Pathophysiologische und therapeutische Aspekte beim akuten Lungenversagen (ARDS)

Abstract

Since the first characterization of the adult respiratory distress syndrome (ARDS), knowledge of its aetiology and pathogenesis has grown considerably. In spite of this, mortality remains up to 50 to 90%, particularly if multiple organ failure is present. Because no causative clinical therapy is available up to now, significant attention is given to preventive measures like early operative stabilisation of long bone fractures, or prophylaxis of nosocomial infections. After clinical manifestation of ARDS, treatment focuses on functional disturbances of the cardiopulmonary system and on the underlying disease. The aim of this symptomatic therapy is to ensure oxygen supply according to the organisms demand. It is still unknown, however, whether the mortality of patients with ARDS can be reduced by optimising the oxygen supply. In general, oxygen supply can be enhanced by improving pulmonary gas exchange, cardiac output and blood oxygen transport capacity. For practical use the therapy often ends up with a therapeutical dilemma: On one hand, the improvement of the pulmonary gas exchange by application of PEEP can be associated with a critical decline in cardiac output, particularly if the afterload of the right ventricle is elevated. On the other hand, to increase cardiac output, both volume replacement and vasodilators can severely affect pulmonary gas exchange if the alveolo-capillary permeability is increased and pulmonary hypoxic vasoconstriction is disturbed. Thus, oxygen supply can be optimised only via invasive monitoring of the cardiorespiratory system. Although still experimental, the most promising approaches seem to be pharmacological interventions directed at suppressing the formation and effects of various humoral and cellular mediators. An improved understanding of the inflammatory processes might provide new insights in the pathophysiology of ARDS and the related therapeutic interventions.