Acute chest syndrome, a life-threatening complication of sickle cell anemia, is characterized by a range of symptoms that occur when sickle cells clump together inside of the lungs. Sickle cells are only present in the blood of sickle cell anemia patients, so acute chest syndrome only occurs in these individuals. The red blood cells in individuals with sickle cell anemia are irregularly shaped and non-functional. Clumps of these sickle cells that develop in the lungs can cause an obstruction in normal blood flow through the lungs. They also can impair the process of carbon dioxide-oxygen exchange that occurs between the lungs and blood. No single condition causes acute chest syndrome, but certain conditions can trigger it, including pneumonia, asthma, and pulmonary embolism. Acute chest syndrome is diagnosed through the use of a chest x-ray in patients with sickle cell anemia.
Shortness Of Breath
Shortness of breath (dyspnea) is described as the sensation of tightness in the chest, a feeling of suffocation, and being unable to inhale enough air. Shortness of breath occurs in a healthy individual when they participate in strenuous exercise, are obese, in conditions of extreme temperatures, and at high altitudes. The sensation of dyspnea occurs when an individual is breathing at a higher rate than normal. An increased breathing rate is a common manifestation of acute chest syndrome because of how it affects the mechanism the body uses to regulate breathing. Respiration rate is managed by a combination of interactions between the brain, chemicals in the air, and chemicals in the blood. The amount of carbon dioxide, oxygen, and hemoglobin in the blood all have an influence on the rate of breathing. In acute chest syndrome, the sickle cells clump in the lungs and stop adequate oxygen exchange in the blood. This insufficient oxygen exchange causes blood carbon dioxide levels to increase. The brain detects this increase, and it tells the lungs to breathe faster and deeper. The fast and deep breathing in individuals with acute chest syndrome is what makes them feel like they have shortness of breath.
Low Oxygen Levels
Acute chest syndrome commonly presents with low oxygen levels that accompany other symptoms. General low oxygen levels happen because of a few processes that occur in sickle cell anemia patients. The red blood cells in individuals who have sickle cell anemia have hemoglobin that is irregularly shaped and does not function to carry oxygen. The presence of these abnormal red blood cells causes a decrease in the production of healthy red blood cells that can carry oxygen. In addition, the red blood cells in sickle cell anemia patients have a much shorter lifespan at sixteen days than red blood cells in healthy individuals, which live for 120 days. Both mechanisms result in a low number of red blood cells circulating in the blood. When there are less red blood cells to transport oxygen, there will be a decreased oxygen levels in the blood. The clumping of sickle cells in the lungs that occurs in acute chest syndrome has a compounding effect on top of the other oxygen reducing factors of sickle cell anemia. It is this combination that makes the blood oxygen level in individuals with acute chest syndrome so abnormally low.