Lung

Abstract

Triggering of the systemic inflammatory response syndrome (SIRS) by conditions such as sepsis, multisystem trauma, shock (and massive transfusions), burns, and pancreatitis produces a pulmonary vascular flood of products of the activated humoral cascade system, where inflammatory cells, bacterial toxins, and toxin-produced cellular mediators clearly assume responsibility. Depending on its severity this diffuse injury is characterized as acute lung injury (ALI) or acute respiratory distress syndrome (ARDS). ALI is a syndrome of inflammation and increased permeability that leads to physiologic, radiologic, and clinical abnormalities. When ALI is severe, ARDS is the term used to describe the condition. The consensus definition of ALI includes (1) acute onset; (2) PaO2/FiO2 ≤ 300; (3) bilateral infiltrates on frontal chest radiograph; and (4) pulmonary artery wedge pressure ≤ 18 mmHg, or in the absence of a pulmonary artery catheter no clinical evidence of left atrial hypertension.1 The consensus definition of ARDS is ALI with PaO2/FiO2 ≤ 200. Although ARDS can be primary (due to direct causes such as pneumonia and gas inhalation), it is more strongly linked to outside lung events, which appear to trigger the systemic inflammatory syndrome (SIRS). This type of ARDS is called secondary (or indirect) and is often associated with the multiple organ dysfunction syndrome (MODS).KeywordsNitric OxideAcute Lung InjurySystemic Inflammatory Response SyndromeAcute Respiratory Distress SyndromeInjury Severity ScoreThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.