Comparison of Paravertebral Block With General Anesthesia in Patients Undergoing Breast Cancer Surgery

A Comparison of Ultrasound-assisted Paravertebral Block and General Anesthesia for Outpatient Breast Cancer Surgery, a Prospective Randomized Trial

The purpose of this project is to determine if there is a difference between paravertebral block and general anesthesia in terms of time to discharge from the Post-Anesthesia Care Unit and pain level in patients undergoing outpatient breast cancer surgery.

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.

Inclusion Criteria:

• Women 18 years of age or older with suspected breast carcinoma scheduled for unilateral lumpectomy or mass excision with sentinel node biopsy and possible axillary dissection.

Exclusion Criteria:

• A diagnosis of chronic pain, regular use of opioid medications, infection at the injection site, allergy to amide local anesthetics, bleeding disorder, contraindication to LMA, and patient refusal.