Acute respiratory distress syndrome (ARDS) is a clinical syndrome associated with oxygenation failure resulting from a direct pulmonary or indirect systemic insult. It is a complex etiological phenomenon involving an array of immune cells acting in a delicate balance between pathogen clearance and immunopathology. There is emerging evidence of the involvement of different immune cell types in ARDS pathogenesis. This includes polarization of alveolar macrophages (AMs), neutrophil netosis, the pro-inflammatory response of T helper 17 subsets, and the anti-inflammatory and regenerative role of T regulatory cell subsets. Knowledge of these pathogenic mechanisms has led to translational opportunities, for example, research in the use of methylprednisolone, DNAse, aspirin, keratinocyte growth factor and in the development of stem cell therapy for ARDS. Discovering subgroups of patients with ARDS afflicted with homogenous pathologic mechanisms can provide prognostic and/or predictive insight that will enable precision medicine. Lastly, new high dimensional immunomic technologies are promising tools in evaluating the host immune response in ARDS and will be discussed in this review.

Overall mortality rate in pediatric ARDS is approximately 24%. Studies conducted and published later were associated with better survival.

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Aim: Acute respiratory distress syndrome (ARDS) represents the most severe form of acute lung injury. The aim of our study is to describe the epidemiology of pediatric ARDS in Singapore and compare the outcomes of ARDS using the following respiratory indices: PaO2/FiO2 ratio (P/F ratio), SpO2/FiO2 ratio (S/F ratio), oxygenation index (OI), and oxygen saturation index (OSI).Methods: We examined medical records of patients admitted to the Children’s Intensive Care Unit in KK Women’s and Children’s Hospital from 2009 to 2012. Those who fulfilled criteria for the American-European Consensus Conference definition for ARDS were identified. Demographic, clinical, and radiographic information were extracted and analyzed.Results: We identified 70 patients with ARDS. Median age (interquartile range) was 6.2 (1.4, 10.4) years. The most common risk factor was pneumonia [50 (71%)]. Overall mortality was 44 (63%) patients. Thirty-two (56%) patients had an underlying chronic comorbidity; 18 (46%) were hematology–oncology conditions. Fifty-six (80%) patients had multiorgan dysfunction. Adjunct therapies used in our patients included inhaled nitric oxide [5 (7%)], prone position [22 (31%)], steroids [26 (37%)], and neuromuscular blockade [26 (37%)]. A high OI and low PF ratio after 24 h of diagnosis of ARDS were associated with mortality. From day 3 onward, all four respiratory indices appropriately differentiated survivors from non-survivors. Severity based on the S/F ratio and OSI demonstrated association with decreased ventilator free days and ICU free days.Conclusion: Risk factors for mortality included having an underlying comorbidity, multiorgan dysfunction, a low PF ratio, and high OI at 24 h of ARDS. Abnormal SpO2-based measurements were reliable markers of poor outcomes in pediatric ARDS.