Table 2

R–R interval changes following a 60° head-up tilt

No of subjectsMean (SD) heart rate (bpm)Mean (SD) minimim R-R (ms)Mean (SD) maximim R-R (ms)Mean (SD) ratio(max:min R–R)Mean (SD) No of beats (min-max)
Quiet sleep
 Prone33128.8 (6.9)410.8 (35.9)550.1 (82.0)1.3 (0.3)15.3 (6.2)
 Supine34125.5 (8.8)414.1 (28.6)585.0 (82.4)1.4 (0.2)15.3 (5.7)
Active sleep
 Prone23129.3 (7.8)390.3 (27.6)517.5 (56.4)1.3 (0.1)15.0 (5.0)
 Supine20131.5 (7.9)387.0 (29.9)522.5 (66.0)1.3 (0.1)15.1 (6.2)