The Local and Systemic Exposure to Oxygen in Children With Severe Bronchiolitis on Invasive Mechanical Ventilation: A Retrospective Cohort Study

Abstract

OBJECTIVES: Oxygen supplementation is a cornerstone treatment in critically ill children with bronchiolitis in the PICU. However, potential deleterious effects of high-dose oxygen are well-known. In this study, we aim to describe the pulmonary (local) and arterial (systemic) oxygen exposure over the duration of invasive mechanical ventilation (IMV) in children with severe bronchiolitis. Our secondary aim was to estimate potentially avoidable exposure to high-dose oxygen in these patients. DESIGN: Retrospective cohort study. SETTING: Single-center, tertiary-care PICU. PATIENTS: Children younger than 2 years old admitted to the PICU for severe bronchiolitis receiving IMV. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Hourly measurements of F io 2 and peripheral oxygen saturation (Sp o 2 ), and arterial blood gas data were collected up to day 10 of IMV. A total of 24,451 hours of IMV were observed in 176 patients (median age of 1.0 mo [interquartile range (IQR), 1.0–2.3 mo]). The pulmonary exposure to oxygen was highest during the first day of IMV (median time-weighted average [TWA]–F io 2 0.46 [IQR, 0.39–0.53]), which significantly decreased over subsequent days. The systemic exposure to oxygen was relatively low, as severe hyperoxemia (TWA–Pa o 2 > 248 Torr [> 33 kPa]) was not observed. However, overuse of oxygen was common with 52.3% of patients ( n = 92) having at least 1 day of possible excessive oxygen exposure and 14.8% ( n = 26) with severe exposure. Furthermore, higher oxygen dosages correlated with increasing overuse of oxygen (r repeated measures , 0.59; 95% CI, 0.54–0.63). Additionally, caregivers were likely to keep F io 2 greater than or equal to 0.50 when Sp o 2 greater than or equal to 97%. CONCLUSIONS: Moderate to high-dose pulmonary oxygen exposure and potential overuse of oxygen were common in this cohort of severe bronchiolitis patients requiring IMV; however, this was not accompanied by a high systemic oxygen burden. Further studies are needed to determine optimal oxygenation targets to prevent overzealous use of oxygen in this vulnerable population.

Validation and Extension of the Association Between Potentially Excess Oxygen Exposure and Death in Mechanically Ventilated Children

“…Although the Spo 2 cutoff for eCEOE calculation in the current study was 95%, which itself is not a normal oxygen saturation in healthy children (17,18), most Spo 2 values for patients with eCEOE >0 were 98-100%. In a recent study of oxygen exposure in patients with bronchiolitis, potentially excess oxygen exposure, defined similarly to our study, was observed on almost 29% of patient-days (19), demonstrating that high Fio 2 in patients with near-normal or normal oxygen saturations may be commonplace.…”

Editor’s Choice Articles for February

“…We have two systematic reviews: one on noninvasive ventilation (NIV) in acute respiratory failure–four of 15 articles were about bronchiolitis care (15); the other on use of high-flow nasal cannula (HFNC) oxygen therapy or NIV in 28 reports of bronchiolitis (16). We also have a retrospective study of oxygen exposure during IMV in 176 patients with bronchiolitis, in which the authors are interested in oxygen overuse and the potential for optimal oxygenation targets (17). In this context, please look at the recently published protocol for the randomized controlled trial on conservative versus liberal oxygenation targets in critically ill children (18).…”