Respiration 63 additional clinical informations and influence on patient’s treatment. With the new spiral CT scan is possible to measure the total lung volume, the percentage of lung tissue and gas, being a linear correlation between the physical den- sity and the CT coefficient of attenuation. Aim of this study was to evaluate in vitro a new computer program “Maluna” (University of Mannheim, Germany) dedicated to measure the lung volume, weight and gas/tissue ratio. Materials and Methods: A series of different known volumes of water (100, 500, 1500 and 2000 ml) were studied. In addition, the contrast material was diluted with water to obtain solutions of increasing concentrations (0, 0.5, 1, 1.5, 2.5 and 5%). The spiral CT was performed at 120 KV and 240 mA. Each CT section was manually delineated by a trained physician. The total volume was computed as the total number of voxels present in a given region times the volume of the voxels while the CT number was directly related to the physical density. Results and Discussions: In the panel is shown the Bland Altman’s analysis between the known volumes of water and the measured volumes by “Maluna”. We found a linear correlation between the concentration of contrast material and CT attenuations read by Maluna (r 2 = 0.99, Y = 2.6 + 83X). Conclusion(s): These data show that “Maluna” is able to correctly compute the volumes in a huge range and CT number. A-230 Repeatibilty of the quantitative analysis of lung computed tomography in ALI/ARDS patients D. Chiumello, M. Cressoni, M. Racagni, L. Landi, A. D’Adda, S. Azzari, S. Terragni, M. Lazzerini, B. Finamore Institute of Anesthesia and Critical Care, Policlinico Hospital,Milano, Italy Background and Goal of Study: The CT scan allows an accurate morpho- logic analysis of an “ARDS” lung. In addition with the spiral CT it is also possible a quantitative analysis using dedicated software. However due to the necessity of a manually drawing of the lung (i.e., to include the lung parenchyma and to exclude big vessels, trachea, pleural effusion,…) it would be possible to increase the error of the analysis. Aim of this study was to evaluate the accuracy of analysis between trained physician (4 medical doctor) and two radiology. Materials and Methods: We enrolled 12 intubated sedated paralyzed ALI/ARDS patients (mean age 63.5  16.9 years, BMI 24.1  4.7 Kg/m 2 , ventilated with a tidal volume of 532  195 ml, PEEP 11.2  1.9 cmH 2 O, PaO 2 /FiO 2 205  57). The CT scan was performed independently from this study. CT scan was done, in static conditions, at end expiration 5 or 15 cmH 2 O of PEEP and at end inspiration 45 cmH 2 O of airway pressure. The exposures were taken at 120 KV and 250 mA. The lung volume, weight and the distribution of lung weight between the different compartments was measured using the “Maluna” software (University of Mannheim, Germany). Results and Discussions: Results are expressed as mean  standard deviation. Physicians Radiology Total volume (ml) 3956  1608 3598  1654 Total weight (mg) 1419  471 1391  449 Weight hyperinflated (mg) 41  79 41  82 Weight normally inflated (mg) 442  160 440  164 Weight poorly inflated (mg) 439  269 419  270 Weight not inflated (mg) 496  350 489  362 Conclusion(s): These show that the quantitative analysis although required a physician to manually drawing the region of interest of the lung, present a very low of inaccuracy. A-232 The variability of indices of oxygenation K. Ingram, J.G. Hardman Department of Anaesthesia, University Hospital, Nottingham United Kingdom Background and Goal of Study: Quantification of the impairment of oxygenation allows monitoring of critically ill patients’ disease severity and treatment efficacy and allows stratification for research. Current indices include PaO 2 /FIO 2 and venous admixture (QS/QT). Although these have been shown to be dependent upon FIO 2 , 1 they are widely used. Previous investigators used a lung model to examine the effect of FIO 2 on PaO 2 /FIO 2 and QS/QT. 1 The model lacked tidal ventilation and hypoxic pulmonary vasoconstriction (HPV). Our aim was to re-examine the relationship using a sophisticated pulmonary model. Materials and Methods: Extra-pulmonary shunt fractions of 10–40% of cardiac output were set in a validated, computational model of the human respiratory system, 2 and ventilation-perfusion defects were added to attain a measured shunt fraction of 40% of cardiac output at FIO 2 0.3. Tidal vol- ume was adjusted to set PaCO 2 at 5.1 kPa at FIO 2 0.3. We varied FIO 2 from 0.3 to 1.0 and recorded the resulting values of PaO 2 /FIO 2 and QS/QT. Results and Discussion: In the figure, open symbols describe QS/QT and solid symbols describe PaO 2 /FIO 2 . Both varied with changing FIO 2 . The induced variation in PaO 2 /FIO 2 and QS/QT differed from previous findings. 1 Conclusion(s): PaO 2 /FIO 2 and QS/QT do not independently quantify oxygenation-defect. We suggest that our results disagree with previous work because of the incorporation into our model of HPV and tidal ventilation. References: 1 Nirmalan M et al. Br J Anaesth 2001; 86: 477–85. 2 Hardman JG, Aitkenhead AR. Anesth Analg 2003; 97: 1840–5. A-233 Intraoperative lung water changes: correlation with pulmonary edema after liver transplantation M. de Nadal, D. Ruiz, C. Bosch, A. Camps, D. Varona, A. Mora Department of Anesthesiology, Vall dHebron University Hospital, Barcelona, Spain Background and Goal of Study: In patients undergoing orthotopic liver transplantation (OLT), intrathoracic blood volume (ITBV) has been shown to increase after reperfusion and to influence pulmonary function (1). Pulmonary edema is common after OLT and will influence postoperative recovery in transplant patients (2). This study was designed to determine the incidence of radiological pulmonary edema in the first 24 hours after transplantation and its relationship with intraoperative extravascular lung water (ELWI) changes. Materials and Methods: We reviewed 87 chest radiographs from 29 patients who had undergone OLT, obtained before surgery, immediately after surgery and 20–24 hours after surgery. Films were assessed for evidence of pulmonary edema using a standarized system (3). ITBV and ELWI were 0 20 40 60 80 100 0.2 0.4 0.6 0.8 1 FIO 2 0.0 0.1 0.2 0.3 0.4 QS/QT 40% shunt 30% shunt 20% shunt 10% shunt PaO 2 /FIO 2 (kPa) Mean of the volumes (ml) 0 500 1000 1500 2000 2500 Difference of the volumes (ml) -200 -100 0 100 200