title: Expansion pattern of terminal air-spaces in the premature rabbit lung after tracheal deposition of surfactant.
abstract: The expansion pattern of the lungs of full-term and premature newborn rabbits was evaluated by direct observation of the lung surface during an inflation-deflation cycle, with particular reference to the effect of tracheal deposition of surfactant before the first breath. In non-treated premature fetuses, aeration of alveoli was initiated at an endotracheal pressure of 35 cm H2O; the mean corresponding 'opening pressure' was 25 cm H2O in both full-term and surfactant-treated premature animals. The process of alveolar aeration was asynchronous in all groups but at maximal inflation pressure (35 cm H2O) the expansion pattern was uniform in full-term and surfactant-treated premature fetuses; these animals also developed residual volume. In non-treated premature animals aeration was patchy, even at maximal inflation, and the lungs emptied at the end of deflation.
mesh_terms: D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D005865:Gestational Age; D011312:Pressure; D011650:Pulmonary Alveoli / Q000502:physiology*; D011663:Pulmonary Surfactants / Q000494:pharmacology*; D011817:Rabbits; D012115:Residual Volume; D012119:Respiration / Q000187:drug effects*; D013499:Surface Properties
chemical_list: D011663:Pulmonary Surfactants