[Diagnostic value of procalcitonin in ventilator associated pneumonia]

To explore the diagnostic value of procalcitonin (PCT) quantification in ventilator associated pneumonia (VAP).

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.

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).

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.