Severe influenza: overview in critically ill patients

Abstract

Purpose of review Overview of influenza infection, focusing on outcome and complications in critically ill patients. We also discuss relevant elements in immunopathogenesis and their role as predictors of severity. Recent findings Pandemic influenza A (H1N1) virus circulates seasonally and remains the predominant subtype among intensive care patients. Mortality in acute respiratory failure (ARF) is around 20%, independent of influenza subtypes. During severe infection, the imbalance between pro-inflammatory and anti-inflammatory molecules, such as Th1 and Th17 cytokines, is associated with complicated infections and mortality. Primary viral pneumonia presents in more than 70% of ICU influenza patients and more than 50% develop acute respiratory distress syndrome. Bacterial secondary infection occurs in 20% of severe cases and Streptococcus pneumoniae and Staphylococcus aureus remain the prevalent pathogens. Myocarditis and late-onset cardiovascular complications are associated with mortality. Antiviral therapy within 48 h after onset, avoidance of corticosteroids and rescue therapies for ARF or myocarditis, such as extracorporeal membrane oxygenation, improve survival. Summary The present review summarizes current knowledge on pathogenesis and clinical manifestations of severe influenza. Immunological dysfunction during viral infection correlates with severity and mortality among ICU patients. A theranostics strategy should be implemented to improve outcomes.

High-Dose Intravenous Immunoglobulins in the Treatment of Severe Acute Viral Pneumonia: The Known Mechanisms and Clinical Effects

“…Furthermore, in MERS patients, the significantly increased release of pro-inflammatory cytokines from Th1 and Th17 during the acute phase was considered to be at least partly responsible for the immunopathology (142). Early abundant secretion of Th1-and Th17-related cytokines (e.g., IL-6 and IL-17) has furthermore been associated with complicated infections and mortality in severe influenza patients (143,144).…”

Energy Requirements for Loss of Viral Infectivity

“…Influenza virus causes a respiratory infection that can lead to severe illness and death (Sarda et al 2019). Influenza's animal reservoir is in birds (Bodewes and Kuiken 2018) and various strains have jumped from birds to humans over the years (Horman et al 2018).…”

Post-COVID-19 Pulmonary Fibrosis: Novel Sequelae of the Current Pandemic

“…Among those requiring MV, mortality was reported to be between 52-64% [38][39][40][41][42][43][44][45]. The 2009 Influenza A H1N1 pandemic led to ICU admission in 9-31% of adults and mortality of 14-27% among the critically ill with rates as high as 42% for patients requiring MV [39,[46][47][48][49][50][51]. For MERS-CoV, ICU mortality rates have been reported to be between 58-90% and 72-75% among those requiring MV [39,52].…”