Acute chest syndrome, or ACS, is a sudden illness affecting the lungs of patients with sickle cell disease. The textbook "Clinical Practice of Emergency Medicine" notes that ACS is the leading cause of death among patients with sickle cell disease. Early recognition and aggressive medical management are essential with ACS.
Slowed Blood Flow
In patients with sickle cell disease, the red blood cells are sickle-shaped, whereas normal red blood cells are relatively round. Red blood cells deliver oxygen. Because sickle-shaped cells are sticky and less flexible than normal red blood cells, they do not flow well and clog small vessels. When blood and oxygen are not flowing normally to major organs, such as the lungs, the patient experiences pain. This is called a vaso-occlusive crisis, meaning pain crisis. ACS is a painful crisis in the lungs.
Causes
ACS does not have one specific cause, but there are several processes that can trigger the disease. Infection, such as pneumonia, or a fat embolism are considered common causes. A fat embolism is a fat particle that travels through the bloodstream and becomes lodged in a blood vessel causing a blockage. With ACS, the fat embolism causes blockage in the lungs. According to "Hospital Physician," it has been suggested that a decreased gas exchange in the lungs or excessive fluid in the lungs may also be possible causes. Other lung diseases, such as asthma, may contribute to the disease. The University of Maryland Medical Center notes that in about half of the cases, the cause cannot be established.
Recognizing ACS
ACS can be very painful and dangerous. Early recognition of ACS by the physician is important. "Hospital Physician" states that ACS is currently defined as a new infiltrate, which is an abnormal substance seen on the patient's chest x-ray, and one other new symptom or sign to include a fever greater than 103.5 degree Fahrenheit, chest pain, and/or cough. According to the University of Maryland Medical Center, ACS pain often lasts for several days. In about half the patients, severe pain develops about two to three days before there are any signs of lung or chest abnormalities.
Treatment
A primary goal in the treatment of patients with ACS is to make sure oxygen is being supplied to the tissues. When blood is not flowing as it should, oxygen is not being delivered. Supplemental oxygen is given to the patient as needed. It will be necessary to make sure the patient is well hydrated, but it is equally important to make sure they are not over-hydrated. Patients in crisis are often dehydrated and need fluids, but at the same time, because the lungs are not working properly in ACS, too much fluid could cause additional respiratory complications. Pain medications are prescribed to promote comfort. ACS patients require antibiotic's to treat any infection. Because ACS affects the respiratory system, bronchodilators may be prescribed. Bronchodilators dilate the air passages of the lungs, decreasing airway resistance and facilitate airflow. Some patients require assisted breathing from a machine called a ventilator. A transfusion of red blood cells may be considered.
Outcome
Because the exact causes of ACS are not always identified, the medical management and treatment may be difficult. In addition to treating infections, pain and hydration, severe cases of ACS can rapidly cause respiratory failure. When respiratory failure occurs, the lungs are no longer able to perform the exchange of oxygen and carbon dioxide, and will eventually shut down, leading to death. Persons with ACS should be admitted to the hospital where they can be closely monitored and receive aggressive treatment as needed.
References
- "Clinical Practice of Emergency Medicine"; Lippincott Williams & Wilkins; 2010
- "Nursing"; What you need to know about acute chest; Claudia Hernandez, Elaine Patterson; June 2009
- "Hospital Physician"; Acute Chest Syndrome of Sickle Cell Disease; Bernard A et al; Janurary 2007
