ACUTE LUNG INJURY AFTER INSTILLATION OF HUMAN BREAST-MILK OR INFANT FORMULA INTO RABBITS LUNGS

Background: Recent interest In shortening the fasting interval after i ngestion of milk products demonstrated large volumes of breast milk in the stomach 2 h after breastfeeding, Although aspiration is a rare ev ent, if it were to occur with human breast milk, it is important to un derstand the extent of the lung injury that might occur. Therefore, th e response to Instillation of acidified breast milk and Infant formula in the lungs of adult rabbits was studied. Methods: In 18 anesthetize d adult rabbits, 1 of 3 fluids (in a volume of 0.8 ml . kg(-1) and PH level of 1.8, acidified with hydrochloric acid); saline, breast milk, or infant formula (SMA, Wyeth, Windsor, Ontario), was instilled into t he lungs via a tracheotomy. The lungs were ventilated for 4 h after in stillation. Alveolar-to-arterial oxygen gradient and dynamic complianc e were measured before and at hourly intervals after instillation. Aft er 4 h, the rabbits were killed and the lungs were excised. Neutrophil Infiltration was quantitated by a pathologist blinded to the instille d fluid. a histologic control group of four rabbits was ventilated und er study conditions without any intratracheal fluid instillation. Resu lts: Alveolar-to-arterial oxygen gradient increased and dynamic compli ance decreased significantly during the 4 h after instillation of both breast milk and infant formula compared with baseline measurements an d with saline controls (P < 0.05). The neutrophil counts in the lungs from the saline, breast milk, and formula rabbits were significantly g reater than those in the control group. Conclusions: Instillation of a cidified breast milk or infant formula (in a volume of 0.8 ml . kg(-1) and pH level of 1.8) into rabbits' lungs induces acute lung injury of similar intensity that lasts at least 4 h.