From the EM Model
8.0 Hematologic Disorders
8.5 Red Blood Cell Disorders

Editors Note: In last month’s ACEP News, “Focus On… Critical Decisions,” we presented an overview of the pathophysiology of sickle cell disease in children, focusing on common and concerning presentations. In this month’s article, we continue the discussion, looking at emergency department evaluation and management of this condition.

Objectives

On completion of this lesson, you should be able to:

1. Explain the rationale for specific diagnostic studies and treatments.
2. List the indications for blood transfusion in a patient with SCD.
3. Describe the indications for hospital admission.

Sickle cell disease (SCD) is a hereditary hemoglobinopathy that is characterized by anemia and a wide array of pathology secondary to intermittent small blood vessel occlusion. It is estimated that 1 in 600 African Americans in the United States has the disease; SCD can also be seen in people of Indian, Mediterranean, and Middle Eastern descent. Children with SCD presenting to the emergency department represent a unique challenge. Even though vasoocclusive crisis (VOC) is the most common presentation, there is a much higher incidence of potentially life-threatening pulmonary, central nervous system, gastrointestinal, and infectious complications in children because of the unique anatomic and physiologic characteristics of children. This, along with the challenges in obtaining an accurate history and physical examination, makes it important that emergency physicians understand the complexities of SCD in children.

Case Presentation

A 7-year-old boy is brought in by his parents because the child had a seizure at home about 1 hour earlier. The seizure was described as generalized, uncontrolled shaking that lasted about 5 minutes. The patient had been complaining of a headache for several hours that was not relieved by over-the-counter analgesics. There is no fever, history of recent illness, nausea, or vomiting. The patient does not have a history of seizure disorder; his only significant medical history is SCD, although he has not had any problems in the previous year.

His vital signs are blood pressure 95/50, pulse rate 90, respiratory rate 20, temperature 36.7°C (98°F), and pulse oximetry 98% on room air. On physical examination, the child appears tired and is lying quietly on the gurney. He is able to answer questions appropriately. His pupils are equal and reactive to light, and extra-ocular movements are intact. There is no facial asymmetry. There is no nuchal rigidity. His lungs are clear to auscultation; his heart has a regular rhythm and normal rate, and there are no murmurs. His abdomen is nondistended, has normal bowel sounds, and is soft and nontender to palpation. Strength testing reveals mild weakness in the left upper and lower extremities.

CRITICAL DECISION

What diagnostic tests should be ordered?

As with most disease processes, the use of laboratory and radiographic testing is guided by the history and physical examination. However, given the unique nature of the disease in children, emergency physicians should have a low threshold for ordering certain tests.

The CBC and the reticulocyte count are the two most important tests that should be considered when treating an SCD patient with complications.

When a pediatric SCD patient with pulmonary complaints presents, the emergency physician should obtain a chest radiograph. The presence of cough, fever, wheezing, or shortness of breath should prompt a search for pneumonia, pulmonary infarct, and acute chest syndrome. Other studies should be ordered based on the clinical presentation. Given the susceptibility to encapsulated bacteria, emergency physicians should have a low threshold for ordering a urinalysis, blood cultures, and a lumbar puncture. CT scanning should be obtained in the SCD child presenting with a headache or a neurologic deficit.

CRITICAL DECISION

Does the patient require analgesics and/or antibiotics?

Immediate and aggressive analgesia (typically in the form of parenteral narcotics) is the mainstay of treatment for SCD patients presenting to the emergency department and is the required intervention in the patient suspected of experiencing a painful crisis. During the course of the emergency department visit, the patient’s pain level should be regularly assessed to ensure adequacy of analgesia. A number of pain assessment tools for children exist (visual analog scale, numeric rating scale, Wong-Baker face scale). The choice of tool depends on factors such as age, cognitive ability, and emotional state.¹

Acetaminophen and nonsteroidal anti-inflammatory drugs (NSAIDs) can be used for the management of mild to moderate pain. Opioids are considered to be the drugs of choice for more severe episodes of VOC pain. There are no studies that demonstrate superiority of one drug over another. Oral agents such as codeine (0.5-1 mg/kg), oxycodone (0.05-0.15 mg/kg), and hydromorphone (0.03-0.08 mg/kg) may be tried. For severe pain, parenteral narcotics are indicated. Morphine is one of the most frequently used parenteral narcotics in this setting.

The starting dose is 0.1 to 0.15 mg/kg; it may be given intravenously, intramuscularly, subcutaneously, or rectally. The patient should be reassessed frequently; repeated doses can be administered until adequate pain control is achieved or until sedation or respiratory depression approaches an unacceptable level. Additional adverse effects include rash, pruritus, hypotension, and nausea and vomiting. Meperidine had been used commonly as an analgesic for SCD. However, of all the opioids, it likely has the least favorable pharmacologic profile. Given the availability of other, equally effective, narcotics, emergency physicians should avoid meperidine.

As SCD patients are at high risk for infection by organisms such as Pneumococcus, Staphylococcus species, Haemophilus influenzae, and Salmonella, and as children with SCD have a several hundred-fold higher risk for sepsis than healthy children, one must have a low threshold for administering appropriate antibiotics. A careful history and physical examination coupled with appropriate diagnostic studies will guide the choice of antibiotics.

CRITICAL DECISION

Which patients require blood transfusions?

Transfusion in the acute setting is used to treat significant and symptomatic anemia and to reduce or prevent complications.³ Severe anemia usually occurs in the setting of aplastic crisis and hyperhemolytic syndrome. In general, SCD patients exhibiting signs (severe tachycardia, hypotension) or symptoms (dyspnea, syncope, severe pain) along with a significant drop in hemoglobin or an absolute hemoglobin below 6 g/dL will benefit from simple red cell transfusion. Exchange transfusion (in which the patient’s abnormal RBCs are removed and replaced with normal RBCs) is generally accepted for the treatment for acute chest syndrome, stroke, intrahepatic cholestasis, acute splenic sequestration, and multiorgan failure.³ Although not well studied, it is also used for the treatment of priapism that is unresponsive to pharmacologic therapy. All transfusions should be done in consultation with a hematologist.

CRITICAL DECISION

Who requires admission to the hospital?

In general, children who present to the emergency department with complications of SCD should be admitted to the hospital. This is because of the high risk for associated sepsis/infection, anemia, and acute chest syndrome. Additionally, the difficulties inherent in obtaining an accurate history and a reliable physical examination in children make it important that the emergency physician have a low threshold for admitting these patients. The patient with typical, uncomplicated VOC with adequate pain control in a timely fashion in the emergency department (typically an older child with the ability to communicate effectively) may be discharged. Those discharged from the emergency department must have a supportive home environment and close followup care.

Case Resolution

In the case of the boy who had a seizure, an emergent CT of the head showed an area of hypodensity in the right parietal lobe. There was no evidence of hemorrhage. Both a pediatric hematologist and a pediatric neurologist were consulted. Because of the patient’s neurologic symptoms, arrangements were made for an exchange blood transfusion, and he was admitted to the pediatric ICU.

During his hospital stay, the patient gradually regained strength in his left extremities and was eventually discharged from the hospital with minimal motor deficits. He was also seizure free throughout his hospital stay.

Summary

Children with SCD represent a unique challenge given the potential for life-threatening pulmonary, central nervous system, gastrointestinal, and infectious complications associated with the unique anatomic and physiologic characteristics of children.

Emergency physicians must maintain a high suspicion for complications, as they may not be apparent on the initial evaluation. Pain control, in the form of parenteral narcotics, is the mainstay of treatment for SCD patients presenting to the emergency department, but emergency physicians must also be prepared to initiate transfusion or admit those patients requiring transfusion. Through vigilant care, the emergency physician can help achieve improved outcomes for these patients.

References

1. Ellison AM, Shaw K. Management of vasoocclusive pain events in sickle cell disease. Pediatr Emerg Care. 2007;23(11):832-838.
2. Ballas SK. Management of sickle pain. Curr Opin Hematol. 1997;4:104-111.
3. Ohene-Frempong K. Indications for red cell transfusion in sickle cell disease. Semin Hematol. 2001;38: 5-13.