Corticosteroids in Adult Respiratory Distress Syndrome

Adult respiratory distress syndrome (ARDS) is associated with numerous severe underlying medical and surgical conditions. It is the result of the lung's response to many types of injury to its capillary endothelium and alveolar epithelium. Because of the various causes of this syndrome, the place of corticosteroid treatment remains debatable. Definite clinical studies of high dose corticosteroid treatment in ARDS are lacking. Their use is often based on extrapol~tion from studies in patients with shock: about 20% of all patients with Gram­negative sepsis develop ARDS and about 65% of those complicated with shock develop ARDS. However, in the literature on the use of high dose corticosteroids in sepsis, evidence is about equal for and against any corticosteroid benefit. Good clinical trials are difficult to conduct due to the numerous causes of ARDS, lack of knowledge about its natural history and the complicating effects of other therapies, supportive measures, other disease processes etc.

The effects of high dose corticosteroids on particular characteristics of ARDS have been studied as an alternative approach. One such characteristic is the increase in lung microvascular permeability to fluid and protein. It was concluded by the investigators that the increased permeability to proteins can be reversed using corticosteroids, particularly if given early in the course of the disorder. This in turn allows time to try to control the underlying disease. However, in animal studies, it has been found that high dose corticosteroids have no effect on permeability once lung injury is fully developed (although in some animal models, such treatment can prevent increased permeability if given prior to lung injury). These stUdies do not necessarily indicate an effect on microvascular barrier function, as the passage of fluid and protein across injured microvascular endothelium can be decreased by maintenance of intravascular pressures at the minimum levels for adequate tissue perfusion and oxygenation. Thus normal control subjects, and controls for haemodynamic variables, must be included in useful trials.

More studies are required of the adverse effects of high dose corticosteroids: these include compromised host defences, increased occurrence of Gram-negative infections, and impaired healing. 'Until more and better information is available, pharmacologic doses of steroids cannot be considered either safe or effective therapy in ARDS.' Flick. M.R. and Murray, J.F : Journal 01 the American Medical Association 251: 1054 (24 Feb 1984)

0156-2703/84/0331-0003/ 0$01.00/0 © ADIS Press INPHARMA® 31 Mar 1984 3