Acute respiratory distress syndrome (ARDS), previously called adult respiratory distress syndrome is a severe form of acute lung injury that warrants immediate emergency care and management. This clinical syndrome is best characterized by a sudden and progressive edema of the pulmonary cavity, insufficiency of oxygen exchange, hypoxemia despite oxygen supplementation and reduced lung expansion.
Individuals with acute respiratory distress syndrome usually suffer from some form of cardiac insufficiency and would necessarily require the aid of a mechanical ventilation because of the non-compliance of self respiratory effort. Ventilatory support to individuals with ARDS need a higher-than-normal airway pressure because these individuals have a severe compromised respiratory gas exchange. A wide range of factors is associated with the development of ARDS including; direct injury to the lungs, shock and underlying medical conditions affecting the general respiratory system.
Pathophysiology of acute respiratory distress syndrome
Acute respiratory distress syndrome occurs as a result of an inflammatory trigger that instigate the release of chemical and cellular mediators causing direct injury to the alveolar capillary membrane. This leads to leakage of fluid into the alveolar interstitial spaces and alterations in the capillary bed. Severe ventilation-perfusion mismatching is a typical scenario in ARDS along with alveolar collapse due to the inflammatory infiltrate,blood, fluid and surfactant dysfunction. Moreover, small airways are narrowed because of interstitial fluid and bronchial obstruction. Furthermore, lung compliance becomes narrowly decreased as a resulting characteristic decrease in residual capacity and severe hypoxemia which leads to gas exchange becoming insufficient as blood returning to the lungs through the non ventilated and non functioning areas of the lung causing pulmonary shunting.
Clinical manifestations of acute respiratory distress syndrome
Clinically, the initial phase of acute respiratory distress syndrome is marked by a rapid onset of severe dyspnea that usually happens within the first 48 hours after the initial event. A universal characteristic of ARDS is arterial hypoxemia that does not respond well to supplemental oxygen. Chest x-ray findings are similar to those seen with pulmonary edema and appears as a bilateral infiltrate that progressively worsens. The acute lug injury can later progress the stiffening of the lung parenchyma with severe and persistent hypoxemia and central cyanosis. Moreover, the individual with ARDS experiences increased alveolar dead space (non-functioning alveolus), and decreased pulmonary perfusion will generally require ventilatory support. In a clinical perspective, the individual in the recovery phase will significantly improve if the hypoxemia due to the primary cause is corrected.
Medical management of acute respiratory distress syndrome
The primary focus in the management of individuals with ARDS includes identification and treatment of the underlying cause of the
condition. Aggressive, supportive care must be provided in order to have good compensation for the said dysfunction of the respiratory system. The supportive management and therapy always include the need for intubation and mechanical ventilation for oxygen supplementation. In addition to the prompt circulatory support, the health care team should provide adequate fluids and nutritional support as an adjunct to the recovery of patients with ARDS. Furthermore, a patient with ARDS is generally considered to be critically ill and will require intensive monitoring of the patient’s respiratory status because acute respiratory distress syndrome could quickly become life threatening.