Pulmonary Embolism Support Group
By far the most common form of pulmonary embolism is a thromboembolism, which occurs when a blood clot, generally a venous thrombus, becomes dislodged from its site of formation and embolizes to the arterial blood supply of one of the lungs. Symptoms may include difficulty breathing, pain during breathing, and more rarely circulatory instability and death.
When I was in the hospital, my doctor wanted me to try to take deep breath at least once an hour in order to prevent pneumonia. I never got pneumonia, so I guess it worked!
I know I've heard the same thing with other, similar types of issues. Like our mayor fell off his bike a couple years ago and cracked ribs and they kept in the hospital a couple days just to remind him to take deep breaths occasionally so he wouldn't get pneumonia.