What should an anesthesiologist anticipate and consider (pre‑operative assessment, intra‑operative management, and postoperative care) for a patient undergoing a modified radical mastectomy for breast cancer?

Anesthetic Considerations for Modified Radical Mastectomy

As an anesthesiologist managing a modified radical mastectomy, your primary focus should be on optimizing perioperative pain control with multimodal analgesia including regional anesthesia, anticipating moderate blood loss from axillary dissection, and preparing for potential complications related to patient comorbidities and prior neoadjuvant chemotherapy exposure.

Pre-operative Assessment

Patient History & Comorbidities

• Assess prior chemotherapy exposure: Many patients undergo neoadjuvant chemotherapy before mastectomy, particularly those with HER2-positive or triple-negative disease 1, 2. Anthracycline-based regimens can cause cardiotoxicity, requiring cardiac evaluation 1.
• Evaluate for trastuzumab-related cardiac dysfunction: Patients with HER2-positive tumors receive trastuzumab for at least 9 weeks preoperatively 1. This can cause reversible cardiomyopathy—obtain baseline echocardiogram or MUGA scan if available.
• Screen for radiation therapy effects: Some patients receive preoperative radiation for locally advanced disease 1. This may cause pulmonary fibrosis affecting ventilation and skin changes complicating IV access.
• Document endocrine therapy use: Postmenopausal women on aromatase inhibitors may have osteoporosis and bone fragility 3, 4. Tamoxifen increases thromboembolic risk 3.

Surgical Scope & Duration

• Modified radical mastectomy includes: Complete breast tissue removal plus level I/II axillary lymph node dissection 1. Expect 2-4 hours surgical time.
• Anticipate immediate reconstruction: Delayed or immediate reconstruction may be planned 1. If tissue expander or implant placement is planned, surgical time extends significantly 5.
• Axillary dissection considerations: Level I/II dissection requires at least 10 lymph nodes for adequate staging 1. This involves significant dissection near neurovascular structures.

Intra-operative Management

Anesthetic Technique

• General anesthesia is standard: Endotracheal intubation with controlled ventilation for optimal surgical exposure and airway protection.
• Regional anesthesia is strongly recommended: Paravertebral block or pectoralis nerve blocks (PECS I/II) provide superior postoperative analgesia and reduce opioid requirements. This is critical for enhanced recovery.
• Avoid nitrous oxide: Risk of nausea/vomiting is high in breast surgery; use total intravenous anesthesia (TIVA) with propofol and remifentanil for better PONV prophylaxis.

Positioning & Access

• Supine position with arm abduction: Arm positioned at 90 degrees or less to prevent brachial plexus injury during axillary dissection. Pad all pressure points.
• IV access considerations: Place IV in contralateral arm to preserve ipsilateral arm veins for future chemotherapy access and avoid lymphedema risk. If bilateral mastectomy, use lower extremity or central access 1.
• Avoid blood pressure cuff on operative side: Use contralateral arm or lower extremity to prevent lymphedema and preserve limb for future use 1.

Hemodynamic Management

• Anticipate moderate blood loss: Axillary dissection can cause 200-500 mL blood loss, particularly with extensive nodal involvement. Type and screen blood preoperatively.
• Maintain normotension: Avoid hypertension during dissection to minimize bleeding, but maintain adequate perfusion for flap viability if reconstruction is performed.
• Fluid management: Balanced crystalloid approach; avoid excessive fluid administration which can worsen lymphedema risk and compromise flap perfusion if reconstruction is performed.

Airway & Ventilation

• Standard endotracheal intubation: Ensure adequate depth to prevent coughing during dissection near neurovascular structures.
• Lung-protective ventilation: Tidal volumes 6-8 mL/kg ideal body weight, PEEP 5-8 cmH2O, especially if prior chemotherapy or radiation exposure 1, 6.
• Monitor for pneumothorax: Rare but possible with deep axillary dissection or if internal mammary nodes are addressed 1.

Temperature Management

• Active warming is essential: Hypothermia increases infection risk and impairs wound healing. Use forced-air warming blankets and warmed IV fluids.
• Target normothermia: Core temperature >36°C throughout procedure, particularly important if reconstruction is performed to optimize flap perfusion 5.

Postoperative Care

Pain Management

• Multimodal analgesia protocol: Combine regional anesthesia, acetaminophen, NSAIDs (if not contraindicated), and opioids as rescue 2, 7.
• Regional anesthesia duration: Paravertebral or PECS blocks provide 12-24 hours of analgesia. Consider continuous catheter techniques for extensive reconstruction.
• Avoid excessive opioids: Nausea/vomiting is common; use opioid-sparing techniques and aggressive PONV prophylaxis with multimodal approach (5-HT3 antagonist, dexamethasone, scopolamine patch).

Monitoring & Complications

• Drain management: Surgical drains are typically placed in axilla and mastectomy site. Monitor output and secure drains to prevent dislodgement.
• Seroma/hematoma risk: Most common early complication. Maintain normotension and avoid anticoagulation in immediate postoperative period unless high thrombotic risk.
• Lymphedema prevention: Educate patient on arm protection, avoid BP cuffs and venipuncture on operative side indefinitely 1.
• Nerve injury assessment: Intercostobrachial nerve injury during axillary dissection causes numbness in upper inner arm—common and usually permanent 1.

Specific Chemotherapy-Related Concerns

• Anthracycline cardiotoxicity: Monitor for arrhythmias and heart failure symptoms postoperatively 1. Have low threshold for ECG and troponin if chest pain or dyspnea develops.
• Immunosuppression: Patients on active chemotherapy have increased infection risk. Strict aseptic technique and consider antibiotic prophylaxis per institutional protocol 1, 7.
• Bone marrow suppression: Check preoperative CBC; thrombocytopenia or anemia may require transfusion support 1.

Common Pitfalls to Avoid

• Do not place IV or BP cuff on operative side: This is critical for lymphedema prevention and preserving limb function 1.
• Do not underestimate pain: Mastectomy with axillary dissection is significantly painful; inadequate analgesia delays recovery and increases chronic pain risk. Regional anesthesia is not optional—it is essential.
• Do not forget PONV prophylaxis: Breast surgery has high baseline PONV risk; use at least 2-3 antiemetic agents prophylactically.
• Do not overlook cardiac assessment in chemotherapy patients: Trastuzumab and anthracyclines cause cardiac dysfunction that may be subclinical preoperatively but decompensate under anesthetic stress 1.
• Do not assume "routine" case: These patients often have complex oncologic histories with multiple prior therapies affecting multiple organ systems. Review all prior treatments systematically 1, 2, 7.