Peds - Bronchiolitis

Question 1

Relatively, how much/many cartilage, cilia, and goblet cells do bronchioles have?

Answer 1

Not much cartilage and cilia. Few goblet cells.

Question 2

How is peripheral resistance different between adults and infants/children younger than 5 years old?
Why is this important?

Answer 2

In adults, 90% of resistance is from central airways, only 10% from peripheral airways.
In children < 5 years, it’s a 50-50 split.

This means that things that increase peripheral resistance - i.e. bronchiolitis, will have a much greater detrimental impact on children/infants < 5 years old.

Question 3

Most common etiology of bronchiolitis in children < 2 years old?

Answer 3

RSV -responsible for around 60ish?% of bronchiolitis.

Though other viruses, like rhinovirus etc. are important cause.

Question 4

RSV mortality in healthy children?

Answer 4

< 1% (in the US. It’s worse in developing nations.)

Question 5

What percent of children < 2 years with RSV are hospitalized?

Answer 5

2-3%
Which leads to >120,000 hospitalizations annually.
(in the US)

Question 6

RSV doesn’t kill as many babies as does S. pneumo.

Answer 6

But it’s the most common viral cause.

Question 7

Does infection with RSV induce immunity?

Answer 7

No. The immunity isn’t very good, and it’s not durable… though future infections may be more mild.
(anti-RSV antibodies are made… but even patients who make lots of anti-RSV Abs can get reinfected in the future)

Question 8

Definition of epidemic RSV?

Answer 8

> 10% of tests for RSV come back positive.

…kind of a weird definition.

Question 9

How is RSV transmitted?

Answer 9

Droplets, large particles, and fomites.

Wash your goddamn hands. And alcohol your stethoscope when dealing with young kids/infants.

Question 10

What does RSV do to the airways?

Answer 10

Replicates.
Causes necrosis/lysis, and release of inflammatory mediators.
Causes edema, mucus production.
Airways get filled with cellular debris…

Question 11

Clinical presentation of bronchiolitis?

Answer 11

Watery, copious rhinorrhea.
Cough.
Low-grade fever (<103 deg. F)
Tachypnea, retractions.
Grunting, nasal flaring.
Wheezing, crackles.
Apnea.
Conjunctivitis.

Question 12

4 changes in pulmonary function with bronchiolitis?

Answer 12

Hypoxemia.
Tachypnea with hypopnea.
Gas trapping.
Abnormal compliance.
Atelactasis - esp of right upper lobe.

Question 13

Which children/infants are at highest risk for severe RSV?

Answer 13

Premature infants. - most sto
Chronic lung disease.
Congenital heart disease.
Neuromuscular disease.
Immune deficiency.

Question 14

Why are premature infants so at risk for severe RSV?

Answer 14

Mainly, we think, because they lack transplacental maternal Abs - which double in the last few weeks.
Also premature babies can have airways with reduced diameter, increased goblet cells.

Question 15

How is diagnosis of RSV confirmed?

Answer 15

A variety of ways… culture, Ag detection, fluorescent Abs…
but PCR is probably the best.

Question 16

How is severity of RSV bronchiolitis assessed?

Answer 16

Increased work of breathing.
Apea.
Need for interventions: IV fluids, O2, mechanical ventilation.

Question 17

3 mainstays of bronchiolitis therapy?

Answer 17

IV fluids.
Secretion removal.
O2.

Question 18

What’s the 60-60 rule?

Answer 18

If the respiration rate is > 60, the pO2 is probably < 60 mmHg.

Question 19

Downside of fluid replacement?

Answer 19

Can cause edema, making breathing worse.

Question 20

Options of respiratory support in infants with bronchiolitis?

Answer 20

Supplemental O2 - head box, high-flow nasal cannula.
CPAP.
Mechanical ventilation.

Question 21

What’s the only therapy that shortens hospital stays of infants with bronchiolitis?

Answer 21

Inhaled hypertonic saline to loosen secretions.

Question 22

5 potential therapies for bronchiolitis? (they won’t necessarily all work well)

Answer 22

Chest physiotherapy - doesn't usually work.
Steroids - maybe useful in complicated cases, doesn't hurt.
Bronchodillators - response varies.
Hypertonic saline (inhaled) - works quite well.
Antivirals - probably doesn't do anything.

Question 23

What’s the response to bronchodilator therapy like in bronchiolitis?

Answer 23

1/3 of patients improve.
1/3 have no effect.
1/3 get worse, possibly because relaxation of smooth muscle allows airway collapse.
(so if you use it, monitor the response!)

Question 24

Why is giving an antiviral like ribavirin usually not effective for speeding recovery from RSV bronchiolitis?

Answer 24

By the time the patient is hospitalized, the viral load has probably just about peaked, and will be falling rapidly anyway.
Exception: In respiratory failure, the virus seems to not be clearing, so ribivarin may help.

Question 25

Aside from avoiding exposure to RSV (not sending to daycare, washing your damn hands, etc.), what can be done to help prevent infection in high-risk patients?

Answer 25

Passive immunoprophylaxis - give humanized anti-RSV mAb. (Palivizumab).

Question 26

Anti-RSV mAbs are really expensive. Who should get them?

Answer 26

Children at high risk due to:
Prematurity.
Chronic lung disease.
Congenital heart disease.

Question 27

Sequelae of childhood bronchiolitis?

Answer 27

Increased risk for asthma.
Wheezing - can last a long time, up to 10 years.

Bronchiolitis obliterans (chronic obstruction)

Question 28

Bronchiolitis obliterans is on a spectrum. What can happen?

Answer 28

Bronchiolitis obliterans can manifest as…

• bronchiole inflammation.
• peribrochiolar fibrosis.
• complete scarring off of bronchioles.

Question 29

RSV isn’t the main cause of bronchiolitis obliterans (I guess? But it can predispose to it?). What are some pathogens that can cause it?

Answer 29

Adenovirus.
Mycoplasma.
Influenza A
Bordatella pertussis.
Measles.
Varicella.

Question 30

Supportive treatment for bronchiolitis obliterans?

Answer 30

O2.
Airway clearance.
ABx.
Bronchodilators.
Nutritional support.

Question 31

Directed treatment for obliterive bronchiolitis? (3 things)

Answer 31

Corticosteroids.
Immunosuppresion.
Lobectomy / pneumonectomy of affected area.