[Diagnostic strategy for acute respiratory failure in patients with haematological malignancy]

The challenge of avoiding intubation in immunocompromised patients with acute respiratory failure

INTRODUCTION

A growing number of immunocompromised (IC) patients with acute hypoxemic respiratory failure (ARF) is admitted to the intensive care unit (ICU) worldwide. Areas covered: This review provides an overview of the current knowledge of the ways to prevent intubation in IC patients with ARF. Expert commentary: Striking differences oppose ARF incidence, characteristics, etiologies and management between IC and non-IC patients. Survival benefits have been reported with early admission to ICU in IC patients. Then, while managing hypoxemia and associated organ dysfunction, the identification of the cause of ARF will be guided by a rigorous clinical assessment at the bedside, further assisted by an invasive or noninvasive diagnostic strategy based on clinical probability for each etiology. Finally, the initial respiratory support aims to avoid mechanical ventilation for the many yet recognizing those patients for whom delaying intubation expose them to suboptimal management. We advocate for not using noninvasive ventilation (NIV) in this setting. A proper evaluation of High-flow nasal cannula oxygen (HFNC)  is required in IC patients as to demonstrate its superiority compared to standard oxygen therapy. Day-to-day decisions must strive to avoid delayed intubation, and make every effort to identify ARF etiology.

Burden of respiratory viruses in patients with acute respiratory failure

Respiratory viruses (RVs) are ubiquitous pathogens that represent a major cause of community-acquired pneumonia and chronic pulmonary diseases exacerbations. However, their contribution to acute respiratory failure events requiring intensive care unit admission in the era of rapid multiplex molecular assay deserves further evaluation. This study investigated the burden of viral infections in non immunocompromised patients admitted to the intensive care unit for acute respiratory failure using a multiplex molecular assay. Patients were investigated for RVs using immunofluoresence testing and a commercial multiplex molecular assay, and for bacteria using conventional culture. Half the patients (34/70, 49%) had a documented RVs infection. No other pathogen was found in 24 (71%) patients. Viral infection was detected more frequently in patients with obstructive respiratory diseases (64% vs. 29%; P = 0.0075). Multiplex molecular assay should be considered as an usefull diagnostic tool in patients admitted to the intensive care unit with acute respiratory failure, especially those with acute exacerbations of chronic obstructive pulmonary disease and asthma.

Molecular detection of respiratory viruses in immunocopromised ICU patients: incidence and meaning

Purpose

Prospective single-center study to assess the sensitivity and clinical relevance of molecular testing for respiratory viruses in critically ill immunocompromised patients with acute respiratory failure (ARF).

Methods

100 consecutive critically ill immunocompromised patients with ARF in 2007–2009. Among them, 65 had hematologic malignancies (including 14 hematopoietic stem cell transplant recipients), 22 had iatrogenic immunosuppression, and 13 had solid malignancies. A multiplex molecular assay (MMA) was added to the usual battery of tests performed to look for causes of ARF.

Results

Nasopharyngeal aspirates and/or bronchoalveolar lavage fluid were tested for respiratory viruses using both the MMA and immunofluorescence. A virus was detected in 47 (47%) patients using the MMA and 8 (8%) patients using immunofluorescence (P = 0.006). MMA-positive and MMA-negative patients had similar clinical and radiographic presentations and were not significantly different for the use of ventilatory support (58% vs. 76%, P = 0.09), occurrence of shock (43% vs. 53%, P = 0.41), use of renal replacement therapy (26% vs. 23%, P = 0.92), SAPS II (35 [26–44] vs. 38 [27–50], P = 0.36), time spent in the ICU (6 vs. 7 days, P = 0.35), or ICU mortality (17% vs. 28%, P = 0.27). Using MMA, a virus was found in 6 of the 12 patients with no diagnosis at the end of the etiologic investigations.

Conclusions

In critically ill immunocompromised patients, an MMA was far more sensitive than immunofluorescence for respiratory virus detection. Patients with RVs detected in the respiratory tract had the same clinical characteristics and outcomes as other patients.