title: Effects of high versus low positive end-expiratory pressures in acute respiratory distress syndrome.
abstract: A recent study by the Acute Respiratory Distress Syndrome Network compared the traditional lower end-expiratory pressure strategy with a higher end-expiratory pressure strategy in patients with the acute respiratory distress syndrome ventilated with low tidal volumes. Clinical outcomes were similar whether lower or higher positive end-expiratory pressure (PEEP) levels were used. We applied both the lower (9 +/- 2 cm H2O) and higher (16 +/- 1 cm H2O) PEEP strategy in 19 patients. In nine recruiters, the higher end-expiratory pressure strategy resulted in significant alveolar recruitment (587 +/- 158 ml), improvement in arterial oxygen partial pressure/inspired oxygen fraction ratio (from 150 +/- 36 to 396 +/- 138), and reduction in static lung elastance (from 23 +/- 3 to 20 +/- 2 cm H2O/L). In 10 nonrecruiters, alveolar recruitment was minimal, oxygenation did not improve, and static lung elastance significantly increased (from 26 +/- 5 to 28 +/- 6 cm H2O/L). The increase in oxygenation, the reduction in static lung elastance, and the shape of the volume-pressure curve during the lower PEEP strategy were independently associated with alveolar recruitment. In conclusion, the protocol proposed by the Acute Respiratory Distress Syndrome Network, lacking solid physiologic basis, frequently fails to induce alveolar recruitment and may increase the risk of alveolar overinflation.
authors.affiliation: Dipartimento dell'Emergenza e Trapianti d'Organo (DETO), Sezione di Anestesiologia e Rianimazione, Ospedale Policlinico, Piazza Giulio Cesare 11, Bari, Italy 70124. grassos@libero.it
authors.forename: Salvatore
authors.initials: S
authors.lastname: Grasso
authors.forename: Vito
authors.initials: V
authors.lastname: Fanelli
authors.forename: Aldo
authors.initials: A
authors.lastname: Cafarelli
authors.forename: Roberto
authors.initials: R
authors.lastname: Anaclerio
authors.forename: Marilisa
authors.initials: M
authors.lastname: Amabile
authors.forename: Giovanni
authors.initials: G
authors.lastname: Ancona
authors.forename: Tommaso
authors.initials: T
authors.lastname: Fiore
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D016014:Linear Models; D008176:Lung Volume Measurements; D008297:Male; D008875:Middle Aged; D011175:Positive-Pressure Respiration / Q000379:methods*; D011312:Pressure; D011650:Pulmonary Alveoli / Q000503:physiopathology; D011659:Pulmonary Gas Exchange; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*