From the Guidelines
Yes, acute chest syndrome can cause pulmonary infiltrates without pneumonia. Acute chest syndrome (ACS) is a serious complication of sickle cell disease characterized by new pulmonary infiltrates on chest imaging, along with fever, chest pain, tachypnea, wheezing, or cough, as described in the guidelines for health supervision for children with sickle cell disease 1. While pneumonia can be a trigger for ACS, the pulmonary infiltrates in ACS often result from other mechanisms including vaso-occlusion, fat embolism from bone marrow infarction, and in-situ pulmonary thrombosis. These processes lead to lung injury, inflammation, and subsequent infiltrates visible on imaging without bacterial or viral infection being present. The pathophysiology involves sickling of red blood cells in the pulmonary microvasculature, leading to vascular occlusion, tissue hypoxia, and inflammatory responses that can mimic pneumonia radiographically but have a different underlying cause. It's also worth noting that other noninfectious processes can be mistakenly labeled as pneumonia, including atelectasis, congestive heart failure, pulmonary embolus with infarction, lung contusion, and chemical pneumonitis from aspiration, as mentioned in the guidelines for the management of adults with hospital-acquired, ventilator-associated, and healthcare-associated pneumonia 1. However, the most recent and highest quality evidence on acute chest syndrome comes from the study on health supervision for children with sickle cell disease 1, which highlights the importance of early recognition and aggressive treatment of ACS to prevent rapid deterioration and improve outcomes. Key aspects of treatment include oxygen therapy, pain management, hydration, incentive spirometry, bronchodilators if wheezing is present, blood transfusions, and antibiotics given empirically even without confirmed infection. Given the potential for morbidity and mortality associated with ACS, it is crucial to prioritize its diagnosis and treatment, even in the absence of pneumonia.
From the Research
Definition and Causes of Acute Chest Syndrome
- Acute chest syndrome (ACS) is an acute pulmonary illness in patients with sickle cell disease, characterized by fever, respiratory symptoms, and new pulmonary infiltration 2.
- The etiology of ACS is often multifactorial, involving increased adhesion of sickle red cells to pulmonary microvasculature in the presence of hypoxia, infection, pulmonary fat embolism, and infarction 3.
- Infection is a common cause in children, whereas adults usually present with pain crises 3.
Pulmonary Infiltrates without Pneumonia
- ACS can cause pulmonary infiltrates without pneumonia, as evidenced by the presence of new pulmonary infiltrates on chest X-ray in patients with ACS, which may not always be associated with infection 4, 3.
- Pulmonary fat embolism and infarction of segments of the pulmonary vasculature are other etiologies that can cause pulmonary infiltrates without pneumonia in patients with ACS 5, 4.
Clinical Presentation and Management
- Patients with ACS may present with mild respiratory illness to acute respiratory distress syndrome, and the presence of severe hypoxemia is a useful predictor of severity and outcome 3.
- Management of ACS includes hydration, analgesia, supplemental oxygen, antibiotics, blood transfusion, and mechanical ventilation, with early detection and aggressive management limiting its severity and preventing complications 2, 6.
- Bronchodilators should be considered if there is a history of asthma or in the presence of acute bronchospasm, and treatment with hydroxyurea should be considered for prevention of recurrent episodes 3.