1. Temporal dynamics of lung aeration determined by dynamic CT in a porcine model of ARDS 
K. Markstaller, B. Eberle, H.-U. Kauczor, A. Scholz, A. Bink, M. Thelen, W. Heinrichs, N. Weiler 
British Journal of Anaesthesia 
Volume 87, Issue 3, Pages (September 2001)
DOI: /bja/
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

2. Fig 1
Example of least-squares fit procedures. Increase of aerated lung area (in cm2) following an airway pressure increase from 0 to 50 cm H2O (animal no. 5; lavage ARDS). The increase of aerated area (representing alveolar distension as well as recruitment) described by a mono-exponential fit to the data yields a τ of 11.2 s, whereas a bi-exponential fitting procedure allows discrimination of two different τ of 0.5 and 8 s, and a better fit.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

3. Fig 2
Transverse supradiaphragmatic CT scans of healthy lungs during airway pressure increase from 0 to 50 cm H2O. (a) At end-expiration, an antero-posteriorly increasing density gradient is visible. (b) After 3 s of CPAP maintained at 50 cm H2O, lung parenchyma appears almost homogeneous, with only slightly increased lung density in basal lung areas. (c) Lung parenchyma appears homogeneously aerated 31 s after the airway pressure increase to 50 cm H2O CPAP.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

4. Fig 2
Transverse supradiaphragmatic CT scans of healthy lungs during airway pressure increase from 0 to 50 cm H2O. (a) At end-expiration, an antero-posteriorly increasing density gradient is visible. (b) After 3 s of CPAP maintained at 50 cm H2O, lung parenchyma appears almost homogeneous, with only slightly increased lung density in basal lung areas. (c) Lung parenchyma appears homogeneously aerated 31 s after the airway pressure increase to 50 cm H2O CPAP.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

5. Fig 2
Transverse supradiaphragmatic CT scans of healthy lungs during airway pressure increase from 0 to 50 cm H2O. (a) At end-expiration, an antero-posteriorly increasing density gradient is visible. (b) After 3 s of CPAP maintained at 50 cm H2O, lung parenchyma appears almost homogeneous, with only slightly increased lung density in basal lung areas. (c) Lung parenchyma appears homogeneously aerated 31 s after the airway pressure increase to 50 cm H2O CPAP.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

6. Fig 3
Transverse supradiaphragmatic CT scans of lavage-ARDS lungs during airway pressure increase from 0 to 50 cm H2O. (a) At end-expiration, large areas of atelectatis and a marked antero-posterior density gradient can be observed. (b) After 3 s of CPAP maintained at 50 cm H2O, a reduction of atelectasis is visible, although a marked density gradient remains. (c) At end-inspiration, 31 s after increase to 50 cm H2O CPAP, the entire cross-sectional lung area appears aerated, although to a variable degree. Nevertheless, ground-glass opacities caused by increased lung water content persist. In the scans acquired subsequently, a slightly varying slice position can be noted as a result of a cranio-caudal motion of the lung during the manoeuvre.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

7. Fig 3
Transverse supradiaphragmatic CT scans of lavage-ARDS lungs during airway pressure increase from 0 to 50 cm H2O. (a) At end-expiration, large areas of atelectatis and a marked antero-posterior density gradient can be observed. (b) After 3 s of CPAP maintained at 50 cm H2O, a reduction of atelectasis is visible, although a marked density gradient remains. (c) At end-inspiration, 31 s after increase to 50 cm H2O CPAP, the entire cross-sectional lung area appears aerated, although to a variable degree. Nevertheless, ground-glass opacities caused by increased lung water content persist. In the scans acquired subsequently, a slightly varying slice position can be noted as a result of a cranio-caudal motion of the lung during the manoeuvre.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

8. Fig 3
Transverse supradiaphragmatic CT scans of lavage-ARDS lungs during airway pressure increase from 0 to 50 cm H2O. (a) At end-expiration, large areas of atelectatis and a marked antero-posterior density gradient can be observed. (b) After 3 s of CPAP maintained at 50 cm H2O, a reduction of atelectasis is visible, although a marked density gradient remains. (c) At end-inspiration, 31 s after increase to 50 cm H2O CPAP, the entire cross-sectional lung area appears aerated, although to a variable degree. Nevertheless, ground-glass opacities caused by increased lung water content persist. In the scans acquired subsequently, a slightly varying slice position can be noted as a result of a cranio-caudal motion of the lung during the manoeuvre.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

9. Fig 4
(a) Relative increase of aerated lung area after airway pressure increased from 0 to 50 cm H2O in lavage ARDS. Aerated lung area (pixels with densities ranging from –910 to –300 HU) is expressed as fraction (in per cent), which becomes aerated from the airway pressure increase from ZEEP. (b) Relative decrease of aerated lung area after airway pressure decreased from 50 to zero cm H2O in lavage ARDS. Aerated lung area (pixels with densities ranging from –910 to –300 HU) is expressed as fraction (in per cent), which collapses from the airway pressure step-down to ZEEP. Individual animals are represented by different symbols.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

10. Fig 4
(a) Relative increase of aerated lung area after airway pressure increased from 0 to 50 cm H2O in lavage ARDS. Aerated lung area (pixels with densities ranging from –910 to –300 HU) is expressed as fraction (in per cent), which becomes aerated from the airway pressure increase from ZEEP. (b) Relative decrease of aerated lung area after airway pressure decreased from 50 to zero cm H2O in lavage ARDS. Aerated lung area (pixels with densities ranging from –910 to –300 HU) is expressed as fraction (in per cent), which collapses from the airway pressure step-down to ZEEP. Individual animals are represented by different symbols.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions

11. Fig 5
Increase in area (relative to endexpiration at ZEEP) of density ranges of growing bandwith (lower threshold –910 HU; upper threshold increasing from –800 to –200 HU), if a step-wise inspiratory manoeuvre is performed to a CPAP of 50 cm H2O (data from Markstaller and colleagues3). The solid line describes the behaviour of density ranges in healthy lungs, the dashed line in lavage-ARDS lungs. In healthy lungs, sensitivity to changes in parenchymal aeration is already at the maximum for the density range from –910 to –700 HU (a), whereas in the lavage-ARDS model the range from –910 to –300 HU (c) is the most sensitive, encompassing all states of parenchymal aeration except overdistension. The response of the commonly used range (–910 to –500 HU) to inspiration is submaximal but similar for both healthy and lavaged lungs (b). Such an offset from the maximum would cause the analysis, in ARDS lungs, to miss some recruitment of atelectasis, whereas in healthy lungs, it is an unnecessary inclusion of cross-sectional area which does not respond to inspiration.
British Journal of Anaesthesia  , DOI: ( /bja/ )
Copyright © 2001 British Journal of Anaesthesia Terms and Conditions