRI (RMSSD) estimates short-term variation of HR caused by parasympathetic activity [BP variability was assessed as a marker of efferent sympathetic vascular modulation [