title: The effect of exogenous surfactant on alveolar interdependence.
abstract: To investigate the nature of alveolar mechanical interdependence, we purposefully disturbed the equilibrium condition by administering exogenous surfactant in physiological non-surfactant deprived conditions. Changes in alveolar morphology induced by intra-tracheal delivery of CUROSURF were evaluated after opening a pleural window allowing in-vivo microscopic imaging of sub-pleural alveoli in 6 male anesthetized, tracheotomized and mechanically ventilated rabbits. Surfactant instillation increased the surface area of alveoli smaller than 20,000 μm(2) up to ∼ 50% at 15 min after instillation, reflecting a lowering of surface tension due to local surfactant enrichment. Conversely, for alveoli greater than 20,000 μm(2), surface area decreased by ∼ 5%. Opposite changes in alveolar surface are interpreted as reflecting a new inter-alveolar mechanical equilibrium modified by local surfactant distribution and by a decrease in lung distending pressure. We propose that smaller alveoli, representing the majority of alveolar population, might mostly contribute to improve the oxygenation index following surfactant replacement therapy in case of surfactant deficiency.
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy. Electronic address: caterina.salito@polimi.it.
authors.forename: Caterina
authors.initials: C
authors.lastname: Salito
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy.
authors.forename: Andrea
authors.initials: A
authors.lastname: Aliverti
authors.affiliation: Dipartimento di Elettronica, Informazione e Bioingegneria, Politecnico di Milano, Milano, Italy.
authors.forename: Enrico
authors.initials: E
authors.lastname: Mazzuca
authors.affiliation: Dipartimento di Scienze della Salute, Università di Milano Bicocca, Milano, Italy.
authors.forename: Ilaria
authors.initials: I
authors.lastname: Rivolta
authors.affiliation: Dipartimento di Scienze della Salute, Università di Milano Bicocca, Milano, Italy.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Miserocchi
mesh_terms: D000818:Animals; D001688:Biological Products / Q000494:pharmacology*; D008297:Male; D009929:Organ Size; D010743:Phospholipids / Q000494:pharmacology*; D011650:Pulmonary Alveoli / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology*; D011663:Pulmonary Surfactants / Q000494:pharmacology*; D011817:Rabbits; D012121:Respiration, Artificial; D013500:Surface Tension / Q000187:drug effects; D013997:Time Factors; D014140:Tracheotomy
chemical_list: D001688:Biological Products; D010743:Phospholipids; D011663:Pulmonary Surfactants; C068291:poractant alfa
keywords: Alveolar mechanics; In-vivo microscopy imaging; Surfactant