降钙素原检测对呼吸机相关肺炎诊治的意义

目的 探讨降钙素原（PCT）对呼吸机相关肺炎（VAP）的诊断价值并评估其指导抗生素治疗的可行性.方法 60例呼吸机辅助通气患者按机械通气7d内是否发生VAP分为VAP组和非VAP组,两组于机械通气前后采用双抗体夹心免疫发光法全定量检测血清PCT水平.VAP组又分为PCT组和对照组,前者在PCT指导下使用抗生素,后者则根据临床经验用药,CPIS≤6分时停用抗生素.同时检测CRP及WBC.结果 机械通气前VAP组和非VAP组的CRP和WBC差异均无统计学意义（均P＞0.05）,机械通气后VAP组CRP高于非VAP组（P＜0.05）,WBC平均值较非VAP组升高但差异无统计学意义（P＞0.05）.以CRP≥28 mg/L和WBC≥10×109/L为阳性阈值,CRP和WBC对VAP诊断的敏感性分别为73.3%和66.7%,特异性为50.0%和43.3%.以PCT≥0.40 μg/L为阳性阈值,机械通气前VAP组和非VAP组PCT阳性率差异无统计学意义（P＜0.05）;发生VAP后,VAP组较非VAP组PCT阳性率显著升高（P＜0.01）,其对VAP诊断敏感性为93.3%,特异性为73.3%,ROC曲线下面积为0.823（P＜0.01）.PCT组和对照组抗生素疗程分别为（12.6±5.6）d和（15.1±9.1）d（P＜0.05）,PCT≤0.25 μg/L时停用抗生素可使平均疗程缩短2.5 d（P＜0.05）.结论 PCT在细菌性VAP诊断中有较高敏感性,PCT联合CPIS可提高VAP诊断的准确性,以PCT指导VAP抗生素治疗可缩短抗生素疗程.

The clinical value of procalcitonin detection in diagnosis and treatment of ventilator associated pneumonia

Objective To assess the value of procalcitonin(PCT) in diagnosis and treatment of ventilator associated pneumonia(VAP). Methods 60 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 VAP group again was divided into PCT group and the control group. Data of PCT, C-reactive protein (CRP) and WBC were assessed at baseline, in 6 hours when VAP was suspected, and every two days after mechanical ventilation. The control group received antibiotics according to usual practice and stopped when CPIS≤6 scores. Antibiotic treatment of the PCT group was based on serum PCT concentrations. Results The CRP and WBC showed no obvious difference between the VAP and non-VAP group before mechanical ventilation ( all P ＞ 0. 05 ), after ventilation both mean values increased, with the P 0. 046 and 0. 822,respectively;Taking CRP≥28mg/L and WBC≥ 10×109/L as the cutoff value,the diagnostic sensitivity of CRP and WBC for VAP were 73.3% and 66.7% respectively,their specificity was 50% and 43.3 % ,respectively.Taking PCT ≥0.40μg/L 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, it was much higher in the VAP group than that of non-VAP group after mechanical ventilation( P ＜ 0. 01 ). The PCT level of 0.40 ug/l yielded a 93.3% sensitivity and a 73.3 % specificity for VAP in the study cohort ( AUROCC = 0. 823; 95 % CI,0.71-0. 94; P ＜ 0. 01 ). The antibiotic duration of the PCT group was( 12. 6 ± 5.6) days compared with( 15. 1 ± 9.1 ) days for the control group (P ＜ 0. 05). Patients assigned to the PCT group had 2.5 days shorter mean duration of antibiotic therapy for the first episode of infection than the control group ( P ＜ 0. 05 ). Conclusion PCT had high sensitivity in the diagnosis of VAP. CPIS ≥6 combined with serum levels of PCT ≥0. 40μg/L markedly improved the specificity( 100% ). PCT guidance substantially reduced antibiotic use in VAP, so that timely surveillance of serum PCT was necessary for patients on ventilator.