Pectoralis (Pecs) Blocks Overview

Introduction

• Pectoralis blocks, or "Pecs blocks," are fascial plane blocks for anesthetizing nerves of the chest wall.
• Two types: Pecs One and Pecs Two, used together or separately.

Pecs One Block

• Targets: Plane between pectoralis major and minor muscles.
• Blocks medial and lateral pectoral nerves (supply to pec muscles, not the overlying skin).
• Used for breast reconstruction, relieving dull achy sensation associated with stretching of pec muscles.
• Applied during modified radical mastectomy and thoracoscopic surgery.

Pecs Two Block

• Targets: Plane between pectoralis minor and serratus anterior muscles.
• Anesthetizes lateral cutaneous branches (T2 to T6), skin, breast, and soft tissue.
• Suitable for breast surgery, chest wall procedures, axillary dissection, and sentinel node biopsy.
• Consistently blocks the intercostobrachial nerve (branch of T2).

Procedure and Technique

• Positioning: Arm abducted 90 degrees to stretch pec muscles.
• Probe Placement: On chest wall, medial to coracoid process, parasagittal orientation.
• Probe Maneuvers: Tilt medially, twist to align with deltopectoral groove.
• Rib Identification: Count ribs underneath axillary vein (2nd rib), translate to locate 3rd and 4th ribs.
• Injection Sites:
  • Pecs One: Between pec major and minor (third rib level).
  • Pecs Two: Between pec minor and serratus anterior (fourth rib level).
• Local Anesthetic:
  • Pecs One: 10 ml.
  • Pecs Two: 20 ml.
• Needle Technique: Negative aspiration, careful passage through pec muscles.

Tips for Success

• Perform Pecs Two first to avoid obscuring visualization.
• Recommended volumes: 10 ml for Pecs One, 20 ml for Pecs Two.
• For larger patients, consider out-of-plane approach.

Clinical Efficacy and Safety

• Pecs blocks provide post-operative analgesia comparable to paravertebral blocks.
• Effective for breast, axilla, and chest wall procedures.
• Safe, easy to perform, and part of the regional anesthesia toolkit.