Table 2.
Weaning parameters and arterial blood gas findings between the two groups
| Clinical outcome | Total (N = 85) | NIV weaning | P value | |
|---|---|---|---|---|
| Success (N = 56) | Failure (N = 29) | |||
| Weaning index (on NIV within 2 h) | ||||
| RSBI, mean (SD), breaths/(min mL)a | 103.1 ± 60.0 | 100.0 ± 60.4 | 109.1 ± 59.7 | 0.512 |
| VE, median (IQR), La | 6.3 (4.8–9.1) | 7.0 (5.1–9.1) | 5.1 (4.2–9.3) | 0.100 |
| TV, median (IQR), mLa | 271.0 (198.0–378.5) | 275.5 (209.2–407.0) | 242.0 (173.0–339.0) | 0.218 |
| RR, mean (SD), breaths/mina | 24.8 ± 6.9 | 24.7 ± 6.6 | 25.0 ± 7.5 | 0.877 |
| MIP, median (IQR), −cmH2Oa | 30.0 (20.0–40.0) | 34.0 (20.0–40.0) | 26.0 (17.0–38.0) | 0.205 |
| MEP, median (IQR), +cmH2Oa | 36.0 (22.0–44.0) | 36.0 (22.5–48.0) | 36.0 (21.5–41.5) | 0.263 |
| Blood gas analysis (on NIV within 2 h) | ||||
| Arterial pH, mean (SD)a | 7.31 ± 0.07 | 7.31 ± 0.06 | 7.31 ± 0.08 | 0.707 |
| PaO2, median (IQR), mmHga | 90.0 (78.5–113.1) | 91.1 (79.4–114.1) | 88.0 (75.5–114.0) | 0.777 |
| PaCO2, median (IQR), mmHga | 60.5 (48.6–67.3) | 60.4 (48.2–66.1) | 61.1 (48.8–68.4) | 0.838 |
| HCO3, mean (SD), mEq/La | 29.3 ± 6.9 | 29.5 ± 6.9 | 28.9 ± 7.0 | 0.705 |
| BE, mean (SD), mmol/La | 4.2 ± 7.7 | 4.0 ± 7.0 | 4.6 ± 8.9 | 0.733 |
| SaO2, median (IQR), (%)a | 96.0 (93.0–97.0) | 96.0 (94.0–97.0) | 94.0 (92.5–98.5) | 0.373 |
| Weaning index (before turning off NIV within 2 h) | ||||
| RSBI, median (IQR), breaths/(min mL)a | 53.5 (29.8–83.2) | 38.5 (18.7–58.9) | 84.9 (55.3–128.8) | < 0.001* |
| VE, median (IQR), La | 7.4 (5.9–9.9) | 7.9 (6.4–10.2) | 6.2 (5.5–8.1) | 0.016* |
| TV, median (IQR), mLa | 408.0 (272.5–571.0) | 444.5 (360.2–671.2) | 264.0 (219.0–395.5) | < 0.001* |
| RR, mean (SD), breaths/mina | 19.8 ± 6.8 | 17.7 ± 6.2 | 23.7 ± 6.5 | < 0.001* |
| MIP, median (IQR), −cmH2Oa | 36.0 (24.0–52.0) | 44.0 (30.5–55.2) | 30.0 (20.0–40.0) | 0.014* |
| Predict MIP, median (IQR), (%)a, c | 42.0 (29.0–61.0) | 49.0 (33.2–67.7) | 35.0 (24.0–47.0) | 0.013* |
| MEP, median (IQR), +cmH2Oa | 44 (28.0–60.0) | 48.5 (40.0–67.0) | 28.0 (20.0–50.0) | 0.004* |
| Predict MEP, median (IQR), (%)a, c | 41.0 (27.0–59.0) | 44.0 (33.2–60.5) | 30.0 (21.0–54.0) | 0.012* |
| Blood gas analysis (before turning off NIV within 2 h) | ||||
| Arterial pH, mean (SD)a | 7.41 ± 0.49 | 7.41 ± 0.50 | 7.42 ± 0.48 | 0.186 |
| PaO2, median (IQR), mmHga | 95.4 ± 34.2 | 92.3 ± 30.5 | 101.4 ± 40.6 | 0.257 |
| PaCO2, mean (SD), mmHga | 45.7 ± 10.8 | 45.4 ± 10.4 | 46.4 ± 11.6 | 0.704 |
| HCO3, median (IQR), mEq/La | 29.6 (22.8–33.6) | 29.5 (22.8–33.0) | 29.8 (22.6–34.1) | 0.765 |
| BE, mean (SD), mmol/La | 4.6 ± 6.5 | 4.0 ± 6.3 | 5.9 ± 6.9 | 0.235 |
| SaO2, median (IQR), (%)a | 96.0 (94.0–97.7) | 96.0 (93.2–97.0) | 97.0 (94.2–98.0) | 0.226 |
| Clinical outcome (after NIV treatment) | ||||
| In-hospital mortality, N (%)b | 12 (14.1) | 3 (5.4) | 9 (31.0) | 0.002* |
| Readmission after discharge within 60 days, N (%)b | 28 (32.9) | 20 (35.7) | 8 (27.6) | 0.450 |
BE bicarbonate; IQR interquartile range; MEP maximal expiratory pressure; MIP maximal inspiratory pressure; NIV noninvasive ventilation; PaO2 partial pressure of oxygen; PaCO2 partial pressure of carbon dioxide; RR respiratory rate; RSBI rapid shallow breathing index; TV tidal volume; VE minute ventilation; SaO2 arterial oxyhemoglobin saturation; SD standard deviation
aContinuous variables are expressed as mean ± SD or median (IQR)
bCategorical variables are expressed as N (%)
cIncluding data from studies in the review by Evans et al. [21]. Male MIP reference: 120−(0.41 × age); female MIP reference: 108−(0.61 × age); male MEP reference: 174−(0.83 × age); female MEP reference: 131−(0.86 × age), percentage of predict MIP or MEP of percentage = real data (MIP or MEP)/reference (MIP or MEP)
*P < 0.05, significant