Utility of C-reactive protein measurements for empyema diagnosis after pneumonectomy

Serum C-reactive protein (CRP) levels were studied serially during the postoperative period in 151 consecutive patients who underwent pneumonectomy. Virtually all patients who had a simple postoperative course (115 of 120), as well as 9 patients who had a bronchial infection of the remaining lung, 3 with a pulmonary embolus, and 2 who suffered postoperative bleeding requiring reoperation, demonstrated a similar postoperative evolution in their CRP values: a rapid postoperative rise until a peak or a plateau (mean peak value, 132 +/- 25 mg/L) was reached within 3 to 6 days, followed by a progressive decline to a value of less than 75 mg/L on day 9, and less than 50 mg/L on day 12. Conversely, all 12 patients who suffered empyema postoperatively, as well as 3 patients with bacterial pneumonia, 1 patient with chylothorax, and 1 patient with inflammatory pericarditis, demonstrated either a markedly persistent elevation in their CRP values or a secondary rise in the levels which exceeded 100 mg/L. Because of the high sensitivity (100%) and specificity (91.4%) of the CRP levels in detecting postpneumonectomy empyema, we recommend the routine use of this measure. Furthermore, a low CRP value after pneumonectomy (less than 50 mg/L) may help in deciding whether to confidently discharge a patient from the hospital in the absence of empyema. The negative predictive value of this method was found to be 100%.