Viral Induced Wheeze Flashcards
What is viral induced wheeze?
It refers to an acute wheezy illness associated with viral infection
What is a wheeze?
It describes a whistling sound caused by narrowed airways, typically heard during expiration
Describe the pathophysiology of viral induced wheeze
In children under the age of three, airways tend to be relatively small
This means that when they encounter a virus, commonly RSV or rhinovirus, they develop inflammation and oedema of the airways – restricting the space for air to flow
This airway inflammation also triggers the smooth muscles of the airways to constrict, which further narrows the space for air to flow
Why do viral infections not induce wheeze in older children and adults? What law explains this?
A viral infection still causes swelling and constriction in older children and adults, however due to the fact that their airways are larger in diameter the effect on airflow is minimised
Poiseuille’s law, which states that flow rate is proportional to the radius of the tube to the power of four. Therefore, halving the diameter of the tube decreases flow rate by 16 fold.
What are the four risk factors for viral induced wheeze?
Family History
Maternal Smoking During Pregnancy
Second-Hand Smoke Exposure
Bronchiolitis
What are the four clinical features of viral induced wheeze?
Viral Illness Features
Dyspnoea
Respiratory Distress Features
Expiratory Wheeze Throughout Chest
What are three typical viral illness features?
Fever
Cough
Corzyal features
What are the four typical corzyal features?
Runny nose
Sneezing
Mucus in throat
Watery eyes
Describe the course of viral induced wheeze presentation
The onset is related to viral infection, resulting in the development of viral illness features
Following onset, patient will then develop respiratory features after 1-2 days
What does a focal wheeze indicate?
Focal airway obstruction, which could be related to an inhaled foreign body or tumour
What are the three differences that distinguish viral induced wheeze from asthma?
Viral induced wheeze results in the following features (as opposed to asthma)…
- Onset age < 3 years old
- No atopic history
- Presentation following viral infections only
What complication can viral induced wheeze patients develop later in life?
Asthma
