Peds - Bronchiolitis Flashcards
Relatively, how much/many cartilage, cilia, and goblet cells do bronchioles have?
Not much cartilage and cilia. Few goblet cells.
How is peripheral resistance different between adults and infants/children younger than 5 years old?
Why is this important?
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.
Most common etiology of bronchiolitis in children < 2 years old?
RSV -responsible for around 60ish?% of bronchiolitis.
Though other viruses, like rhinovirus etc. are important cause.
RSV mortality in healthy children?
< 1% (in the US. It’s worse in developing nations.)
What percent of children < 2 years with RSV are hospitalized?
2-3%
Which leads to >120,000 hospitalizations annually.
(in the US)
RSV doesn’t kill as many babies as does S. pneumo.
But it’s the most common viral cause.
Does infection with RSV induce immunity?
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)
Definition of epidemic RSV?
> 10% of tests for RSV come back positive.
…kind of a weird definition.
How is RSV transmitted?
Droplets, large particles, and fomites.
Wash your goddamn hands. And alcohol your stethoscope when dealing with young kids/infants.
What does RSV do to the airways?
Replicates.
Causes necrosis/lysis, and release of inflammatory mediators.
Causes edema, mucus production.
Airways get filled with cellular debris…
Clinical presentation of bronchiolitis?
Watery, copious rhinorrhea. Cough. Low-grade fever (<103 deg. F) Tachypnea, retractions. Grunting, nasal flaring. Wheezing, crackles. Apnea. Conjunctivitis.
4 changes in pulmonary function with bronchiolitis?
Hypoxemia. Tachypnea with hypopnea. Gas trapping. Abnormal compliance. Atelactasis - esp of right upper lobe.
Which children/infants are at highest risk for severe RSV?
Premature infants. - most sto Chronic lung disease. Congenital heart disease. Neuromuscular disease. Immune deficiency.
Why are premature infants so at risk for severe RSV?
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.
How is diagnosis of RSV confirmed?
A variety of ways… culture, Ag detection, fluorescent Abs…
but PCR is probably the best.
How is severity of RSV bronchiolitis assessed?
Increased work of breathing.
Apea.
Need for interventions: IV fluids, O2, mechanical ventilation.
3 mainstays of bronchiolitis therapy?
IV fluids.
Secretion removal.
O2.
What’s the 60-60 rule?
If the respiration rate is > 60, the pO2 is probably < 60 mmHg.
Downside of fluid replacement?
Can cause edema, making breathing worse.
Options of respiratory support in infants with bronchiolitis?
Supplemental O2 - head box, high-flow nasal cannula.
CPAP.
Mechanical ventilation.
What’s the only therapy that shortens hospital stays of infants with bronchiolitis?
Inhaled hypertonic saline to loosen secretions.
5 potential therapies for bronchiolitis? (they won’t necessarily all work well)
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.
What’s the response to bronchodilator therapy like in bronchiolitis?
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!)
Why is giving an antiviral like ribavirin usually not effective for speeding recovery from RSV bronchiolitis?
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.
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?
Passive immunoprophylaxis - give humanized anti-RSV mAb. (Palivizumab).
Anti-RSV mAbs are really expensive. Who should get them?
Children at high risk due to:
Prematurity.
Chronic lung disease.
Congenital heart disease.
Sequelae of childhood bronchiolitis?
Increased risk for asthma.
Wheezing - can last a long time, up to 10 years.
Bronchiolitis obliterans (chronic obstruction)
Bronchiolitis obliterans is on a spectrum. What can happen?
Bronchiolitis obliterans can manifest as…
- bronchiole inflammation.
- peribrochiolar fibrosis.
- complete scarring off of bronchioles.
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?
Adenovirus. Mycoplasma. Influenza A Bordatella pertussis. Measles. Varicella.
Supportive treatment for bronchiolitis obliterans?
O2. Airway clearance. ABx. Bronchodilators. Nutritional support.
Directed treatment for obliterive bronchiolitis? (3 things)
Corticosteroids.
Immunosuppresion.
Lobectomy / pneumonectomy of affected area.
