Abstract
Intratracheal administration of a perfluorocarbon liquid (perfluorooctyl bromide, PFOB) during continuous positive-pressure ventilation (partial liquid ventilation, PLV) improves lung function in animals with lung injury. We attempted to determine whether there is a correlation between improvement of oxygenation and distribution of PFOB in a rabbit lung injury model using 1H and 19F nuclear magnetic resonance imaging.
Oleic acid was administered intravenously at 0.1ml·kg-1 to induce lung injury in six anesthetized rabbits ventilated at FIO2 1.0. After baseline blood gas analysis, 45ml of PFOB was given intratracheally and the blood gas was analyzed every 30min thereafter. Postmortem 1H and 19F magnetic resonance imaging (MRI) was conducted using a 4.7-T, 33cm horizontal bore Varian NMR (nuclear magnetic resonance) spectroscopy/imaging system. Seven slices of both 1H and 19F lung images were obtained using the FLASH (fast low angle shot) method. Improvement of oxygenation was calculated by subtracting the baseline PaO2 from the PaO2 (mmHg) at 30min after PLV. Distribution of PFOB was calculated by dividing the sum of PFOB areas of seven lung slices using 19F imaging by the sum of the lung areas in the same slices using 1H imaging.
Fluorothorax developed in one animal and PaO2 did not improve. This animal was therefore excluded from further analysis. PaO2 improved from 66±23mmHg (mean±SD) at the baseline to 159±91mmHg at 30min after PLV. PFOB was distributed in 54±29% of the lung area in five animals. It was distributed mainly in the dependent lung region, probably because of its high specific gravity (1.92 at 25°C). There was no correlation (r2=0.60, P>0.05) between the improvement of oxygenation and the distribution area of PFOB. It was suggested that reexpansion of dependent lung alveoli by PFOB might be one of the beneficial effects of PLV.
