Intravital laser confocal microscopy of pulmonary edema resulting from intestinal ischemia-reperfusion injury in the rat

Objective: To observe pulmonary edema resulting from intestinal ischemia-re perfusion injury. We used a newly developed laser confocal microscope to ob serve the subpleural capillary network and the superficial alveoli under in travital conditions, and created three-dimensional images of the pulmonary microcirculation to analyze the time course and spatial pattern of pulmonar y exudative changes during intestinal ischemia-reperfusion injury in vivo. Design: Prospective, randomized, unblinded study. Setting: Laboratory of a university hospital. Subjects: Male Sprague-Dawley rats. Interventions: The rats were injected intravenously with bovine serum album in labeled with fluorescein isothiocyanate and subjected to 60 mins of inte stinal ischemia, followed by 180 mins of reperfusion. During mechanical ven tilation, the upper lobe of the right lung was examined in the intravital s tate using a high-speed confocal fluorescence microscope. Measurements and Main Results: Interstitial edema and alveolar leakage were recognized as changes of interstitial fluorescence in the subpleural capil lary network and as changes of alveolar fluorescence in the alveolar cross- sectional view. Although exudative changes in the interstitium and alveoli were observed during intestinal ischemia, there was a marked increase in bo th interstitial edema and alveolar leakage after intestinal reperfusion. Conclusion: We observed pulmonary edema under intravital conditions and dem onstrated the utility of a newly developed laser confocal microscope. This system not only enabled us to analyze the development of pulmonary edema th ree-dimensionally, but also allowed us to evaluate the pulmonary microcircu lation.