Acute chest syndrome
Background
- The leading cause of death in patients with HbSS in the United States
- HbSS individuals are at higher risk than HbSC, but acute chest may occur in both genotypes
- Occurs most commonly in the 2-4yr old age group and then declines with age
- Pathophysiology is due to deoxygenation of Hb, leading to sickling in the pulmonary vasculature, causing vaso-occlusionm, ischemia, and endothelial injury[1]
- In pediatric population, ACS is more often triggered by asthma or viral/bacterial pulmonary infection, leading to local hypoxia
- In adult population, ACS is commonly associated with vaso-occlusive pain, which may lead to hypoventilation or long bone fat/marrow emboli
- However, a specific cause is not identified in a majority of cases
Causes
- Pulmonary infection
- Chlamydophila pneumoniae and Mycoplasma pneumoniae are most common organisms
- May also be caused by S. aureus, H. influenzae, Klebsiella, and viruses
- Infection due to S. pneumoniae is now rare due to pneumococcal immunization and prophylactic penicillin therapy
- Fat emboli
- Suspect if symptoms start 2-3 days following acute pain crisis
- Can cause microvasculature occlusion in the pulmonary circulation, leading to bone marrow infarction
- Autopsies have shown bony slivers and marrow fat found in pulmonary vasculature of patients
- Rib infarction
- Overly aggressive IV hydration
- Vaso-occlusive pain crisis
- Asthma
- Iatrogenic
- Opioid analgesics can lead to hypoventilation
Clinical Features
- New infiltrate on chest x-ray PLUS one of the following signs or symptoms
Complications
- Pulmonary Embolism (bone marrow, fat or thrombotic)
- Pneumonia
- CVA
- Sepsis
Differential Diagnosis
Sickle cell crisis
- Vaso-occlusive pain crisis
- Bony infarction
- Dactylitis
- Avascular necrosis of femoral head
- Acute chest syndrome
- Asthma
- Pulmonary hypertension
- Gallbladder disease
- Acute hepatic sequestration
- Infection
- Parvovirus B19
- Splenic sequestration
- CVA
- Cerebral aneurysm and ICH
- Priapism
- Papillary necrosis
Evaluation
Work-Up
- CBC
- Retic count
- VBG / ABG
- Blood culture /sputum cultures
- CXR
- Type and screen/crossmatch
Imaging
- New infiltrate seen on chest x-ray
- Chest x-ray findings may lag behind clinical features
- Lung ultrasound to CXR or CT finding correlations[2]
- Consolidation seen as hyperechoic punctiform air bronchograms
- Ground-glass opacities seen as coalescent B lines
- Pleural effusion, defined as large if interpleural distance > 25 mm
- Consider CTPE for persistent hypoxia with unclear cause
Management
- O2
- Titrate to pulse oximetry >95%
- NNoninvasive or invasive positive pressure ventilation may be required in severe cases
- Hydration
- Oral hydration preferred
- IV hydration with hypotonic fluid if patient unable to tolerate PO
- Consider D5 + 1/2 Normal saline at 1-1.5x maintenance rate
- While dehydration can predispose sickling, overhydration can cause pulmonary edema that exacerbates sickling
- Analgesia
- Opioids often required for adults and sometimes needed for pediatrics
- However, attempt to prevent oversedation and hypoventilation, atelectasis
- Incentive Spirometry
- Bronchodilators
- Antibiotics
- 3rd generation cephalosporin + macrolide
- Simple Transfusion (leucocyte depleted)
- Consider transfusion to goal of hemoglobin 11 / hematocrit 30 for:
- O2 Sat <92% on room air
- hematocrit/hemoglobin 10-20% below patient's usual values, or continuously dropping hematocrit/hemoglobin
- Consider transfusion to goal of hemoglobin 11 / hematocrit 30 for:
- Exchange transfusion
- Consider for:
- Progression of acute chest syndrome despite simple transfusion
- Severe hypoxemia
- Multi-lobar disease
- Previous history of severe acute chest syndrome or cardiopulmonary disease
- Can prevent the need for intubation
- Consider for:
Disposition
- Admission
- Consider consultation to hematologist
See Also
External Links
Video
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References
- ↑ Friend A, Settelmeyer TP, Girzadas D. Acute Chest Syndrome. [Updated 2023 Feb 6]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2023 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK441872/
- ↑ Razazi et al. Bedside Lung Ultrasound During Acute Chest Syndrome in Sickle Cell Disease. Medicine (Baltimore). 2016 Feb; 95(7): e2553.