The EN group gradually restored enteral nutrition, while the PN group continued to receive parenteral nutrition treatment. Both groups received between 20 to 25 kcal/kg/day and 1.5 g/kg/day of protein. Because of the low volume, concentration, and calorie amount, on the first day, tube feeding utilized 500 ml with the speed of 30 ~ 50 ml/h. On the second day, tube feeding utilized 1000 ml with the speed of 60 ~ 80 ml/h. On the third day, tube feeding utilized 1500 ~ 2000 ml with the speed of 100 ~ 120 ml/h. If enteral nutrition could not meet a patient's caloric requirements, PN supplement was started on the fourth day. The required calories and protein for each individual in the two groups was assumed to be achieved after three days of therapy. The PN group continued to receive parenteral nutrition.

white blood cell count, C reactive protein(CRP), pro-inflammatory cytokines (TNF-a,IL-1,IL-6), and anti-inflammatory cytokines (IL-4, IL-10)