Table 2.
Clinical variables, gas exchange, cardiac function and lung aeration before and at the end of the spontaneous breathing trial
| Before the SBT | End of the SBT | |||||
|---|---|---|---|---|---|---|
| SBT success | SBT failure | p | SBT success | SBT failure | p | |
| n | 22 | 31 | 22 | 31 | ||
| Clinical variables | ||||||
| Systolic ABP, mmHg | 121 (110–139) | 140 (118–151) | 0.041 | 130 (109–154) | 149 (128–170) | 0.007 |
| Heat rate, min−1 | 94 (77–101) | 93 (84–104) | 0.840 | 97 (86–105) | 105 (96–121) | 0.036 |
| Respiratory rate, min−1 | 19 (15–23) | 21 (18–26) | 0.101 | 21 (19–31) | 28 (21–35) | 0.030 |
| Laboratory variables | ||||||
| pH | 7.42 (7.38–7.48) | 7.43 (7.38–7.45) | 0.732 | 7.43 (7.40–7.47) | 7.38 (7.34–7.43) | 0.027 |
| PaO2/FiO2 ratio | 327 (237–381) | 227 (168–280) | 0.004 | 253 (197–298) | 160 (107–205) | < 0.001 |
| PaCO2, mmHg | 36 (30–43) | 42 (36–49) | 0.009 | 39 (33–43) | 50 (38–57) | 0.002 |
| Lactate, mmol.L−1 | 1.2 (0.8–1.6) | 1.3 (1.0–1.8) | 0.254 | 0.9 (0.7–1.2) | 1.1 (1.0–1.5) | 0.015 |
| Haemoglobin, g.dL−1 | 8.3 (7.8–10.4) | 9.4 (8.4–10.7) | 0.227 | 8.6 (7.9–10.7) | 9.8 (8.8–11.5) | 0.073 |
| Delta haemoglobin, % | – | – | 0 (-5–5) | 5 (1–9) | 0.013 | |
| Protein, g.L−1 | 55 (48–59) | 60 (54–65) | 0.021 | 53 (49–59) | 64 (58–69) | 0.001 |
| Delta protein, % | – | – | 4 (0–5) | 7 (2–9) | 0.014 | |
| Cardiac function | ||||||
| LEVF, % | 60 (50–60) | 60 (50–60) | 0.319 | 60 (50–60) | 60 (50–60) | 0.321 |
| CI, L.min−1.m−2 | 3.1 (2.6–3.9) | 3.6 (2.9–4.2) | 0.264 | 3.6 (2.8–4.1) | 4.3 (3.6–4.9) | 0.167 |
| e’ wave, cm.s−1 | 11 (9–12) | 10 (9–12) | 0.904 | 10 (9–13) | 11 (9–13) | 0.939 |
| E/A ratio | 0.8 (0.7–1.1) | 1.0 (0.8–1.4) | 0.177 | 0.9 (0.7–0.9) | 1.1 (0.9–1.3) | 0.001 |
| E/e’ ratio | 7.1 (5.3–8.6) | 8.1 (6.6–10.5) | 0.092 | 7.4 (5.3–9.2) | 9.3 (7.2–1.28) | 0.022 |
| E/e’ > 14, n (%) | 2 (10) | 1 (3) | 1 (10) | 5 (19) | ||
| DTE, ms | 175 (142–210) | 172 (137–201) | 0.967 | 169 (142–228) | 157 (140–200) | 0.329 |
| Systolic PAP, mmHg | 23 (20–28) | 27 (20–35) | 0.255 | 24 (21–36) | 30 (21–53) | 0.165 |
| TAPSE, cm | 2.3 (1.9–2.6) | 2.1 (1.9–2.7) | 0.988 | 2.3 (2.1–2.7) | 2.3 (1.9–2.9) | 0.839 |
| S wave, cm s−1 | 15.8 (13.7–18.7) | 16 (14.0–21.1) | 0.621 | 17.4 (14.1–20.1) | 17.0 (15.6–20.5) | 0.829 |
| Diaphragm function | ||||||
| Ptr,stim, cmH2O | 6.8 (3.4–8.8) | 4.1 (2.7–7.9) | 0.098 | 6.0 (3.8–8.3) | 4.3 (2.2–6.9) | 0.192 |
| Lung aeration | ||||||
| Lung consolidation, n | 2 (1–4) | 4 (0–10) | 0.026 | 2 (0–1) | 6 (0–10) | 0.025 |
| LUS | 10 (3–19) | 17 (4–33) | 0.123 | 9 (3–20) | 20 (5–33) | 0.060 |
| Posterior LUS | 7 (2–12) | 10 (1–17) | 0.377 | 6 (2–14) | 11 (4–17) | 0.112 |
SBT, spontaneous breathing trial; ABP, arterial blood pressure; LEVF, left ventricular ejection fraction; CI, cardiac index; E/A, early (E) over late (A) diastolic wave velocity ratio; E/e’, E wave over tissue Doppler early (e’) wave velocities at the lateral mitral valve annulus; DTE, deceleration time of the E wave; TAPSE, tricuspid annular plane systolic excursion (TAPSE); PAP, pulmonary artery pressure; LUS, lung ultrasound score