Hi, this is Tom, and in this episode I'm going to be going through viral-induced wheeze.

And you can find notes at zero-to-finals.com or in the zero-to-finals pediatrics book.

And you can find flashcards and questions to train your knowledge at members.0 tofinals.com.

And at the end of this episode, there'll be some questions you can use to test yourself on what

you just heard. So let's jump straight in. Viral induced wheeze occurs when a viral infection

causes airway narrowing, leading to shortness of breath and wheeze.

It's very common and typically affects children under three years of age.

Children with viral induced wheeze are more likely to develop asthma.

Viral induced wheeze only occurs during viral infections. Viral infections can also trigger

symptoms of asthma, however the symptoms of asthma can be triggered by other factors as well,

such as exercise, cold weather, dust and strong emotions. Let's go through the pathophysiology.

Small children have small airways.

Viral infections, commonly respiratory syncytial virus or RSV or rhinovirus,

can cause airway inflammation and edema or swelling, which narrows the diameter of the

airway and restricts the flow of air. The inflammation of the airway can trigger the smooth

muscles of the airways to constrict, which further narrows the space for the air to flow.

Airway narrowing, caused by a viral infection, has little noticeable effect on the larger

airways of older children or adults. However, due to the small diameter of a child's airway, minimal narrowing leads to a proportionately

larger restriction in airflow. Airflow obstruction causes shortness of breath and wheeze.

Let's go through the presentation. Patients will have evidence of a viral illness, such as a low-grade fever,

dry cough, and carisal symptoms, such as a runny nose, sneezing and sore throat.

Typically, the viral symptoms are present for one to two days before the onset of shortness of breath, signs of respiratory distress,

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