[Analysis of the static pressure volume curve of the lung in experimentally induced pulmonary damage by CT-densitometry].
OBJECTIVE
To study quantitative changes of lung density distributions when recording in- and expiratory static pressure-volume curves by single slice computed tomography (CT).


METHODS
Static in- and expiratory pressure volume curves (0 to 1000 ml, increments of 100 ml) were obtained in random order in 10 pigs after induction of lung damage by saline lavage. Simultaneously, CT acquisitions (slice thickness 1 mm, temporal increment 2 s) were performed in a single slice (3 cm below the carina). In each CT image lung segmentation and planimetry of defined density ranges were achieved. The lung density ranges were defined as: hyperinflated (-1024 to -910 HU), normal aerated (-910 to -600 HU), poorly aerated (-600 to -300 HU), and non aerated (-300 to 200 HU) lung. Fractional areas of defined density ranges in percentage of total lung area were compared to recorded volume increments and airway pressures (atmospheric pressure, lower inflection point (LIP), LIP*0.5, LIP*1.5, peak airway pressure) of in- and expiratory pressure-volume curves.


RESULTS
Quantitative analysis of defined density ranges showed no differences between in- and expiratory pressure-volume curves. The amount of poorly aerated lung decreased and normal aerated lung increased constantly when airway pressure and volume were increased during inspiratory pressure-volume curves and vice versa during expiratory pressure-volume loops.


CONCLUSIONS
Recruitment and derecruitment of lung atelectasis during registration of static in- and expiratory pressure-volume loops occurred constantly, but not in a stepwise manner. CT was shown to be an appropriate method to analyse these recruitment process.
David
M
M
Klinik für Anästhesiologie, Johannes Gutenberg-Universität, Mainz. david@mail.uni-mainz.de
Bletz
C
C
David
S
S
Karmrodt
J
J
Herwelling
A
A
Heussel
C P
CP
Markstaller
K
K
D015502:Absorptiometry, Photon / Q000379:methods*; D000403:Airway Resistance; D000818:Animals; D008168:Lung / Q000000981:diagnostic imaging / Q000503:physiopathology; D008176:Lung Volume Measurements / Q000379:methods*; D011654:Pulmonary Edema / Q000139:chemically induced / Q000000981:diagnostic imaging* / Q000503:physiopathology*; D011857:Radiographic Image Interpretation, Computer-Assisted / Q000379:methods*; D012965:Sodium Chloride; D013552:Swine; D013990:Tidal Volume; D014057:Tomography, X-Ray Computed / Q000379:methods
D012965:Sodium Chloride