Pulmonary infections prime the development of subsequent ICU-acquired pneumonia in septic shock.

Purpose: To investigate the determinants and the prognosis of intensive care unit (ICU)-acquired pneumonia in patients with septic shock.

Methods: This single-center retrospective study was conducted in a medical ICU in a tertiary care center from January 2008 to December 2016. All consecutive patients diagnosed for septic shock within the first 48 h of ICU admission were included. Patients were classified in three groups: no ICU-acquired infections (no ICU-AI), ICU-acquired pneumonia and non-pulmonary ICU-AI. The determinants of ICU-acquired pneumonia and death were investigated by multivariate competitive risk analysis.

Results: A total of 1021 patients were admitted for septic shock, and 797 patients were alive in the ICU after 48 h of management. The incidence of a first episode of ICU-AI was 31%, distributed into pulmonary (17%) and non-pulmonary ICU-AI (14%). Patients with septic shock caused by pneumonia were at increased risk of further pulmonary ICU-AI with a cumulated incidence of 34.4%. A pulmonary source of the initial septic shock was an independent risk factor for subsequent ICU-acquired pneumonia (cause-specific hazard 2.33, 95% confidence interval [1.55-3.52], p < 0.001). ICU-AI were not associated with a higher risk of ICU mortality after adjustment in a multivariate-adjusted cause-specific proportional hazard model.

Conclusion: Septic shock of pulmonary origin may represent a risk factor for subsequent ICU-acquired pneumonia without affecting mortality.