Clinical impact of ventilator-associated pneumonia in patients with the acute respiratory distress syndrome: a retrospective cohort study

Marc Le Pape; Céline Besnard; Camelia Acatrinei; Jérôme Guinard; Maxime Boutrot; Claire Genève; Thierry Boulain; François Barbier

doi:10.1186/s13613-022-00998-7

Clinical impact of ventilator-associated pneumonia in patients with the acute respiratory distress syndrome: a retrospective cohort study

Ann Intensive Care. 2022 Mar 15;12(1):24. doi: 10.1186/s13613-022-00998-7.

Authors

Marc Le Pape^{1

2}, Céline Besnard¹, Camelia Acatrinei¹, Jérôme Guinard³, Maxime Boutrot², Claire Genève², Thierry Boulain¹, François Barbier^{4

5}

Affiliations

¹ Médecine Intensive-Réanimation, Centre Hospitalier Régional d'Orléans, 14, avenue de l'Hôpital, 45100, Orléans, France.
² Réanimation Chirurgicale, Centre Hospitalier Régional d'Orléans, Orléans, France.
³ Laboratoire de Bactériologie, Pôle de Biopathologies, Centre Hospitalier Régional d'Orléans, Orléans, France.
⁴ Médecine Intensive-Réanimation, Centre Hospitalier Régional d'Orléans, 14, avenue de l'Hôpital, 45100, Orléans, France. francois.barbier@chr-orleans.fr.
⁵ Centre d'Étude des Pathologies Respiratoires (CEPR), INSERM U1100, Université de Tours, Tours, France. francois.barbier@chr-orleans.fr.

Abstract

Background: The clinical impact and outcomes of ventilator-associated pneumonia (VAP) have been scarcely investigated in patients with the acute respiratory distress syndrome (ARDS).

Methods: Patients admitted over an 18-month period in two intensive care units (ICU) of a university-affiliated hospital and meeting the Berlin criteria for ARDS were retrospectively included. The association between VAP and the probability of death at day 90 (primary endpoint) was appraised through a Cox proportional hazards model handling VAP as a delay entry variable. Secondary endpoints included (i) potential changes in the PaO₂/FiO₂ ratio and SOFA score values around VAP (linear mixed modelling), and (ii) mechanical ventilation (MV) duration, numbers of ventilator- and vasopressor-free days at day 28, and length of stay (LOS) in patients with and without VAP (median or absolute risk difference calculation). Subgroup analyses were performed in patients with COVID-19-related ARDS and those with ARDS from other causes.

Results: Among the 336 included patients (101 with COVID-19 and 235 with other ARDS), 176 (52.4%) experienced a first VAP. VAP induced a transient and moderate decline in the PaO₂/FiO₂ ratio without increase in SOFA score values. VAP was associated with less ventilator-free days (median difference and 95% CI, - 19 [- 20; - 13.5] days) and vasopressor-free days (- 5 [- 9; - 2] days) at day 28, and longer ICU (+ 13 [+ 9; + 15] days) and hospital (+ 11.5 [+ 7.5; + 17.5] days) LOS. These effects were observed in both subgroups. Overall day-90 mortality rates were 35.8% and 30.0% in patients with and without VAP, respectively (P = 0.30). In the whole cohort, VAP (adjusted HR 3.16, 95% CI 2.04-4.89, P < 0.0001), the SAPS-2 value at admission, chronic renal disease and an admission for cardiac arrest predicted death at day 90, while the COVID-19 status had no independent impact. When analysed separately, VAP predicted death in non-COVID-19 patients (aHR 3.43, 95% CI 2.11-5.58, P < 0.0001) but not in those with COVID-19 (aHR 1.19, 95% CI 0.32-4.49, P = 0.80).

Conclusions: VAP is an independent predictor of 90-day mortality in ARDS patients. This condition exerts a limited impact on oxygenation but correlates with extended MV duration, vasoactive support, and LOS.

Keywords: Acute respiratory distress syndrome; COVID-19; Hospital-acquired infection; Intensive care unit; Mechanical ventilation; Outcome; Ventilator-associated pneumonia.