What is the diagnosis and treatment for Acute Respiratory Distress Syndrome (ARDS)?

From the Guidelines

Acute Respiratory Distress Syndrome (ARDS) is a life-threatening condition characterized by hypoxemic respiratory failure, requiring mechanical ventilation with a positive end-expiratory pressure (PEEP) of at least 5 cmH2O and a fraction of inspired oxygen (FiO2) of at least 0.3 1.

Diagnosis

The diagnosis of ARDS is based on the development of bilateral opacities on chest radiography indicative of pulmonary edema within 1 week of known clinical insult, in combination with impaired oxygenation as measured by the ratio of arterial to inspired oxygen (PaO2/FIO2) despite the application of at least 5 cm H2O of positive end-expiratory pressure (PEEP) 1.

Treatment

Management involves lung-protective ventilation with tidal volumes of 6-8 mL/kg predicted body weight and plateau pressures limited to 30 cmH2O 1.

• Pharmacological interventions, such as neuromuscular blockers like cisatracurium at a dose of 0.15-0.30 mg/kg/hour for 48 hours, may be considered to facilitate ventilation and improve oxygenation.
• Prone positioning for more than 12 h/d in severe ARDS may also be considered 1.
• Corticosteroids may be used for patients with ARDS, although the evidence is not strong 1.
• Venovenous extracorporeal membrane oxygenation (VV-ECMO) may be considered in selected patients with severe ARDS, although the evidence is limited 1. Some key points to consider in the management of ARDS include:
• Optimizing PEEP to avoid lung derecruitment and overdistension 1
• Avoiding vigorous spontaneous breathing to prevent lung edema and RV failure 1
• Using prone positioning to improve uniformity of ventilation and attenuate VILI 1
• Monitoring hemodynamics closely to guide fluid management and vasopressor use 1
• Considering the use of neuromuscular blockers to facilitate ventilation and improve oxygenation 1

From the Research

Diagnosis of Acute Respiratory Distress Syndrome (ARDS)

• ARDS is characterized by hypoxemic respiratory failure, which can be refractory and life-threatening 2
• The Berlin definition proposes 3 categories of ARDS based on the severity of hypoxemia: mild, moderate, and severe 3
• The diagnosis of ARDS is based on clinical characteristics, including the acute onset of pulmonary edema of non-cardiogenic origin, bilateral pulmonary infiltrates, and reduction in respiratory system compliance 4

Treatment of ARDS

• The cornerstone of management remains mechanical ventilation, with a goal to minimize ventilator-induced lung injury (VILI) 5, 3
• Lung-protective mechanical ventilation, including low tidal volume and inspiratory pressure ventilation, is recommended 3
• Adjunctive interventions, such as prone positioning, neuromuscular blockade, inhaled vasodilators, and recruitment maneuvers, may be used to further minimize VILI 2, 3, 4
• Extracorporeal membrane oxygenation (ECMO) is a salvage therapy aimed at ensuring adequate gas exchange for patients suffering from severe ARDS with profound hypoxemia where conventional mechanical ventilation has failed 6
• A holistic framework of respiratory and hemodynamic support should be provided to patients with ARDS, aiming to ensure adequate gas exchange by promoting lung recruitment while minimizing the risk of ventilator-induced lung injury 4

Nonventilatory Strategies

• Nonventilatory strategies, such as conservative fluid management, intravenous corticosteroids, and nutritional modification, may produce a more gradual improvement in oxygenation in ARDS 2
• These interventions may be considered for use, particularly for cases of refractory severe hypoxemia, with proper appreciation of potential costs and adverse effects 2