List three causes of mediastinal shift and the direction of the shift associated with each

1. Decreased lung volume, such as occurs in patients with atelectasis, following pneumonectomy, and in patients with a hypoplastic or agenetic lung (mediastinum shifts toward the lesion)
2. Increased lung volume, such as occurs in patients with a massive tumor or severe expansile pneumonia, such as that caused by K. pneumoniae or anaerobic organisms (mediastinum shifts away from the lesion)
3. Pleural disease, such as tension pneumothorax, large pleural effusion, or large diaphragmatic hernia (mediastinum shifts away from the lesion)