Table 1.
Description of parameters related with the radial artery pulse-pressure wave and other bio-signal characteristics
| Variable (units) | Description |
|---|---|
| Radial pressure pulse wave | |
| SE0-10Hz (Vrms 2, 10−1) | Sum of the spectral energy within 0–10 Hz |
| SE10-30Hz (Vrms 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 |
| Heart rate variability | |
| 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 |
| Photoplethysmogram signals | |
| PPG amplitude (V) | Maximum amplitude in average PPG |
| PPG systolic area (Vs) | Area of systolic phase in average PPG |
| Respiration signals | |
| Respiration rate (bpm) | Number of respirations per minute. |
| Impedance cardiography | |
| 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 |
| Combined variable from radial pressure pulse wave and electrocardiography | |
| PTT (ms) | Time delay between the R-peak of the ECG and the peak of the RPPW |