Too Cute To Be Bored: Acute Chest Syndrome

It’s a beautiful day outside, and the pediatric ED is packed with super cute, snot-nosed children. While you are busy at work, you are happy that all of these kiddos are so adorable. You are wondering if your shift can get any cuter, when a 17 year-old patient with known sickle cell disease is brought in complaining of chest pain, fever, and shortness of breath. She says her pain is 10/10. Vital signs are HR 100, BP 110/70, T 101.5, RR 28, POx 92%. On exam she has diffuse bony tenderness over her chest and sternum, ronchi in the right lung, and some scattered wheezing.

Whelp, you think, things definitely just got more a-cute! panda-on-ride

What is Acute Chest Syndrome (ACS)?

ACS is defined by a new infiltrate on chest X-ray PLUS at least one new sign/symptom: fever, cough, wheezing, tachypnea, hypoxia, or chest pain. It is caused by infection, fat emboli / thrombo-emboli, rib infarction, or lung sequestration of sickled RBCs. Possible iatrogenic causes include aggressive hydration causing pulmonary edema or opioids causing respiratory depression / poor inspiratory effort, and atelectasis.

In those with infectious etiologies, ACS is most commonly caused by atypicals – Chlamydia pneumoniae and Mycoplasma pneumoniae – but certainly can be caused by viral pneumonias or other common bacterial pathogens.

Although you must see a new infiltrate on chest X-ray for the diagnosis, the chest X-ray can lag behind the clinical symptoms, so keep a high index of suspicion.

Thought fat emboli were only from long bone fractures?

Think again! Bony ischemia and necrosis may lead to necrotic pieces of bone marrow breaking off and embolizing.

Here is a great example of a-cute chest syndrome:

acute-cat-chest

How do all of these different etiologies cause the same syndrome?

Each of these triggers causes lung injury, V/Q mismatch, and hypoxemia, which themselves promote more inflammatory mediators, erythrocyte adhesion, and vaso-occlusion … leading to more lung injury, infection, and hypoxemia! It’s a vicious cycle! Vicious!!

This is Miss Maggie Moo. She is a vicious beast. And super-cute.

maggiezbw

What is the treatment for acute chest syndrome?

Despite the multiple etiologies of ACS, it is impossible to know the underlying cause in the ED. So, treat them all: fluids, antibiotics, oxygen, pain control, and possible blood transfusion or exchange transfusion.

Hypotonic fluids: Oral hydration is best. For IV hydration, hypotonic solutions such as 1/2 NS promote osmotic swelling of cells (one of the only times we really want this effect) to help plump up those sickly sickled cells. Rate: 1.5x maintenance.
Empiric antibiotics: Cover community-acquired pneumonia (azithromycin, ceftriaxone) and go broad if they have been hospitalized recently.
Analgesia: Opioids are a mainstay of treatment for our sickle cell patients and should be used here, but be cautious about respiratory depression and poor inspiratory efforts which can worsen the syndrome.

If you hear wheezing, consider albuterol to help calm the inflammatory cascade that is contributing the cycle of viciousness.

Exchange transfusion? Solid evidence is lacking, but in a severe crisis when the hgb level is not too low ( > 9), exchange transfusion can filter out the culprit cells while replenishing with functioning RBCs.

Dispo?

Acute chest syndrome is the leading cause of death in sickle cell patients! Because this is a VICIOUS cycle, they can decomensate quickly and need intubation, transfusions, and a high level of care. Get them to the MICU or a monitored bed.

Want more cuteness?

This is Toby. He enjoys scratching things that shouldn’t be scratched, food, and sleeping.

toby1

References:
Williams-Johnson J, Williams E. Chapter 231. Sickle Cell Disease and Other Hereditary Hemolytic Anemias. In: Tintinalli JE, Stapczynski J, Ma O, Cline DM, Cydulka RK, Meckler GD, T. eds. Tintinalli’s Emergency Medicine: A Comprehensive Study Guide, 7e. New York, NY: McGraw-Hill; 2011.

Special Thanks to Dr. Willis and Dr. deSouza