Early Evaluation Of Surgical Site Infection In The Lumbar Spine By Detection Of Drainage Fluid In The Surgical Area

Background and purpose:In spine surgery,surgical site infection(SSI)is a common complication of lumbar spine surgery,which increases the length of hospital stay,medical costs,and unplanned reoperation rates,causing significant challenges for both physicians and patients.Early identification of SSI can lead to early response programs and effectively reduce the physical and mental burden on patients and the cost of medical treatment.At present,the diagnosis of SSI mainly depends on fever,redness of surgical site and detection of inflammatory indicators in peripheral blood(WBC,CRP,ESR,PCT,IL,TNF,etc.).However,postoperative SSI of lumbar spine is mostly low toxic infection,and there is no early inflammatory response in the whole body and surgical site,and the influence of inflammatory indicators in peripheral blood is relatively small,so there are still delays,missed diagnosis and misdiagnosis in diagnosing early SSI.Our group found that patients with lumbar spine surgery had more drainage fluid volume in the surgical area,and the color of drainage fluid was red and turbid 3 days after surgery,and the incidence of SSI was significantly higher in these patients at a later stage.This study aimed to analyze the cellular components and characteristics of postoperative drainage fluid from the lumbar spine and explore its value in the early diagnosis of SSI.Method:A prospective clinical study of patients undergoing lumbar spine surgery who met the inclusion criteria between February 2020 and July 2021.These patients retained their surgical drains at least until the third postoperative day and were analyzed for the white blood cell count(WBC),percentage of neutrophils,and routine testing(microscopy and traits)of the drainage fluid in the SSI versus non SSI groups.At the same time,inflammatory indicators such as leukocytes,erythrocyte sedimentation rate and C-reactive protein in peripheral blood of patients were detected on the third day after surgery.Observe the incision redness and tenderness,exudation and the temperature of the patient after operation.Using spss26 0 for statistical analysis,the measurement data of two groups were compared and analyzed by Non-parametric test,and the counting data were tested by Chi-square test,and P<0.05 was considered statistically significant.Using the results of the receiver operating characteristic curve(ROC),to determine the predictive ability and cut-off values of these test parameters in SSI.Result:Most of the lumbar postoperative patients had their drains removed on the first postoperative day,and of the 104 patients who met the inclusion criteria,31(29.8%)were confirmed to have clinical infection(SSI).The white blood cell count in the drainage fluid was significantly higher in the SSI group than in the non-SSI group(P<0.001).The incidence of drainage fluid opacity and dark red color was significantly higher in the SSI group than in the non SSI group(83.9%vs 38.4%,P<0.001;19.4%vs 2.8%,P=0.019).The optimal cut-off value for variables was determined by taking the maximum value according to the Youden index(sensitivity+specificity-1),and the optimal cut-off value for leukocytes 3 days after surgery was 1.125×10~9/L,which had a sensitivity of 80.6%and a specificity of 78.1%;Area under the curve 0.876.Conclusions:On postoperative day 3,the white blood cell count in the drainage fluid of the surgical area and the examination of the drainage fluid characteristics are valuable methods for predicting early SSI after lumbar spine surgery,achieving a noninvasive,accurate,and early diagnosis of postoperative SSI in clinical work,but further studies are needed to validate the results of this study and investigate its wider applicability.