By Chris Carroll, MD, MS
We are firmly in the throes of bronchiolitis season. So that means, as a pediatric ICU doctor, for the last month I’ve given the same speech several times a day to each parent with a child admitted to my ICU. I’ve gotten pretty good at it. So I thought I’d share it in a blog.
Bronchiolitis is ubiquitous in the winter. Everybody gets it, pretty much every year. The most common cause of bronchiolitis is Respiratory Syncytial Virus (RSV), but there other causes that we don’t routinely test for, so not every child with bronchiolitis is “positive” for RSV.
Not all bronchiolitis infections are serious. Most are really minor and just seem like a “cold”, especially in adults, older children, and toddlers. But in some infants, these infections can be serious and can require hospitalization. Each year in the state of Connecticut, where there are about 40,000 infants under a year of age, we admit about 350 children with bronchiolitis to Connecticut Children’s for the treatment of severe breathing issues.
Most of those admitted to the regular hospital ward need supplemental oxygen, delivered through a nasal cannula (small nose prongs). Sometimes these children need breathing treatments, intravenous fluids, or help with feedings and most go home in 1-3 days. But 1 in 7 of these children admitted to the hospital need to go the intensive care unit (ICU) for the treatment of more severe respiratory disease and difficulty breathing.
Of the 50 children admitted to our ICU each year with bronchiolitis, most need what is called non-invasive positive pressure. This provides support for their breathing and is typically delivered using a heated high-flow nasal cannula (sometimes just referred to as “high flow”). This involves a somewhat larger nasal prong that fits just inside an infant’s nose and allows us to give more support than a regular nasal cannula. In some children, even more support is needed than “high flow”, and a slightly larger nasal prong is used to provide “CPAP” or continuous positive airway pressure.
A small number of children need even more support than can be provided non-invasively. These infants are more acutely ill and have more severe respiratory distress. About 1 in 10 children admitted to the ICU (or about 5-6 per year), need to be “intubated” or to have a breathing tube placed in their throat so that we can provide invasive mechanical ventilation (aka life support). But the best news about bronchiolitis is that children very rarely die of this disease. Even children who need to be intubated generally do very well, although it may be a long road to recovery in these children.
Most children admitted to the ICU with bronchiolitis are admitted for 2-3 days, plus another 1-3 days on the regular ward before discharge (so 3-6 days total). But that’s an average. So some kids only need 1-2 days of hospitalization. And some kids need 1-2 weeks. Each child is different and responds differently to the infection and the treatment. It is hard to know up front how quickly children some children will recover.
So why are some kids so sick from bronchiolitis while others are home with a more mild illness? This is a question I get asked a lot. There are some risk factors for more severe disease. For example, children born very prematurely (before 34 weeks), and children with heart disease have a greater risk of more severe bronchiolitis. But the vast majority of the infants we admit to the hospital each year have no risk factors and are previously healthy.
So again, why do only some kids get so sick with bronchiolitis? The short answer is we don’t know. For lack of a better description, it’s essentially bad luck. But there is a longer answer. One possible explanation to why some kids might have more severe disease is that they might have an immune deficiency or be more prone to severe diseases in general. But we’ve followed children admitted to the hospital with bronchiolitis. And they don’t have immune deficiency when we’ve tested for it. And for the vast majority, this is the one and only time they’ve ever been admitted to the hospital. Even the children who need to be intubated go on to live long and happy lives free of recurrent illness. Could it be some super strain of virus that these children are infected with? The answer to this is also “no”. We’ve done studies of the viruses infecting these children, and they are infected with the same stains as everyone else.
So we’re left with just a bad interaction between this year’s strain of the virus and that child’s immune system. We’ve seen this in other infectious diseases, and we’re starting to tease out these relationships with RSV as well. Just as each of us responds differently to medications, people respond differently to infections. Unfortunately, someone has to be on the more severe end of the disease spectrum. We are conducting research at Connecticut Children’s into how these interactions affect infants with RSV, but we are years away from answers that will change clinical care.
A part I never get to in my speech is how do you prevent bronchiolitis in your infant? The short answer is that you probably can’t. But the long answer is that there is some good common sense things parents can do to try to reduce the risk of infection. Parents should avoid contacts with sick people. (Spoiler. That’s a big reason so many babies are sick this time of year: sick relatives kissing babies at Thanksgiving and Christmas.) Don’t invite sick people over to see the new baby. Don’t let sick people hold or kiss the baby. Have people wash their hands before holding the baby. And if you have other children at home, try to wash your hands and their hands frequently, and to clean surfaces (in the kitchen, the bathrooms, door handles, etc) to try to prevent the spread of germs.
I’ll freely admit that I’m the type of doctor no one wants to meet. As a pediatric ICU doctor, I see parents at the worst points in their lives. But fortunately, the vast majority of children recover from bronchiolitis, and never return to the hospital again. So keep sick people away from your infants if you can. And I hope you’ll never have to meet me in the ICU.
Chris Carroll, MD, MS is the Medical Director, Surgical Critical Care and Research Director, Pediatric Critical Care, and an active and productive researcher, administrator, educator, and clinician at Connecticut Children’s. Follow him on Twitter at @ChrisCarrollMD.