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

Abstract

Purpose: 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.

Methods: 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.

Results: 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.

Conclusions: 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.