Application of heart-rate variability in patients undergoing weaning from mechanical ventilation

Table 3 Measurement of heart-rate variability during pre-SBT and SBT periods

Frequency-domain measures	Pre-SBT	SBT	P value^a	P value^b
VLF [ln(ms²)]
Successful SBT	6.9 (1.3)	6.3 (1.6)	0.220
Failed SBT	6.6 (1.1)	5.5 (1.5)
LF% (nu)
Successful SBT	38 (20)	40 (23)	0.687
Failed SBT	38 (20)	38 (20)
HF% (nu)
Successful SBT	45 (15)	44 (18)	0.775
Failed SBT	47 (14)	45 (16)
TP [ln(ms²)]
Successful SBT	7.9 (1.0)	7.7 (1.0)	0.036	0.092
Failed SBT	8.2 (0.7)	7.4 (0.9)		0.003
LF/HF [ln(ratio)]
Successful SBT	1.0 (0.2)	1.0 (0.3)	0.597
Failed SBT	1.0 (0.1)	1.0 (0.2)

^aFor comparison between successful and failed spontaneous-breathing trial groups.
^bFor comparison between pre-spontaneous-breathing trial and spontaneous-breathing trial periods within a group.
Data are presented as mean (standard deviation).
SBT, spontaneous breathing trial; VLF, very low frequency; HF, high frequency; LF, low frequency; ln, natural logarithm; nu, normalized unit; TP, total power.

ISSN: 1364-8535