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

Table 7 Measurement of heart-rate variability during SBT and postextubation periods

Frequency-domain measures	SBT	Postextubation	P value^a	P value^b
VLF (ln(ms²))
Successful extubation	6.4 (1.7)	6.9 (1.2)	0.015	0.003
Extubation failure	6.1 (1.4)	5.5 (1.9)		0.187
LF% (nu)
Successful extubation	43 (23)	43 (19)	0.783
Extubation failure	26 (12)	27 (18)
HF% (nu)
Successful extubation	43 (18)	44 (15)	0.956
Extubation failure	51 (14)	52 (15)
TP (ln(ms²))
Successful extubation	7.7 (1.0)	8.1 (0.8)	0.025	0.004
Extubation failure	7.5 (1.1)	7.2 (0.9)		0.182
LF/HF (ln(ratio))
Successful extubation	1.0 (0.3)	1.0 (0.2)	0.954
Extubation failure	0.9 (0.1)	0.9 (0.2)

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

ISSN: 1364-8535