Severe bilateral pulmonary contusions may present with hypoxia - but more usually hypoxia develops as the pulmonary contusions blossom or as a result of subsequent ARDS.
Chest X-ray
Most significant pulmonary contusions are diagnosed on plain chest X-ray. However the chest X-ray will often under-estimate the size of the contusion and tends to lag behind the clinical picture. Often the true extent of injury is not apparent on plain films until 24-48 hours following injury.