Acute Respiratory Distress Syndrome (ARDS) continues to contribute significantly to the disease burden in today’s arena of pediatric critical care medicine. It is an acute, diffuse, inflammatory lung injury caused by diverse pulmonary and non-pulmonary etiologies. Pathophysiology is characterized by increased vascular permeability, increased lung weight and loss of aerated tissue within the 7 days of insult. Hypoxemia, bilateral opacities on the chest x-ray, decreased lung compliance and increased physiological dead space are telltale clinical signs. Diffuse alveolar damage characterized by edema, inflammation, hyaline membrane formation or pulmonary hemorrhage are the pathological hallmark.
Here are the most recent practice essentials from critical care stand point. The Berlin definition eliminated the taxonomy of Acute Lung Injury (ALI) and classified ARDS in to mild, moderate and severe categories based on severity of oxygenation compromise. Minimum PEEP requirement was included for the assessment of oxygen requirement. It also eliminated necessity of pulmonary artery wedge pressure criteria for pulmonary edema. They instead suggested utilization of clinical criteria, in case of presence of risk factors of ARDS. They recommended echocardiogram and the other objective assessment, if the risk factors for ARDS are not present.
A panel of 27 pediatric experts, the Pediatric Acute Lung Injury Consensus Conference (PALICC) Group, subsequently developed nomenclature pertinent for pediatric patients. They included oxygenation index (OI), oxygen saturation index (OSI) and the pulse oximetric saturation to fraction of inspired oxygen ratio – S/F (SPO2/FiO2). The committee recommended utilization of low tidal volume (5-8 mL/kg of predicted body weight), positive end expiratory pressure (PEEP) in the range of 0-15 cm H2O, limiting plateau pressure to 28-32 cm H2O, permissive hypercapnia strategy and acceptance of low SPO2 in the range of 88-92% if PEEP is as high as 10 cm H2O. Routine use of steroids, prone positioning, surfactant and liquid ventilation is not recommended. Utilization of High Frequency Oscillatory Ventilation (HFOV) can be considered in cases with plateau airway pressure higher than 28. Although PALICC had a weak agreement on this recommendation. Meticulous consideration of inhaled nitric oxide therapy in severe ARDS cases and in cases bridging to extra corporeal life support (ECLS).