Anesthesia for Extrathoracic Breast Surgery and Resconstruction Flashcards
Describe the Anatomy & Physiology of the Breast
The breast overlies:
Pectoralis major
Serratus anterior
External oblique muscles
2nd to 6th ribs (costal cartilages) but the mammary gland is more extensive than the breast and generally extends into the axilla as an “axillary tail”
Breast contains 15–20 lobes
Fat covers the lobes & gives breast size & shape
Lobules fill each lobe
Sacs at the end of lobules produce milk
Ducts deliver milk to the nipple
Retromammary Space: Space between Breast & Deep Fascia
Breast is divided into Quadrants for clinical identification
Explain Arterial Perfusion & Venous drainage of the Breast.
Three main arteries supply the breast: Internal mammary artery Internal/Lateral thoracic artery Axillary artery The veins of the breast correspond with the arteries, draining into the axillary and internal thoracic veins.
What Muscles are Relevant to Breast Surgery?
Pectoralis Major Pectoralis Minor Serratus Anterior Latissimus Dorsi Intercostal Muscles
Describe the Pectoralis Major Muscle.
Attachments: The distal attachment of both heads is into the intertubercular sulcus of the humerus.
Clavicular head – originates from the anterior surface of the medial clavicle.
Sternocostal head – originates from the anterior surface of the sternum, the superior six costal cartilages and the aponeurosis of the external oblique muscle.
Function: Adducts and medially rotates the upper limb, and draws the scapula anteroinferiorly. The clavicular head also acts individually to flex the upper limb. Clavicular head allowes flexion of shoulder.
Innervation: Lateral and medial pectoral nerves.
Describe the Pectoralis Minor Muscle.
The pectoralis minor lies underneath its larger counterpart muscle, pectoralis major. Both of these muscles form part of the anterior wall of the axilla region.
Attachments: Originates from the 3rd-5th ribs, and inserts into the coracoid process of the scapula.
Function: Stabilizes the scapula by drawing it anteroinferiorly against the thoracic wall.
Innervation: Medial pectoral nerve.
The Serratus Anterior Muscle:
The serratus anterior is a muscle that originates on the surface of the 1st to 8th ribs at the side of the chest and inserts along the entire anterior length of the medial border of the scapula.
The serratus anterior acts to pull the scapula forward around the thorax. The muscle is named from Latin: serrare = to saw, referring to the shape, anterior = on the front side of the body.
The function of the serratus anterior muscle is to allow the forward rotation of the arm and to pull the scapula forward and around the rib cage. The scapula is able to move laterally due to the serratus anterior muscle, which is vital for the elevation of the arm. The serratus anterior muscle also allows the upward rotation of the arm, which allows a person to lift items over their head.
The Latissimus Dorsi Musle:
The latissimus dorsi muscle is one of the largest muscles in the back. There muscle is divided into two segments, which are configured symmetrically along the backbone.
The muscle is located in the middle of the back, and it is partially covered by the trapezius. It originates along the seventh thoracic vertebra (T7) region of the spine and extends to its insertion point on the humerus.
The muscle also covers the lower tip of the scapula, or shoulder blade. When flexed, the muscle works at extending, adducting and rotating the arm. Because of its size and central location, injury to this muscle can be debilitating.
The latissimus dorsi is responsible for extension, adduction, transverse extension also known as horizontal abduction, flexion from an extended position, and (medial) internal rotation of the shoulder joint.
The Intercostal Muscles:
Intercostal muscles are muscle groups that are situated in between the ribs that create and move the chest wall.
The muscles are broken down into three layers, and are primarily used to assist with the breathing process.
The three layers are: external intercostal muscles, internal intercostal muscles, and the innermost intercostal muscles.
These muscles are innervated and supplied with blood by the intercostal nerves, intercostal veins, and intercostal arteries.
The Lymphatic Duct:
Lymphatic duct
Drains Right side of head & neck, Right upper limb, Right lung and Thoracic wall, Right side of heart and Right surface of Liver.
The Thoracic Duct:
Thoracic duct
Drains 3/4 of the body via the left jugular trunk, left subclavian, left bronchomediastinal, left and right lumbar and intestinal trunks.
Largest Lymphatic Trunk Starts in abdomen lower border T12 (as continuation of cisterna chyli)
Enters post mediastinum through aortic opening of diaphragm (T12)
T5 shifts to left & runs in superior mediastinum
C7 arches laterally then downwards
Ends at angle formed by union of left internal jugular vein & left subclavian vein
Lymphatic Drainage of Upper Limb & Breast:
Clinical importance due to its role in the metastasis of breast cancer cells.
3 groups of lymph nodes that receive lymph from breast tissue axillary nodes (75%), parasternal nodes (20%) posterior intercostal nodes (5%)
The skin of the breast also receives lymphatic drainage:
Skin – drains to the axillary, inferior deep cervical & infraclavicular nodes.
Nipple and areola – drains to the subareolar lymphatic plexus.
Sentinel Lymph Node & Intraoperative Lymphatic Mapping:
Which lymph node is the sentinel lymph node for dissection?
The 1st Lymph Node downstream from the tumor
The sentinel lymph node is the node most likely to harbor metastatic disease if it is present
Mapping:
Pre-op lymphoscintigraphy - injection of Tc99m sulfur colloid 4 hours prior to surgery
Intra-op gamma probe
Vital blue dye (1% isosulfan blue/Lymphazurin)
Breast Innervation:
The breast is innervated by the anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves. These nerves contain both sensory and autonomic nerve fibers (the autonomic fibers regulate smooth muscle and blood vessel tone).
It should be noted that the nerves do not control the secretion of milk. This is regulated by the hormone prolactin, which is secreted from the anterior pituitary gland.
What nerve innervates the latissimus muscle?
Thoracodorsal nerve
What nerve innervates the serratus anterior muscle?
Long thoracic nerve
Respiratory Risk Assessment Prior to Extrathoracic Surgery
Patient Risk Factors:
Patient Risk Factors Age Chronic Lung Disease Asthma Smoking Obesity OSA Pulmonary Hypertension Heart Failure General Health Status
Respiratory Risk Assessment Prior to Extrathoracic Surgery
Procedure Risk Factors:
Procedure Risk Factors Surgical Site/Technique: The incidence of pulmonary complication inversely related to distance of incision to diaphragm. Surgery Duration Type of Anesthesia Type of Neuromuscular Blockade (residual block) Preoperative Clinical Evaluation PFT’s ABG CXR Exercise Testing Pulmonary Risk Incides
Describe Breast Lumpectomy/Partial Mastectomy +/- Needle Localization.
Tissue sparing Partial Mastectomy. The mass is removed in addition to surrounding tissue sent for pathology.
Needle Localization Partial Mastectomy is used when clinically unable to palpate mass. It is placed pre-operatively in radiology.
Describe Simple Mastectomy vs. Modified Radical Mastectomy and Radical Mastectomy.
Simple or total: removal of entire breast without removal of lymph nodes
Modified Radical Mastectomy: A simple mastectomy with the removal of the lymph nodes under the arm (called an axillary lymph node dissection).
Radical: removal of the entire breast and lymph node dissection and the pectoral (chest wall) muscles under the breast.
This surgery was once very common, but less extensive surgery (such as the modified radical mastectomy) has been found to be just as effective and with fewer side effects, so this surgery is rarely done now.
Other modifiers are:
Skin sparing
Nipple sparing
Where does the long thoracic nerve arise, travel?
What occurs when the long thoracic nerve is injured?
The long thoracic nerve arises from the posterior aspect of C5, C6, and often C7 ventral rami. It travels within the scalenus medius muscle. It then runs over the lateral surface of the serratus anterior supplying it with multiple branches
What occurs when the long thoracic nerve is injured?
Long Thoracic Nerve Palsy
Winging of the scapula
Where does the thoracodorsal nerve arise?
What occurs when the thoracodorsal nerve is injured?
The thoracodorsal nerve (C6, C7, and C8) arises from the posterior cord. It courses anterior to the latissimus dorsi muscle along with the corresponding vessels and supplies the muscle.
What occurs when the thoracodorsal nerve is injured?
Loss of sensation in axilla
Upper extremity weakness
