[gchappel]

So sorry about your father, my prayers go out to him.
Yes pulmonary emboli "dissolve" over time-with treatment.
Treatment will depend on their size and location.
They also need to make sure no new clots migrate to the lungs.
He will be on blood thinners for several months at least.
I assume they have looked at his legs for dvt, the most common location for the clots that move to the lungs. If there are still large clots in the legs treatment becomes more complex- as these could "break off" and migrate to the pulmonary vessels. That might be a reason to limit movement. At times an ivc filter is placed, basically a filter in the main vein in the abdomen that goes from the legs to the lungs- stops the bigger clots from making it to the lungs. This has its own limitations and risks, so not an easy decision and only useful in the correct settings.
Patients usually do pretty well, he is at higher risk because of his other lung disease.
Best of luck to him.
Gary