The Relationship Between Neutrophil To Lymphocyte Ratio(NLR)and Severe Traumatic Brain Injury-Induced Acute Lung Injury

BackgroundTraumatic brain injury(TBI)is caused by mechanical forces in the brain,including subdural hematomas,subarachnoid hemorrhage,and brain contusions.As its more common complication:secondary acute lung injury.It plays an important role in the occurrence and development of traumatic brain injury(TBI).Some literatures show that inflammatory response is an important factor for acute lung injury caused by traumatic brain injury(TBI).The imbalance between the pro-inflammatory and anti-inflammatory systems has largely affected secondary changes in patients with craniocerebral injury.The role of different inflammatory cells in TBI,such as neutrophils,lymphocytes,and other white blood cells,has been thoroughly studied.Among these cells,neutrophils and lymphocytes have attracted special attention,and the neutrophil to lymphocyte ratio(NLR)has proven to be a reliable and simple indicator of inflammation.Whether the ratio of neutrophils to lymphocytes(NLR)can be used as evidence to predict acute lung injury caused by traumatic brain injury(TBI)is unknown.The literature indicates that NLR is time-dependent and usually increases within a few days after onset.Therefore,considering that NLR on day 1 may reach limited conclusions,the purpose of this study was to reveal the relationship between peak NLR and clinical outcomes in sTBI patients.In addition,we evaluated factors associated with larger NLR peaks.Objective:The purpose of this study was to review the predictive value of the neutrophil-to-lymphocyte ratio(NLR)in predicting secondary lung injury(TBI-ALI)following severe head injury.MethodThis study used a retrospective cohort study method,and all patients with severe head injury were listed.Use electronic medical record system,inspection report system and imaging system to collect baseline demographic data and clinical imaging data.According to the median NLR level of 2.92,patients were divided into high NLR group and low NLR group,and the differences in baseline characteristics between the two groups of patients were observed and compared.Spearman correlation analysis of the correlation between NLR and various research factors.Multivariate logistic regression and linear regression analysis were used to estimate the relationship between NLR and TBI-ALI.Result.This study included 58 patients with craniocerebral injury at the Trauma Treatment Center of the Third Affiliated Hospital of Southern Medical University from September 2017 to December 2019.Grouping was based on the presence or absence of secondary lung injury.29 cases in the traumatic brain injury group(TBI),aged 18-65 years,with an average age of(61.62 ± 14.90)years;29 cases in the traumatic brain injury secondary lung injury group(TBI-ALI),aged 18-65 years,The average age was(58.56 ± 10.74)years old,and there was no difference in age between the two groups(P>0.05).There were 18 males and 11 females in the traumatic brain injury group(TBI);20 males and 9 females in the traumatic brain injury secondary lung injury group(TBI-ALI).There was no difference in gender between the two groups(P>0.05).There was no difference in the number of patients with hypertension,coronary heart disease and smoking history between the two groups(P>0.05).The NLR level of patients in the traumatic brain injury group(TBI)was lower than that in the traumatic brain injury secondary lung injury group(TBI-ALI)(P<0.05).The levels of WBC and CRP in the traumatic brain injury group(TBI)were lower than those in the traumatic brain injury secondary lung injury group(TBI-ALI)(P<0.05).There were differences in neutrophil count,lymphocyte count and CRP among the high NLR group and the low NLR group,and the difference was statistically significant.According to the standard of NLR median,it is divided into NLR<2.92 group and NLR>2.92 group.The NLR<2.92 group was 18-65 years old with an average age of(61.62 ± 14.90)years old;the NLR>2.92 group was 18-65 years old with an average age of(58.56 ± 10.74)years old,and there was no difference between the two groups(P>0.05).There were 12 males and 11 females in the NLR<2.92 group;there were 21 males and 14 females in the NLR>2.92 group,and there was no difference between the two groups(P>0.05).There was no difference in the number of patients with hypertension,coronary heart disease and smoking history between the two groups(P>0.05).11 patients with secondary lung injury in the NLR<2.92 group,accounting for 43.2%;20 patients with secondary lung injury in the NLR>2.92 group,accounting for 56.3%.The secondary lung injury in the NLR>2.92 group was higher than that in the NLR<2.92 group(P>0.05).The levels of WBC and NEU in patients with NLR<2.92 were lower than those with NLR>2.92(P<0.05).Conclusion:1.NLR is positively correlated with some indicators related to inflammatory response.2.NLR is positively correlated with lung injury in patients with traumatic brain injury.It may be one of the biomarkers for predicting lung injury in patients with traumatic brain injury,and it has more advantages than NEU and CRP.