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Difficulty: MediumHematology and Oncology

A 5454-year-old man is evaluated in the emergency department for a fever and chills that started 66 hours ago. He has a history of diffuse large B-cell lymphoma and received his most recent cycle of chemotherapy 1010 days ago. His temperature is 39.1∘39.1^\circ C (102.4∘102.4^\circ F), blood pressure is 110/70110/70 mm Hg, pulse is 115115/min, and respirations are 2424/min. Physical examination is unremarkable, with no focal source of infection identified. His central venous port site appears clean without erythema or induration.

Laboratory results are as follows:

Laboratory TestResultReference Range
Hemoglobin9.29.2 g/dL13.513.5–17.517.5 g/dL
Platelet count90,00090,000/mm3^3150,000150,000–400,000400,000/mm3^3
Leukocyte count800800/mm3^34,5004,500–11,00011,000/mm3^3
Absolute neutrophil count200200/mm3^3≥1,500\geq 1,500/mm3^3
Thyroid-stimulating hormone (TSH)1.11.1 μ\muU/mL0.50.5–5.05.0 μ\muU/mL
Free thyroxine (T4)0.50.5 ng/dL0.90.9–1.71.7 ng/dL
Arterial Blood GasResultReference Range
pH7.487.487.357.35–7.457.45
pCO2_22929 mm Hg3535–4545 mm Hg
HCO3−_3^-2222 mEq/L2222–2828 mEq/L

Which of the following is the most appropriate next step in the management of this patient?

  1. Obtain blood cultures and start intravenous cefepimeAnswer
  2. B
    Obtain blood cultures and start intravenous vancomycin
  3. C
    Delay antibiotic therapy pending blood culture results
  4. D
    Initiate oral levothyroxine therapy
  5. E
    Administer intravenous sodium bicarbonate

Answer

Obtain blood cultures and start intravenous cefepime
The correct answer is to obtain blood cultures and start an intravenous antipseudomonal beta-lactam such as cefepime. This patient has febrile neutropenia, defined as a single oral temperature of ≥38.3∘\geq 38.3^\circ C (101∘101^\circ F) or a sustained temperature ≥38.0∘\geq 38.0^\circ C (100.4∘100.4^\circ F) for ≥1\geq 1 hour, accompanied by an absolute neutrophil count (ANC) <500< 500/mm 3^3. Because these patients lack a robust inflammatory response, bacterial infections can rapidly progress to overwhelming sepsis and death. The most critical initial step is to immediately draw blood cultures and administer empiric, broad-spectrum intravenous antibiotics. The initial antibiotic regimen must have activity against Pseudomonas aeruginosa, as it is associated with a rapidly fatal course in neutropenic patients. Cefepime, meropenem, or piperacillin-tazobactam are appropriate choices for initial monotherapy.

Step-by-Step Solution

1
Identify the primary life-threatening condition based on the presentation and complete blood count.
The patient has a temperature of 39.1∘39.1^\circ C and an absolute neutrophil count of 200200/mm 3^3, establishing the diagnosis of febrile neutropenia.
Febrile neutropenia is an oncologic emergency requiring immediate intervention to prevent rapid progression to sepsis.
2
Determine the most appropriate initial empiric management for high-risk febrile neutropenia.
Blood cultures must be drawn, followed immediately by the administration of broad-spectrum intravenous antibiotics with antipseudomonal activity (e.g., cefepime, meropenem, or piperacillin-tazobactam).
Patients with severe neutropenia cannot mount a sufficient inflammatory response, making them highly susceptible to fatal infections, particularly from Pseudomonas aeruginosa.
3
Evaluate the distracting laboratory abnormalities to rule out other immediate interventions.
The thyroid studies indicate euthyroid sick syndrome, and the arterial blood gas shows respiratory alkalosis secondary to fever/tachypnea. Neither requires specific targeted treatment.
Treating incidental physiologic adaptations or misinterpreting the acid-base status distracts from the life-saving step of administering antibiotics.

Key Concept

Management of febrile neutropenia requires immediate empiric administration of broad-spectrum intravenous antibiotics with antipseudomonal coverage, such as cefepime.
Estimated Time:1m 30s
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Topics

Hematology and Oncology

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