Bronchiolitis: The Rationale Behind the New AAP Guideline

Ricardo A. Quinonez, MD; Shawn L. Ralston, MD


November 13, 2014

That said, we didn't have a lot of data to support the general feeling that the use of continuous pulse oximetry was leading to more hospitalizations and prolonging length of stay, although there are some retrospective evaluations and a randomized controlled trial that should be published at some point this year. We also considered evidence that suggested that continuous pulse oximetry and intermittent pulse oximetry were at least equivalent in terms of safety.[4]

Since the guideline was developed, I think the biggest bombshell has been the study by Schuh and colleagues published in JAMA in August of this year.[5] This was not a study evaluating use of continuous pulse oximetry, which I understand was your question, but I'm using it to shore up my argument that pulse oximetry really dictates what we do in bronchiolitis. In this study, the researchers randomly assigned infants with bronchiolitis to one of two pulse oximetry groups: The first group was placed on a pulse oximeter that displayed true saturation values, and the second group of infants was placed on oximeters in which measurements had been artificially elevated three percentage points above true values. They then followed these two cohorts of patients to determine whether hospitalization rates differed. Patients who had the true pulse ox values displayed were hospitalized quite a bit more, although outcomes were the same when controlling for other markers of disease severity. This seems to illustrate that the clinical aspect of the patient gets ignored and the number gets acted upon. What we know is that, in the absence of incorporation of clinical findings into an overall assessment of the infants, the pulse ox really doesn't predict much.

What we wanted to do with the guideline was to be careful not to make a non-evidence-based statement about management. There isn't any evidence to support the use of continuous pulse oximetry. I think we've accepted this technology and brought it into our regular practice, but there was never any evidence that it was beneficial or something that needed to be done in patients. I think that as time goes on and more people continue to evaluate the technology, we're going to find that there's a significant downside.

Dr Quinonez: Let's switch gears and talk about hypertonic saline. Two recent studies on use of hypertonic saline in infants in the ED setting came to somewhat different conclusions.[6.7] An accompanying editorial[8] concluded that the jury was still out on use of this therapy in the ED. However, the guideline committee did endorse its use in those instances in which length of stay may be greater than 3 days. Can you address why the guideline committee chose to recommend it?

Dr Ralston: This was also a heavily debated and difficult topic because of the conflicting evidence. I think the preponderance of the evidence now is clear, that short-term use of hypertonic saline doesn't have much clinical impact. The Wu study[6] was the only study that showed an impact in an ED setting. Certainly one could quibble about the number of doses or the concentration, or any of those things, but there is a large number of other studies showing a clear preponderance that one, two, or three doses in an ED setting is not likely to affect the risk for hospitalization.

However, the issue of sustained use is much more difficult. There was a Cochrane review[9] published in 2013 which showed a 1-day decrease in length of stay. That's hard to ignore. However, the preponderance of the studies considered in the Cochrane review had much longer lengths of stay than we were finding in the United States. But we also wanted to consider the Wu data, as well as information from another randomized controlled trial that was completed this year and had been presented in abstract form at the Pediatric Academics Society meeting.[10] We wanted to add the available American research without ignoring the Cochrane review. When we did so, it tempered, to a large degree, the impact on length of stay. This made it difficult to make a recommendation.

What we believe, based on the pattern of the evidence and the physiologic evidence, is that hypertonic saline may be useful in bronchiolitis but it needs to be administered in a sustained fashion over a relatively prolonged period. We're not sure how large of an effect it's likely to have in that setting. It was one of our most important recommendations for future research. We strongly believe that an outpatient trial should be undertaken. You will note that our recommendation on the inpatient side is a weak recommendation because, again, once we take into consideration the two large American trials, the impact on length of stay is substantially decreased. I think this is going to be a topic with a lot of further research; we'll see how it all plays out.


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