Table 1 Description of parameters related with the radial artery pulse-pressure wave and other bio-signal characteristics

 SE_0-10Hz (V_rms ², 10⁻¹)

Sum of the spectral energy within 0–10 Hz

 SE_10-30Hz (V_rms ², 10⁻³)

Sum of the spectral energy within 10–30 Hz

 PPI (V)

Pulse power index; Maximum amplitude of the voltage response in radial artery pulse

 PDI (mm)

Pulse depth index; measure of the pulse depth based on the sensor displacement in the direction normal to the skin surface

 Systolic area (Vs)

Area of systolic phase in average pulse

 Diastolic area (Vs)

Area of diastolic phase in average pulse

 SEVR (%, 10⁻²)

Subendocardial viability ratio; ratio between the diastolic and systolic area

 AIX (%)

Radial augmentation index normalized to a heart rate of 75 bpm; (late systolic pressure/systolic pressure) × 100

 NN (s)

Normal to normal interval

 SDNN (ms)

Standard deviation of the NN interval

 RMSSD (ms)

Square root of the mean squared differences of NN intervals

 TF (ms²)

Total frequency power within 0–0.4 Hz

 LF (ms²)

Low frequency power within 0.04–0.15 Hz

 HF (ms²)

High frequency power within 0.15–0.4 Hz

 nLF (%)

LF power in normalized units; LF/(LF + HF)

 nHF (%)

HF power in normalized units; HF/(LF + HF)

 LF/HF

Ratio of low to high frequency components; LF/HF

 PPG amplitude (V)

Maximum amplitude in average PPG

 PPG systolic area (Vs)

Area of systolic phase in average PPG

 Respiration rate (bpm)

Number of respirations per minute.

 SV (ml)

Stroke volume: volume of blood pumped from the left ventricle per beat

 CO (ml/min)

Cardiac output: volume of blood being pumped from the heart per minute; stroke volume × heart rate

 PTT (ms)

Time delay between the R-peak of the ECG and the peak of the RPPW