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<< Current Guidelines For Sickle Cell Disease: Management Of Acute Complications

The Management Of Sickle Cell Disease.

This 2002 document was developed by a multidisciplinary group that was organized by the National Heart Lung and Blood Institute. The portion of the document devoted to treatment of acute and chronic complications of SCD is divided into 12 chapters. Each chapter was prepared by 1 or more experts in the group and then reviewed by other members of the panel; however, there is no explicit methodology presented for developing the document. Recommendations are referenced and based on best evidence and standards of practice, but there is no grading system for the quality of evidence or the strength of recommendations. The guideline is, therefore, a literature-based consensus document developed without systematic methodology.

Panel members' conflicts of interest are not disclosed in the document. The guidelines apply to all patients with SCD and are meant for all health care practitioners who care for patients with SCD. Only recommendations that pertain to emergency medicine are summarized and reviewed here.

Infection Recommendations
  • Parents should be discouraged from using antipyretics at home and informed that a temperature > 38.5C (101.3F) is an emergency requiring medical evaluation.
  • All "toxic-looking" patients and those with meningismus should receive a lumbar puncture.
  • Children with SCD and fever may be considered for outpatient therapy if:
    • The patient is non-toxic appearing
    • Maximum temperature is < 40C (104F)
    • The patient has no history of sepsis
    • White blood cell, platelets, and hemoglobin counts are at baseline levels for that patient
    • The patient remains stable in the ED for at least 3 hours
    • There is no history of endemic Streptococcus pneumoniae resistance to antibiotics in the community
    • The patient is appropriately trained and reliable
    • There is a followup program in place
  • Well-appearing children with SCD and fever should still be admitted if any of the following are present:
    • Infiltrate on chest x-ray or abnormal oxygen saturation
    • White blood cell count > 30,000/μL or < 5,000/μL
    • Platelet count < 100,000/μL
    • Hemoglobin < 5 g/dL
    • History of sepsis
  • Children with SCD and fever who are discharged from the ED should be given 1 dose of parenteral antibiotic that covers Haemophilus influenzae and Streptococcus pneumoniae (eg, ceftriaxone 75 mg/kg).
  • In patients with bone pain and fever, cultures of subperiosteal or joint fluid should be obtained by aspiration of the suspected bone lesion prior to initiation of antibiotics.

Editoral Commentary:

Infection is the major cause of mortality in SCD. Virtually all patients with SCD are functionally asplenic, predisposing them to overwhelming infections from encapsulated microorganisms. Children are at the greatest risk, and Streptococcus pneumoniae sepsis is the most common cause of death in children with SCD.10 Adults are less vulnerable because their immune systems have matured to allow type-specific polysaccharide antibody production; however, fever must be taken very seriously in all patients with SCD. 
The National Institutes of Health guidelines reflect the danger that fever presents in a SCD patient. The criteria for discharging a febrile patient should be used cautiously and with the support of a treating outpatient physician. Given their immunocompromised state, SCD patients have the capacity to decompensate in the setting of apparently mild illness.

The most controversial recommendation in this section of the guidelines involves aspirating from infected bone prior to administering antibiotics. This recommendation is based on the similar radiographic appearance of non-infected bone and osteomyelitis in patients with SCD; infection may be obscured by the administration of antibiotics prior to culture of the affected area.

Though use of antibiotics prior to culture in SCD patients with bone pain may complicate later treatment decisions, this recommendation must be balanced with the consequences of delaying antimicrobial coverage in patients with significant potential to deteriorate, especially when a clinician skilled in bone aspiration is not immediately available. In clinically toxic patients, antibiotics should not be delayed to obtain subperiosteal cultures.

Transient Red Cell Aplasia: Recommendations
  • Patients with transient red cell aplasia (TRCA) should be transfused only if they become symptomatic from their anemia.
  • Patients with TRCA should be treated with intravenous immunoglobulin (IVIg) once the diagnosis is made.
  • Patients with TRCA should be isolated from pregnant healthcare workers and other pregnant patients.
Editoral Commentary:

Patients with TRCA will typically exhibit reticulocytopenia 5 days after an upper respiratory or gastrointestinal illness. Anemia develops on the sixth day and hemoglobin on presentation was, on average, 3.9 g/dL.11 The majority of TRCA is caused by parvovirus B19 infection.12 The virus, which is directly cytotoxic to erythroid precursors, causes transient suppression of erythropoiesis. This condition can be recognized by significant anemia after an illness without signs of hemolysis. IVIg infusion is the standard of care for this condition, based on biological plausibility and case reports of successful treatment.13 Once the infection has resolved, immunity is lifelong. Parvovirus infection is highly communicable, and most adults have acquired immunity. The recommendation that patients with TRCA be isolated is based on the potential for parvovirus infection during the second trimester of pregnancy to result in hydrops fetalis and stillbirth.14

Stroke: Recommendations
  • Tissue plasminogen activator (tPA) is not recommended for the treatment of acute ischemic stroke (AIS) in children with SCD.
  • Transfusion is the treatment of choice for AIS in children with SCD. Exchange transfusion is preferred over simple transfusion.
  • Fever and hyperthermia should be treated aggressively in children with stroke; however, there is insufficient evidence to recommend therapeutic hypothermia.
  • When transient ischemic attack (TIA) is suspected, children with known cerebrovascular disease (as documented by magnetic resonance imaging or transcranial Doppler) should receive exchange transfusion. If it is not known whether the child has cerebrovascular disease, an urgent transcranial Doppler, PET, or magnetic resonance spectroscopy should be performed and the child transfused if the results are suggestive of an ischemic insult.
  • Antiplatelet agents are not indicated for the treatment of AIS in children with SCD.
  • In adults with SCD and ischemic stroke, tPA should be considered. Aspirin is recommended if tPA is not used.

Editoral Commentary:

Children with SCD are at greatly increased risk for both ischemic and hemorrhagic stroke.15 In contrast to conventional thrombotic or embolic stroke, the mechanism for ischemic stroke in children with SCD is thought to result from abnormal cell adhesion, intravascular sickling, and abnormal smooth muscle tone. Because of these differences, conventional therapies are not recommended for these patients. The treatment for ischemic stroke in children with SCD is exchange transfusion, and in situations such as TIA where the diagnosis may be unclear, the child should be admitted for a cerebrovascular evaluation (transcranial Doppler, PET, or magnetic resonance spectroscopy).16

Stroke symptoms in adults with SCD are thought to be more likely due to common ischemic stroke mechanisms; therefore, in adults, conventional therapies are recommended. Tissue plasminogen activator has never been studied in patients with SCD, so it is recommended that administration of tPA should be in accordance with institutional guidelines and in consultation with a neurologist.

Ophthalmologic Emergencies: Recommendations
  • In patients with SCD, eye trauma with or without hyphema requires emergent ophthalmologic consultation and evaluation.
  • In patients with sickle cell trait, eye trauma with or without hyphema requires emergent ophthalmologic consultation and evaluation.
  • In situations such as retinal detachment or non-clearing vitreous hemorrhage where emergent surgical intervention is required, patients should receive partial exchange transfusion with a target of 50 to 60% normal red blood cells prior to surgery.

Editoral Comment:

Patients with SCD are predisposed to a number ofophthalmologic complications.17 Proliferative and non-proliferative changes on the retina cause vitreous hemorrhage and retinal detachment. Because the propensity for vascular occlusion predisposes patients to central retinal artery occlusion, all acute visual changes in patients with SCD must be regarded as true ophthalmologic emergencies.

Additionally, even minor eye trauma can place a SCD patient's eye at risk. This concept applies not only to patients with SCD, but also to patients with sickle cell traitan otherwise benign condition. Anterior segment trauma may result in hemorrhage into the anterior chamber of the eye, allowing sickled erythrocytes to clog the trabecular outflow channels and raise the intraocular pressure, producing an acute glaucoma syndrome. Classically, with hemorrhage into the anterior chamber, a hyphema can be observed. The guidelines recommend ophthalmologic consultation even in the absence of hyphema because microscopic amounts of hemorrhage can clog trabecular channels and raise intraocular pressure. Emergency physicians may consider discharging SCD patients with minor eye trauma with prompt ophthalmologic follow-up if hyphema is absent, visual acuity is normal, and serial measurements of intraocular pressure remain normal over several hours of ED observation.

Acute Chest Syndrome: Recommendations
  • In patients with acute chest syndrome (ACS), a baseline arterial blood gas (ABG) measurement should be obtained, followed by serial ABG measurements to evaluate for worsening A-a gradient.
  • In patients with ACS and moderate hypoxemia (PaO2 = 70 to 80 mm Hg, O2 saturation = 92% to 95%), supplemental oxygen should be administered via nasal cannula at a rate of 2 liters per minute.
  • Patients with ACS should use an incentive spirometer to prevent hypoventilation.
  • In patients with ACS, exchange (or conventional) transfusion should be initiated if the PaO2 is below 70 mm Hg on room air or if there is a drop in PaO2 greater than 10 mm Hg in patients with chronic hypoxemia.
  • All patients with ACS should receive antibiotics that cover typical and atypical microorganisms.
  • Intravenous fluids given to patients with ACS should not exceed 1.5 times maintenance. Normal saline is contraindicated and 5% dextrose in water, one-quarter or half normal saline should be used.
Editoral Comment:

Acute chest syndrome is variably defined in the literature, but a conservative definition would include fever and respiratory symptoms accompanied by a new pulmonary infiltrate on chest x-ray. This presentation may be clinically indistinguishable from pneumonia (and indeed, the cause of ACS is frequently infection), but it also includes other etiologies including fat embolus and pulmonary infarctions.8 Acute chest syndrome carries a high risk of progression to respiratory failure and should be considered in all SCD patients with respiratory signs or symptoms.

The treatment for ACS is exchange transfusion (or simple transfusion if exchange transfusion is unavailable) and the NIH guidelines recommend a transfusion trigger based on ABG measurements. In some cases, the decision to transfuse can be made clinically without the evaluation of arterial blood. Patients with pulmonary infiltrate and marked respiratory distress or poor pulse oximetry will undoubtedly require transfusion and ABG measurements should not delay this therapy. The recommendation for serial ABG measurements is also controversial. Cohort studies indicate that A-a gradient is the best predictor of clinical severity and the guidelines recommend that all patients with worsening A-a gradients be managed in an intensive care setting.18 Arterial blood gas evaluation can assist but should never supersede clinical judgment, and patients can be assigned to an appropriate level of care without the repeated use of this invasive test.

Splenic Sequestration: Recommendations
  • All patients with acute splenic sequestration should be admitted for observation.
  • All patients with acute splenic sequestration should be transfused immediately.

Editoral Commentary:

Acute splenic sequestration is the most common cause of an acute exacerbation of anemia in patients with SCD.19 It typically occurs between the ages of 3 months to 5 years but has been reported as early as 5 weeks of age. Acute splenic sequestration is clinically defined as a drop in hemoglobin of more than 2 g/dL, elevated reticulocyte count, and an enlarging spleen. Patients typically present with sudden weakness, pallor, tachycardia, tachypnea, and abdominal fullness. The mortality of this disease is approximately 12%, and death can occur within a matter of hours. All patients should be transfused emergently and admitted.20

Priapism: Recommendations
  • Upon arrival to the ED, if the patient has had priapism for less than 2 hours, conservative treatment with IV fluids and analgesics should be initiated.
  • Once priapism has been present for 3 hours, drainage of the corpora cavernosa followed by irrigation of the corpora cavernosa with a 1:1,000,000 solution of epinephrine in saline should be performed.
  • In patients with priapism, if drainage and irrigation fail, exchange transfusion should be considered.
Editoral Comment:

Priapism is a well-recognized complication of SCD that can result in fibrosis and impotence even when proper treatment is initiated. The NIH recommendations are based on the experience from a small prospective cohort that obtained good clinical results.21 In patients who fail conventional therapy, exchange transfusion may be considered, but clinicians should be aware that exchange transfusion for priapism has been anecdotally associated with neurologic events such as seizure and stroke (referred to as the ASPEN syndrome).
Source: US Department of Health and Human Services; National Institutes of Health; National Heart, Lung, and Blood Institute.

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Last Modified: 07/23/2017
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