1.7 Medical Emergencies in Radiation Oncology

1.7 Medical Emergencies in Radiation Oncology

Radiation therapists operate in high-acuity environments where oncology patients are vulnerable to acute, life-threatening complications caused directly by tumor progression, treatment side effects, or procedural interventions. Immediate recognition and rapid intervention are critical to prevent irreversible neurologic injury or death. This section outlines the standardized protocols for managing major medical emergencies within the radiation department.

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Superior Vena Cava (SVC) Syndrome

Etiology: The Superior Vena Cava is a thin-walled, low-pressure vessel draining blood from the head, neck, and upper extremities. Extrinsic compression by massive mediastinal tumors—most commonly Small Cell Lung Cancer (SCLC), Non-Small Cell Lung Cancer (NSCLC), and bulky lymphomas—obstructs venous return to the right atrium.

Clinical Presentation:

• Stokes Sign: Severe facial and periorbital edema (worse in the morning or upon bending forward).
• Severe dyspnea, orthopnea, and cyanosis.
• Dilated collateral veins across the chest wall and neck (jugular venous distension).
• Central nervous system symptoms (headache, visual changes, syncope) due to cerebral venous hypertension.

Emergency Management Protocol:

1. Immediate Positioning: Place the patient in a high Fowler position (head of bed elevated 45–90 degrees) to utilize gravity for venous drainage.
2. Oxygen Therapy: Administer supplemental O2 to manage hypoxia.
3. Pharmacotherapy: Intravenous Dexamethasone (4-8 mg IV q6h) to reduce peritumoral edema, and loop diuretics (furosemide) if fluid overload is present.
4. Radiation/Surgical Intervention:
   • Emergency endovascular stenting provides the fastest symptom relief (within 24-48 hours).
   • Emergency Radiation Therapy: To achieve rapid tumor debulking, hypofractionated regimens are used initially (3.0-4.0 Gy x 3 fractions), followed by conventional fractionation (2.0 Gy/fx) to definitive doses.

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Metastatic Spinal Cord Compression (MSCC)

Etiology: Hematogenous spread of cancer (frequently breast, prostate, lung, and renal cell carcinomas) to the vertebral bodies causes bony destruction and epidural mass expansion, physically compressing the spinal cord or cauda equina. It is an extreme neurologic emergency.

Symptom Timeline (Progression of Ischemia):

1. Localized Back Pain: Often the first symptom; classically worsens when lying flat (recumbent position increases epidural venous engorgement).
2. Motor Weakness: Progressive leg heaviness, difficulty climbing stairs.
3. Sensory Level Deficit: Numbness or paresthesia below the dermatome level of the compression.
4. Autonomic Incontinence: Loss of bowel/bladder sphincter control (late, often irreversible sign).

Emergency Management Protocol:

• Mandatory Diagnostic Rule: An urgent whole-spine MRI must be obtained within 24 hours of suspected MSCC.
• Steroid Loading: Immediate Dexamethasone 10-16 mg IV bolus, followed by 4 mg q6h to aggressively decrease spinal cord edema and restore microvascular perfusion.
• Definitive Treatment:
  • Neurosurgical decompression (laminectomy/corpectomy) if the spine is mechanically unstable or radioresistant.
  • Emergency Radiation Therapy: Common schedules include 8 Gy in 1 fraction, 20 Gy in 5 fractions, or 30 Gy in 10 fractions.

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Increased Intracranial Pressure (ICP) & Brain Metastases

Etiology: Brain tumors (primary or metastatic) exert mass effect within the rigid, fixed-volume skull. They also break down the blood-brain barrier, causing massive vasogenic edema (leakage of fluid into the brain parenchyma).

Clinical Presentation:

• Classic Triad: Waking with a morning headache, projectile vomiting without preceding nausea, and altered mental status (lethargy, confusion).
• Impending Herniation (Cushing's Triad): A pre-terminal physiological response indicating brainstem compression:
  1. Systolic Hypertension with a widened pulse pressure.
  2. Bradycardia.
  3. Cheyne-Stokes Respirations (irregular, deep, and apneic breathing).

Emergency Management Protocol:

• Steroids: High-dose IV Dexamethasone (10-20 mg bolus, 4-8 mg q6h).
• Osmotic Diuretics: Mannitol (20% solution, 0.5-1.0 g/kg IV) rapidly draws fluid out of the brain tissue into the intravascular space.
• Emergency RT: Whole Brain Radiation Therapy (WBRT) typically 30 Gy in 10 fractions, or Stereotactic Radiosurgery (SRS) for limited oligo-metastatic disease.

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Contrast Media Anaphylaxis

Etiology: Intravenous iodinated contrast agents used during CT simulation can trigger severe, IgE-mediated or direct mast-cell degranulation anaphylactic reactions within minutes of injection.

Symptom Spectrum:

• Mild: Urticaria (hives), pruritus, nasal congestion.
• Moderate: Diffuse wheezing, facial edema, mild hypotension.
• Severe (Anaphylactic Shock): Severe bronchospasm, laryngeal edema (stridor), profound hypotension, and cardiovascular collapse.

                  [ ANAPHYLAXIS EMERGENCY RESPONSE ]
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           1. STOP INFUSION & CALL CODE BLUE IMMEDIATELY
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           2. AIRWAY & BREATHING: High-Flow O2 (10-15 L/min 
              via Non-Rebreather Mask)
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           3. EPINEPHRINE (First-Line Lifesaving Drug)
              - 1:1,000 concentration (1 mg/mL)
              - 0.3 to 0.5 mg Intramuscular (IM)
              - Inject into Anterolateral Thigh
              - Repeat every 5-15 minutes as needed
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           4. CIRCULATION: Rapid IV NS Fluid Bolus (1-2 Liters)
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           5. ADJUNCT MEDS (Second-Line)
              - H1 Blocker: IV Diphenhydramine 25-50 mg
              - Corticosteroid: IV Methylprednisolone 125 mg

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Basic Life Support (BLS) & Cardiac Arrest

If a patient becomes unresponsive on the treatment couch, immediate initiation of the BLS chain of survival is critical. Therapists must be deeply familiar with the CAB Sequence (Compressions, Airway, Breathing).

Step-by-Step BLS Protocol:

1. Assess Responsiveness & Call for Help: "Are you okay?" If no response, initiate Code Blue and call for the AED.
2. Check Pulse & Breathing: Simultaneously palpate the carotid pulse and watch for chest rise for no more than 10 seconds.
3. Initiate CPR (Compressions first):
   • Rate: 100 to 120 compressions per minute.
   • Depth: 2.0 to 2.4 inches (5 to 6 cm) for adults. Allow full chest recoil.
   • Ratio: 30 compressions to 2 ventilations (30:2).
4. Defibrillation: Apply the AED immediately upon arrival. Defibrillation is indicated for Ventricular Fibrillation (VF) and Pulseless Ventricular Tachycardia (pVT).

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Additional Emergencies: Hemorrhage & Seizures

Carotid Blowout Syndrome (CBS): A catastrophic hemorrhage occurring when a necrotic tumor, prior radiation, or radical neck dissection compromises the carotid artery wall.

• Presentation: Massive arterial bleeding from the mouth, neck wound, or tracheostomy.
• Action: Apply immediate, direct, crushing pressure to the bleeding site. Do NOT release pressure to "check" the wound. Call Code Blue. Secure the airway and prepare for massive transfusion and emergency endovascular embolization.

Seizure Management: Patients with brain tumors may experience tonic-clonic seizures on the treatment table.

• Action: DO NOT place objects in the mouth. DO NOT physically restrain the patient. Clear the area of hard objects. Lower the treatment couch to its lowest position. Turn the patient gently on their side (recovery position) to prevent aspiration of saliva/emesis. Time the seizure; if it lasts >5 minutes (Status Epilepticus), prepare for IV Lorazepam administration.