Early pneumonia and timing of antibiotic therapy in patients after nontraumatic out-of-hospital cardiac arrest

BACKGROUND: While early pneumonia is common in patients after out-of-hospital cardiac arrest (OHCA), little is known about the impact of pneumonia and the optimal timing of antibiotic therapy after OHCA. METHODS: We conducted a 5-year retrospective cohort study, including patients who suffered from OHCA and were treated with therapeutic hypothermia. ICU treatment was strictly standardized with defined treatment goals and procedures. Medical records, chest radiographic images and microbiological findings were reviewed. RESULTS: Within the study period, 442 patients were admitted to our medical ICU after successfully resuscitated cardiac arrest. Of those, 174 patients fulfilled all inclusion and no exclusion criteria and were included into final analysis. Pneumonia within the first week could be confirmed in 39 patients (22.4 %) and was confirmed or probable in 100 patients (57.5 %), without a difference between survivors and non-survivors (37.8 % vs. 23.1 % confirmed pneumonia, p = 0.125). In patients with confirmed pneumonia a tracheotomy was performed more frequently (28.2 vs. 12.6 %, p = 0.026) compared to patients without confirmed pneumonia. Importantly, patients with confirmed pneumonia had a longer ICU- (14.0 [8.5-20.0] vs. 8.0 [5.0-14.0] days, p < 0.001) and hospital stay (23.0 [11.5-29.0] vs. 15.0 [6.5-25.0] days, p = 0.016). A positive end expiratory pressure (PEEP) > =10.5 mbar on day 1 of the hospital stay was identified as early predictor of confirmed pneumonia (odds ratio 2.898, p = 0.006). No other reliable predictor could be identified. Median time to antibiotic therapy was 8.7 [5.4-22.8] hours, without a difference between patients with or without confirmed pneumonia (p = 0.381) and without a difference between survivors and non-survivors (p = 0.264). Patients receiving antibiotics within 12 hours after admission had a shorter ICU- (8.0 [4.0-14.0] vs. 10.5 [6.0-16.0] vs. 13.5 [8.0-20.0] days, p = 0.004) and hospital-stay (14.0 [6.0-25.0] vs. 16.5 [11.0-27.0] vs. 21.0 [17.0-28.0] days, p = 0.007) compared to patients receiving antibiotics after 12 to 36 or more than 36 hours, respectively. CONCLUSIONS: Early pneumonia may extend length of ICU- and hospital-stay after OHCA and its occurrence is difficult to predict. A delayed initiation of antibiotic therapy in OHCA patients may increase the duration of the ICU- and hospital-stay. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/s13054-016-1191-y) contains supplementary material, which is available to authorized users.