Asthma

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Asthma

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Questions

USMLE® Step 1 style questions USMLE

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An 11-year-old girl is brought to the emergency department by her parent due to acute-onset wheezing and shortness of breath. The patient was visiting her neighbor, who recently got a pet kitten, when she suddenly started feeling short of breath. Past medical history is significant for asthma, and she has normally found relief after using an albuterol inhaler. However, the inhaler has been ineffective during the current episode. Temperature is 37.0°C (98.6°F), pulse is 94/min, respirations are 22/min, blood pressure is 132/84 mm Hg, and oxygen saturation is 95% on room air. Physical examination reveals accessory muscle use while breathing. Diffuse expiratory wheezes are heard bilaterally on chest auscultation. The patient is re-evaluated in 10 minutes. Which of the following findings, if present on repeat examination, is most concerning for impending respiratory failure?  

External References

First Aid

2024

2023

2022

2021

Albuterol p. 241

asthma p. 706

Antileukotrienes

for asthma p. 706

Asthma p. 692

albuterol for p. 241

β -blockers and p. 245

breast milk and p. 646

cromolyn sodium for p. 409

drug therapy p. 706

eczema and p. 485

epinephrine for p. 241

gastroesophageal reflux disease p. 384

hypertension treatment with p. 320

immunosuppressants p. 118

muscarinic antagonists for p. 240

omalizumab for p. 120

pulsus paradoxus in p. 477

salmeterol for p. 241

type I hypersensitivity p. 110

β2 -agonists

asthma p. 706

Corticosteroids

asthma p. 706

Cough p. 148, 567

asthma p. 692

Dyspnea

asthma p. 692

Pulsus paradoxus p. 477

asthma p. 692

Tachypnea

asthma p. 692

Upper respiratory infections (URIs)

asthma trigger p. 692

Transcript

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Asthma comes from the Greek word for “panting”, which makes sense because it causes chronic inflammation of the airways, making them narrow and more difficult to breathe through.

People with asthma can have asthma exacerbation or asthma attacks, which are usually triggered by something in the environment which causes immune cells to generate inflammation in the lungs which can make them even narrower and potentially be life-threatening.

So, if we take a look at the lungs, you’ve got the trachea, which branches off into right and left bronchi, and then continues to branch into thousands of bronchioles.

In the bronchioles you’ve got the lumen, the mucosa, which includes the inner lining of epithelial cells, as well as the lamina propria, and the submucosa which is where the smooth muscle lives.

The molecular pathway that leads to asthma is actually pretty complex but it is often initiated by an environmental trigger.

In asthma there is often an excessive reaction from type 2 helper cells or Th2 cells against specific allergens.

Th2 cells, are an immune cell subtype, which are known to be involved in asthma, as well as atopic dermatitis, and allergic rhinitis, making up what’s called the atopic triad.

What can happen with asthma is allergens from environmental triggers, like cigarette smoke, are picked up by dendritic cells which present them to a Th2 cell which produce cytokines like IL-4 and IL-5 leading to a number of features of asthma.

For example IL-4 leads the production of IgE antibodies which coat mast cells and stimulate them to release granules containing things like histamines, leukotrienes and prostaglandins. IL-5, on the other hand, activates eosinophils which promote an immune response by releasing more cytokines and leukotrienes.

Sources

  1. "Robbins Basic Pathology" Elsevier (2017)
  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "CURRENT Medical Diagnosis and Treatment 2020" McGraw-Hill Education / Medical (2019)
  5. "Asthma-related comorbidities" Expert Review of Respiratory Medicine (2011)
  6. "Genes, environments, development and asthma: a reappraisal" European Respiratory Journal (2006)
  7. "Asthma: Clinical expression and molecular mechanisms" Journal of Allergy and Clinical Immunology (2010)
Elsevier

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