The catheters were connected to pressure transducers useful site and to an integrated bedside monitor (PiCCO, Volef; Pulsion Medical Systems). After instrumentation, the animals were placed in the prone position for the rest of the study and baseline values were recorded.Experimental protocolThe animals were randomly allotted to one of two groups: 1) acid aspiration pneumonitis (AAP) and 2) Control (Control).Acid aspiration pneumonitis (AAP) AAP was induced by intrabronchial installation of hydrochloric acid (HCI; 0.1 N, pH 1.1; 2.5 ml/kg body weight) during the inspiratory phase of ventilation. The acid was divided into two aliquots and instilled through a suction catheter into the right and left main bronchus. The injury was considered stable if PaO2 was constantly lower than 300 mmHg at an FiO2 of 1.

0 60 minutes after instillation.Control Control animals had the same instrumentation for hemodynamic monitoring as those in the AAP group but nothing was instilled into the lungs.MeasurementsMeasurements were performed at baseline (T0) and then 60, 120 and 240 minutes either after lung injury was established or after baseline measurements in the control group.Hemodynamics and gas-exchange Cardiac output (CO), stroke volume, global ejection fraction, left and right end-diastolic volumes, right ventricular ejection fraction, systemic and pulmonary pressures, extravascular lung water index (ELWI), and intrathoracic blood volume index (ITBI) were measured. Thermodilution measurements were performed in triplicate by the same investigator with 20 ml ice-cold 0.9% saline solution.

Arterial and mixed venous samples were collected and immediately analyzed for blood gases (ABL 510, Radiometer, Copenhagen, Denmark).Lung and brain imaging and analysis CT scans of the lungs were obtained from apex to base during an end-expiratory hold at a PEEP of 5 cm H2O (GE Light Speed VCT, GE Medical Systems, M��nchen, Germany), thickness 5 mm, interval 0.5 mm, 100 mA, 100 kV). The method used for quantitative image analysis has been described previously [16]. Quantitative analysis of the entire lung was performed to assess lung density (Hounsfield units, HU) and the extent of lung tissue aeration (normal, poor and none). Analysis of individual lung regions was performed by dividing the lung into 10 equidistant horizontal sections along the sagittal axis.Pulmonary parenchyma with a CT density ranging from -1,000 to -900 HU was classified as overinflated, a range of -900 to -500 HU as normal, -500 to -100 HU as poorly aerated, Carfilzomib and -100 to +300 HU as non-aerated (atelectatic).Three consecutive horizontal sections of the cerebral CT scans starting below the external auditory meatus were analyzed. The brain CT density window was set from -10 to +100 HU.