Risk Factors Of Debridement For Early Surgical Site Infections After Posterior Lumbar Fusion With Degenerative Lumbar Diseases

BackgroundLumbar degenerative disease is a common disease in the department of spine surgery,which mainly occurs in middle-aged and elderly people.Lumbar degenerative diseases mainly include lumbar disc herniation,lumbar spinal stenosis and lumbar instability/spondylolisthesis,which cause a series of pathological changes such as compression of dural sac and nerve root,resulting in some clinical symptoms,which can seriously affect the life of patients and endanger their physical and mental health.The posterior lumbar spinal canal decompression and bone graft fusion with internal fixation is the most common surgery for lumbar degenerative disease in the clinical,which can relieve clinical symptoms and prevent neurologic deterioration on the basis of solid fixation,reliable fusion and sufficient decompression of dural sac and nerve root.Nowadays,Surgical Site Infection is the third most common hospital acquired infection,following pneumonia and urinary system infections.Surgical site infection has gradually become a health problem in the world,which has drawn more and more spine surgeons’ concern and attention.Once SSIs occur,both patients and doctors will have many negative effects.For patients,SSIs can increase medical expenditure,prolong hospital stay,increase physical and mental pain,and lead to dysfunction or life-threatening in severe cases.For doctors,it can increase the workload of clinicians,undermine the confidence of young doctors and the possibility of potential doctor-patient disputes.The risk factors of SSIs can be divided into preoperative,intraoperative and postoperative factors according to the time classification.Preoperative and intraoperative stages are the key ones for the prevention of postoperative SSIs.Appropriate adjustment of the adjustable factors will be expected to reduce the incidence of SSIs.ObjectiveTo explore the risk factors of debridement for early surgical site infections(SSI)after posterior lumbar fusion with instrumentation,and to provide theoretical basis for reducing its incidence in the future.MethodsThe data of patients with degenerative lumbar diseases undertaken posterior lumbar fusion with instrumentation in department of spine surgery,form September 2012 to September 2018 were retrospectively collected and analyzed.The 60 patients with SSI which needed irrigation and debridement after operation were enrolled in debridement group.Meanwhile,the 240 patients without SSI were randomly selected as control group by 1:4 ratio.Through our system of electronic medical records in patients with two groups of data collection,including demographics: gender,age,type of lumbar degenerative disease(lumbar spinal stenosis,lumbar disc herniation or lumbar instability/spondylolisthesis),hypertension,diabetes mellitus,smoking,ASA score,preoperative hospitalization days and days of hospital stay,total medical costs and elapsed time to a diagnosis SSI;operation related variables:Spinal Invasiveness Index(SII),duration of operation,number of operative segments,intraoperative blood loss and blood transfusions;imaging parameters and preoperative laboratory results: subcutaneous fat thickness,paravertebral muscle thickness,preoperative hemoglobin,preoperative white blood cell count,thrombocyte count,total lymphocyte count,C-reactive protein(CRP),erythrocyte sedimentation rate(ESR),serum albumin,glycosylated hemoglobin,blood glucose and microbiological culture results.The above data were analyzed by univariate analysis between two groups,and the indicators with significant statistical differences were screened and further analyzed in Binary Logistic regression to explore the risk factors related to SSI,and drew the receiver operating characteristic curve(ROC).Results1.A total of 2326 patients were enrolled,60 patients needed surgical debridement due to SSI were enrolled in debridement group,with an incidence of 2.58%(60/2326).According to the predetermined proportion,240 patients without SSI were randomly selected as the control group.Univariate analysis showed ASA score,diabetes mellitus,days of total hospital stay,total medical costs,SII,duration of operation,number of operative segments,intraoperative blood loss,blood transfusions,subcutaneous fat thickness,preoperative hemoglobin,preoperative white blood cell count,total lymphocyte count,CRP,serum albumin and blood glucose were significantly different between the two groups(P<0.05),while there was no significant difference in gender,age,type of lumbar degenerative disease,preoperative hospitalization days,smoking,hypertension,paravertebral muscle thickness,thrombocyte count,ESR and glycosylated hemoglobin(P>0.05).Further analysis with logistic analysis showed that SII,subcutaneous fat thickness,serum albumin and preoperative blood glucose were risk factors of debridement for early SSI after posterior lumbar fusion.The cut-off value of SII was 9.5,subcutaneous fat thickness was 23.5mm,serum albumin was 35.8g/L and glucose was 6.18mmol/L on ROC curve.2.Microbiological culture results: patients of debridement group with tissue or secretion culture results showed that Staphylococcus aureus is the most common pathogenic bacteria,accounting for 31.7%(19/60),e.coli and no bacterial growth ranked second,accounting for18.3%(11/60),subsequent epidermis staphylococcus were 6 cases(10.0%),pseudomonas aeruginosa were 4 cases(6.6%),enterococcus were 3 cases(5.0%)and klebsiella pneumonia were 2 cases(3.3%),etc.3.Total medical costs and days of hospital stay: the total medical costs of debridement group was 76.3% higher than the non-infected group,and the days of total hospital stay was244.9% longer than the non-infected group.Conclusions1.Higher SII,thicker subcutaneous fat thickness,lower serum albumin and higher glucose increase the risk of debridement for early SSI after posterior lumbar fusion.2.The cut-off value of SII was 9.5;The cut-off value of subcutaneous fat thickness was23.5mm;The critical value of preoperative serum albumin was 35.8 g/L;The critical value of preoperative blood glucose was 6.18 mmol/L.For patients with one or more of the following conditions,SII > 9.5,subcutaneous fat thickness > 23.5 mm,preoperative serum albumin <35.8 g/L,preoperative blood glucose > 6.18 mmol /L,we should be more alert to the occurrence of debridement for early SSI after posterior lumbar fusion.3.The most common pathogenic bacteria causing debridement of early SSI after posterior lumbar fusion is Staphylococcus aureus.Antibiotics can be given preventatively for Gram-positive cocci during and after operation.