Severe influenza: overview in critically ill patients

Area of Science:

• Critical care medicine
• Infectious diseases
• Immunology

Background:

• Influenza A (H1N1) is a predominant cause of severe respiratory illness in intensive care units (ICUs).
• Mortality in patients with acute respiratory failure (ARF) due to influenza approaches 20%.

Purpose of the Study:

• To review the pathogenesis, clinical manifestations, and outcomes of severe influenza in critically ill patients.
• To identify immunopathogenesis elements and predictors of severity.
• To discuss management strategies for improved survival.

Main Methods:

• Literature review of current knowledge on severe influenza.
• Analysis of immunopathogenesis and clinical data in ICU patients.
• Evaluation of treatment outcomes and survival predictors.

Main Results:

• Severe influenza, especially H1N1, causes high rates of viral pneumonia (70%) and acute respiratory distress syndrome (ARDS) (50%).
• Secondary bacterial infections (e.g., Streptococcus pneumoniae, Staphylococcus aureus) occur in 20% of severe cases.
• Imbalances in pro- and anti-inflammatory cytokines (Th1, Th17) correlate with infection severity and mortality.
• Myocarditis and cardiovascular complications are associated with mortality.
• Early antiviral therapy (within 48 hours), avoidance of corticosteroids, and supportive care (e.g., ECMO) improve survival.

Conclusions:

• Immunological dysfunction is a critical factor in severe influenza outcomes and mortality among ICU patients.
• A theranostics approach, integrating diagnostics and therapeutics, is recommended to enhance patient outcomes.
• Timely intervention with antivirals and appropriate critical care management are essential for reducing influenza-related mortality.