Table 1.

Parameters for time-domain and frequency-domain analyses of heart rate variability (HRV) signals.

Method	Parameter	Unit	Description
Time-domain Analysis	Mean HR	1/min	Mean heart rate
	Mean RR	Ms	Mean RR interval
	SDNN	Ms	Standard deviation of RR interval
	RMSSD	Ms	Square root of mean squared differences between successive RR intervals
Frequency-domain Analysis	pNN50	%	NNN50 divided by total number of RR intervals
	VLF	ms2	Absolute power of VLF band
	LF	ms2	Absolute power of LF band
	HF	ms2	Absolute power of HF band
	LF norm	n.u.	LF power in normalized units LF/(Total Power-VLF) × 100
	HF norm	n.u.	HF power in normalized units HF/(Total Power-VLF) × 100
	LF/HF	-	Ratio of LF band power to HF band power