• Phase II: Number of adverse events and the proportion of participants who had study drug reduced in dosage and/or prematurely discontinued because of arrhythmia or other adverse events [ Time Frame: Adverse events observed to 72 hours after last study dose, in first 100 patients enrolled ] [ Designated as safety issue: Yes ]
  
• Phase III: Number of ventilator free days (VFD) [ Time Frame: Measured at Day 28 ] [ Designated as safety issue: No ]
  

• Phase III: Mortality prior to hospital discharge with unassisted breathing [ Time Frame: Participants alive in hospital at Day 60 will be considered to have survived ] [ Designated as safety issue: No ]
  
• Mortality before hospital discharge home, with unassisted breathing, to Day 90 [ Time Frame: Participants alive in hospital at Day 90 will be considered to have survived ] [ Designated as safety issue: No ]
  
• Number of ICU-free days at Day 28 following study entry [ Time Frame: Measured at Day 28 ] [ Designated as safety issue: No ]
  
• Number of organ failure-free days at Day 28 following study entry (liver, kidney, heart, central nervous system, and hematologic) (Bernard, 1997). [ Time Frame: Measured at Day 28 ] [ Designated as safety issue: No ]
  
• Number of days between the day of first meeting criteria for weaning-readiness (protocol defined) and Day 28 following study entry [ Time Frame: Measured at Day 28 ] [ Designated as safety issue: No ]
  
• Mortality and VFDs in participants with pre-randomization PaO2/FIO2 less than or equal to 200 [ Time Frame: Mortality to study day 60, VFDs to study day 28 ] [ Designated as safety issue: No ]
  
• Change in plasma and mini-BAL levels of IL-6, IL-8, VWF, SPD, and total protein concentrations from baseline to Day 3 [ Time Frame: Measured at Day 3 ] [ Designated as safety issue: No ]
  
• Ventilator free days and mortality prior to hospital discharge with unassisted breathing to day 60 and number of ventilator-free days to day 28 in patients with shock (protocol defined) at the time of study entry [ Time Frame: Measured at Day 60 or 28, as noted ] [ Designated as safety issue: No ]
  

Aerosolized beta-2 agonist therapy is anticipated to diminish the formation of lung edema, enhance clearance of lung edema and decrease pulmonary inflammation in patients with acute lung injury. Because beta-2 agonists have been shown to reduce permeability induced lung injury, it is anticipated that the severity of lung injury will be reduced by aerosolized beta-2 agonist therapy. The therapy may work by enhancing resolution of pulmonary edema by upregulating alveolar epithelial fluid transport mechanisms that will in turn enhance the clearance of alveolar edema. A reduction in the severity of lung injury and the quantity of alveolar edema should result in earlier extubation and more ventilator free days, improved pulmonary oxygen uptake, and improved lung compliance.

Study design: phase II/III prospective, randomized double-blind, placebo controlled trial.

• In Phase II, patients will be treated with aerosolized albuterol 5.0 mg vs. normal saline (n=40-50)administered every 4 hours for 10 days following randomization or until 24 hours following extubation, whichever occurs first. The protocol stipulates that the 5.0 mg dose will be reduced to 2.5 mg if patients exceed defined heart rate limits.
• In Phase III, the 5.0 mg dose will be used unless there is evidence that this dose has an unacceptable safety profile or dose reductions for tachycardia occur in a large fraction of patients. In that case, a lower dose of 2.5 mg will be used.
• Patients will be followed for 90 days or until discharge from the hospital to home with unassisted breathing whichever occurs first.