Definition: painful episodes due to vaso-occlusion; can be life threatening.

Evaluation

• Try to determine precipitating factor(s). Common precipitants include stress, dehydration, drug and alcohol use, infection, hypoxia and MI.
• "Routine" pain crises without specific precipitants are not uncommon. While pain crises often present with non-specific elevations in WBC and low-grade fevers, complete work up of concomitant infection is important.

Acute Chest Syndrome

• One of the dreaded complications of sickle cell disease and a leading cause of death in adults. 
• Consider this diagnosis in any patient with cough, chest pain, wheezing, shortness-of-breath, fever, and/or new infiltrate on CXR. A clear chest X-ray does not rule out acute chest syndrome. 
• Etiology is not fully known, but thought to involve micro/macro-vascular infarction, pulmonary fat emboli, and concurrent viral/bacterial infection. 
• Initial management consists of supportive care, bronchodilators, incentive spirometry, treatment of coexisting infection, and transfusions if needed. However, true acute chest syndrome almost always requires exchange transfusion. The goal of these transfusions is to get HgbS <30% and Hgb up to 9-10 g/dL. Discuss this with your Hematology consultant whenever there is a concern for acute chest syndrome. Simple transfusions are only appropriate when patient is severely anemic and simple transfusion can achieve the numbers above (rare).

Aplastic Crisis

• A sharp decrease in erythropoiesis, aplastic crisis, can cause acute anemias in patients with sickle cell disease.
• Patients will typically present with a new anemia and markedly decreased reticulocytes.
• Commonly associated with parvovirus infections, aplastic crisis also may result from a number of infectious agents.

Management

• Use an individualized pain protocol if available. 
• IV fluids: moderate hypotonic (e.g., D5½NS) hydration (1.0-1.5x maintenance needs). Note that aggressive hydration can lead to or exacerbate acute chest syndrome.
• Nursing: O2 0-4 L/min by NC.
• Labs: CBC, reticulocyte count, electrolytes, BUN, creatinine, bilirubin, LDH, urinalysis, CXR, blood and urine cultures. Draw red top tube to hold for a type and screen. (If patient is to be transfused, alert the blood bank as patients with sickle cell disease will be screened more thoroughly to avoid alloimmunization associated with frequent transfusions.)
• Meds: folic acid 1 mg PO daily in addition to analgesia. Avoid demerol, as these patients will likely require large doses of opioids to control pain, and are at greatly increased risk of seizures from large doses of demerol. If antibiotic coverage is indicated, ceftriaxone + an atypical (e.g., macrolide) is usually a good starting point.

Key Points

• Stroke, MI, persistent priapism, or intractable pain characterize acute vaso-occlusive crises. Exchange transfusion is indicated in these cases. Also, multi-organ failure requires urgent exchange transfusion.
• If patient with frequent episodes of pain crisis, consider hydroxyurea as prophylaxis.
• Do not be surprised by massive opioid tolerance and the need to rapidly escalate the analgesia dose required for relief. 
• Remember that physicians typically under-treat pain and that patients with sickle cell disease are often unfairly stereotyped as “drug-seeking.”

Mehta SR, Afenyi-Annan A, Byrns PJ, et al.  Opportunities to improve outcomes in sickle cell disease.  Am Fam Physician 2006;74:303-310.