The purpose of this study is to compare ultrasound and predetermined distance techniques for finding the paravertebral space to inject the local anesthetic (numbing medicine) when you are given anesthesia for surgery. The paravertebral space is located on either side of the spinal cord and contains the nerves that provide sensation to the chest wall. The predetermined distance technique is a series of measurements taken to determine the location of the paravertebral space where the local anesthetic is injected. The ultrasound technique uses direct visualization of the local anesthetic being placed in the paravertebral space. This type of anesthesia has many benefits including decreasing your pain after breast surgery.