ULTRASOUND GUIDANCE Start by placing the ultrasound probe inferior to the clavicle in a paramedian orientation, to identify the axillary artery, vein and pectoralis major and minor. Once you identify the 3rd rib, rotate the probe 90 degrees and slide it toward the lateral aspect of the chest wall.

Thoracic epidurals and paravertebral blocks have long been the gold standards for breast surgery anesthesia, but both are associated with significant challenges. Thoracic epidurals aren't really suited to the outpatient realm, and paravertebral blocks, the most widely used technique of regional anesthesia for breast surgeries, require a high degree of skill and confidence, due to the risk of iatrogenic pneumothora or inadvertent entry of a needle into the vertebral canal with consequent spinal cord trauma.

But regional blocks have some distinct advantages in this area. For one, they help mitigate the increased risk of PONV and the significant level of post-op pain associated with breast surgery — a level that typically requires narcotics to be part of the multimodal analgesia regimen.

Additionally, at least one study (osmag.net/NNoYn6) suggests that when breast cancer surgery is performed with ultrasound-guided blocks, tumor recurrence and metastases are substantially reduced. Why? Investigators theorize that surgery causes tumor cells to be released into surrounding healthy tissue and circulation, and that the risk of recurrence likely depends on immune system capability. Regional anesthesia and analgesia may help preserve immune function by attenuating the surgical stress response and reducing the need for opioids.

Fortunately, anesthesia providers can master pectoral nerves blocks, an easy and reliable superficial block.

• PECs I block. This technically simple block covers the median (C8, T1) and lateral pectoral nerves (C5, 6, 7), which lie between the pectoralis major (PM) and pectoralis minor (Pm) muscles. It's best suited for pacemakers and port-a-caths and for majority coverage for insertion of breast expanders and subpectoral prosthesis. It doesn't cover the axillary area, however, and both expanders and prosthesis may result in additional pain in this area.
• PECs II block. The PECs II block incorporates the injection and coverage of the PECs I, but also adds a second injection between the planes of the pectoralis minor and the anterior serratus muscle. This second injection covers the long thoracic nerve (the nerve to the serratus anterior), thoracic intercostal nerves from T2 to T6 and the thoracodorsal nerve (the nerve to the latissimus dorsi). This provides coverage of the axillary area, which provides analgesia for surgeries such as sentinel node biopsy, mastectomies and complete reconstructions.

EASY AND RELIABLE
How to Administer a Pectoral Nerves Block

LANDMARKS The PEC I and PEC II blocks should be relatively easy to master with practice.

1. Place the ultrasound probe inferior to the clavicle in a paramedian orientation. At this location you can identify the axillary artery, vein and pectoralis major and minor. If a rib is visible, it will be the 2nd rib with the pleura below.


2. Scan down the chest in a caudad direction and count the ribs as you go. Once you identify the 3rd rib, rotate the probe 90 degrees and slide it toward the lateral aspect of the chest wall. At this point you'll be able to identify pectoralis major and minor, the pectoral branch of the thoracoacromial artery between them, the 3rd and 4th ribs, and the pleura between them. This is the optimal position for both blocks.
COVERAGE The PEC I (left) covers the median and lateral pectoral nerves, which lie between the pectoralis major and pectoralis minor muscles. The PEC II covers those plus the axillary area.
3. For PECs I, place 20 ml of local anesthetic between the pectoralis major and minor in the vicinity of the thoracoacromial artery.
4. For PECs II, simply place the needle between the anterior serratus and pectoralis minor, inject 20 ml of local anesthetic and, on the way out, inject 10 cc of local anesthetic between the pectoralis major and minor in the vicinity of the thoracoacromial artery. The injection sequence is important, because injecting between the pectoralis minor and major first could compress or distort the anatomy and make it harder to identify the anterior serratus and pectoralis major planes.

— Mike MacKinnon, CRNA

These blocks significantly decrease the need for opioids and can decrease recurrent cancer risk, making them a win-win for the patient and provider. OSM