EF | V’_{E} | V_{T} | f_{R} | |||

sd/n | RMSSD/n | sd/n | RMSSD/n | sd/n | RMSSD/n | |

r | −0.531 | −0.511 | −0.442 | −0.452 | −0.507 | −0.510 |

p-value | 0.034 | 0.043 | 0.076 | 0.068 | 0.037 | 0.036 |

*V*’_{E}: minute ventilation;*V*_{T}: tidal volume;*f*_{R}: respiratory frequency; RMSSD: root mean square successive differences; n: number of breaths.