The primary purpose of this study is therefore to demonstrate the safety and efficacy of a recruitment protocol designed to maximally recruit collapsed lung in children with acute lung injury. Each study patient will follow a recruitment protocol (see Appendix 2). Two 'controls' will be utilized in this study: baseline ventilation (no recruitment maneuver) and the open lung approach (a sustained inflation followed by increased PEEP). Efficacy will be defined as an improvement in lung volume (as measured by nitrogen washout and electrical impedance tomography), and by an improvement in measured arterial partial pressure of oxygen. Safety will be defined as the incidence of barotrauma and hemodynamic consequences which occur during the protocol.