Acute Chest Syndrome

Acute Chest Syndrome

We have discussed previously (in Splenic Sequestration – Be a Spleen Detective!) how being vigilant for “badness” is paramount when caring for patients with sickle cell disease.  Often, the dreaded complications that we are taught to look for don’t present to us in the Emergency Department, but develop and evolve during the hospitalization that began with the patient seeing us in the ED.  Our skill can help the child in distress, but our vigilance can detect the evolving Acute Chest Syndrome and perhaps even prevent it.

Acute Chest Syndrome

  • Acute Chest Syndrome is one of the most common complications of Sickle Cell Disease (SCD).
  • Pulmonary complications (Acute Chest Syndrome and Pulmonary Hypertension) are the most common causes of death in patients with SCD.
    • Some estimate that Acute Chest Syndrome accounts for 25% of all SCD- related deaths.
  • Acute Chest Syndrome is a new pulmonary infiltrate, often accompanied by fever, chest pain, cough, wheezing, or tachypnea.

Causes of Acute Chest Syndrome

  1. Pulmonary Infection
    1. Most common agents are atypical bacteria and viruses.
    2. Streptococcus pneumoniae is also a prevalent culprit
      1. Incidence of Acute Chest Syndrome has actually declined since conjugated 7-valent pneumococcal vaccine.
      2. Unclear of whether there is a causal relationship… but a lower incidence is still a good thing!
  2. Fat Embolization from Bone Marrow
    1. Vaso-occlusive crisis involving multiple bones, especially pelvis and femur, leads to infarction and edema of the marrow.
    2. The marrow then undergoes necrosis, leading to its contents (like fat) being released into the bloodstream.
  3. Vaso-occlusion of the pulmonary vasculature by Sickled RBCs

These, and other factors, all play a role in the downward spiral of Acute Chest Syndrome

  • As the lung becomes involved, V/Q mistmatch develops leading to hypoxemia, which then leads to more sickling of RBCs, accelerating the process.
  • Pain also leads to chest wall splinting, hypoventilation, and atelectasis, further increasing the V/Q mismatch.
  • Reactive-airway disease, which is present in up to 53% of children < 10yrs of age, can further accelerate this process.
  • Over-sedation from narcotics can also lead to hypoventilation and V/Q mistmatch.

Clinical Appearance of Acute Chest Syndrome

  • Unfortunately, Acute Chest Syndrome may present with severe respiratory distress.
    • In the patient who has increased work of breathing, but doesn’t yet require intubation, consider noninvasive ventilation early to help improve V/Q mismatch.
  • More often, Acute Chest Syndrome  develops within the first 1-3 days of a Vaso-occlusive crisis.
    • Almost 50% of patients diagnosed with Acute Chest Syndrome develop respiratory complication during hospitalization for another diagnosis, such as pain crisis.
  • Fever is the most common presentation of Acute Chest Syndrome.
    • Acute Chest Syndrome needs to be considered when evaluating a patient with SCD and fever.
  • Cough is the second most common presenting symptom.
    • Acute Chest Syndrome often presents with cough and fever
      • Even without initial sickling, a pneumonia leads to hypoxemia which can lead to a secondary Acute Chest Syndrome.
      • Pneumonia in a patient with Sickle Cell Disease and Acute Chest Syndrome are often clinically managed similarly… so consider them the same!
  • Chest Pain may be present, but chest pain is less commonly seen in children than in adults with Acute Chest Syndrome.
  • Physical Exam findings are less reliable – 35% of children with Acute Chest Syndrome have initially normal exams.

Risk Factors for Acute Chest Syndrome

{from Chang, 2013}

  • History of Acute Chest Syndrome  (Adjusted OR = 15.9)
  • ANC >/= 9×10^9/L  (Adjusted OR = 2.4)
  • URI symptoms  (Adjusted OR = 2.1)
  • Noncompliance with Penicillin  (Adjusted OR = 3.2)
  • Hemoglobin < 8.6 g/dL  (Adjusted OR = 1.6)
  • Hypoxemia < 93% on RA  (Adjusted OR = 1.9)

Help treat Acute Chest Syndrome before it occurs!

  • Incentive Spirometry – help keep those small alveoli open!
  • PCA Pump delivered narcotics – to help avoid oversedation and hypoventilation!
  • Albuterol and bronchodilators!

Treat Acute Chest Syndrome aggressively once it is present!

  • Frequent reassessments is key, as the patient may decline rapidly.
  • Be prepared to manage the airway!
  • Provide and encourage good pulmonary toilet (bronchodilators, positive expiratory pressure, incentive spirometry)
  • Antibiotics (include azithromycin to cover atypical bacteria)
  • RBC transfusion
    • Provide this in concert with the hematologist.
    • Based on the patient’s hemoglobin level a straight transfusion or exchange transfusion may be required.
    • More mild versions of Acute Chest Syndrome may not require initial transfusion, but this needs to be a part of the discussion with the hematologist.
Chang TP, Kriengsoontorkij W, Chan LS, Wang VJ. Clinical Factors and Incidence of Acute Chest Syndrome or Pneumonia Among Children with Sickle Cell Disease Presenting with Fever: A 17 year Review. Pediatr Emer Care 2013; 29: 781-786.
Crabtree EA, Mariscalco MM, Hesselgrave J, et al. Improving Care for Children with Sickle Cell Disease / Acute Chest Syndrome. Pediatrics 2011; 127: e480
Gladwin MT, Virchinsky E. Pulmonary Complications of Sickle Cell Disease. NEJM 2008; 359: 2254-65.


Sean M. Fox
Sean M. Fox
Articles: 583


  1. Which is more beneficial to patients? exchange transfusion or straight transfusion? thanks for answering

    • Depends on what the patient can tolerate. If the patient requires a transfusion, but the hemoglobin is at or near the baseline, then it might not be advisable to do a straight transfusion, as this can lead to hyperviscosity and complications (ex, CVA). Exchange transfusion is much more involved of a process though.

      In the end, the goal is to increase the Hgb Adult to Hgb Sickle ratio… and the strategy selected is based on a number of factors and you need to include the hematology team in the decision.

      Hope that that helps.
      Thank you,

  2. What r the indications of exchange or normal transfusion in ACS??
    Where should be admitted to ward?? or TO icu ??

    • Straight (normal) transfusion is the most common method, but can cause hyperviscosity if the patient’s hemoglobin level is at or near his/her normal hemoglobin level. If the patient has had a significant drop in the hemoglobin level, then straight transfusion is likely appropriate. In the event that the hemoglobin is at, or near, the patient’s normal level, then exchange transfusion may be the best means to increase the patient’s Adult Hemoglobin level. Transfusion for sickle cell patients is best done in conjunction with the patient’s Heme specialist.

      As for admission, the criteria for ICU admission will vary with specific hospitals and their resources. In general, we should all have a healthy respect for acute chest and its potential for causing significant morbidity and mortality.

      Thank you,

  3. Bronchodilators would work? Arent them for large airway disease? Acute chest syndrome is a small airway disease ( pneumonia ) + pulmonary vasculature disorder ( obstruction of sickled cells ) isnt it?

    • Ryan,
      Bronchodilators can affect the smaller airways as well… Reactive Airway Diseases, like Asthma often involve smaller airways as well.

      Kids with Sickle Cell disease often have reactive airway disease concurrently. Using albuterol for the patient who presents with pain crisis is meant to help augment the pulmonary toilet as much as possible, which can help prevent acute chest from developing. The kid who has a pain crisis begins to have lower tidal volumes and develop atlectasis because of pain and splinting in addition to the effects of sedation from the administered pain medicines. An incentive spirometer and albuterol hopefully will help keep those smaller airways open and hopefully prevent acute chest from developing.

      Thank you for your comment!

Comments are closed.