Table 2: Normal limits of autonomic cardiovascular indices

Variable	Mean ± SD	*Normal limit	**Previous reference values
Variable	Mean ± SD	*Normal limit	Normal	Borderline	Abnormal
SBP response to CP	- 4.26 ± 9.17	-19.00 - 11.00	≤10	11 - 29	≥30
DBP response to SH	20.14 ± 17.35	0.00 - 54.00	≥16	11 - 15	≤10
Valsalva ratio	1.55 ± 0.40	1.10 - 2.40	≥1.21	1.11 - 1.20	≤1.10
HDB	31.82 ± 10.81	13.00 - 48.75	≥15	11 - 14	≤10
30:15 ratio (PTI)	1.41 ± 0.31	1.08 - 1.84	≥1.04	1.01 - 1.03	≤1.00
Tachycardia ratio	0.80 ± 0.12	0.58 - 1.00	-	-	-
Bradycardia ratio	1.21 ± 0.20	0.95 - 1.60	-	-	-
RHR	70.61 ± 12.23	53.00 - 93.00	-	-	-

RHR: Heart rate (beats per minute), SBP: Systolic Blood Pressure (mmHg), DBP: Diastolic Blood Pressure (mmHg), HDB (beats per minute): Heart rate response to Deep Breathing (maximum inspiratory heart rate - minimum expiratory heart rate) , PTI: Postural Tachycardia Index, RR: Interval between two successive R waves, SH: Sustained Handgrip, CP: Change of Posture (supine to erect), * Normal limit determined at 5th and 95th percentiles, ** Ewing et al. 1982.