Table 4 |
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|
Intra-individual changes between 58 pairs of consecutive CT scans in sheep |
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|
Changes between CTs (whole-lung analysis) |
Bias (limits of agreement) |
|
|
|
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|
Vtotal (ml) |
551 (121 to 1863) |
6.5 (-72.5 to 85.5) |
|
Vnon (%) |
2.6 (0.0 to 11.6) |
-0.1 (-0.5 to 0.4) |
|
Vpoor (%) |
4.8 (0.3 to 20.7) |
-0.2 (-1.1 to 0.8) |
|
Vnorm (%) |
8.5 (0.0 to 22.2) |
-0.2 (-1.4 to 0.9) |
|
Vhyper (%) |
0.5 (0.0 to 4.5) |
0.0 (-0.8 to 0.8) |
|
Vgas (%) |
6.4 (1.6 to 16.0) |
-0.1 (-0.9 to 0.7) |
|
Mtotal (g)* |
43 (0 to 189) |
-1.5 (-33.0 to 30.0) |
|
Mnon (%) |
6.7 (0.0 to 34.4) |
-0.1 (-1.6 to 1.4) |
|
Mpoor (%) |
8.7 (0.2 to 28.4) |
-0.3 (-2.0 to 1.3) |
|
Mnormal (%) |
21.0 (0.7 to 38.7) |
-0.4 (-2.3 to 1.5) |
|
Mhyper (%) |
0.2 (0.0 to 1.9) |
0.0 (-0.3 to 0.3) |
|
|
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|
Data are median (range) for changes of lung volume and masses between two consecutive CTs given in the left column. Bias (95% limits of agreement) from the Bland-Altman analysis of the agreement of changes calculated by extrapolation from 10 CT slices or whole-lung analysis are given in the right column. CT, computed tomography; g, grams; Mhyper, hyperaerated volume or mass; ml, milliliters; Mnon, nonaerated volume or mass; Mnormal, normally aerated volume or mass; Mpoor, poorly aerated volume or mass; Vgas, pulmonary gas volume; Vtotal/Mtotal, total lung volume or mass. Volumes and masses of differently aerated lung compartments were calculated as percentage of Vtotal or Mtotal, respectively. *The sheep studied had gross atelectasis of otherwise normal lungs; the change in airway pressure therefore resulted in large changes in lung volume but only small changes in total lung mass. |
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Reske et al. Critical Care 2011 15:R279 doi:10.1186/cc10563 |
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