Application Value Of Plasma Concentrations Of NGAL And Cystatin C Detection For Early Diagnosis And Treatment Along With Prognosis Of Acute Kidney Injury In Surgical Critically Ill Patients

Objective:1.To assess and compare the roles of plasma concentrations of neutrophil gelatinase associated lipocalin (NGAL)and Cystatin C for early diagnosis and treatment of acute kidney injury (AKI) in adult Surgical critically ill patient;2.To investigate the correlation of plasma NGAL, CysC level changing in patients with acute kidney injury in SICU and the APACHE II scores, and analyse the effectiveness of new markers used to evaluate condition changing;3.Preliminarily evaluate the value of serum level of NGAL, Cys C changing for the prognosis of the patients with AKI in SICU.Methods:The surgical critically ill patients of the SICU of our hospital between June2013and December2013were included. Patients were divided into two groups as non AKI and AKI. Plasma samples for NGAL and Cystatin C were determined on arrival in the surgical intensive care unit(SICU)(TO) and24hours after arrival in SICU(Tl). In addition, we collected the clinical data of all subjects, including gender, age, height, weight, history of basic diseases, the worst value of all kinds of laboratory test data within24hours (blood routine, blood gas analysis, renal function, arterial blood electrolyte, etc.), therapeutic method(mechanical ventilation, the application of antibiotic and early hormone treatment, continuous renal replacement therapy), and carries on the pathology of acute physiology and chronic health evaluation (APACHE) Ⅱ score until SICU discharge, record the outcome and survival time of all patients. Plasma NGAL, CysC level of the two groups of patients on TO and T1were determinated by ELISA and PETIA respectively. SPSS for Windows17.0software was used for the statistical analysis of the results. Results are presented as mean±SD and percentiles or median (range) values. The independent samples t-test, the Chi square and Mann-Whitney U tests were used for comparison of the categorical and continuous variables. NGAL and Cys C values and other parameters of non AKI and AKI groups were evaluated and compared with Kruskal Wallis one-way analysis of variance (ANOVA) analysis. In order to identify the cutoff values of urine and plasma NGAL and Cystatin C tests for the prediction of septic AKI, receiver operating characteristic (ROC) curves were used and specificities and sensitivities of the tests were assessed using the area under ROC curves (AUC). While for AKI group patients, require further a subgroup analysis and prognosis analysis. We had put TO as a starting point, clinical outcome (dead or alive) as the destination, the accumulation of patients survival curves drawn by Kaplan Meier-method, survival is the log-rank test. P<0.05was considered statistically significant.Results:1-100patients were studied;63in non AKI groups,37in AKI groups., male55, female45, age:55±14years. Between28days after diagnosis and time of diagnosis,12cases died, the mortality was12%;2.Although plasma NGAL on T1performed less well (AUC0.69), with a threshold value of92ng/ml (70.3%%sensitivity,57%specificity), Plasma NGAL showed significant discrimination for AKI diagnosis (AUC0.85) with a threshold value of65.95ng/ml (81.8%sensitivity,76.2%specificity) on TO. Both plasma Cystatin C on TO and T1worked well for the diagnosis of AKI (AUC0.90and0.88, thresholds1.49and1.47mg/L respectively,),with diagnostic sensitivity of89.2%,82.5%respectively, specificity of83.8%,76.2%respectively;3.Compared with patients in non AKI group, both plasma NGAL and Cystatin C level of patients in AKI group on TO and T1increased significantly, the difference between the two groups has significant statistical difference (P<0.01); Compared with non sepsis patients, the NGAL, Cys C levels of patients with sepsis group had increased significantly (P<0.05), but plasma NGAL level difference between NGAL in sepsis-AKI and sepsis-non AKI group had showed no statistical difference (P>0.05); 4.With the APACHE Ⅱ score increased, both plasma NGAL and Cystatin C level of patients in AKI group on TO and T1also increased, difference between each groups was statistically significant (P<0.05), difference of mortality between each groups showed statistically significance (P<0.05); With the degree of AKI aggravated. serum Cys C level on TO and T1also increased, its difference between1、2and3stage groups in patients with AKI showed statistically significance (P<0.01); Although plasma NGAL levels also increased along with the aggravation of AKI, its difference between three groups has no statistical significance (P>0.05);5.Kaplan and Meier survival curves show that the survival rate of patients group with low levels both plasma NGAL and Cys C were the best, the group with high plasma NGAL levels+low plasma Cys C level were the second, the group with low plasma NGAL+high plasma Cys C group were the third, the survival rate of patients group with high level both plasma NGAL and Cys C were the lowest, there is statistically significant differences between the four groups (Log rank test, P<0.05). Conclusion:Plasma NGAL and Cystatin C are useful markers in predicting AKI in surgical critically ill patients. Plasma NGAL raises in patients with sepsis in the absence of AKI and should be used with caution as a marker of AKIin septic SICU patients., Plasma NGAL and Cystatin C level test for SICU patients with AKI has a certain guiding value for the whole condition assessment and determine the severity of kidney damage In the SICU.