Episode 18: Oncologic emergencies with Leon Chen

A look at oncology-related emergencies in the ICU, with Leon Chen (@CCMNP), NYC nurse practitioner specializing in oncology critical care. Takeaway lessons * Extremely elevated leukocyte count should always raise suspicion for a “liquid tumor” such as leukemia.* The principal acute complication is leukostasis from poor flow, potentially causing hyperviscosity issues such as stroke, MI, pulmonary embolism, and mesenteric ischemia. Such patients are (despite their white count) also functionally immunosuppressed and at risk for infectious complications.* Fungal infection is not uncommon, but does not necessarily need empiric coverage up front.* Don’t hesitate to be broad with your investigations. Feel free to CT widely, cover broadly with antimicrobials, etc. Consider bronchoscopy for BAL.* Tumor lysis syndrome is always a possibility and can occur spontaneously in patients with such extreme leukocyte elevations. Check labs such as BMP, magnesium, calcium, phosphate, LDH, and uric acid every ~4 hours at first; however, the risk is probably highest for lysis when the white count begins to fall (e.g. due to initiating treatment).* Tumor lysis is much more common with liquid than solid tumors, and much more with certain chemotherapy regimens.* Extreme leukocytosis can cause “leukocyte larceny,” where blood gasses demonstrate false hypoxemia due to leukocytes consuming oxygen in the sample before it can be processed. Pulse oximetry is more reliable.* Spurious “pseuohyperkalemia” can also occur due to lysis of delicate immature leukocytes. This can be resolved with whole blood samples or point-of-care assays, which decrease transport time and sample agitation.* Uric acid is associated with renal injury and may need medical treatment. Allopurinol prophylaxis is generally safe, but rasburicase is the treatment of choice if uric acid is very high. LDH elevation is benign but are a good marker of response to treatment, as it should drop with appropriate chemotherapy.* Pulmonary hyperviscosity usually results in clear lungs on imaging. If infiltrates are present, consider infection. Also consider PCP pneumonia and fungal studies.* Leukapheresis, a dialysis-like process, involves selective removal of leukocytes to reduce viscosity.* Prophylaxis: Bactrim is a good choice for PCP, but beware of hyperkalemia. Atovaquone, pentamidine are next line options. Acyclovir for viral prophylaxis and posaconazole for fungal (galactomannan and beta-d glucan are helpful)* The blast count is suggestive of leukemia, but definite diagnosis will require bone marrow biopsy.* Initial stabilization of this sort of oncologic emergency is within the bailiwick of most hospitals, but it’s reasonable to then consider transfer to a specialty oncology center for the focused treatments like leukapheresis and chemotherapy. References A good, free review: Klemencic S, Perkins J. Diagnosis and Management of Oncologic Emergencies. West J Emerg Med. 2019 Mar;20(2):316-322. doi: 10.5811/westjem.2018.12.37335. Epub 2019 Feb 14. PMID: 30881552; PMCID: PMC6404710.