Reviewing “Episode 33: Oncologic Emergencies” From Emergency Medicine Cases

Today, I reviewed and linked to Episode 33: Oncologic Emergencies from Emergency Medicine Cases*.

*Written Summary and blog post by Claire Heslop, edited by Anton Helman May, 2013.  Foote, J, Yaphe, J, Helman, A. Oncologic Emergencies. Emergency Medicine Cases. May, 2013. https://emergencymedicinecases.com/episode-33-oncologic-emergencies/. Accessed 2-28-2023.

All that follows is from the above resource:

For more on oncologic emergencies on EM Cases:
Rapid Reviews Videos on Oncologic Emergencies
Best Case Ever 16: Oncologic Emergencies

In this episode on Oncologic Emergencies Dr. John Foote (University of Toronto’s CCFP(EM) residency program director) and Dr. Joel Yaphe (the director of the University of Toronto’s Annual Update in Emergency Medicine conference in Whistler), review 5 important presentations in the patient with cancer: fever, shortness of breath, altered mental status, back pain and acute renal failure; with specific attention to key cancer-related emergencies such as febrile neutropenia, hypercalcemia, superior vena cava syndrome, hyperviscosity syndrome and tumor lysis syndrome.

FEBRILE NEUTROPENIA

The majority of cancer patients with febrile neutropenia will have a bacterial infection. While the priority is to identifying and treat these infections, other complications from cancer (tumor burden and necrosis, drug and transfusion reactions, and PE) must be considered in the differential diagnosis.

Nausea and Vomiting in Oncologic Emergencies

Consider possible causes (gastritis, GI obstruction, medication reactions, metabolic/electrolyte disorders, etc.) and treat the underlying cause when possible. There are two main classes of drugs to choose from:

1. Antiseritonergic drugs (eg: ondansetron) work best on chemoreceptor trigger for nausea, NB: can cause QT prolongation
2. Anti-dopaminergic medications (metoclopramide, prochlorperazine, olanzapine) work best when the nausea is secondary to opioids or slow GI transit time.

**Be cautious with anti-histamine type anti-nausea drugs [eg: Dimenhydrinate (Gravol)], as they can cause significant anti-cholinergic side effects, esp. in the elderly.**

Typhlitis is an Appendicitis Mimic in Oncologic Emergencies

When febrile, neutropenic cancer patients present with GI symptoms consider necrotizing enterocolitis (typhlitis), usually involving the iliocecal region. Neutropenia, loss of bowel integrity, and bacterial translocation leads to serious illness, which may mimic appendicitis, or present with generalized abdominal symptoms.

Investigations: CT abdomen (rather than U/S)

Treat: IV antibiotics, an NG tube “gut rest,” a surgical & medical consult, admit.

SHORTNESS OF BREATH IN ONCOLOGIC EMERGENCIES

Shortness of breath may be due to lung tumour burden, SVC syndrome, malignant pericardial effusion, pulmonary embolism, or other complications of malignancy.

Do all cancer patients need a CT to rule out PE? No good evidence to answer this, but most cancer patients admitted for shortness of breath of unclear etiology will need PE ruled out by CT

What is SVC syndrome?

SVC obstruction (acutely or subacutely) either by solid tumour or SVC thrombus. Intravascular devices (pacemakers, PICC lines) are an increasingly prevalent cause of SVC syndrome.

Symptoms of SVC syndrome can be mild, such as complaints of facial swelling, arm swelling, dyspnea, cough, and facial redness. Mental status changes from raised ICP, or voice hoarseness from airway edema are rare, but are very ominous signs of severe SVC obstruction. SVC thrombi can embolize and cause PE.

Investigations: the test of choice for SVC syndrome is a CT chest with contrast, to look for SVC obstruction and collateral vessels.

ALTERED MENTAL STATUS IN ONCOLOGIC EMERGENCIES

The differential diagnosis for altered mental status in cancer patients includes CNS metastases, raised ICP, electrolyte disturbances such as hypercalcemia, medication side effects, and hyperviscosity syndrome. (Don’t forget the usual, non-cancer causes of altered mental status!)

Hypercalcemia

Up to 1/3 of patients with hypercalcemia will have a malignancy, and 1/3 of cancer patients will develop hypercalcemia.

The most common malignancies that present with hypercalcemia are multiple myeloma, lung, renal, and breast cancers. The hypercalcemia is due to a parathyroid-like hormone secreted by the tumours. Consider serum PTH to rule out primary hyperparathyroidism in first presentations of hypercalcemia.

For a great chapter on hypercalcemia, See Hypercalcemia
June 25, 2021 by Dr. Josh Farkas from his Internet Book Of Critical Care:

evaluation:

• Ionized calcium level.
• Electrolytes including Mg/Phos.
• Parathyroid hormone (PTH).
• Thyroid stimulating hormone (TSH).
• 25-OH vitamin D & 1,25-OH vitamin D.
• PTH-related peptide (PTH-rp).

management if symptomatic/severe:

volume resuscitation (more)

• If hypovolemic, rapidly resuscitate with plasmalyte to target euvolemia.
• No role for forced diuresis (furosemide plus fluid).

calcitonin (more)

• 4 units/kg s.q. q12 hours.
• Calcitonin only works transiently, so it must be given simultaneously with a bisphosphonate.

IV bisphosphonate (more)

• Indicated for most cases of hypercalcemia, except:
  • Milk-alkali syndrome. 
  • Premenopausal women.
• Zoledronic acid is preferred:
  • The usual dose is 4 mg IV, infused over 60 minutes (slow infusion improves safety).
  • Dose-reduce in renal failure:
    • GFR 50-60 ml/min: 3.5 mg
    • GFR 40-49 ml/min: 3.3 mg
    • GFR <39 ml/min: 3 mg

Resuming the excerpts from Episode 33: Oncologic Emergencies:

Hyperviscosity Syndrome

Elevated WBCs or severe hyperproteinemia can cause high serum viscosity and micro-circulatory problems in patients with Waldenstrom’s macroglobulinemia, multiple myeoma or acute leukemia.

Classic Triad is mucosal bleeding (epistaxis, vaginal/rectal bleeding, hematuria), visual disturbances, and altered LOC.

A clue to the diagnosis is that often lab sample processing is delayed due to high sample viscosity, and Rouleau may be seen in blood smears.

Raised Intracranial Pressure

Raised intracranial pressure in cancer patients can be caused by brain mets, hydrocephalus, bleeding, and brain abscess. A non-contrast CT should show most symptomatic mass lesions, however contrast enhancement may be needed to identify metastases.

Managing Impending Brain Herniation

Intubate & hyperventilate to PCO2 of 30 temporarily.

Avoid hypotension, and consider giving hypertonic 3% saline or mannitol. Give Dexamethasone IV for metastases with edema. One meta-analysis suggested hypertonic saline may be more effective than mannitol for treating elevated ICP (4), but this may not be generalizable to cancer patients. A meta-analysis of prophylactic anti-siezure meds for brain mets did not reduce the frequency of first seizures.

For a detailed review of the above, please see Elevated intracranial pressure (ICP),
July 16, 2022 by Dr. Josh Farkas from his outstanding Internet Book Of Critical Care [Table of Contents].

RENAL FAILURE IN ONCOLOGIC EMERGENCIES

Pre-renal causes (i.e. hypovolemia) are a common cause of renal failure in cancer patients. However, pelvic masses can cause post-renal obstruction, and Infiltrating tumours, amyloidosis, nephrotoxic drugs, and tumour lysis syndrome may also cause renal failure.

What is tumour lysis syndrome? Electrolyte and metabolic derangements secondary to rapid cell destruction, usually following chemotherapy for lymphoma or leukemia. These patients present with hyperkalemia, hyperphosphatemia, hypocalcemia, and severe renal failure.

Treatment for tumor lysis syndrome: The first treatment priority is to lower the potassium. Be cautious about giving calcium, as these patients have high phosphate! in case dialysis is needed.

Rasburicase (an enzyme that transforms uric acid into soluble allantoin) is used to manage tumor lysis syndrome

Multiple Myeloma

Multiple myeloma is a malignancy of plasma cells, which accumulate in the bone marrow and produce paraproteins.

Patients present with fatigue, weakness, weight loss, and bone pain. Anemia and renal failure are common. Rarely, bony infiltration can cause cord compression.

Paraproteins can cause a low anion gap, pseudo-hypercalcemia (free calcium levels will be normal), and hyperviscosity syndrome.