Description
In the emergency department, the approach to severe respiratory distress begins with a rapid assessment to determine the underlying cause, including airway obstruction, pulmonary pathology, or cardiovascular issues. Immediate interventions, such as oxygen supplementation, nebulized bronchodilators, intubation, or non-invasive ventilation, are implemented based on the severity and etiology, with close monitoring for signs of deterioration.
Summary Listen
- ARDS, or Acute Respiratory Distress Syndrome, is a clinical syndrome characterized by dyspnea, rapid onset hypoxemia, and diffuse pulmonary infiltrates leading to respiratory failure. It involves inflammation and protein-rich fluid accumulation in the alveolar spaces, decreasing diffusion capacity. ARDS is distinguished from Acute Lung Injury (ALI) by the PaO2/FiO2 (P/F) ratio, with ARDS having a P/F ratio less than 200, while ALI is less than 300.
- Diagnosis of ARDS requires acute onset, a predisposing condition, bilateral infiltrates on imaging, a P/F ratio less than 200, and a pulmonary capillary wedge pressure (PCWP) less than 18. Causes can be direct (pneumonia, pulmonary contusion, aspiration) or indirect lung injury (sepsis, trauma, pancreatitis).
- Pathophysiology involves diffuse alveolar damage, capillary damage, and inflammatory cell infiltration. Cytokine release activates macrophages, leading to protease secretion that damages alveolar cells and increases alveolar edema. This disrupts gas exchange, leading to hypoxemia and the development of pulmonary hypertension. Histologically, ARDS presents with hyaline membranes, cellular congestion, and thickened interstitial walls.
- Clinical presentation involves rapid breathing, elevated pulse, and hypoxia, typically within 12-48 hours of a predisposing event. ABG analysis is crucial for monitoring PO2, PCO2, and pH levels. Chest X-rays demonstrate bilateral infiltrates, and further investigations include CT scans and BNP levels to rule out cardiogenic pulmonary edema.
- Management of ARDS includes treating the underlying cause and providing cardio-pulmonary support. Spontaneous breathing patients may be managed with oxygen supplementation up to 60% FiO2, while mechanical ventilation is indicated for inadequate oxygenation, elevated PCO2, or respiratory failure.
- Mechanical ventilation strategies focus on increasing PaO2 while minimizing ventilator-induced lung injury. The ARDSnet protocol recommends volume-assisted control (VAC) mode, tidal volume of 6 ml/kg, and a plateau pressure less than 30 cm H2O. The aim is to use low tidal volume ventilation to prevent overinflation of healthy lung tissue and support alveolar recruitment.
- Weaning from mechanical ventilation requires fulfilling specific criteria, including stable blood pressure, absence of neuromuscular blockade, and tolerance of spontaneous breathing trials. Evidence-based recommendations for ARDS management include low tidal volume, high PEEP, and prone positioning. Other methods include high-flow nasal cannula and ECMO (Extracorporeal Membrane Oxygenation) as a last resort.
- Supportive therapies include conservative fluid management, potential steroid use in early stages, targeted antibiotics, and DVT prophylaxis. Prognosis for ARDS is poor, with mortality ranging from 26-44%. Risk factors include chronic conditions like advanced age, kidney disease, liver disease, alcohol abuse, and immunosuppression. Early intervention and aggressive management are crucial.
- Endotracheal intubation in the emergency department carries potential complications, including bleeding, oral and pharyngeal trauma, tube dislodgement or blockage, and drug-related complications from RSI (Rapid Sequence Intubation). Careful technique and visualization are important to minimize injuries.
Sample Certificate
About the Speakers
Dr. Harshil Mehta
Zonal Head - Emergency Medicine, Marengo CIMS Hospital, Ahmedabad, Gujarat
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