A R D S Acute Respiratory Distress Syndrome
Acute respiratory distress syndrome (ARDS) is a syndrome of severe respiratory failure associated with pulmonary infiltrates, similar to infant hyaline membrane disease. The 1994 American-European Consensus Committee defines ARDS as the acute onset of bilateral infiltrates on chest radiography, a partial pressure of arterial oxygen (PaO2) to fraction of inspired oxygen (FIO2) ratio of less than 200 mm Hg and a pulmonary artery occlusion pressure of less than 18, or the absence of clinical evidence of left arterial hypertension. To put simple, ARDS is the presence of pulmonary edema in the absence of volume overload or depressed left ventricular function.
Sepsis and the systemic inflammatory response syndrome (SIRS) are the most common predisposing factors associated with development of ARDS A number of clinical conditions are. o These conditions may result from the indirect toxic effects of neutrophil-derived inflammatory mediators in the lungs. o Severe traumatic injury (especially multiple fractures), severe head injury, and pulmonary contusion are strongly associated with development of ARDS. Long bone fractures may give rise to ARDS through fat embolism. After severe head injury, ARDS is thought to result from a sudden discharge of the sympathetic nervous system, leading to acute pulmonary hypertension and injury to the pulmonary capillary bed. Pulmonary contusions cause ARDS through direct trauma to the lung. o Multiple transfusions are another important risk factor for ARDS, independent of the reason for transfusion or the coexistence of trauma.Overdoses of narcotics (eg, heroin), salicylates, tricyclic antidepressants, and other sedatives have been associated with development of ARDS. (Overdoses of tricyclic antidepressants are the most common.)
Patients may present early in the course of the disease without symptoms or signs.
- Mild tachypnea may be the only manifestation.
- Severe respiratory distress eventually ensues.
- Frequent Rales on auscultation of the lungs. Findings may be surprisingly minimal when contrasted with chest Radiographic findings.
- Signs of volume overload, as a third heart sound (S3) on auscultation of the heart or jugular venous distention, should be noticeably absent.