Nasal high flow in management of children with status asthmaticus: a retrospective observational study

Abstract

Background: Asthma is the most common obstructive airway disease in children and adults. Nasal high flow (NHF) is a recent device that is now used as a primary support for respiratory distress. Several studies have reported use of NHF as a respiratory support in status asthmaticus; however, there are no data to recommend such practice. We therefore conducted this preliminary study to evaluate NHF therapy for children with status asthmaticus admitted to our PICU in order to prepare a multicentre randomized controlled study.

Results: Between November 2009 and January 2014, 73 patients with status asthmaticus were admitted to the PICU, of whom 39 (53%) were treated with NHF and among these 10 (26%) presented severe acidosis at admission (pH < 7.30). Thirty-four less severe children (41%) were treated with standard oxygen. For one child (2.6%) NHF failed and was then switched to non-invasive ventilation. NHF was discontinued in another patient because of the occurrence of pneumothorax after 31 h with NHF; the patient was then switched to standard oxygen therapy. Mean ± SD heart rate (165 ± 21 vs. 141 ± 25/min, p < 0.01) and respiratory rate (40 ± 13 vs. 31 ± 8/min, p < 0.01) decreased significantly, and blood gas improved in the first 24 h. In the subgroup of patients with acidosis, median [IQR] pH increased significantly between hour 0 and 2 (7.25 [7.21-7.26] vs. 7.30 [7.27-7.33], p = 0.009) and median [IQR] pCO₂ decreased significantly (7.27 kPa [6.84-7.91 vs. 5.85 kPa [5.56-6.11], p = 0.007). No patient was intubated.

Conclusion: This retrospective study showed the feasibility and safety of NHF in children with severe asthma. Blood gas and clinical parameters were significantly improved during the first 24 h. NHF failed in only two patients, and none required invasive ventilation.

Keywords: Asthma; Children; High-flow nasal cannula; Non-invasive ventilation; Paediatric intensive care unit.

Fig. 1

Patient flow chart. PICU paediatric intensive care unit, NHF nasal high flow, NIV non-invasive ventilation, IV invasive ventilation

Fig. 2

Proportion of children treated by nasal high flow and standard oxygen from 2009 to 2014 (p = 0.66 with Fisher’s exact test). NHF nasal high flow

Fig. 3

Change of heart rate (a), respiratory rate (b), and SpO₂/FiO₂ ratio (c) during the first 24 h in 38 children with status asthmaticus treated by nasal high flow. Heart rate, respiratory rate, and SpO₂/FiO₂ ratio significantly change over time according to the repeated-measures analysis of variance (ANOVA). *Significant difference with pairwise post hoc analysis (p < 0.01). Bars indicate 95% confidence intervals. H hours

Fig. 4

Change of pH (a) and pCO₂ (b) at admission and at hour 2 in ten children with severe acidosis treated with nasal high flow for status asthmaticus, including one child (discontinuous line) who failed to HFNC