Assessing predictive accuracy for outcomes of ventilator-associated events in an international cohort: the EUVAE study

Abstract

Purpose: To analyze the impact on patient outcome of ventilator-associated events (VAEs) as defined by the Centers for Disease Control and Prevention (CDC) in 2008, 2013, and the correlation with ventilator-associated pneumonia (VAP) or tracheobronchitis (VAT).

Methods: This was a prospective, observational, multicenter, international study conducted at 13 intensive care units (ICUs); thirty consecutive adults mechanically ventilated for ≥ 48 h per site were eligible, with daily follow-up being recorded in a collaborative web database; VAEs were assessed using the 2013 CDC classification and its 2015 update.

Results: A total of 2856 ventilator days in 244 patients were analyzed, identifying 33 VAP and 51 VAT episodes; 30-day ICU mortality was significantly higher (42.8 vs. 19.6%, p < 0.007) in patients with VAP than in those with VAT. According to the 2013 CDC definitions, 117 VAEs were identified: 113 (96%) were infection-related ventilator-associated complication-plus (IVAC-plus), while possible ventilator-associated pneumonia (PVAP) was found in 64 (56.6%) of them. VAE increased the number of ventilator days and prolonged ICU and hospital LOS (by 5, 11, and 12 days, respectively), with a trend towards increased 30-day mortality (43 vs 28%, p = 0.06). Most episodes (26, 55%) classified as IVAC-plus without PVAP criteria were due to atelectasis. PVAP significantly increased (p < 0.05) ventilator days as well as ICU and hospital LOS (by 10.5, 14, and 13 days, respectively). Only 24 (72.7%) of VAP and 15 (29.4%) of VAT episodes met IVAC-plus criteria.

Conclusions: Respiratory infections (mainly VAT) were the most common complication. VAE algorithms only identified events with surrogates of severe oxygenation deterioration. As a consequence, IVAC definitions missed one fourth of the episodes of VAP and three fourths of the episodes of VAT. Identifying VAT (often missed by IVAC-plus criteria) is important, as VAP and VAT have different impacts on mortality.

Keywords: Hypoxemia; Surveillance; Ventilator-associated events; Ventilator-associated pneumonia; Ventilator-associated tracheobronchitis.

Fig. 1

Ventilator associated events, CDC 2013 classification and 2015 update [3, 10, 34]

Fig. 2

Previous and new 2013 CDC classification [3, 10, 34]. ^jVAE ventilator-associated event, ^aVARI ventilator-associated respiratory infection, ^bLOS length of stay, ^cMV Days invasive mechanical ventilation days, ^dVAP ventilator associated pneumonia, ^eVAT ventilator associated tracheobrochitis, ^fVAC ventilator associated condition, ^gIVAC infectious ventilator-associated complication, ^hPVAP possible ventilator associated pneumonia, ⁱARDS acute respiratory distress syndrome, ^kSuspicion of infection: leukocytosis (≥ 12,000 cells/mL) or leukopenia (≤ 4000 cells/mL) or fever (≥ 38 °C) or hypothermia (≤ 36 °C)

Fig. 3

Relationship between 2008 and 2013 CDC classifications [10, 15, 36]. 2013 classification is represented with circles and 2008 classification with ovals. VAC ventilator associated condition, IVACp infectious ventilator-associated complication plus, VAP ventilator associated pneumonia, VAT ventilator associated tracheobronchitis