摘要目的 评估降钙素原(PCT)在呼吸机相关性肺炎(VAP)诊断中的价值.方法 采用前瞻性诊断试验,将2009年6月1日至10月1日连续收住四川大学华西医院重症监护病房(ICU)接受机械通气超过48 h、疑诊为VAP的患者作为观察对象,排除进入ICU时已存在明确感染或诊断为肺癌以及在观察期间并发肺外器官感染的患者.测定合格研究对象进入研究时以及疑诊VAP当日的PCT、C-反应蛋白(CRP)水平,计算临床肺部感染评分(CPIS),并进行统计学分析.结果 机械通气≥48 h的372例患者中,共有31例筛查合格的研究对象在研究期间49例次达到VAP疑诊标准,其中确诊23例次,未确诊26例次.确诊组在疑诊VAP当51 PCT[0.68 μg/L(四分位间距0.28,2.31)]显著高于未确诊组[0.18 μg/L(0.06,0.28),P<0.01].以0.31 μg/L为截断值,PCT的诊断敏感性为73.9%,特异性为80.8%;相比而言,CPIS以5分为截断值时的诊断敏感性较高,为95.7%,但特异性较低,仅53.8%;CRP以109.5 mg/L为截断值的诊断准确性最差,敏感性和特异性分别56.5%、61.5%.以PCT≥0.31 μg/L和CPIS≥5分联合诊断VAP,其敏感性无明显改善,为69.6%,但特异性显著提高,为88.5%.结论 在VAP的早期诊断中,PCT的特异性明显优于CRP以及CPIS;将PCT与CPIS联合诊断,可以显著提高诊断的特异性,从而有效排除诊断假阳性,对VAP的确诊有一定临床价值.

abstractsObjective To evaluate the diagnostic value of procalcitonin(PCT)in ventilator-associated pneumonia(VAP).Methods Prospective study was performed.All adult patients who were admitted into the intensive care unit(ICU)of West China Hospital of Sichuan University between June 1st and October 1st and were clinically suspected of having developed VAP after 48 hours of mechanical ventilation were enrolled.Patients who had active infection or lung cancer at ICU admission or developed extrapulmonary infection during the study period were excluded.PCT and C-reactive protein(CRP)levels were measured and the clinical pulmonary infection score(CPIS)was calculated at study entry and on the day of VAP suspicion.Results In total,49 suspected episodes of VAP in 31 cases were microbiologically confirmed in 23 and refuted in 26.Median PCT levels were 0.68 μg/L(interquartile range 0.28,2.31)and 0.18 μg/L(0.06,0.28)respectively in patients with and without VAP on the suspicion day(P＜0.01).Using 0.31 μg/L as the best cutoff,PCT had 73.9% sensitivity and 80.8% specificity.The CPIS resulted in higher sensitivity (95.7%)but lower specificity(53.8%)when the cutoff of CPIS≥5.CRP had the lowest sensitivity and specificity(56.5%,61.5%)when the cutoff of CRP was 109.5 mg/L.A CPIS≥5 combined with serum levels of PCT≥0.31 μg/L did not improve the sensitivity(69.6%),but resulted in 88.5% specificity.Conclusion PCT had better specificity than CRP and CPIS in early diagnosis of VAP.Combined values of PCT and CPIS below the cut-off points could effectively exclude false-positive diagnosis of VAP.