Sorry for your loss. If she actually had SQ emphysema when you saw her that day, I would be concerned that she may have had an air leak and may have developed a tension pneumothorax. A tension pneumothorax can potentially lead to progressive shortness of breath and cardiac tamponade which would drop her blood pressure. In that situation, I would have expected her to be having some chest pain prior to the event and for symptoms to build up. If this happened very suddenly, then I agree that a pulmonary embolus is more likely.
Yea I watched my son die of a PE we knew it was eventually going to happen and the gurgling made me immediately think of that. Sorry for your loss. Please consider some counseling as it can really help work through dealing with unexpected deaths.