P0468 - High flow nasal cannula versus bilevel positive airway pressure for status asthmaticus: a retrospective cohort study

Background: Bilevel positive airway pressure (BiPAP) is a well described adjunct therapy for status asthmaticus (SA). Heated, humidified high flow nasal cannula (HFNC) as non-invasive ventilation (NIV) support for SA is increasingly applied owing to perceptions of convenience and elevated patient comfort compared to BiPAP. Yet, no comparative data are published to support HFNC use for SA.

Objective: We aim to explore the characteristics of patients placed on HFNC for SA in our institution and determine if differences exist in clinical outcomes as compared to those on BiPAP.

Methods: We performed a retrospective cohort study from January 2016 - June 2019 in children 5-17 years of age admitted to the pediatric intensive care unit (PICU) for SA on BiPAP or HFNC. Exclusion criteria were acute chest syndrome, pulmonary hypertension, or pre-existing NIV. Primary outcomes were duration of continuous albuterol, length of stay (LOS), and concurrent anxiolysis. Secondary outcomes were demographics, comorbidities, asthma severity scores, recognized asthma-severity historical factors, applied adjunctive therapies, admission nutritional status, duration of NIV, and NIV parameters. Comparative analyses included Fisher’s exact, student’s t, and Wilcoxon rank-sum tests.

Results: Of the 39 children on NIV, 13 (33%) were on HFNC and 26 (66%) BiPAP. Compared to children placed on BiPAP, those on HFNC were younger (6.8 ± 2.2 vs 10.9 ± 3.7 years, p = 0.001), had lower rates of severe persistent asthma (0 vs 38%, p = 0.01), greater rates of concurrent bacterial pneumonia (69 vs 19%, p = 0.002), and less frequent history of previous PICU admission (15 vs 62%, p = 0.013). Children on BiPAP had greater median duration of continuous albuterol (1.7 [1,3.1] vs 0.9 [0.7,1.6] days, p = 0.033) and concurrent anxiolysis (42 vs 8%, p = 0.027). No differences were noted in median LOS (3.6 [2.4,5] vs 3.6 [2.6,5.6] days, p = 0.64), duration of NIV (0.6 [0.4,1.4] vs 0.9 [0.6,1.3] days, p = 0.51), nil per os status (77 vs 96%, p = 0.06) or adjunctive asthma therapies for those on HFNC vs BiPAP. There were no observed mortalities, use of extracorporeal life support, or mechanical ventilation in this sample.

Conclusions: Children with SA placed on HFNC were younger, had less severe asthma, and did not require sedation for NIV. We did not detect differences in LOS, duration of NIV, or frequency of other PICU asthma therapies. Prospective, controlled and adequately powered analyses are still needed to support HFNC use in SA.