Table 3 Variations in physiological and ventilatory parameters during the first (n = 42), the second (n = 37) and the third (n = 31) proning sessions
| Â | Overall | Success | Failure | p value |
|---|---|---|---|---|
Variation in PaO2/FiO2, mmHg, from pre-PP to end-PP | ||||
1st pronation |  + 75 (+ 54 to + 114) |  + 86 (+ 66 to + 125) |  + 58 (+ 10 to + 73) | 0.001 |
2nd pronation |  + 69 (+ 33 to + 123) |  + 74 (+ 34 to + 126) |  + 50 (+ 8 to + 117) | 0.53 |
3rd pronation |  + 48 (+ 24 to + 68) |  + 52 (+ 16 to + 74) |  + 45 (+ 26 to + 69) | 0.80 |
Variation in FiO2, from pre-PP to end-PP | ||||
1st pronation | − 0.20 (− 0.33 to − 0.15) | − 0.25 (− 0.38 to − 0.17) | − 0.18 (− 0.24 to − 0.02) | 0.02 |
2nd pronation | − 0.10 (− 0.30 to − 0.05) | − 0.10 (− 0.30 to − 0.05) | − 0.10 (− 0.31 to + 0.04) | 0.68 |
3rd pronation | − 0.10 (− 0.20 to − 0.05) | − 0.10 (− 0.20 to − 0.03) | − 0.15 (− 0.27 to − 0.05) | 0.50 |
Variation in Aa-gradient, mmHg, from pre-PP to end-PP | ||||
1st pronation | − 160 (− 232 to − 100) | − 170 (− 248 to − 124) | − 105 (− 169 to − 13) | 0.01 |
2nd pronation | − 98 (− 205 to − 34) | − 98 (− 214 to − 40) | − 98 (− 194 to + 21) | 0.68 |
3rd pronation | − 85 (− 138 to − 41) | − 85 (− 132 to − 9) | − 95 (− 187 to − 52) | 0.45 |
O2 responders | ||||
1st pronation | 37/42 (88%) | 29/30 (97%) | 8/12 (67%) | 0.002 |
2nd pronation | 29/37 (78%) | 22/27 (82%) | 7/10 (70%) | 0.66 |
3rd pronation | 22/31 (71%) | 17/25 (68%) | 5/6 (83%) | 0.64 |
Variation in VR, from pre-PP to end-PP | ||||
1st pronation | 0.02 (− 0.28 to 0.21) | − 0.13 (− 0.34 to  + 0.13) |  + 0.13 (− 0.14 to  + 0.22) | 0.21 |
2nd pronation |  + 0.08 (− 0.17 to + 0.28) |  + 0.07 (− 0.16 to + 0.29) |  + 0.09 (− 0.21 to + 0.40( | 0.72 |
3rd pronation |  + 0.27 (− 0.08 to + 0.37) |  + 0.25 (− 0.06 to + 0.40) |  + 0.27 (− 0.14 to + 0.33) | 0.85 |
Variation in VD/VT HB, from pre-PP to end-PP | ||||
1st pronation |  + 0.01 (− 0.03 to 0.02) | − 0.01 (− 0.08 to  + 0.02) | 0.01 (− 0.02 to  + 0.03) | 0.19 |
2nd pronation |  + 0.01 (− 0.04 to + 0.04) |  + 0.02 (− 0.03 to + 0.03) |  + 0.01 (− 0.04 to + 0.06) | 0.86 |
3rd pronation |  + 0.04 (− 0.01 to + 0.06) |  + 0.04 (− 0.01 to  + 0.07) |  + 0.02 (− 0.01 to + 0.06) | 0.77 |
CO2 responders | Â | Â | Â | Â |
1st pronation | 21/42 (50%) | 16/30 (53%) | 5/12 (42%) | 0.51 |
2nd pronation | 14/37 (38%) | 9/27 (33%) | 5/10 (50%) | 0.45 |
3rd pronation | 9/31 (29%) | 7/25 (28%) | 2/6 (33%) | 0.77 |
Variation in PEEP, cmH2O, from pre-PP to end-PP | ||||
1st pronation | 0 (0 to 0) | 0 (− 1 to 0) | 0 (0–0) | 0.99 |
2nd pronation | 0 (− 2 to 0) | 0 (− 2 to 0) | 0 (− 2 to 0) | 0.95 |
3rd pronation | 0 (− 1 to 0) | 0 (− 1 to 0) |  + 1 (0 to + 2) | 0.08 |
Variation in Pplat, cmH2O, from pre-PP to end-PP | ||||
1st pronation | − 1 (− 3 to + 1) | − 1 (− 3 to + 1) | 1 (− 1 to  + 2) | 0.11 |
2nd pronation | − 1 (− 3 to 0) | − 2 (− 4 to 0) |  + 2 (0 to + 6) |  < 0.001 |
3rd pronation | − 1 (− 2 to + 1) | − 1 (− 2 to 0) | 0 (− 1 to + 4) | 0.09 |
Variation in ∆P, cmH2O, from pre-PP to end-PP | ||||
1st pronation | − 1 (− 2 to + 1) | − 1 (− 3 to + 1) | 1 (− 1 to + 3) | 0.14 |
2nd pronation | − 1 (− 2 to 0) | − 1 (− 3 to 0) |  + 3 (+ 2 to + 6) |  < 0.001 |
3rd pronation | 0 (− 2 to + 1) | 0 (− 2 to + 1) | 0 (− 1 to + 2) | 0.42 |
Variation in CRS, ml/ cmH2O, from pre-PP to end-PP | ||||
1st pronation |  + 2.7 (− 2.4 to + 7.3) |  + 3.8 (− 2.1 to + 8.2) | − 0.5 (− 6.3 to + 3.8) | 0.13 |
2nd pronation |  + 2.3 (− 0.9 to + 7.8) |  + 3.9 (0 to + 8.2) | − 6.3 (− 14.1 to − 1.6) |  < 0.001 |
3rd pronation |  + 0.8 (− 3.2 to + 5.4) |  + 1.7 (− 3.4 to + 5.4) | 0 (− 3.3 to 5.7) | 0.89 |