Positive end-expiratory pressure in acute respiratory distress syndrome - an old yet mysterious tool.

A recent study by Bruhn and colleagues, discussed here, confirms that even high levels of positive end-expiratory pressure (PEEP) - up to 20 cmH2O - may be applied in conditions of moderate acute respiratory distress syndrome. Such levels of PEEP were found to be safe in terms of their impact on cardiac output and adequacy of gastric mucosal perfusion once systemic haemodynamics were stabilized by adequate fluid replacement and catecholamine therapy. However, we strongly recommend that the reader does not oversimplify the conclusions of that study. PEEP therapy is not inherently safe with respect to haemodynamics and regional organ perfusion, but it may be used safely, even at high levels of up to 20 cmH2O, if haemodynamic therapy is appropriate.