Value of procalcitonin for diagnosis of early onset pneumonia in hypothermia-treated cardiac arrest patients

Early onset pneumonia is frequently reported after cardiac arrest, despite the fact that therapeutic hypothermia and post-resuscitation disease manifestations make it difficult to diagnose. We aimed to assess the ability of serum procalcitonin (PCT) measurements to help diagnose pneumonia in this setting. Retrospective study of consecutive patients admitted to a single academic medical intensive care unit (ICU) for successfully resuscitated cardiac arrest (July 2006-March 2008). All patient files were reviewed to assess the development of pneumonia during the first 5 days of ICU stay. Serum PCT was measured at admission, days (D) 1, 2 and 3. Among 132 patients included, pneumonia was diagnosed in 86, and antibiotics were initiated in 115 patients during the first 5 days. PCT was significantly higher in patients with pneumonia at D1 (4.58 vs. 1.03 ng/ml, p = 0.017), D2 (3.76 vs. 0.73, p = 0.002) and D3 (3.76 vs. 0.73, p = 0.046). Areas under the ROC curves were 0.59 at admission, 0.64 at D1, 0.68 at D2 and 0.63 at D3. Using a threshold of 0.5 ng/ml, negative predictive values were 39% at admission, 42% at D1 and 52% at D2, whereas positive predictive values were 72, 68 and 70%, respectively. Patients with post-resuscitation shock (n = 66) had significantly higher PCT levels than vasopressor-free patients from D1 to D3. The diagnostic value of PCT is poor after cardiac arrest and should not be performed to assess early onset pneumonia. The post-resuscitation disease itself could play a major role in this lack of specificity and predictive value.