Abstract: Objective To explore the dynamic changes in gut microbiota structure and immunologic function in patients with cranial trauma under enteral nutritional support.Methods 106 patients with traumatic brain injury who were treated in the hospital from January 2023 to October 2024 were retrospectively analyzed.They were divided into tolerance group and intolerance group,and 50 patients with traumatic brain injury who received parenteral nutrition at the same time were selected as the control group.The laboratory indexes and adverse reactions of the three groups were compared.Results After treatment,the levels of Escherichia coli in the tolerance group,intolerance group and control group were (7.02 ±1.23) copies/g and (9.31±1.61) copies/g and (12.21±2.16) copies/g,respectively.Before treatment,they were (12.06±1.91) copies/g,(11.82±2.05) copies/g and (11.63±1.81) copies/g,respectively.After treatment,there was a statistically significant difference between the tolerance group and the intolerance group and before treatment (P<0.05),compared with the control group,the difference was statistically significant (P<0.05),the difference between the tolerance group and the intolerance group was statistically significant (P<0.05).After treatment,the levels of trimethylamine oxide (TMAO) in the tolerance group,intolerance group and control group were (2.25±0.37)ng/ml,(2.60±0.35)ng/ml and (2.81±0.32)ng/ml,respectively.Before treatment,they were (3.92±0.41)ng/ml,(3.95±0.37)ng/ml and (4.05±0.42)ng/ml,respectively,and the difference was statistically significant (P<0.05),the tolerance group was lower than the intolerance group,both were lower than the control group,and the difference was statistically significant (P<0.05).After treatment,the Lactobacillus levels in the tolerance group,intolerance group and control group were (10.28±1.32) copies/g,(9.71±1.19) copies/g and (5.42±1.05) copies/g,respectively.Before treatment,they were (7.09±1.17) copies/g,(7.14±1.21) copies/g and (7.21±1.20) copies/g,respectively.There was a statistically significant difference before and after treatment in the same group (P<0.05).After treatment,the tolerance group was higher than the intolerance group,both were higher than the control group,and the difference was statistically significant (P<0.05).After treatment,the bifidobacterium levels in the tolerance group,intolerance group and control group were (13.67±1.80) copies/g,(10.91±1.31) copies/g and (9.11±1.23) copies/g,respectively.Before treatment,they were (8.15±0.71) copies/g,(8.34±0.90）copies/g and (8.27±0.83) copies/g,respectively.Before and after treatment in the same group,the difference was statistically significant (P<0.05).After treatment,the tolerance group was higher than the intolerance group,both were higher than the control group,and the difference was statistically significant (P<0.05).After treatment,the butyric acid levels in the tolerance group,intolerance group and control group were (3.39±0.65) μg/ml,(3.15±0.62) μg/ml and (2.89±0.57) μg/ml,respectively.Before the treatment,they were (2.26±0.34)μg/ml,mu g/ml (2.29±0.30)μg/ml and (2.17±0.31)μg/ml,respectively.Before and after treatment in the same group,the difference was statistically significant (P<0.05).After treatment,the tolerance group was higher than the intolerance group and both were higher than the control group,and the difference was statistically significant (P<0.05).Compared with before treatment,the levels of plasma albumin,serum prealbumin and hemoglobin in the three groups increased after treatment.The levels in the tolerance group were higher than those in the intolerance group and were all higher than those in the control group.The differences were statistically significant (P<0.05).After treatment,the proportions of neutrophils,white blood cell count,CRP and PCT in the three groups decreased.The tolerance group was lower than the intolerance group and all were lower than the control group,and the differences were statistically significant (P<0.05).The counts of CD4⁺T cells in the tolerance group,intolerance group and control group were 34.02±4.15,31.71±4.08 and 28.19±4.11,respectively,and those of IgA were 3.36±0.49,3.08±0.52 and 2.86±0.34,respectively.The IgG values were 12.89±1.31,11.15±1.04 and 10.13±1.07,respectively.Compared with before treatment,the counts of CD4⁺T cells,the ratio of CD4⁺/CD8⁺,IgA,IgM and IgG in the three groups increased after treatment,and the differences were statistically significant (P<0.05); After treatment,the tolerance group was higher than the intolerance group,both were higher than the control group,and the difference was statistically significant (P<0.05).The incidences of diarrhea and pneumonia in the tolerance group were lower than those in the intolerance group and the control group,and the difference was statistically significant (P<0.05).Conclusion Early enteral nutrition support helps regulate the gut microbiota in patients with cranial trauma,enhance immune function,and reduce the risk of infection,with better outcomes observed in patients with gastrointestinal tolerance.

Key words: enteral nutrition support, cranial trauma, gut microbiota, tolerance