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Table 2 Changes in respiratory mechanics, blood gas analysis and VDalv in PP

From: PaCO2 and alveolar dead space are more relevant than PaO2/FiO2 ratio in monitoring the respiratory response to prone position in ARDS patients: a physiological study

Parameters Supine PP H3 PP H6 PP H9 PP H12 PP H15 P value
PaO2/FiO2, mmHg 70 (51 to 77) 91 (81 to 103) 87 (73 to 139) 90 (81 to 111) 93 (83 to 137) 99 (83 to 139) < 0.0001
PaCO2, mmHg 58 (52 to 60) 54 (51 to 58) 54 (45 to 59) 50 (47 to 59) 54 (47 to 56) 52 (47 to 56) 0.04
Pplat, cmH2O 27 (26 to 28) 25 (23 to 27) 25 (22 to 26) 25 (23 to 26) 25 (21 to 26) 25 (24 to 26) 0.0004
Crs, mL/cmH2O 16 (13 to 30) 18 (14 to 36) 17 (15 to 40) 18 (15 to 38) 19 (15 to 38) 18 (15 to 30) 0.02
VDalv/VT 0.42 (0.35 to 0.47) 0.31 (0.28 to 0.41) 0.35 (0.22 to 0.39) 0.35 (0.26 to 0.39) 0.39 (0.28 to 0.44) 0.40 (0.26 to 0.45) 0.007
  1. aCrs: compliance of the respiratory system; PP: prone position, Pplat: plateau pressure, VDalv/VT: ratio of alveolar dead space to tidal volume. H3, H6, H9, H12 and H15: 3, 6, 9, 12 and 15 hours of PP, respectively. P value is between supine position and PP. Data are expressed as medians (1st to 3rd interquartile range).