Pathogenesis of Adult Respiratory distress syndrome• One of the above causes acts as an insult to the Capillary capillary endothelium or alveolar epithelium leading to disruption of capillary integrity with extravasation of fluid, fibrin, RBCs and WBCs into the lung interstitium and alveoli.• Tumour necrosis factor and IL-1 initiate the inflammatory response, these cytokines then stimulate
IL-8 which perpetuates inflammation and coagulation.
• There is severe hypoxia, the lungs stiffen and become less compliant resulting in difficulty with mechanical
• The pulmonary capillary wedge pressure is usually < 18 mmHg with no evidence of elevated left atrial pressure, pulmonary hypertension may occur as the interstitial edema leads to compression on the blood vessels.
Clinical picture of ARDSSymptoms may develop immediately after the insult but usually are delayed for about 24-48 hours. There is progressive tachypnea, dyspnea followed by :
• Diffuse lung crepitations.
• Acute respiratory failure (diffusion defect) ===> Type I respiratory failure.
Notice the manifestations of the cause
- Adult Respiratory distress syndrome (ARDS) Causes and definition