Table 2.
Summary of physiological indicators computed from raw physiological signals.
| Signal | Indicator | Domain | Description |
|---|---|---|---|
| EDA | Mean raw level | The mean value of filtered EDA signal | |
| Min raw value | The minimum value of filtered EDA signal | ||
| Max raw value | The maximum value of filtered EDA signal | ||
| Std raw value | The standard deviation of filtered EDA signal | ||
| Mean tonic level | The mean value of tonic EDA signal | ||
| Max tonic value | The minimum value of tonic EDA signal | ||
| Min tonic value | The maximum value of tonic EDA signal | ||
| Std tonic value | The standard deviation of tonic EDA signal | ||
| Amp. NS-SCRs | The mean amplitude of NS-SCRs (computed from phasic EDA signal) | ||
| Freq. NS-SCRs | The number of NS-SCRs per minute (computed from phasic EDA signal) | ||
| ECG/RESP | Mean Rate | Time | The mean number of cardiac cycles per minute |
| Mean | The mean time of IBIs/BBs | ||
| Median | The median of the absolute values of the successive differences between adjacent IBIs/BBs | ||
| MAD | The mean absolute deviation of IBIs/BBs | ||
| SD | The standard deviation of IBIs/BBs | ||
| SDSD | The standard deviation of the successive differences between adjacent IBIs/BBs | ||
| CV | The Coefficient of Variation, i.e., the ratio of SD divided by Mean | ||
| mCV | Median-based Coefficient of Variation, i.e., the ratio of MAD divided by Median | ||
| RMSSD | The square root of the mean of the sum of successive differences between adjacent IBIs/BBs | ||
| CVSD | The coefficient of variation of successive differences; the RMSSD divided by Mean | ||
| LF | Frequency | The spectral power density pertaining to low frequency band (0.04 to 0.15 Hz) | |
| HF | The spectral power density pertaining to high frequency band (0.15 to 0.4 Hz) | ||
| LF/HF | The ratio of low frequency power to high frequency power | ||
| SD1 | Non-linear | Measure of the spread of IBIs/BBs on the Poincaré plot perpendicular to the line of identity | |
| SD2 | Measure of the spread of RR intervals on the Poincaré plot along the line of identity | ||
| SD2/SD1 | Ratio between long and short term fluctuations of IBIs (SD2 divided by SD1) | ||
| ECG | pNN50 | Time | The proportion of successive IBIs greater than 50 ms, out of the total number of IBIs |
| pNN20 | The proportion of successive IBIs greater than 20 ms, out of the total number of IBIs | ||
| TINN | The baseline width of IBIs distribution obtained by triangular interpolation | ||
| HTI | The HRV triangular index (total number of IBIs divided by the height of IBIs histogram) | ||
| VHF | Frequency | Variability, or signal power, in very high frequency (0.4–0.5 Hz) | |
| LFn | The normalized low frequency, obtained by dividing the low frequency power by the total power | ||
| HFn | The normalized high frequency, obtained by dividing the low frequency power by the total power | ||
| LnHF | The log transformed HF | ||
| CSI | Non-linear | The Cardiac Sympathetic Index (longitudinal variability of Poincaré plot divided by transverse variability) | |
| CVI | The Cardiac Vagal Index (logarithm of the product of longitudinal and transverse variability) | ||
| CSI_modified | The modified CSI (the square of the longitudinal variability divided by transverse variability) | ||
| RESP | Mean amplitude | Time | The mean respiratory amplitude |
| ApEn | Non-linear | The approximate entropy of RRV | |
| DFA2 | A long-term fluctuation value. Only be computed if mora than 640 breath cycles in the signal | ||
| RSA | Mean | Mean of RSA estimates | |
| Mean Log | The logarithm of the mean of RSA estimates | ||
| SD | The standard deviation of all RSA estimates | ||
| NoRSA | The number of breath cycles from which RSA could not be calculated | ||
| RSA_PB | The Porges–Bohrer estimate of RSA, optimal when the signal to noise ratio is low, in ln(ms^2) |
Identical indicators computed from both ECG and respiration (RESP) signal are grouped together. IBIs refers to interbeat intervals (ECG) and BBs refers to breath-to-breath cycles (RESP).