Bronchiolitis Part VIII: Bringing ’em all home (or into the hospital)

Alas, this is the final post in the bronchiolitis series. I hope you’ve enjoyed it. Parts I, II, III, IV, V, VI, and VII aren’t going anywhere – so check them out if you haven’t done so yet. This post will focus on the disposition of patients with bronchiolitis in the ED. Essentially, who do we feel comfortable sending home (and vice versa)? Let’s take a look at some of the important factors.

What factors are associated with a more severe disease course?

We can refer to Shaw et al, Am J Dis Child, 1991 for this one. The authors looked at a prospective series of 213 infants in the ED in order to “identify the historical, physical, and laboratory clues at initial emergency department evaluation that would help to predict disease severity.” They identified independent findings that were strongly associated with more severe illness. Per the authors the single best objective predictor was the pulse ox reading, with the overal six-variable model having a relatively high specificity.

Pulse ox? Really? OK, could you comment more on hypoxia in bronchiolitis?

Sure. In bronchiolitis mucous plugging leads to V/Q mismatch, which can lead to hypoxia. This all comes back to the Oxygen-hemoglobin dissociation curve. Recall that when a patient’s sats are >90% large increases in PaO2 are associate with small increases in SpO2. Conversely, when the SpO2 is <90%, a small decrease in PaO2 leads to larger decreases in SpO2. Practically speaking, if the sat is >90%, there is little benefit from increasing the PaO2 by putting the patient on supplemental O2, unless they benefit form it with improved respiratory effort and/or feeding.

In the outpatient setting despite earlier studies there is still conflicting evidence to this day as to whether or not a sat <95% is predictive of a severe outcome. In the inpatient setting many of you may have anecdotal experience with a patient that stayed a day longer than they needed to just because the pulse ox transiently dipped to 88% a few times. Studies have indicated that pulse ox monitoring increases the perceived need for supplemental O2, the risk of prolonged hospitalization, ICU admission and mechanical ventilation.

So, less freaking out about the sat is probably appropriate. Are there still select patients where one should have a lower threshold to apply O2? Yes, and this will be highlighted further on in this post, but in general go to supplemental O2 quicker in;