Importance of multiple episodes of hypoxia or cold stress on the development of enterocolitis in an animal model.

Necrotizing enterocolitis, a highly lethal disease in the newborn infant characterized by ischemic necrosis of the gastrointestinal tract frequently leading to perforation, is seen primarily in low birth weight infants who have undergone stress, such as hypoxia. In an animal model it was demonstrated that cold stress was as effective as hypoxia in producing the disease in formula-fed newborn rats. Breast milk was completely protective in both cold- and hypoxic-stressed animals. Presumably cold stress produces the same selective circulatory ischemia as does hypoxia. The experiment further supports the concept that any insult or stress which decreases mesenteric blood flow may initiate the changes leading to necrotizing enterocolitis. It was shown also that the incidence of the disease in formula-fed rats was related directly to the number of episodes of either cold or hypoxic stress. These results suggest that a critical amount of ischemia is necessary to initiate these changes and may help to explain the fact that not all infants exposed to hypoxia or cold stress developthe disease.