Table 2.
Description of the variables that will be extracted from raw electrophysiological signals monitored with the medical device NeXus-10 MKII.
| Group of variables | Electrophysiological signal | Physiological variables | Description |
| HRVa or PRVb | ECGc or PPGd | HRe,f (bpm)g | Mean HR |
| HRV or PRV | ECG or PPG | IBIf (ms)h | Mean IBI |
| HRV or PRV | ECG or PPG | pNN50f (%) | Percentage of adjacent normal beats intervals differing from each other by >50 ms |
| HRV or PRV | ECG or PPG | SDNNf (ms) | SD of normal beats intervals |
| HRV or PRV | ECG or PPG | RMSSDf (ms) | Root mean square of successive differences between normal beats |
| HRV or PRV | ECG or PPG | SDSDf (ms) | SD of differences between adjacent R-R peaks intervals |
| HRV or PRV | ECG or PPG | VLFi (s−2) | Absolute power of the VLF band (0.003-0.04 Hz) |
| HRV or PRV | ECG or PPG | LFf,j (s−2) | Absolute power of the LF band (0.04-0.15 Hz) |
| HRV or PRV | ECG or PPG | HFf (s−2)k | Absolute power of the HF band (0.15-0.4 Hz) |
| HRV or PRV | ECG or PPG | LF/HF ratiof | Ratio of LF to HF power |
| HRV or PRV | ECG or PPG | HFnf (nu) | Relative power of the HF band normalized |
| PATl | ECG and PPG | PAT (ms) | Mean PAT, the time between the beat detected by ECG and the pulse by PPG |
| PAT | ECG and PPG | stdPAT (ms) | SD of PAT |
| Breathing | Respiration | RRm (Hz) | Mean RR |
| Breathing | Respiration | Pk (%) | Peak of respiratory power spectra |
| EDAn | EDA | Tonicf (µS) | Average value of the tonic component, that is, slowly changing skin conductance level, also known as SCLo |
| EDA | EDA | Phasicf (µS) | Average value of the phasic component, that is, fast-changing responses typically associated with short-term events, also known as SCRp |
| EDA | EDA | aucPhasicf (µS·s) | Area under the curve of the phasic component, which is related to SCR |
| EDA | EDA | EDASympf (µS) | Electrodermal response in the power spectrum (0.045-0.25 Hz) |
| Peripheral temperature | STq | TFingerf (°C) | Mean finger temperature |
| Peripheral temperature | ST | TGradientf (°C) | Mean gradient of finger temperature |
| Peripheral temperature | ST | TPowerf (°C2) | Mean power of finger temperature |
aHRV: heart rate variability.
bPRV: pulse rate variability.
cECG: electrocardiogram.
dPPG: photoplethysmography.
eHR: heart rate.
fThese will also be extracted from the recordings of the Empatica E4 wearable device.
gbpm: beats per minute.
hIBI: interbeat interval.
iVLF: very low frequency
jLF: low frequency.
kHF: high frequency.
lPAT: pulse arrival time.
mRR: respiratory rate.
nEDA: electrodermal activity.
oSCL: skin conductance level.
pSCR: skin conductance response.
qST: skin temperature.