Dear Shaky
The truth is combining these various procedures without a doubt increases the risk of mortality. The real questions is what is the marginal increased risk of death to me if my plastic surgeon combines all of these procedures at the same time? The fact of the matter is that we simply do not know. However, combination surgery has proven to increase at least marginally the rate of mortality.
Hypothetically, if the risk of death from having breast implant surgery under general anesthesia is 1:50,000, what is the risk of adding a tummy tuck at the same time. Is it 1:50,000 plus 1:50,000 which would be 1:25,000 cases or something else? Most likely, the risk is higher than than simply adding the risk of death of the two procedures. Is the risk of death worth taking if the risk more than doubles by having all these surgeries together? That is a personal choice. Remember, the risk of having neck liposuction awake in your dermatologists office is less than 1:300,000 cases.
However, you can't have a tummy tuck and a breast surgery under local. Is the convenience of having combined surgery worth the increased risk? Most likely both you and your surgeon will be unable to really understand the choice. The law of large numbers takes this out of the realm of every day experience. Even your surgeon most likely has not experienced an operative death so it is difficult to them to weight these relative risks.
Of course their equation is different. They are concerned that if they don't combine all these surgeries at once for you, they face the risk that perhaps you will find a surgeon who will take this risk with you. As the commander said in the movie Top Gun:" Son, your ego is writing checks your body can't cash."