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Respiratory system




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USMLE® Step 1 questions

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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?  

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Albuterol p. 243

asthma p. 712


for asthma p. 712

Asthma p. 698

albuterol for p. 243

β -blockers and p. 247

breast milk and p. 652

cromolyn sodium for p. 411

drug therapy p. 712

eczema and p. 489

epinephrine for p. 243

gastroesophageal reflux disease p. 386

hypertension treatment with p. 323

immunosuppressants p. 118

muscarinic antagonists for p. 242

omalizumab for p. 120

pulsus paradoxus in p. 481

salmeterol for p. 243

type I hypersensitivity p. 110

β2 -agonists

asthma p. 712


asthma p. 712

Cough p. 148, 572

asthma p. 698


asthma p. 698

Pulsus paradoxus p. 481

asthma p. 698


asthma p. 698

Upper respiratory infections (URIs)

asthma trigger p. 698


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.


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  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)

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