Figure 3

The cardiorespiratory synchrogram for subject 5 at sea level was plotted at the top. The solid dots located at 48 s to 88 s and 230 s to 251 s respectively composed 7 parallel lines in synchrogram and demonstrated CRPS with the ratio of 7:2 (n = 7 heartbeats within m = 2 consecutive respiratory cycles) during the 300 s periods. f _HR /f _RespR which was the instantaneous ratio of heart rate (f _HR ) to respiratory rate (f _RespR ) was plotted at the bottom.