Acute lung injury in caused by all of the following except .
Answer is C (Cardiopulmonary bypass with hea lung machine): Cardiopulmonary bypass is a cause for indirect lung injury while the rest three cause direct injury to lungs. Although all four options may cause acute lung injury, the single best answer of exclusion would be cardiopulmonary bypass.
Aspiration
Toxic gas inhalation
Cardiopulmonary bypass with hea lung machine.
Lung contusion.