• Time in minutes until the patient is declared ready for discharge from the Post Anesthesia Care Unit (PACU) [ Time Frame: Until PACU discharge ] [ Designated as safety issue: No ]
  
• Visual Analog Scale (VAS) pain scores at 30, 60, 90, and 120 minutes after PACU admission. A VAS score will also be assessed on the first postoperative day. [ Time Frame: Until PACU discharge and for 24 hours ] [ Designated as safety issue: No ]
  

• The need for postoperative opioids in the PACU and during the first postoperative day will be assessed. [ Time Frame: 24 hours ] [ Designated as safety issue: No ]
  
• Episodes of nausea or vomiting in the PACU and during the first postoperative day will be assessed. [ Time Frame: 24 hours ] [ Designated as safety issue: No ]
  
• Total time spent in the operating room [ Time Frame: Perioperative ] [ Designated as safety issue: No ]
  
• Overall patient satisfaction [ Time Frame: After hospital discharge ] [ Designated as safety issue: No ]
  

The optimal anesthetic technique for breast cancer surgery allows for good postoperative pain relief and rapid discharge. Breast cancer surgery with potential axillary dissection is often performed under general anesthesia due to the potential for poor analgesia with local anesthetic infiltration at the surgical site alone. General anesthesia can be associated with increased post-operative pain, nausea, and delayed discharge when compared to regional anesthesia for breast and other types of procedures (1,2).

The paravertebral block is a technique that has been used perioperatively for breast (3,4), thoracic (5), abdominal (6), and hernia surgeries (7). It has also been used for pain control after rib fractures and penetrating trauma (8,9). The paravertebral block is performed by injecting local anesthetic above or below the transverse processes of the vertebral bodies where the spinal nerve roots emerge from the intervertebral foramina. The most common technique is to insert a needle 2.5 centimeters lateral to the spinous process at each level and "walk off" the transverse process. Injections at one or multiple levels block the somatic and sympathetic innervation to these dermatomes (10).

Rare complications of thoracic paravertebral blocks include epidural spread, intrathecal injection, and Horner's Syndrome (1,11,12). One of the most feared complications of the traditional technique is pleural puncture, which has an incidence of 0.64% to 6.7% in the published literature (3,11,13).

Ultrasound guidance in regional anesthesia is gaining widespread popularity. This technology provides visualization of key anatomic structures and has been shown to decrease block placement and onset times (14,15) and improve patient comfort (15). Ultrasound-guided blocks are associated with success rates of greater than 90% (15,16). In the thoracic region, ultrasound can be used to identify the vertebral transverse processes, as well as the ribs and the pleura of the lungs (17). In this way, pleural puncture can be avoided during paravertebral block placement.

To date there have been no published prospective, randomized trials comparing the multiple injection thoracic paravertebral technique using ultrasound guidance to general anesthesia in breast cancer surgery patients.

Our hypothesis is that paravertebral block anesthesia will result in shorter Post Anesthesia Care Unit (PACU) stays and decreased Visual Analog Scale (VAS) scores when compared to general anesthesia in patients undergoing breast cancer surgery. Secondary endpoints will include the need for postoperative opioids and the presence of nausea and/or vomiting.