There are many comments from Board Certified Plastic Surgeons regarding your question as well as a similar question asked previously on RealSelf.com, "Alternative to General Anesthesia for Breast Augmentation?"
I have performed many hundreds of under-the-muscle breast augmentations over many years under IV sedation, and for me this technique has many benefits:
Dramatic reduction in postoperative pain and recovery. The anesthesiologists and CRNAs I have worked with over the years 100% agree that by thoroughly blocking the breast with long-acting local anesthesia, patients have a profound improvement in comfort.
Significant reduction in chances of post-op nausea and vomiting.
Significant reduction in general fatigue as is always seen to some degree with general anesthesia.
I performed this procedure yesterday under IV sedation while a Plastic Surgeon was visiting from Europe. This surgeon regularly uses general anesthesia and he was quite surprised to see that at the conclusion of the procedure, our patient was awake, talking, smiling and reporting "no pain" and "just a little pressure, maybe a one or a two."
Bottom line is this: both General Anesthesia and IV Sedation are options for Breast Augmentation, and both can be safely performed. As Dr. Dabbah mentioned in response to your question, the more important issues are being certain that your are selecting a reputable Board Certified Plastic Surgeon and are having your procedure performed in a Licensed and Accredited surgical facility.
I recommend selecting a Plastic Surgeon that is a member of the ASPS and ASAPS. A surgeon with these credentials has board certification by the American Board of Plastic Surgery, advanced education in aesthetic surgery and signifies that they will only perform surgical procedures in an accredited surgical facility.
***With apologies to the surgeon stating that general anesthesia is "the way to go" for breast augmentation, I do not believe there is any evidence to support this claim and believe that both IV sedation and general anesthesia can be safe and effective options.
Hope this helps,
Nick Slenkovich MD, FACS
The video below is a patient of mine undergoing breast augmentation under Local anesthesia -- which can also be an option for carefully selected patients. This video is about 3 minutes long, and clearly demonstrates that I can thoroughly make sensation to the breast go "to sleep," which has major benefits for post-op recovery.