Management of ARDS

Definition and diagnosis. By the Berlin definition, ARDS requires all four of: onset within one week of a known insult; bilateral opacities on chest imaging not fully explained by effusion, collapse or nodules; respiratory failure not fully explained by cardiac failure or fluid overload (objectively assessed, e.g. by echocardiography); and hypoxaemia graded on PaO /FiO with PEEP ≥ 5 cmH O — mild 200–300, moderate 100–200, severe ≤ 2 2 2

Pathologically there is diffuse alveolar damage with non-cardiogenic pulmonary oedema, surfactant loss and hyaline membranes.

Treat the cause and give supportive care. Identify and treat the precipitant — pneumonia and sepsis (commonest), aspiration, pancreatitis, trauma, transfusion (TRALI), drugs, burns. Give source control and appropriate antimicrobials, plus general intensive care: VTE prophylaxis, stress-ulcer prophylaxis, early enteral nutrition, glycaemic control, sedation minimisation, delirium prevention and early mobilisation.

Lung-protective ventilation — the single most important intervention. Tidal volume 4–6 mL/kg of PREDICTED body weight, plateau pressure < 30 cmH O and driving pressure < 15 cmH O (ARMA/ARDSNet — 2 2 an absolute mortality reduction of about 9%). Accept permissive hypercapnia with pH above 7.20. Use higher PEEP in moderate–severe ARDS guided by a PEEP–FiO table, targeting SpO 88–95% or PaO 55–80 mmHg. Routine 2 2 2 recruitment manoeuvres with aggressive PEEP titration are not recommended (ART trial showed harm).

Prone positioning and neuromuscular blockade. Prone position for at least 16 hours per day in moderate-to-severe ARDS with PaO /FiO < 150 — the PROSEVA trial showed a large mortality reduction. Neuromuscular 2 2 blockade (cisatracurium) for 48 hours may be used in early severe ARDS with ventilator dyssynchrony, but is not routine (ROSE trial was neutral) and risks ICU-acquired weakness, which is particularly disabling in the old. In older patients, pressure-area care, eye and airway protection and careful positioning during proning need explicit attention.

Fluids, pharmacotherapy and rescue. Conservative fluid strategy once shock has resolved (FACTT) — this shortens ventilator days. Corticosteroids: dexamethasone improved outcomes in DEXA-ARDS and are standard in COVID-19-related ARDS; use is reasonable in early moderate–severe ARDS but not universal. No benefit from inhaled nitric oxide (oxygenation improves but mortality does not), surfactant, statins or beta-agonists. Veno-venous ECMO for refractory severe ARDS in expert centres (EOLIA) — age above 65–70 with frailty and comorbidity is generally a contraindication.

Geriatric considerations and outcome. Older age is an independent predictor of ARDS mortality, and survivors face ICU-acquired weakness, sarcopenia, prolonged weaning, delirium, post-intensive-care cognitive impairment and loss of independence. Therefore: establish goals of care and a ceiling of treatment early with the patient and family; consider whether NIV or HFNO is the appropriate ceiling; involve physiotherapy, nutrition, speech and swallow and geriatric medicine from day one; plan early tracheostomy where prolonged ventilation is expected; and provide rehabilitation and palliative care alongside organ support.

The 2023 New Global Definition of ARDS (a global consensus conference endorsed by ESICM/ATS) broadened the Berlin definition to make ARDS diagnosable outside well-resourced intensive care units. It adds a "non-intubated ARDS" category for patients on high-flow nasal oxygen at ≥ 30 L/min or non-invasive ventilation with CPAP ≥ 5 cmH O; permits SpO /FiO ratio ≤ 315 (with SpO ≤ 97%) as an alternative to 2 2 2 2 PaO /FiO where blood gases are unavailable; and accepts lung ultrasound as well as chest radiograph or CT 2 2 for the bilateral-opacity criterion. This makes the diagnosis workable in resource-limited settings, including much of India, and in older patients managed outside the ICU.