title: Effects of ventilation on the surfactant system in sepsis-induced lung injury.
abstract: The present study examined the effects of mechanical ventilation, with or without positive end-expiratory pressure (PEEP), on the alveolar surfactant system in an animal model of sepsis-induced lung injury. Septic animals ventilated without PEEP had a significant deterioration in oxygenation compared with preventilated values (arterial PO(2)/inspired O(2) fraction 316 +/- 16 vs. 151 +/- 14 Torr; P < 0.05). This was associated with a significantly lower percentage of the functional large aggregates (59 +/- 3 vs. 72 +/- 4%) along with a significantly reduced function (minimum surface tension 17.7 +/- 1.8 vs. 11.8 +/- 3.8 mN/m) compared with nonventilated septic animals (P < 0.05). Sham animals similarly ventilated without PEEP maintained oxygenation, percent large aggregates and surfactant function. With the addition of PEEP, the deterioration in oxygenation was not observed in the septic animals and was associated with no alterations in the surfactant system. We conclude that animals with sepsis-induced lung injury are more susceptible to the harmful effects of mechanical ventilation, specifically lung collapse and reopening, and that alterations in alveolar surfactant may contribute to the development of lung dysfunction.
authors.affiliation: Departments of Physiology and Medicine, Lawson Research Institute, St. Joseph's Health Centre, University of Western Ontario, London, Ontario, Canada N6A 4V2. jmalloy@julian.uwo.ca
authors.forename: J L
authors.initials: JL
authors.lastname: Malloy
authors.forename: R A
authors.initials: RA
authors.lastname: Veldhuizen
authors.forename: J F
authors.initials: JF
authors.lastname: Lewis
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000502:physiology; D018893:Bronchoalveolar Lavage; D001992:Bronchoalveolar Lavage Fluid / Q000737:chemistry; D006339:Heart Rate / Q000502:physiology; D008168:Lung / Q000473:pathology / Q000503:physiopathology; D008171:Lung Diseases / Q000209:etiology / Q000503:physiopathology*; D008297:Male; D011510:Proteolipids / Q000032:analysis; D011650:Pulmonary Alveoli / Q000737:chemistry / Q000503:physiopathology*; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants / Q000032:analysis*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012121:Respiration, Artificial; D012143:Respiratory Physiological Phenomena; D018805:Sepsis / Q000150:complications*
chemical_list: D011510:Proteolipids; D037661:Pulmonary Surfactant-Associated Proteins; D011663:Pulmonary Surfactants