Table 2: Normal limits of autonomic cardiovascular indices


Variable Mean ± SD *Normal limit **Previous reference values
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.