ETUDE CRITIQUE DES DIFFERENTES CONCEPTIONS DE LA PRESSION POSITIVE EXPIRATOIRE (PEEP) OPTIMALE

Various concepts of optimal PEEP are critically analysed in relation to data published in the literature and the authors' personal studies. PEEP has always been considered to be a simple therapeutic adjuvant only, optimal PEEP levels being a compromise between the resulting beneficial action on PaO₂ and the adverse effects on cardiac output; the criteria usually applied being arterial oxygen transport, and more recently, the almost static total pulmonary compliance. This concept has led to the application of often ineffective low PEEP levels. It should, in fact, be considered as an active therapy because of its action on collapsed alveoli, healing being favored by their reopening. The optimal PEEP level is therefore that which produces maximal alveolar recruitment, as assessed in an intrapulmonary shunt ≤ 15% and/or a PaO₂ ± 53.3 kPa (400 Torr) with pure O₂, cardiac output being maintained constant. Pulmonary compliance studies show that an almost static compliance is a poor criterion of optimal PEEP, and that the static pressure-volume curve can define the minimal PEEP leel but not its optimal level.