BACKGROUND: Since respiratory dysfunction is the main cause of death in patients with severe acute pancreatitis (SAP), elucidating the critical period of acute pancreatitis-associated lung injury (APALI) is of important clinical value. This study aimed to define the risk period of APALI by a series of studies including a dynamic analysis of total water content, ultrastructure and number of type Ⅱ alveolar epithelial cells, and reactive oxygen metabolites (ROMs) of lung tissue in a mouse model of SAP, and a clinical analysis of APALI patients.
METHODS: ICR mice were selected to establish a SAP model. They were given 7 intraperitoneal injections of cerulein (50 µg/kg body weight) at hourly intervals, followed by an intraperitoneal injection of lipopolysaccharide (15 mg/kg body weight). The total water content, ultrastructure, and number of type Ⅱ alveolar epithelial cells, and ROMs of lung tissue were assessed before (0 hour) and after the establishment of SAP model (6 hours, 12 hours, 1 day, 4 days, and 7 days). In addition, we analyzed the data from 215 patients with APALI (PaO2 <60 mmHg) treated at our hospital between January 1998 and December 2006. Statistical analyses were made using the F test. P values less than 0.05 were regarded as statistically significant.
RESULTS: The total water content and ultrastructure of type Ⅱ alveolar epithelial cells (mitochondria and lamellar bodies) of the lung in the SAP mice were significantly altered at 12 hours after the establishment of SAP model, and reached a maximum at 1 to 4 days. The number of type Ⅱ alveolar epithelial cells and ROMs increased maximally at 1 day after the establishment of the model. Furthermore, clinical results showed that lung injury occurred at a mean of 3.1435±1.0199 days in patients with SAP. These clinical data were almost consistent with the results of the SAP model.
CONCLUSION: The risk period for APALI is between the first and fourth day during the course of SAP.