What Is Sickle Cell Disease?
Sickle cell disease (SDC) is a blood disorder affecting red blood cells. SDC is an inherited disease genetically passed down from parents to their children. SDC is a common condition prevalent in many parts of the world, including the United States. Red blood cells consist of an oxygen-carrying protein known as hemoglobin. Normally, red blood cells are round in shape and travel through tiny blood vessels to deliver oxygen to all body parts. However, these red blood cells become sickle-shaped in individuals with sickle cell disease due to hemoglobin abnormalities. These sickle-shaped red blood cells die earlier than normal, leading to a constant shortage of red blood cells.
What Is Acute Chest Syndrome?
Acute chest syndrome is characterized by several conditions, including; chest pain, cough, fever, low oxygen levels (hypoxia), and abnormal substances building up in the lungs. Acute chest syndrome is a common complication of sickle cell disease. The majority of hospitalizations and fatalities in sickle cell disease patients occur from this condition because of its rapid progression. Patients with sickle cell disease have acute chest syndrome due to various triggering events that lead to vaso-occlusion in the pulmonary vasculature. All sickle cell disease phenotypes are susceptible to acute chest syndrome. But it occurs more frequently in HbSS (a variant of hemoglobin).
Is Acute Chest Syndrome a Common Condition?
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The most prevalent acute pulmonary condition in sickle cell disease patients is acute chest syndrome.
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One incidence of acute chest syndrome will occur in 50% of sickle cell disease patients.
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The most common age of occurrence of acute chest syndrome in children is between two to four years.
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Acute chest syndrome episodes are more common in patients with sickle cell disease and asthma than in people with just sickle cell disease.
What Causes Acute Chest Syndrome?
The exact cause of acute chest syndrome is uncertain; however, the following factors have a role in the etiology of acute chest syndrome:
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Bone Marrow: Bone marrow necrosis refers to the death of bone marrow (spongy tissues present inside the bones). Bone marrow death is characteristic of vaso-occlusion, which leads to the release of bone marrow into venous circulation.
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Fat Emboli: Embolism refers to the obstruction of blood vessels by a blood clot or air bubble. Fat embolism refers to the presence of fat globules in blood circulation. Sickle cell disease patients' postmortem bronchoalveolar lavage analysis frequently revealed the presence of fat-containing alveolar macrophages.
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Infection: Infections like viral or bacterial pneumonia can cause acute chest syndrome, especially in children and young adults.
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Asthma: Hypoxia (reduction of oxygen in tissues) can result from bronchospasms caused by asthma, which can cause the sickling of red blood cells. Individuals suffering from asthma combined with sickle cell disease are about two to four times more likely to develop acute chest syndrome than others.
What Are the Common Symptoms of Acute Chest Syndrome?
The symptoms of acute chest syndrome differ among children and adult patients. Children usually have an infectious etiology of acute chest syndrome, and they manifest symptoms like wheezing, cough, difficulty in breathing, and fever. Whereas adults present with symptoms like pain in the chest, pain in the legs or arms, dyspnea (shortness of breath), or vaso-occlusive problems anywhere in the body.
Symptoms in Children:
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Persistent cough.
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Fever.
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Hypoxemia (low level of oxygen in the blood).
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Tachypnea (increased breathing rate).
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Wheezing.
Symptoms in Adults:
Adults may have all the symptoms observed in children and the following symptoms as well:
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Pain in the chest during breathing.
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Sudden pain in arms, legs, and back. This may occur due to blocked blood flow to these body parts (vaso-occlusive crisis).
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Pleural effusion (fluid build-up in the lungs).
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Dyspnea (shortness of breath).
How Is Acute Chest Syndrome Diagnosed?
The following tests can be done to confirm the diagnosis of acute chest syndrome:
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Arterial Blood Gas: Arterial blood gases are analyzed to determine the blood's pH, oxygen content, and carbon dioxide content.
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Complete Blood Count: Complete blood count (CBC) may be done to measure the number of red blood cells, white blood cells, and platelets in the blood.
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Imaging Test: An X-ray chest is done to determine the presence of any kind of infection or abnormal infiltrates in the lungs.
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Culture: Additionally, cultures that check the blood, sputum, or other bodily fluids for different infections are performed.
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Bronchoscopy: Bronchoscopy is performed along with bronchoalveolar lavage is done to check for the cause of infection if the patient does not show improvement with antibiotic therapy.
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D-Dimer: D-dimer is a small portion of a protein that is formed when a blood clot dissolves within the body. This test is done to check for pulmonary embolism.
How Is Acute Chest Syndrome Treated?
Acute chest syndrome calls for immediate and aggressive treatment because the condition can quickly worsen. The treatment modalities include the following:
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Pain Management: Ketorolac is typically used as the first line of pain management for kids because it is non-sedating and less prone to cause hypoventilation than opioid painkillers. Pain management in adults can also be started with Ketorolac. However, patients of all ages, including children, who cannot get their pain under control with Acetaminophen and Ketorolac are treated with opioid painkillers.
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Fluid Management: Fluid management is crucial in cases of dehydration because dehydration can exacerbate sickling. However, large volumes of intravenous hydration are not recommended because overhydration can cause pulmonary edema, and this pulmonary edema can cause further respiratory issues.
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Antibiotics: Broad-spectrum antibiotics are advised for every patient suffering from acute chest syndrome. Treatment should be started with a third-generation Cephalosporin for routine bacterial coverage, whereas atypical coverage should be covered with a macrolide.
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Supplemental Oxygen Therapy: Low SpO2 (oxygen saturation) or PaO2 (arterial oxygen pressure) should be treated with supplemental oxygen therapy.
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Blood Transfusion: Transfusion with packed red blood cells has shown some efficacy in treating acute chest syndrome. It has been demonstrated that transfusions enhance both SpO2 and PaO2 and are used to treat acute chest syndrome by improving oxygenation.
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Bronchodilators: Bronchodilators are a class of drugs that helps to breathe easily. They can be used in any situation when bronchospasm has been detected.
What Are the Complications of Acute Chest Syndrome?
Complications of acute chest syndrome are:
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Respiratory failure.
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Pulmonary infarction.
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Acute respiratory distress syndrome (ARDS).
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Severe chest pain.
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Death.
Conclusion:
Acute chest syndrome is a common and severe complication of sickle cell disease, and it usually requires immediate medical attention. However, an individual with sickle cell disease may experience another episode in the future, even after receiving good treatment for acute chest syndrome. The syndrome is also linked to significant morbidity and mortality rates. Poor prognosis is frequent in the absence of aggressive treatment.
