Hematologic and Oncologic Emergencies

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Chapter 37 Hematologic and Oncologic Emergencies

Paul Ishimine, MD, Jenny Kim, MD

HEMATOLOGIC EMERGENCIES

1 How should one approach the evaluation of a child presenting with anemia to the emergency department (ED)?

Anemia is caused by problems of red cell destruction, red cell or hemoglobin production, or blood loss. After patient stabilization, the following features can help determine the underlying cause:

image Historical features: Rapidity of onset, hemorrhage, diet, history of easy bruising or bleeding, family history of blood disorders

image Physical examination findings: Jaundice, splenomegaly, enlarged lymph nodes, bruising/bleeding, occult blood on rectal examination

image Laboratory studies: Complete blood count with manual differential, mean corpuscular volume (MCV), peripheral smear, reticulocyte count, Coombs test

Cohen AR: Pallor. In Fleisher GR, Ludwig S, Henretig FM (eds): Textbook of Pediatric Emergency Medicine, 5th ed. Philadelphia, Lippincott Williams & Wilkins, 2006, pp 535–543.

2 What is the underlying pathophysiology of sickle cell disease (SCD)?

SCD is due to an inherited hemoglobinopathy in which a single mutation causes an amino acid substitution in the β-globin chain. This results in abnormally shaped red blood cells (RBCs) that are prone to aggregation and vascular injury, resulting in vaso-occlusion and resultant complications, such as splenic infarction (resulting in increased susceptibility to infection), stroke, and pain from ischemia. There are many genotypes of sickle cell disease, including SCD-SS, -SC, -Sβ+ thalassemia, and -Sβ0 thalassemia. Patients with SCD-SS and SCD-Sβ0 thalassemia usually have a more severe clinical course.

3 What are the life-threatening complications of SCD?

image Sepsis

image Stroke

image Splenic sequestration crisis

image Acute chest syndrome

image Aplastic crisis

National Institutes of Health/National Heart, Lung, and Blood Institute Division of Blood Diseases and Resources: The Management of Sickle Cell Disease, 4th ed. Bethesda, MD, National Institutes of Health, 2002, NIH publication no. 02–2117, 2002, pp 1–188.

4 Why is a patient with SCD immunocompromised?

Splenic microinfarctions due to sickling of red cells cause altered splenic function. As a result, patients with SCD are prone to infection with encapsulated organisms, such as Streptococcus pneumoniae.

5 What causes painful crisis in patients with SCD?

Vaso-occlusive crises are due to localized sickling and vascular occlusion. This can occur in any organ, but most frequently affects bone and viscera. Most older children report long bone, back, and abdominal pain. Precipitating events may include infection, dehydration, fever, or exposure to cold.

6 How should painful crisis be treated?

Assess the severity of pain and associated organ systems. IV hydration, usually at 1.5 times the maintenance rate, and narcotic administration are frequently required. Administration of oxygen is often recommended. It is important to inquire about pain medications given at home, and if these were ineffective to administer an appropriate dose of a more potent analgesic medication. Morphine is often used at an IV dose of 0.1 or 0.2 mg/kg/dose every 1–4 hours.

7 What is dactylitis?

Dactylitis, or “hand-foot syndrome,” results from vaso-occlusion of the nutrient arteries that supply the metacarpal and metatarsal bones, causing bone marrow infarction in patients with SCD. This is a form of vaso-occlusive crisis most common in young infants (mostly under age 2 years) and results in pain and swelling of the hands and feet, irritability, and refusal to walk. It is usually bilateral, distinguishing it from cellulitis.

8 Define acute chest syndrome and its causes and treatment

Acute chest syndrome is a serious complication of SCD and can be life threatening. The syndrome is defined as a new pulmonary infiltrate and chest pain, hypoxia, fever, tachypnea, wheezing, or cough. Both infectious (e.g., chlamydia, mycoplasma, viruses, bacteria) and noninfectious (e.g., fat embolism, pulmonary infarction) causes have been described. Supportive care measures include analgesia, cautious hydration, oxygen, antibiotics, bronchodilators, and blood transfusions.

Vichinsky EP, Neumayr LD, Earles AN, et al: Causes and outcomes of the acute chest syndrome in sickle cell disease. N Engl J Med 342:1855–1865, 2000.

9 What is splenic sequestration crisis?

Splenic sequestration crisis is a life-threatening complication of SCD that occurs when a large portion of a patient’s blood volume becomes acutely trapped in the spleen. This leads to massive splenomegaly, acute anemia, and hypovolemic shock. Treatment is supportive and includes hospitalization, fluid resuscitation, and blood transfusion. Splenic sequestration is seen in young children, typically between 3 months and 5 years of age.

KEY POINTS: LIFE-THREATENING COMPLICATIONS OF SICKLE CELL DISEASE

1 Sepsis

2 Stroke

3 Splenic sequestration crisis

4 Acute chest syndrome

5 Aplastic crisis

10 Which virus frequently leads to aplastic crisis in children with SCD?

Parvovirus B19. This causes brief suppression of erythropoiesis, which is not tolerated in patients with SCD who are already anemic, and patients may present with fatigue, shortness of breath, and severe anemia with reticulocytopenia. Treatment is supportive, and RBC transfusions are often necessary.

11 Are aplastic crises due to parvovirus B19 seen only in patients with SCD?

No. Parvovirus B19 can also cause aplastic crises in patients with other chronic hemolytic diseases, such as thalassemia or hereditary spherocytosis. These patients have shortened RBC survival and frequently cannot tolerate even a brief suppression of erythropoiesis.

12 How should patients with SCD and fever be treated in the ED?

Because these children are at high risk for serious bacterial infections, febrile children with SCD need rapid treatment with parenteral antibiotics after appropriate cultures are obtained. The greatest risk of serious bacterial infection is between the ages of 6 months and 3 years, when protective antibodies are not adequate and splenic function is greatly diminished. After administration of IV antibiotics, the conventional approach has been to admit these patients to the hospital. Currently, some hematologists advocate cautious outpatient management of selected well-appearing febrile patients.

13 What are considered to be low-risk criteria for outpatient management of febrile patients with SCD?

image Well appearance

image No focal findings

image Temperature < 40°C

image White blood cell count > 5000 but < 30,000 cells/mm3

image No pulmonary infiltrates

image Baseline hemoglobin, white blood cell, and platelet counts

Wilimas JA, Flynn PM, Harris S, et al: A randomized study of outpatient treatment with ceftriaxone for selected febrile children with sickle cell disease. N Engl J Med 329:472–476, 1993.

14 If a patient with SCD meets the above criteria, what is the recommended treatment plan?

These patients should receive an initial dose of parenteral ceftriaxone in the ED. Further treatment may consist of oral amoxicillin. Close follow-up must be arranged if febrile patients with SCD are discharged, including telephone follow-up or scheduling of a revisit within the next 24 hours.

Wilimas JA, Flynn PM, Harris S, et al: A randomized study of outpatient treatment with ceftriaxone for selected febrile children with sickle cell disease. N Engl J Med 329:472–476, 1993.

15 An ill-appearing 6-year-old girl presents with weakness for 2 days. On examination she has jaundice and pale conjunctivae but no bruising or petechiae. Her hemoglobin level is 4 g/dL, but her white blood cell and platelet counts are normal. Her reticulocyte count is 20%. She has unconjugated hyperbilirubinemia, and she has dark-brown urine (which is dipstick-positive for blood but has no RBCs on microscopic examination). This presentation suggests what broad category of anemia?

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