ARDS: Nitric Oxide as Cause and Therapy in Multiple Organ Failure (MOF)

The acute respiratory distress syndrome (ARDS) is characterized by refractory hypoxemia in the presence of bilateral pulmonary infiltrates on chest radiography1. It was recognised that ARDS probably represents only the extreme manifestation of a range of pulmonary insults. Hence, acute lung injury (ALI) was similarly defined but with less severe indices of hypoxemia (Table 1). A wide variety of serious medical and surgical conditions can precipitate the syndrome, only some of which involve the lung (Table 2). Although the mortality associated with ARDS has fallen in recent years (from approximately 70% to 50%) in a number of large centres, it is undoubtedly influenced by the underlying pathology. Furthermore, epidemiological studies have suggested for many years that the majority of patients succumb not to refractory hypoxemia, but rather to sepsis and associated multiple organ failure (MOF). MOF is defined by a constellation of symptoms and clinical signs of which multiple organs (e,g, kidney, heart, GIT, etc) are in a state of dysfunction or failure. Indeed, given that respiratory failure accounts for only 16% of ARDS deaths, improvements in outcome of ARDS may depend more on treatment of sepsis and further understandingJprevention of MOF than on improvements in oxygenation and pulmonary haemodynamics2,3.