2.2. Measurement of Blood Pressure, Heart Rate, Blood Pressure and Heart Rate Variabilities, and Pulse Wave Velocity

All measurements were performed by means of a noninvasive automated oscillometric device (Mobil-O-Graph PWV, IEM, Stolberg, Germany), with the inbuilt ARCSolver method used for both peripheral and central 24 h BP assessment. The system has been validated for brachial BP measurement, according to the European Society of Hypertension International Protocol [20]. Moreover, the methodology for aortic pulse wave velocity (aPWV) estimation has been previously reported and validated against invasive methods [21,22]. The monitor was placed on patients during the first 2 days after admission, starting between 08:00 A.M. and 10:00 A.M. The appropriate cuff was selected according to the patient’s arm circumference. BP (both peripheral and central), heart rate, and aPWV were measured automatically at 15 min intervals over 24 h. All subjects included in this study had recordings of good technical quality (at least 70% of readings were valid, and at least 1 measurement was taken per hour). Otherwise, 24 h measurements were immediately repeated.

Blood pressure and heart rate variabilities were estimated by calculating standard deviations (SDs) for 24 h systolic and diastolic peripheral and central BP, as well as heart rate. BP variability ratio (BPVR) was calculated as the ratio between systolic and diastolic 24 h SD, as previously reported [23].