A new simple method of staining exogenous surfactant in experimental research.

Two commonly used techniques in experimental lung research have helped to determine which variables influence surfactant distribution within the lung: radioactive labelling of surfactant components and admixture of coloured microspheres to surfactant. However, neither technique allows the description of surfactant distribution at the alveolar level. The aim of this study was to establish a new technique using histology colourants for admixture to exogenous surfactant to make exogenous surfactant visible by light microscopy. In a step by step approach the authors evaluated the properties of a variety of green colourants when added to a natural porcine surfactant preparation for their ability to homogeneously mix with surfactant, to bind to surfactant, to adhere to a glass slide, to not be "overstained" by standard haematoxylin-eosin and Elastica van Giesson staining, to not influence in vitro surface tension properties of surfactant using a Wilhelmy balance, to not influence oxygenation and ventilation in a lung-lavage rat model and to preserve their colour and adherence to exogenous surfactant on lung specimens visualized by light microscopy. Only one of the tested green histology colourants (Green Dye) fulfilled all requirements and showed a brilliant green colour in a distribution pattern typical of surfactant at the alveolar level. It is concluded that the authors have established a new, simple and inexpensive method of staining exogenous surfactant for evaluation of its distribution by light microscopy at the alveolar level.

Hemodynamic effects of partial liquid ventilation with perfluorocarbon in acute lung injury.

OBJECTIVE: To assess the effect of partial liquid ventilation with perfluorocarbons on hemodynamics and gas exchange in large pigs with induced acute lung injury (ALI). DESIGN: Randomized, prospective, double-control, experimental study. Experimental intensive care unit of a university. MATERIALS: Eighteen large pigs (50 +/- 5 kg body weight) with an average anterior posterior thoracic diameter of 24 cm and induced acute lung injury. INTERVENTIONS: All animals were surfactant depleted by lung lavage to a PaO2 below 100 mmHg and randomized to receive either perflubron (n = 6) or saline (n = 6) in five intratracheal doses of 5 ml/kg at 20-min intervals, or no instillation (n = 6). MEASUREMENTS AND RESULTS: In all animals heart rate, arterial pressures, pulmonary pressures, cardiac output and blood gases were recorded at 20-min intervals. There was no deleterious effect on any hemodynamic parameter in the perflubron group, whereas systolic and mean pulmonary arterial pressure values showed a persistent decrease after the first 5 ml/kg of perflubron, from 48.7 +/- 14.1 to 40.8 +/- 11.7 mmHg and from 39.7 +/- 13.2 to 35.2 +/- 12.0 mmHg, respectively. Perflubron resulted in a significant (ANOVA P < 0.01), dose-dependent increase in PaO2 values from 86.3 +/- 22.4 to a maximum of 342.4 +/- 59.4 mmHg at a dose of 25 ml/kg; the other groups showed no significant increase in PaO2. CONCLUSIONS: Tracheal instillation of perflubron in induced ALI results in a dose-dependent increase in PaO2 and has no deleterious effect on hemodynamic parameters.