Acute lung injury after instillation of human breast milk into rabbits' lungs - Effects of pH and gastric juice

Background The authors compared the lung injury in rabbits that occurred af ter tracheal instillation of human breast milk (HBM) acidified to pll 1.8 w ith hydrochloric acid (HCl), HEM at its native pH (7.0), and HEM acidified with gastric juice to pH 1.8 and 3.0. Methods: The alveolar-to-arterial oxygen tension gradient and dynamic compl iance were recorded before and hourly for 4 h after intratracheal instillat ion of 0.8 ml/kg HEM acidified with HCl (pH 1.8), HEM at its native pH (7.0 ), HBM acidified with gastric juice (pH 1.8 or 3.0), or 5% dextrose solutio n acidified with gastric juice (pH 1.8) as a control in 30 adult rabbits, T he circulating neutrophil count and phagocyte oxidant activity were determi ned before and 1 and 4 h after instillation. Results: The alveolar-to-arterial oxygen tension gradient increased and dyn amic compliance decreased significantly in all groups after instillation of HBM compared with baseline values and those in the control group. The seve rity of the lung injury after instillation of HBM at all pH values (1.8, 3. 0, and 7.0) and after acidification with gastric juice or HCl was similar. The circulating neutrophil count increased steadily for 4 h after instillat ion (P < 0.013), whereas spontaneous phagocyte oxidant burst activity peake d at 1 h (P < 0.007) and returned to baseline by 4 h after instillation. Conclusions: The severity of the lung injury after tracheal instillation of 0.8 ml/kg HBM in rabbits is similar at pH values between 1.8 and 7.0 after acidification with HCl or gastric juice. Tracheal instillation of HBM incr eases the circulating neutrophil count and phagocyte oxidant burst activity .