CDC.gov/rsv on 1/6/13 for picture credit
Sally is 9-months old; she developed a runny nose after a holiday party she attended with the family last week. Now her mom has been struggling all day to keep Sally comfortable. The doctors in the ED told her last night, Sally had bronchiolitis and she should administer these nebulizer medications to her at home and follow up with her primary care doctor.
What is Bronchiolitis, Doc?
Bronchiolitis is inflammation of a portion of the lower airways, most often triggered by viral infections of the lower airway. The term coined in a seminal article published in 1940 distinctly described this condition frequently seen in children < 2 years old in the winter months in temperate climates around the world. Medical jargon frequently makes its way into colloquial language and gets distorted. Bronchiolitis has suffered similar fate with however less distortion in its meaning and attendant respiratory implication. Most of us intuitively associate the term with respiratory problems even though; it is frequently used interchangeably and incorrectly with another distinct medical condition called, Bronchitis.
Why my baby, Doc? She’s so little and having a lot of trouble with the coughing and breathing.
The number of cases diagnosed with bronchiolitis goes up in the winter months, in tandem with the seasonal spread of the viruses that trigger the illness. These viruses reproduce very quickly once they get access to the cooler portions of the nasal passages and the cascade of lower airway inflammation begins shortly afterwards. The upper respiratory infection symptoms make it difficult for infants as obligate nose breathers to breathe. The mucus partially blocks the nasal passages and the need for gentle suctioning becomes a key portion of supportive therapy. The RSV (Respiratory Syncytial Virus) virus is perhaps the most commonly isolated culprit in the ranks of viruses that frequently make infants and young children come down with Bronchiolitis. Some members of Influenza virus family and a relatively newcomer called, human metapneumovirus are other potential big players.
The lower airway inflammation caused by these germs cause a lot of airway secretion, congestion and copious mucus production which narrows the lumen in these tiny airways even further and presents resistance to the flow of air and gas exchange which we all remember is the primary function of the lungs. Inhaling air is comparatively easier than exhaling air in these patients. Large portions of the inhaled air along with the other gases exchanged get trapped behind the mucus plugging in the lower airways. A narrowed airway creates a four-fold increase in resistance to airflow, which only worsens as the degree of airway obstruction, and narrowing worsens with the disease progression. Coughing and wheezing follow as symptoms of a process where the body tries to forcefully expel the air trapped in the lungs past these areas of airway obstruction. This is a compensatory mechanism in-built by nature to relieve the airway trapping and excessive lung stretching. It is possible though not common for an infant suffering from bronchiolitis to be infected by more than one type of virus.
What about the nebulizer? It doesn’t seem to help!
Bronchiolitis is indeed one of those illnesses where the cornerstone of therapy in infants is oddly aimed at relieving the most pressing symptoms and not the root cause. Home nebulizer kits are part of this limited scope arsenal. These kits are powered and generate a mist usually from instilled medications often prescribed for bronchiolitis, like Albuterol. Some infants respond favorably to these class of medications. They are designed to relieve the airway narrowing and obstructions described above and hopefully enhance airflow in and out of the lungs and provide comfort for the patient. The expectation is that the sequelae of the airway obstruction process like cough, wheezing will attenuate and maybe resolve with use. Many infants however do not respond as anticipated to these medications. Many patient factors beyond the scope of our discussion and the infant’s genetic legacy determine who might respond favorably to Albuterol and this remains an area of intense scientific scrutiny due to the huge disease burden presented by Bronchiolitis annually. Bronchiolitis caused by RSV and the potential for complications can be controlled to an extent with specific medications and antibody injections in select groups of patients. Steroid medications have also been shown to have limited use for many cases of bronchiolitis.
What do I do? Baby’s not breathing well!
Recognition of the signs of respiratory distress is a key part of the management of these infants. Premature infants are especially vulnerable to the severe complications of bronchiolitis. One of the most feared complications is Apnea. This refers to the cessation of breathing, which occurs insidiously over time in the affected infant. Increased work of breathing and increased rate of breathing are universally the key hallmarks- these situations warrant immediate medical attention. Any perception of impending respiratory failure is extreme and is truly a medical emergency and should be treated as such. Parents frequently pay more attention to the noisy breath sounds emanating from the nasal passages. These are often amenable to gentle suctioning and use of comfort measures like saline nose drops, positioning etc. A visit to your healthcare provider for evaluation is necessary in these cases to be sure signs of respiratory distress when present are not missed.
I’m so scared about her breathing and this RSV thing! Shouldn’t the hospital have admitted Sally? Isn’t the RSV supposed to be serious?
Hospital admission for bronchiolitis would be appropriate whenever skilled healthcare personnel make that determination. This is often based on the severity of Infants presentation and other factors directly affecting care of the patient. The isolation of RSV or Influenza viruses during testing at the point of care either in your primary care clinic or in the emergency department does not always mandate hospitalization. Average duration of hospital stay is between 3 to 7days and only patients sick enough to benefit from hospitalization should be admitted. These often involves patients needing oxygen support or other risk factors that make a more severe outcome likely for them. Other groups of patients would need frequent monitoring and access to their primary care provider to ensure a sustained pattern of improvement is established in the medical home.
Does this mean my baby will now have Asthma?
Attacks of bronchiolitis, especially those where the RSV virus is the infectious agent certainly increase the likelihood of reversible airway obstruction occurring time and again after the acute illness is over. This is what construes, asthma and yes there is a link with bronchiolitis. A host of other factors, especially family history of allergy based diseases and genetics and environmental factors like cigarette smoke, domestic pest infestation also affect the possibility of developing asthma after an episode of bronchiolitis. This is a possibility still and time with close monitoring will determine those who would go on to develop chronic airway problems.
There is no known cure for many of the viruses capable of causing bronchiolitis in infants. Infection control and prevention are very important. These viruses spread as droplets and do not float in the air we breathe contrary to the general impression. They travel no more than 3 feet even when aerosolized after a cough or sneeze. The infectious droplets linger on surfaces for extended periods and poor hand hygiene inevitably brings them to areas of the body like the face; nose etc. from these surfaces like : cordless handsets in the home, TV remote control, Door knobs, faucets etc. From here they gain access to the body’s airway tract and begin the illness. Clean hands will go a long way in controlling spread of viral infections. Common sense interventions, such as avoidance of kissing, cuddling sick persons would also stand to reason for the same reason stated above.