Bronchiolitis and RSV: Symptoms, Causes, Diagnosis, Treatment
Bronchiolitis and RSV: Symptoms, causes, diagnosis, treatment, and definition in babies and infants explained! Includes risk factors and more! High-yield notes for nursing!
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Bronchiolitis
This lecture reviews the following about bronchiolitis:
Definition
Pathophysiology
Causes
Epidemiology
Risk Factors
Symptoms
Diagnosis
Treatment
Complications
Bronchiolitis - Quick Notes
Bronchiolitis is inflammation of the bronchioles
RSV is the most common cause
Most commonly affects infants < 6 months old
Typically occurs in children < 2 years old
Most common in the winter months (peak)
Symptoms may include fever, cough, rhinorrhea, etc.
Signs of respiratory distress may include retractions, head bobbing, nasal flaring, etc.
Diagnosis can often be made clinically, depending on the case* (see below)
Treatment for most mild-moderate cases includes supportive care* (see below)
Practice Questions
Make sure to quiz yourself with the practice questions at the end of this lecture!
Enjoy!
Bronchiolitis (RSV): Nursing and medical notes for bronchiolitis (RSV) including symptoms, causes, presentation, exam prompt, etc.
What is Bronchiolitis?
Definition:
Bronchiolitis is inflammation of the small airways in the lungs (bronchioles).
Bronchiolitis is typically caused by a viral infection (RSV is the most common).
The simplest way to remember bronchiolitis is to break down the word:
The root word bronchiol- refers to the bronchioles.
The suffix -itis refers to inflammation.
Therefore, bronchiolitis is inflammation of the bronchioles.
The bronchioles are the small airways in the lungs.
Let’s take a closer look at the bronchioles in the next section.
Bronchiolitis Definition: Bronchiolitis is inflammation of the small airways in the lungs (bronchioles), typically caused by a virus such as RSV.
Bronchial Tree - Anatomy
Definition
The bronchial tree, or the tracheobronchial tree, is the network of branching airways that conduct air from the trachea to the alveoli.
The bronchial tree is part of the lower respiratory tract (below the larynx).
Anatomy - The bronchial tree includes the following structures:
Trachea
Main Bronchi (1°)
Lobar Bronchi (2°)
Segmental Bronchi (3°)
Bronchioles
Conducting
Terminal
Respiratory
Alveolar Ducts/Sacs
Bonus: See labeled diagram below!
1. Trachea
The trachea is also known as the “windpipe”.
The trachea is the main trunk of the bronchial tree, and it allows air to travel from the nose/mouth to the lungs.
The trachea divides or splits (bifurcates) into the right and left main bronchi.
2. Main Bronchi
The trachea (single airway) divides into 2 airways, inferiorly.
The 2 airways are called the right and left main bronchi.
The right main bronchus allows air to enter the right lung.
The left main bronchus allows air to enter the left lung.
The main bronchi are also called the primary (1°) bronchi.
The right and left main bronchi further divide into lobar bronchi.
3. Lobar Bronchi
The right and left main bronchi (2 airways) divide into 5 airways, called lobar bronchi.
The lobar bronchi are also called secondary (2°) bronchi.
The lobar bronchi supply air to the different lobes of the lungs.
This is why they are known as the lobar bronchi.
There are a total of 5 lobes in the lungs (right lung = 3 lobes; left lung = 2 lobes), which is why there are 5 lobar bronchi.
The lobar bronchi further divide into segmental bronchi.
4. Segmental Bronchi
The lobar bronchi (5 airways) divide into smaller airways, called segmental bronchi.
Segmental bronchi are also called tertiary (3°) bronchi.
The segmental bronchi supply air to the specific segments within each lobe of the lung.
This is why they are known as segmental bronchi.
The segmental bronchi further divide into bronchioles.
5. Bronchioles
The segmental bronchi divide into smaller airways, called bronchioles.
The bronchioles are affected by bronchiolitis.
Conducting bronchioles branch into even smaller respiratory bronchioles.
The respiratory bronchioles terminate in the alveolar ducts which connect to the alveolar sacs.
6. Alveolar Ducts/Sacs
The bronchioles terminate in the alveolar ducts.
Alveolar ducts are passageways that connect respiratory bronchioles to alveolar sacs.
Alveolar sacs are clusters of alveoli, which are small ballon-shaped air sacs where gas exchange occurs between the lungs and blood.
Bronchiolitis
As previously mentioned, bronchiolitis is inflammation of the bronchioles.
Therefore, the small airways (bronchioles) explained above are affected.
Let’s take a closer look at the pathophysiology of bronchiolitis, and how this occurs.
Bronchial Tree Anatomy: Labeled diagram of the bronchial tree structures including the trachea, bronchi, bronchioles, alveolar ducts, alveolar sacs, and alveoli.
Bronchiolitis - Pathophysiology
Let’s begin with a simple step-by-step of how bronchiolitis occurs, followed by a more detailed summary.
Bronchiolitis Pathophysiology - Step-by-Step
Bronchiolitis is typically caused by a viral infection
The virus can be transmitted (spread) via respiratory droplets or contact
An infected person coughs/sneezes, or a non-infected person comes in close contact with an infected person or contaminated surface
The virus enters a non-infected person via the eyes, nose, mouth, etc.
The virus travels through the airways to the bronchioles
The virus infects the airway epithelial cells leading to inflammation
There is airway/bronchiole narrowing, edema, obstruction, mucus production, etc.
Respiratory symptoms occur
Bronchiolitis is typically caused by a viral infection.
The most common virus is respiratory syncytial virus (RSV).
The virus can spread via respiratory droplets or contaminated surfaces.
For example, when an infected person coughs or sneezes, the virus can spread via respiratory droplets to a non-infected person.
The virus can also spread if a non-infected person comes in close contact with an infected person, or if the non-infected person touches a contaminated surface.
Whether transmitted via respiratory droplets or contact, the virus can then enter a non-infected person (via the nose, mouth, etc.), and travel down to the bronchioles.
As the virus travels through the airways to the bronchioles (see bronchial tree - above), the airway epithelial cells can become infected.
This can lead to inflammation of the airways.
Inflammation in the bronchioles is what causes bronchiolitis, in this case from a virus.
Inflammation of the bronchioles can cause:
Airway narrowing
Airway edema (swelling)
Airway obstruction
Increased mucus production
Increased air trapping
Decreased lung compliance
Decreased ventilation
Atelectasis
The above airway changes lead to the respiratory symptoms seen in bronchiolitis (see below).
Bronchiolitis Pathophysiology: Diagram showing RSV transmission from an infected person to a non-infected person.
RSV Pathophysiology: Diagram showing the pathway of RSV spread to the bronchioles, leading to inflammation of the bronchioles called bronchiolitis.
What Causes Bronchiolitis?
Bronchiolitis is typically caused by viruses including:
Respiratory syncytial virus (RSV) - MOST COMMON
Parainfluenza virus
Rhinovirus
Adenovirus
Coronavirus
Metapneumovirus
Bronchiolitis Causes: Bronchiolitis is typically caused by viruses, with RSV being the most common in infants/babies.
Risk Factors for Bronchiolitis
The epidemiology and risk factors of bronchiolitis include:
Bronchiolitis typically occurs in:
Children < 2 years old, but can occur at any age
Most common in infants < 6 months old
Most common in winter months
Occurs in the fall and peaks in the winter
Risk factors for bronchiolitis include:
Premature infant
Infant < 5 months old
Parental smoking
Underlying lung disease
The above risk factors also increase the risk for severe disease and symptoms.
Let’s review the symptoms of bronchiolitis next.
Bronchiolitis (RSV) Risk Factors: Risk factors for bronchiolitis include a premature infant, a baby less than 5 months old, parental smoking, and underlying lung disease.
Signs and Symptoms
Common signs and symptoms of bronchiolitis include:
Fever
Cough
Rhinorrhea - runny nose
Nasal congestion
Dyspnea - shortness of breath
Tachypnea - rapid breathing, increased respiratory rate
Wheezing
Crackles in the lungs
Poor feeding
Signs of respiratory distress or increased work of breathing include:
Retractions
When the skin and muscles between or around the ribs pull inward during inhalation
Subcostal - below the ribcage
Suprasternal - above the sternum
Intercostal - between the ribs
Nasal flaring
Grunting
Cyanosis - bluish discoloration of the skin/lips from decreased oxygen in the blood
Head bobbing
Labored breathing
Accessory muscle usage when breathing
Signs of respiratory distress or increased work of breathing may be present, especially in moderate to severe cases of bronchiolitis.
Bronchiolitis (RSV) Symptoms: Symptoms of bronchiolitis (RSV) include fever, cough, runny nose, congestion, shortness of breath, etc.
Bronchiolitis (RSV) Signs & Symptoms: Signs and symptoms of respiratory distress include retractions, nasal flaring, grunting, cyanosis, head bobbing, etc.
Diagnosis
How to diagnose bronchiolitis:
Bronchiolitis Diagnosis - Quick Notes
Most cases can be diagnosed clinically
Respiratory viral panel
Tests for common viruses such as RSV, influenza, etc.
For moderate-severe cases, unclear diagnosis, etc.
Consider chest x-ray
Consider labs/blood work (CBC, chemistry, ABG, etc.)
Most cases of bronchiolitis can be diagnosed clinically from the symptoms discussed above.
This means that imaging and labs may not always be necessary, especially in mild classic cases.
A respiratory viral panel can also be considered.
This is a nasal swab inserted in the nostril.
It tests for common viruses, such as RSV, influenza, etc.
A respiratory viral panel can help diagnose RSV or other specific viruses that can cause bronchiolitis.
If symptoms are moderate to severe, or there is concern for another diagnosis/unclear diagnosis, then additional tests can be considered.
A chest x-ray can be performed.
In the case of bronchiolitis, a chest x-ray may show viral airway disease.
A chest x-ray can also be helpful in identifying pneumonia.
Labs or blood work may also be considered, such as:
CBC - complete blood count
Chemistry
ABG - arterial blood gas
Others
*Diagnostic workup is made on a case-by-case basis by a medical professional. This is for educational purposes only and not medical advice.
Bronchiolitis (RSV) Diagnosis: Tests may include respiratory viral panel, chest x-ray, or blood work depending on the severity, although most cases are diagnosed clinically.
Treatment
Bronchiolitis treatment can be divided into mild-moderate disease and moderate-severe disease.
Bronchiolitis Treatment - Mild to Moderate Disease
Supportive care
Nasal suction
Nasal saline
Humidifiers
Antipyretics - acetaminophen, etc.
Hydration
Can typically be treated outpatient
Bronchiolitis Treatment - Moderate to Severe Disease
May require oxygen and/or breathing support
Nasal cannula, high-flow, CPAP, intubation (severe), etc.
May require IV fluids
Includes supportive care
Nasal suction, nasal saline, antipyretics, etc.
May require inpatient treatment
Bronchiolitis treatment for mild-moderate disease can typically be treated outpatient with supportive care.
Nasal suction, nasal saline, and humidifiers can be used to help with congestion.
Antipyretics, such as acetaminophen, can be used for fever and to ease symptoms.
Hydration is also important.
No specific medications are typically necessary.
Bronchiolitis treatment for moderate-severe disease, signs of respiratory distress, dehydration, etc. may require inpatient management or close monitoring.
The previously mentioned supportive care techniques should be considered.
Additionally, oxygen and/or breathing support may be necessary.
This may include traditional nasal cannula, high-flow nasal cannula, CPAP, intubation (severe cases), etc.
IV fluids may be necessary for hydration.
*Unlike asthma treatment where breathing treatments and/or steroids can be helpful, breathing treatments (bronchodilators, etc.) and steroids for bronchiolitis have not been shown to be overall effective.
**Palivizumab was once considered for high-risk infants to prevent severe lower respiratory tract disease caused by RSV.
Note, however, there are emerging RSV immunizations such as nirsevimab and clesrovimab.
*Treatment is made on a case-by-case basis by a medical professional. This is for educational purposes only and not medical advice.
Bronchiolitis (RSV) Treatment: Management may include supportive care, antipyretics, or oxygen/breathing support depending on the severity of the case.
Complications
Complications of bronchiolitis include:
Acute respiratory distress
Acute respiratory failure
Apnea - temporary cessation of breathing
Cyanosis - bluish discoloration of the skin/lips from low oxygen levels in the blood
Pneumonia
Sepsis
Recurrent infections
Respiratory distress (see symptoms above)
Hypoxia - low oxygen supply to tissues
Tachypnea - rapid breathing, increased respiratory rate
Dehydration
Not all bronchiolitis cases involve complications.
Bronchiolitis (RSV) Complications: Apnea, cyanosis, respiratory distress, pneumonia, etc. are potential complications of bronchiolitis (RSV).
Practice Questions
1. What is the most common cause of bronchiolitis?
A. Parainfluenza virus
B. Respiratory syncytial virus
C. Adenovirus
D. Coronavirus
2. What age group is most commonly affected by bronchiolitis?
A. < 6 months old
B. 2 - 4 years old
C. 4 - 8 years old
D. 8 - 12 years old
3. Which structures in the bronchial tree do the bronchioles most closely connect?
A. Lobar bronchi and alveolar ducts
B. Lobar bronchi and segmental bronchi
C. Segmental bronchi and main bronchi
D. Segmental bronchi and alveolar ducts
4. Which of the following is a sign of respiratory distress?
A. Retractions
B. Head bobbing
C. Nasal Flaring
D. All of the above
5. Which season does bronchiolitis most commonly peak?
A. Summer
B. Fall
C. Winter
D. Spring
6. Which of the following is considered a risk factor for bronchiolitis?
A. No underlying lung disease
B. Parental smoking
C. Age > 2 years
D. Full-term infant
7. How are most cases of uncomplicated bronchiolitis treated?
A. Supportive care
B. Breathing treatments
C. Steroids
D. Antibiotics
8. What measures can be taken to manage bronchiolitis?
A. Nasal suction/saline
B. Humidifiers
C. Antipyretics
D. All of the above
Answers
1. B
2. A
3. D
4. D
5. C
6. B
7. A
8. D