Oxygen Saturation and Bronchiolitis Severity

Principi T, Coates AL, Parkin PC, et al. Effect of oxygen desaturations on subsequent medical visits in infants discharged from the emergency department with bronchiolitis [published online ahead of print February 29, 2016]. JAMA Pediatr. doi: 10.1001/jamapediatrics.2016.0114Investigators from The Hospital for Sick Children in Toronto, Canada sought to determine if oxygen desaturations at home (unknown to parents) in previously healthy infants 6 weeks to 12 months of age who were discharged from the emergency department (ED) with bronchiolitis predict future unscheduled medical visits. Research nurses enrolled study participants who were diagnosed with bronchiolitis and deemed suitable for discharge from the ED. At enrollment, parents were given a pulse oximeter to take home with the child. Although the study pulse oximeters continuously recorded the oxygen saturation, they did not display saturation values and only alarmed for probe dislodgement. Prior to discharge from the ED, a pulse oximeter probe was applied to each study child and parents were taught how to reapply it. Parents were asked to record times of feeding, sleeping, and car seat use while the child was monitored. Parents were contacted 72 hours after discharge from the ED and asked about subsequent medical visits and hospitalizations.Following study completion, data from the pulse oximeters were analyzed using proprietary oximetry software which excluded artifacts and poor signal and generated the oximetry reports. A desaturation was defined as at least 1 oxygen saturation reading of <90% lasting at least 1 minute. Major desaturations were defined as 3 desaturations, or a reading of <90% for 3 minutes continuously or ≥10% of the total monitored time, including percentage of time with saturations 80%–89% and <80%. The primary outcome measure was an unscheduled visit for bronchiolitis within 72 hours of discharge; secondary outcomes included hospitalizations and all-cause medical visits. These outcomes were compared among infants with and without oxygen desaturations.Of the 118 participants, 64% (n = 75) had at least 1 desaturation during home monitoring. Of those with desaturations, 79% spent >1 minute with saturations ≤80%, 39% spent >1 minute with saturations ≤70%, and 53% experienced major desaturations. Most infants with desaturations (77%) experienced them during sleep or while feeding.There was no difference in unscheduled visits for bronchiolitis among infants with or without desaturations (24% vs 26%, respectively; P = .66). There was also no difference in rates of unscheduled visits between those with or without major desaturations. Rates of all-cause medical visits and hospitalizations also did not differ between infants with or without desaturations.The authors conclude that the majority of infants with mild bronchiolitis experienced desaturations at home, and that pulse oximetry does not predict return for care.Dr Garber has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.This is yet another study challenging the value of pulse oximetry in infants with bronchiolitis. Similar studies have been discussed in this journal (see AAP Grand Rounds, December 2014;32[6]:611 and December 2015;34[6]:642). In both of those prior studies the pulse oximeter display was altered to appear higher in the experimental groups, and patients in the experimental groups experienced fewer admissions and equivalent or better outcomes. The current study went further by not displaying any values and not alarming for low saturations. While this monitoring happened at home, the same desaturations occurring in the ED or the hospital may lead to admission or more interventions. Continuous pulse oximetry is more likely to detect these abnormalities and has been shown to be unnecessary for nonhypoxemic infants hospitalized for bronchiolitis.3Detection of transient desaturations without respiratory distress represents overdiagnosis – the identification of an abnormality where detection will not benefit, but may harm the patient.4 While chronic hypoxemia affects cognitive development, the authors of an accompanying editorial suggest that the evidence on the effects of chronic hypoxemia should not be extrapolated to previously healthy children with transient hypoxemia, and mention the difficulty in studying and preventing something as common as brief desaturations in healthy children.5 Perhaps the authors of the current and previous studies are teaching us not just about bronchiolitis but about human nature – once we have data, even clinically insignificant data, it is hard to ignore, and perhaps the best move in a happy nondistressed child with bronchiolitis is turning the oximeter off!It would also be prudent to recognize to whom these results do not apply based on the exclusion criteria used in the study: patients <6 weeks old, those with comorbidities (including prematurity of <36 weeks’ gestation), and/or infants with previous wheeze.

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