How does swine flu cause lung failure?

Inflammatory respons: Several people died of respiratory failure related to swine flu. Interestingly many of these patients were otherwise healthy patients. On bronchoscopy we found that these patient developed densely packed inflammatory cells in their alveoli. It is believed that the patients that did the worst, had the healthiest immune systems and the respiratory failure was actually the patients own immune system.

Air sacs swelling: Swine flu is a mutating virus affecting pigs and spreads to man called zoonotic infection. Human transmission it spreads to blood. Immunity responds with chemicals called cytokine and factors causing swelling in cells. Virus attack membranes and smaller blood vessels abundant in lung causing adult respiratory distress and thus inability to extract oxygen from air to blood causing illness/death.

By damaging lung: Swine flu can cause a reaction in the body that can damage the lung. Rarely, the flu itself can cause pneumonia and cause lung damage that way, also.