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.