Impact of ventilator-associated tracheobronchitis on outcome in patients with chronic obstructive pulmonary disease

Background

In the absence of nosocomial pneumonia (NP), ventilator-associated tracheobronchitis (VAT) may generate weaning difficulties in patients with chronic obstructive pulmonary disease (COPD), resulting in longer duration of mechanical ventilation (MV) and intensive care unit (ICU) stay. The aim of our study is to test this hypothesis.

Methods

A prospective matched risk-adjusted cohort study, in a 30-bed ICU, over a period of 6.5 years. Immunocompetent medical COPD patients who were intubated and ventilated for > 48 hours were eligible. All patients with NP were excluded. Tracheobronchitis was defined as follows: fever (> 38°C) with no other recognizable cause; new or increased sputum production, and a positive (≥ 10⁶ cfu/ml) endotracheal aspirate culture, yielding a new bacterial strain; without radiographic evidence of pneumonia. Only first episodes of VAT occurring after > 48 hours of MV were included. A matching process was conducted according to the following criteria: MV duration before the occurrence of VAT, primary diagnosis for admission, indication for MV, SAPS II on admission ± 5, age ± 5, and date of admission. McNemar's test and the Wilcoxon log-rank test were used to compare cases with controls. Univariate and multivariate analyses were performed in order to determine variables associated with longer than median MV duration among case and control patients.

Results

A total of 1259 patients were eligible; 128 (10%) of them were excluded for NP. VAT was diagnosed in 103 (8%) patients; 11 (10.6%) of them were excluded for subsequent NP. Matching was successful for 88% of the cohort; 81 matched case–control pairs were studied. Acute exacerbation of COPD was the main cause for admission (64%). P. aeruginosa was the most common causing bacteria (27%). Although the mortality rate was similar (40% vs 34%; P = NS), the median duration of MV (20 days vs 12 days; P = 0.015) and ICU stay (25 days vs 18 days; P = 0.022) were higher in cases than in controls. VAT was the only variable independently associated with longer than median duration of MV (OR = 4.7 [95% CI = 2–10.9]; P < 0.001). In patients with VAT, antibiotics were associated with shorter median duration of MV (15 days vs 23 days; P = 0.043), and ICU stay (23 days vs 29 days; P = 0.007) and similar mortality rate (40% vs 41%, P = NS). Appropriate antimicrobial treatment was associated with a tendency towards a better outcome.

Conclusion

VAT is associated with increased duration of MV and ICU stay in COPD patients. Antibiotics are associated with shorter length of MV and ICU stay in patients with VAT. Further studies are required to confirm our results.