Viral infections in the ICU: should we search for them?

Introduction

Respiratory viral infections are usually self-limited in adults but 4 to 30% can be clinically severe and lead to intensive care needs. The aim of this study was to determine the impact of viral respiratory infections in an intensive care setting and the role of systematic viral testing in patients admitted to an ICU.

Methods

A retrospective analysis of all 114 viral tests of respiratory samples of 98 patients admitted to the ICU for four consecutive years was performed. Molecular biology test and immunofluorescence assay for adenovirus, influenza A and B, parainfluenza 1 to 3, metapneumovirus and syncytial respiratory virus (SRV) were performed in tracheal aspirate (TA) (89%) and bronchoalveolar lavage (BAL) (11%). SAPS II was used as the severity index. Patients were stratified according to the primary diagnostic.

Results

Viral tests were performed in 98 patients, 60% were male, mean age 58 years old and 45% had previous respiratory disease. SAPS II was 48. Ninety-two percent need mechanical ventilation (MV) for 8.5 days. Primary diagnostics were community-acquired pneumonia (CAP) (50%) or tracheobronchitis (32%), chronic pulmonary disease exacerbations (6%), aspiration pneumonia (3%), nosocomial infection (5%), septic shock (3%) and meningitis (1%). Length of stay (LOS) was 11 days and ICU mortality was 17.5%. Virus identification was positive in 13 (12.2%) respiratory samples of 12 patients, 12 in TA and one in BAL. Twelve were identified in the winter. Demographic variables, LOS, co-morbidities and severity index of patients with viral infection were similar to the main group. Influenza A (in three CAP, one tracheobronchitis, one nosocomial infection and one septic shock), metapneumovirus (two tracheobronchitis and one CAP), influenza B (one CAP), parainfluenza 3 (one CAP) and SRV (one tracheobronchitis) were identified. In these patients, C-reactive protein was higher and leucocytes were lower. Bacterial co-infection was identified in 33% of the patients, all of them with acquired community pneumonia. Antibiotic step down was done in 62% of the patients with isolated viral infection. In these patients LOS and days of mechanical ventilation were 9.6 and 6.2, respectively, and invasive ventilation-associated pneumonia was reduced.

Conclusions

Although viral tests should not be required for all ICU patients, respiratory samples for viral tests should be performed in patients with tracheobronchitis/pneumonia requiring intensive care, especially in the winter. Positive identification of viral agents could be useful in antibiotic policy.