Measurement of PEEP-induced alveolar recruitment: just a research tool?

For positive end-expiratory pressure (PEEP) to have lung protective efficacy in patients with acute respiratory distress syndrome, it must increase the end-expiratory lung volume through alveolar recruitment while avoiding lung over-inflation. PEEP may increase the end-expiratory lung volume either by increasing the proportion of aerated alveoli at end-expiration or by further inflating already ventilated lung regions. The optimal PEEP regimen is still a matter of debate. In theory, the ability to measure of PEEP-induced alveolar recruitment would be extremely useful in titrating PEEP at the bedside. However, until now this measurement has been confined to clinical research settings. Interesting work by Lu and coworkers, published in the previous issue of this journal, deals with the problem of measuring PEEP-induced alveolar recruitment. The 'gold standard' technique (i.e. the computed tomography method) is compared with the pressure-volume curve method. Because implementation of the latter method at the bedside would be relatively simple, that report, in addition to its intrinsic scientific value, may have important clinical implications.