Oncologic Emergency TLS SVC Cord Compression Case Lab

Case Lab: TLS, SVC Syndrome, and Spinal Cord Compression

Case Snapshot

A patient with newly diagnosed high-grade lymphoma starts treatment and develops nausea, muscle cramps, weakness, and decreasing urine output. A second patient with lung cancer reports facial swelling, dyspnea when supine, and visible distended chest veins. A third with metastatic prostate cancer calls with new severe back pain, leg weakness, and urinary retention. These represent tumor lysis syndrome (TLS), superior vena cava (SVC) syndrome, and malignant spinal cord compression - three high-priority oncologic emergencies the OCN exam tests repeatedly as first-action questions.

Tumor Lysis Syndrome

TLS occurs when rapid tumor-cell breakdown dumps intracellular contents into the blood: hyperkalemia, hyperphosphatemia, hyperuricemia, and secondary HYPOcalcemia (phosphate binds calcium). The result can be acute kidney injury, dysrhythmias, tetany, seizures, and death. Risk is highest with bulky, rapidly proliferating, chemo-sensitive disease, such as Burkitt lymphoma, acute leukemias, and other high-grade lymphomas, and usually appears 12-72 hours after therapy starts, though it can occur spontaneously.

TLS prevention and care include risk recognition before treatment, aggressive IV hydration, strict intake/output and daily weights, telemetry, and lab surveillance of potassium, phosphate, calcium, uric acid, and creatinine. Allopurinol prevents new uric acid formation (prophylaxis); rasburicase breaks down existing uric acid for high-risk or established TLS. A critical safety rule: never give rasburicase to a patient with G6PD deficiency because it triggers severe hemolysis and methemoglobinemia. Escalate before instability develops; do not wait for the patient to crash.

Superior Vena Cava Syndrome

SVC syndrome is obstruction of venous return from the head, neck, arms, and chest, from tumor compression (often lung cancer or lymphoma), thrombosis, or catheter complication. Findings include facial or arm swelling, head fullness, dyspnea, cough, hoarseness, stridor, headache, confusion, distended neck/chest veins, and symptoms worse when bending or lying flat. Airway and breathing are the priority: elevate the head of the bed, assess respiratory status, SpO2, and neuro status, then escalate urgently. Never lay the patient flat. Severe stridor, confusion, syncope, or distress requires emergency response.

Definitive treatment (radiation, chemotherapy, steroids, anticoagulation, or stenting) is provider-directed; the RN role is rapid recognition, positioning, supportive care, and escalation.

Malignant Spinal Cord Compression

Malignant spinal cord compression can cause permanent neurologic loss within hours. Red flags: new localized back pain, pain worse when lying down or with Valsalva, radicular pain, weakness, gait change, a sensory level, numbness, and bowel or bladder dysfunction. Pain commonly precedes neurologic deficit, so waiting for paralysis is unsafe. The prostate-cancer patient with back pain, leg weakness, and urinary retention needs emergency evaluation: assess neuro function, pain, mobility, bowel/bladder status, and fall risk, then escalate immediately.

Protect safety, avoid unnecessary ambulation if weakness is present, and prepare for urgent MRI and high-dose IV dexamethasone, followed by radiation or surgical decompression. Do not offer massage or routine outpatient analgesic changes as the only action.

Education, Documentation, and Reassessment

Teach at-risk patients clear triggers: fever after chemotherapy, decreased urine, palpitations, severe weakness or cramps, facial swelling, breathing trouble, new neurologic deficits, and back pain with weakness or bowel/bladder change. Documentation includes symptom onset, diagnosis and treatment timing, objective assessment, vitals, neuro findings, urine output, labs, provider notification, orders, response, and transfer details. Reassessment focuses on airway, hemodynamics, neuro status, urine output, electrolytes, and response to interventions.

On OCN first-action questions, choose the answer that prevents irreversible harm: protect the airway in SVC syndrome, protect the kidneys in TLS, and protect neurologic function in cord compression.

Numbers, Look-Alikes, and Common Traps

The Cairo-Bishop definition codifies laboratory TLS as two or more abnormalities within three days before to seven days after treatment: uric acid >=8 mg/dL, potassium >=6 mEq/L, phosphorus elevated, and calcium <=7 mg/dL (or a 25% change from baseline). Clinical TLS adds AKI, cardiac dysrhythmia, or seizure. Hyperkalemia is the most immediately life-threatening abnormality because it triggers peaked T waves and fatal dysrhythmias, so continuous telemetry and a stat potassium are priorities. The phosphate-calcium relationship is inverse, which is why TLS produces hypocalcemia, not hypercalcemia.

Facts that separate the right answer from the look-alike:

• Hypercalcemia of malignancy is a different emergency (confusion, constipation, polyuria, weakness) treated with IV fluids and bisphosphonates; do not confuse its high calcium with TLS's low calcium.
• SVC syndrome positioning is upright with head elevated; lying flat is always wrong.
• Cord-compression imaging of choice is MRI of the whole spine, and dexamethasone is started urgently to reduce cord edema while definitive radiation or surgery is arranged.
• The phrase "do not delay escalation for confirmation" is the recurring theme: red flags drive action before labs or imaging return.

The most common distractors offer comfort measures, routine follow-up, or waiting for test results when red flags are already present. For each emergency, pick the action that prevents irreversible organ loss within the next hour, not the one that is merely reassuring.