Sickle Cell Disease NCLEX Review

Sickle cell disease (SCD) is one of the most common inherited hematologic disorders. In SCD, hemoglobin A is either partially or completely replaced with defective hemoglobin called hemoglobin S. The condition is characterized by abnormally shaped red blood cells that can’t effectively carry oxygen to the tissues. In a healthy individual, red blood cells are round and flexible so they can fit through tiny capillaries easily. In SCD, the cell is crescent shaped, rigid and sticky. As a result, these abnormal cells can get lodged in the small blood vessels leading to microvascular occlusion, severe pain, tissue ischemia, and organ damage. When this occurs it is called a vaso-occlusive crisis. Repeat or serious episodes can ultimately lead to organ failure. 

The four crises of sickle cell crisis

When a patient has an exacerbation of sickle cell disease, they are in what is called a “sickle cell crisis” of which there are four types.

• Vaso-occlusive crisis – A common occurrence in those with SCD, a vaso-occlusive crisis involves blockages in the microvasculature leading to ischemia and infarction. 
• Hyperhemolytic crisis – This occurs when there is rapid destruction of red blood cells.
• Splenic sequestration – This serious complication is caused by clumping and pooling of blood in the spleen.
• Aplastic crisis – This crisis is often triggered by folic acid depletion or a viral infection and involves reduced production of red blood cells occurring along with greater destruction of red blood cells.

How else does sickle cell disease affect different systems in the body?

The manifestations and complications of sickle cell disease are widespread, and essentially any organ or tissue can be affected.

Hematologic – The lifespan of sickled cells is much shorter than that of healthy cells and the spleen breaks them down with more frequency. This leads to severe hemolytic anemia.

Spleen – Over time, as the sickled cells cause infarctions throughout the spleen, scarring and fibrosis lead to the spleen becoming non-functional. Additionally, sickle-shaped cells get stuck in the splenic pulp, which leads to severe anemia and a rapidly enlarging spleen in a condition called splenic sequestration. Many patients with SCD will ultimately undergo a splenectomy.

Pulmonary – Acute chest syndrome (ACS) is the most common acute pulmonary condition that affects patients with SCD and is a leading cause of death and hospitalization in this patient population. It is defined as new opacity on a chest x-ray that occurs with respiratory symptoms and fever. In children, it is often triggered by infection, and in adults it is more likely to be triggered by vaso-occlusive events or pulmonary embolism.

Pulmonary hypertension affects approximately 10% of patients with SCD. The pathogenesis of how this occurs is not fully known, but it is thought to be due, in part, to endothelial damage from recurrent sickling. 

Other pulmonary complications of SCD include pulmonary embolism, chronic dyspnea, pulmonary fibrosis, sleep apnea and asthma.

Cardiovascular – Patients with SCD can develop cardiovascular complications including cardiomyopathy, diastolic dysfunction, sudden cardiac death, and thrombosis.

Renal – Sickle cell nephropathy is a group of renal abnormalities that collectively cause renal dysfunction and can lead to chronic kidney disease and renal failure. Some patients will require dialysis or even a kidney transplant.

Neuro – Patients with SCD are at higher risk for stroke. While it affects individuals of all ages, sickle cell disease is the most common cause of stroke in childhood. One study found that the median age of onset for cerebral infarction was age 14 and the median age of onset for intracranial hemorrhage was 30 years.

Other GI – Aside from the spleen, other organs of the gastrointestinal system can be affected. Complications include ischemic colitis, liver infarction, acute sickle hepatic crisis (a pain crisis in the liver), and cholelithiasis.

Other – Other complications include vision loss, painful leg ulcers, avascular necrosis (death of bone tissue that most commonly affects the hip joint), frequent infections, priapism, and of course, the severe pain associated with a vaso-occlusive crisis. 

Life expectancy – Though early newborn screenings have played a large part in increasing life expectancy for individuals with SCD, the median life expectancy remains low at just 54 years. 

Who is most at risk for sickle cell disease?

As an autosomal recessive genetic disorder, both parents must carry the sickle cell gene in order for the trait to manifest in their children. It is most common in individuals of African, Mediterranean, and Middle Eastern descent. A 2020 study revealed that 8% of African Americans possess the gene for sickle cell disease.

Sickle cell disease Straight A Nursing LATTE method:

Now that you have a basic understanding of sickle cell disease, it’s time to review the nursing implications using the Straight A Nursing LATTE Method.

L: How does the patient LOOK?

A patient in sickle cell crisis will have varying symptoms depending on what type of crisis they are experiencing. 

• In vaso-occlusive crisis (the most common clinical manifestation of SCD) the patient will complain of unrelenting abdominal pain as well as swollen and painful hands, feet, and joints. 
• Common signs in hyperhemolytic crisis include anemia, reticulocytosis (increased numbers of immature RBCs), and jaundice. 
• With splenic sequestration, the patient may show signs of significant anemia, hypovolemia and even shock.
• A patient in aplastic crisis will have significant anemia, weakness, and pallor.

Other signs and symptoms of sickle cell disease will vary based on the organ system affected and severity of the condition. This can include:

• Chest pain, tachypnea, shortness of breath, cough and respiratory distress may be present in cases of acute chest syndrome, which can be fatal in and of itself.
• An enlarged liver and/or spleen may be present. Over time, as the splenic tissue becomes scarred, the organ reduces in size and may ultimately be impalpable.
• Jaundice may be present in cases of hepatic involvement.
• Fatigue and exercise intolerance secondary to chronic and acute anemia
• Swollen hands and feet due to blockages in blood vessels
• Reduced visual acuity
• Frequent infections
• Chronic dyspnea
• Swollen, painful joints
• Leg ulcers
• Delayed growth in children as well as delayed puberty

Note that children under six months of age typically do not show symptoms due to the large amount of fetal hemoglobin that is present for the first few months of life.

A: How do you ASSESS the patient?

Since patients are typically hospitalized during vaso-occlusive episodes, a thorough pain assessment is a vital component of your care plan. In addition to obtaining a full set of vital signs, tailor your assessments to whichever organ systems are affected by the condition. 

Some specific assessments include: 

• Conduct a complete neurological assessment, since patients with SCD are at much higher risk for stroke.
• Track I/O and monitor for signs of fluid overload secondary to renal impairment or heart failure. 
• Assess urine output and make note of hematuria or foamy urine (a sign of proteinuria).
• Monitor respiratory status for signs of acute chest syndrome or pulmonary edema secondary to fluid overload. Listen to lungs, measure SpO2, observe work of breathing, inquire about chest pain, and watch for signs of respiratory distress. 

T: What TESTS will be conducted?

In the U.S., the most important test is mandatory early screening of newborns. Testing can also be conducted in utero via amniocentesis or chorionic villus sampling for those at especially high risk. 

Screening tests for sickle cell disease include:

• Sickle turbidity test (also called hemoglobin solubility) – Conducted via fingerstick but may yield a false positive result and is not used on its own for diagnosis
• Stained blood smear – Will show the sickled cells
• Hemoglobin electrophoresis – Shows the presence of hemoglobin S
• CBC with reticulocyte count – This test shows if anemia is present and if there are a large number of immature RBCs (reticulocytes). 

Other ongoing tests for a patient with SCD can include:

• Routine CBC to assess for anemia and infection
• Urinalysis, BUN and Cr will be monitored in patients with sickle cell nephropathy 
• Electrolytes may be abnormal, especially in cases of renal impairment
• Liver function tests will be abnormal in patients with hepatic involvement
• Chest x-ray and arterial blood gas will be utilized to evaluate acute chest syndrome or pulmonary embolism
• Echocardiogram will be utilized to evaluate a patient with heart failure
• MRI scans may be utilized to diagnose avascular necrosis
• Ophthalmological exams will be performed in patients with decreased visual acuity and may reveal corkscrew shaped vessels

T: What TREATMENTS will be provided?

• Treatments for vaso-occlusive crisis include IV fluids (to flush out occlusions and improve blood flow), pain medication, blood transfusions and oxygen therapy.
• Pharmacological treatments are aimed at decreasing hemolysis and the frequency of crisis events. Medications include hydroxyurea, voxelotor, L-glutamine and crizanlizumab. 
  • Hydroxyurea is an antineoplastic agent taken by mouth that helps reduce sickling. A common side effect of this medication is leukopenia (low WBCs), so watch your patient for signs of infection.
  • Voxelotor is a hemoglobin S polymerization inhibitor that binds to hemoglobin S and improves its affinity for oxygen which, in turn, reduces sickling and improves blood viscosity. Common adverse effects include headache, fatigue, fever, nausea, diarrhea, abdominal pain and rash.
  • L-glutamine is a naturally occurring amino acid. Though the mechanism of action is not fully understood, studies show it can reduce the frequency of vaso-occlusive crisis.
  • Crizanlizumab is a monoclonal antibody administered IV. Common adverse effects include fever, joint pain, back pain, abdominal pain and nausea.
• Folic acid supplementation is utilized to replace folate depleted by the increased erythropoiesis that occurs in SCD, and thereby reduce anemia.
• Blood transfusions as needed to address anemia.
• Frequent blood transfusions can cause iron levels to increase, which causes patients with SCD to have more painful episodes and greater risk for organ failure. Iron chelation therapy may be utilized to remove excess iron from the body.
• Splenectomy may be necessary in patients experiencing splenic sequestration crisis, splenomegaly, and splenic infarction.
• Patients with avascular necrosis of the femoral head may undergo hemiarthroplasty.
• Pneumococcal vaccines are administered to prevent infection.
• Prophylactic penicillin is utilized in children with SCD until they receive all their pneumococcal vaccinations or until they reach age 5 (whichever is later).
• Bone marrow transplant is the only available treatment that can cure SCD, though it doesn’t come without risks of its own. Learn more about BMT here.

E: How do you EDUCATE the patient and family?

Because sickle cell disease is a chronic, life-long condition the amount of patient/family teaching is extensive. Many times your teaching will focus on the specific organ involvement your patient is experiencing. General teaching points for sickle cell disease include:

• Teach the patient/parents that triggers for vaso-occlusive crisis can vary from person to person and to avoid anything that has triggered a crisis in the past. Generally, a trigger is going to be anything that puts stress on the body and can include infection/illness, dehydration, exposure to cold, pregnancy, physical exertion and even emotional stress.

• Teach about the importance of regular vaccinations to prevent illness and that patients with SCD are at higher risk for infection.
• Encourage the patient to avoid dehydration, which increases blood viscosity and can trigger a crisis.
• Teach the patient to avoid substances that cause vasoconstriction such as nicotine, caffeine and stimulants.
• Educate the patient on how to take all medications.
  • Key teaching for hydroxyurea: The medication will make the individual more prone to infection so teach infection prevention strategies. Because this medication can cause thrombocytopenia, instruct patients to use a soft toothbrush and electric razor to decrease risk of bleeding. Advise female patients to discuss plans for pregnancy and breastfeeding with their physician as this medication causes fetal harm. They may need to use contraception for a full year after discontinuing hydroxyurea. Additionally, the medication can cause male infertility.
  • Key teaching for voxelotor: Advise female patients to notify their MD if pregnancy is planned or suspected; they should also avoid breastfeeding while taking this medication and for two weeks after the last dose.
  • Key teaching for L-glutamine: Mix the amino acids with 8 oz of water every 2 to 3 hours while awake and take with a meal or snack.
  • Key teaching for crizanlizumab: This medication can also cause fetal harm, so advise female patients to discuss pregnancy and breast feeding with their physician.
• Ensure family members understand the importance of seeking immediate medical care if any neurologic symptoms arise.
• Encourage the patient/family to seek help when experiencing increased shortness of breath, unusual vital signs, increasing pain, and/or increasing fever.

I hope this overview of sickle cell disease increases your understanding. Want to dive into other hematological disorders? Here you go!

Review sickle cell disease for your exams, clinicals, and NCLEX while you’re on the go by tuning in to episode 293 of the Straight A Nursing podcast. Tune in wherever you get your podcast fix, or straight from the website here.

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