降钙素原在呼吸机相关性肺炎中的诊断价值

目的 探讨血清降钙素原（PCT）对呼吸机相关性肺炎（VAP）的诊断价值。方法 61例进入本研究的呼吸机辅助通气患者按照机械通气7d内是否发生VAP分为VAP组和非VAP组。两组于机械通气前及机械通气7d后（非VAP组）或患VAP（VAP组）时采用半定量固相免疫测定法测定血清PCT水平，PCT水平分为〈0．5μg／L．0．5～2．0μg／L，2．O～10．0μg／L和≥10．0μg／L 4个等级。同时检测血清C-反应蛋白（CRP）及白细胞（WBC）计数。结果 机械通气前VAP组和非VAP组的CRP和WBC计数差异均无显著性（P均〉0.05），机械通气后VAP组CRP和WBC计数均较非VAP组显著升高（P均=0．000），CRP与WBC计数对VAP的诊断敏感性分别为73．5％（25／34例）和82．3％（28／34例）;特异性分别为48．1％（13／27例）和55．5％（15／27例）．阳性预测值分别为64．1％（25／39例）和70．0％（28／40例）;阴性预测值分别为59．1％（13／22例）和71．4％（15／21例）。若以血清PCT≥0．5μg／L为阳性阈值，机械通气前VAP组和非VAP组PCT阳性率差异无显著性（P〉0．05）；发生VAP后，VAP组较非VAP组PCT阳性率显著升高，其对VAP诊断敏感性为85．3％（29／34例），特异性为74．1％（20／27例）．阳性预测值为80．5％（29／36例），阴性预测值为80．0%（20／25例）。结论 血清PCT在VAP诊断中有较高敏感性，及时监测血清PCT可能有助于VAP的早期诊断。

Diagnostic value of procalcitonin in ventilator associated pneumonia

OBJECTIVE: To explore the diagnostic value of procalcitonin (PCT) quantification in ventilator associated pneumonia (VAP). METHODS: Sixty-one patients on ventilators were divided into VAP group and non-VAP group depending on whether the patients developed VAP in 7 days or not. The PCT levels were determined with the method of semi-solid phase immunoassay before and 7 days after instillation of mechanical ventilation in these patients. The PCT levels were graded into four categories, i.e. <0.5 microg/L, 0.5-2.0 microg/L, 2.0-10.0 microg/L and > or =10.0 microg/L. At the same time, C reactive protein (CRP) content and white blood cell (WBC) count were also determined. RESULTS: Before mechanical ventilation, the CRP and WBC count showed no obvious difference in both groups (all P>0.05). The CRP content and WBC count were found to be obviously elevated in VAP group compared with non VAP group (all P=0.000). The diagnostic sensitivity of CRP and WBC count for VAP were 73.5% (25/34 cases) and 82.3% (28/34 cases) respectively, their specificity was 48.1% (13/27 cases) and 55.5% (15/27 cases), respectively, and their positive prediction rates were 64. 1% (25/39 cases) and 70.0% (28/40 cases), respectively, and their negative prediction rates were 59.1% (13/22 cases) and 71.4% (15/21 cases), respectively. If serum PCT> or =0.5 microg/L was regarded as the cutoff value, the PCT positive percentage did not show difference between VAP group and non VAP group before mechanical ventilation (P>0.05). However, after VAP, the PCT positive percentage of VAP group was much higher than that of non VAP group. The sensitivity of serum PCT determination for the diagnosis of VAP was 85.3% (29/34 cases), with specificity rate 74.1% (20/27 cases), positive prediction rate 80.5% (29/36 cases), and negative prediction rate 80.0% (20/25 cases). CONCLUSION: The value of serum PCT has high sensitivity rate in the diagnosis of VAP, so that timely surveillance of serum PCT change is helpful for the diagnosis of VAP in the early stage.