recruitment maneuvers cause lung injury

For decades, many critical care experts have championed aggressive lung recruitment strategies in ARDS that include recruitment maneuvers (RM) up to 60 cm H2O and PEEP levels titrated to optimal oxygenation and/or compliance. This is founded on the concept that an “open” lung is the optimal way to manage severe hypoxemic respiratory failure. The counterargument is that such aggressive airway pressures can expose more compliant lung regions to overdistention injury. Moreover, such high airway pressures, even intermittently, can have important adverse hemodynamic effects primarily through reduced cardiac filling. Indeed, in the landmark ARDS Network low tidal volume trial, larger tidal volumes and higher airway pressures were associated with significantly better oxygenation and mechanics but resulted in a worsened mortality. A 2016 Cochrane review of 10 trials involving RMs (and often aggressive PEEP strategies) demonstrated improved oxygenation and mechanics in the treated patients but could not find strong evidence to support these strategies benefiting ultimate outcomes. Importantly, most of these trials also reported significant adverse hemodynamic effects during RMs. More recently, a large trial has been reported addressing this issue and clearly demonstrated that strategies employing RMs and aggressive PEEP do indeed improve oxygenation and global mechanics but produce worse outcomes. In this trial, 1,010 patients were studied; 501 of these patients received RMs up to 60 cm H2O (later reduced to 45 cm H2O) and subsequently titrated PEEP to best compliance +2 cm H2O. Tidal volumes were targeted to 6 mL/kg ideal body weight (IBW). On the first day, PEEP values were higher (16 vs 12 cm H2O), plateau pressures were higher (28 vs 25 cm H2O), and Pao2/Fio2 ratios were higher (222 vs 165 mm Hg) in the treated vs control group. However, all-cause mortality was also significantly higher in the treated group (55% vs 49%). An accompanying editorial noted the consistent lack of supportive outcome data (and the frequent harmful hemodynamic effects) from many trials for aggressive RMs and PEEP strategies and questioned: “Is the door closing on the open lung?” They concluded that the possibility existed that certain ARDS patterns (eg, PEEP responders) might benefit but essentially the door is closed.1234

Footnotes

  1. SEEK Questionnaires ↩

  2. Hodgson C, Goligher EC, Young ME, et al. Recruitment maneuvers for adults with ARDS receiving mechanical ventilation. Cochrane Database Syst Rev. 2016;11:CD006667 ↩

  3. Sahetya SK,Brower RG. Lung recruitment and titrated PEEP in moderate to severe ARDS: is the door closing on the open lung?. JAMA. 2017;318(14):1327-1329. PubMed ↩

  4. Writing Group for the Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial (ART) Investigators., Cavalcanti AB, Suzumura ÉA, et al; Writing Group for the Alveolar Recruitment for Acute Respiratory Distress Syndrome Trial (ART) Investigators. Effect of lung recruitment and titrated positive end-expiratory pressure (PEEP) vs Low PEEP on mortality in patients with acute respiratory distress syndrome: a randomized clinical trial. JAMA. 2017;318(14):1335-1345. PubMed ↩