Brief overview of Acute Chest Syndrome (ACS) in Sickle cell disease.

1. Acute ChestAcute Chest
Syndrome (ACS) inSyndrome (ACS) in
Sickle Cell Anemia.Sickle Cell Anemia.
Department of Family and Specialty Medicine, Team C.
Nisa Premier Hospital, Abuja.
Abdulmumini Shehu, MD

2. Outline
• Introduction
• Definition
• Risk factors
• Causes
• Pathophysiology
• Presentation and Physical findings
• Management
• Prevention
• Conclusion
• References

3. Introduction
• Acute chest syndrome (ACS) is an important cause of morbidity and
mortality in sickle cell disease (SCD).
• ACS is the second most common cause for hospitalization after VOC in
patients with SCD
• More than half of all children with homozygous SCD (HbSS) experience at
least one episode of ACS in the first decade of life
• Patients may present with ACS or may develop this complication during
the course of a hospitalization for acute vaso-occlusive crises (VOC)
• ACS is associated with prolonged hospitalization, increased risk of
respiratory failure, and the potential for developing chronic lung disease

4. Definition:Definition:
Acute chest syndrome (ACS) refers to a life-threatening
pulmonary complication of sickle cell disease defined as a new
radiodensity on chest radiography plus any 2 of the following:
• fever
• respiratory distress
• hypoxia
• cough, or
• chest pain

5. The radiographic findings in ACS are variable but
may include:
single lobe
involvement (predominantly left lower lobe),
multiple lobes (most often
both lower lobes)
and
pleural effusions ( either unilateral or bilateral).

7. Risk Factors for ACS

8. Causes
• The majority of patients with ACS do not have a single identifiable
cause. However the following are the most implicated:
• Pulmonary infection is the most well-known etiology, with the
most common pathogens as S. pneumoniae, Mycoplasma pneumoniae,H. influenza
and Chlamydia sp
• Fat emboli Fat emboli arising from infarcted bone marrow, especially in sickle cell disease patients
presenting with rapid onset of respiratory distress and altered mental status changes.
• Pulmonary infarction and in situ thrombolysis due to increased adhesion of sRBCs to the endothelium
causing vaso-occlusion, which leads to ventilation–perfusion mismatch and exacerbation of hypoxemia.
• Hypoventilation splinting caused by rib infarction can lead to decreased respiratory effort resulting in
hypoventilation and atelectasis
• Others : Asthma/ airway hyperactivity, general anesthesia, smoking etc

9. Pathophysiology of ACS
• The development of ACS represents a vicious cycle of lung infarction,
inflammation, and atelectasis leading to ventilation–perfusion
mismatch, hypoxemia, and acute increases in pulmonary artery and
right ventricular pressures
• At the cellular level, in the presence of low alveolar oxygen tension,
abnormal rheology of the sickled red blood cells (sRBCs) facilitates
adhesion to each other, leukocytes, and the vascular endothelium,
resulting in vaso-occlusion and tissue hypoxia
• These interactions also cause the release of inflammatory cytokines
which promote acute and chronic inflammation in the nearby airways

11. Presentation symptoms and physical
findings
• Fever
• Cough (dry or productive)
• Chest pain (often severe)
• Shortness of breath
• Chills
• Wheezing
• Hemoptysis
• Tachypnea
• Dullness to percussion
• Rales on auscultation
• NOTE- about 35% of patients
have normal lung findings on
examination!

13. Prevention of ACS
• Prophylactic antibiotic administration with Penicillin VK,
• Annual influenza (including H1N1) vaccination from 6 months of age
• 23-valent pneumococcal polysaccharide vaccine (≥2 years of age)
• 13-valent pneumococcal conjugate vaccine (shortly after birth)
• Hydroxyurea (potent inducer of HbF and also decreases the WBC
count, which in turn has a positive effect on decreasing endothelial
inflammation and vaso-occlusion)
• Chronic transfusion therapy ( in recurrent episodes of ACS and non-
responders to hydroxyurea)

14. Conclusion
ACS is a common complication of SCD
necessitating frequent hospital admissions.
Physicians caring for patients with SCD should be
vigilant for the clinical features of early ACS so
that optimal preventive and management
strategies can be instituted.

15. References
• Kliegman, Robert., et al. Nelson Textbook of Pediatrics. Edition 20.
Phialdelphia, PA: Elsevier, 2016
• Acute Chest Syndrome in Children with Sickle Cell Disease, Jain S,
Bakshi N, Krishnamurti L. Pediatr Allergy Immunol Pulmonol. 2017 Dec
1; 30(4): 191-201
• Rapidly progressive acute chest syndrome in individuals with sickle cell anem
.Chaturvedi S, Ghafuri DL, Glassberg J, Kassim AA, Rodeghier M,
DeBaun MR, Am J Hematol. 2016 Dec; 91(12):1185-1190.