Background: Despite the increasing use of non-invasive respiratory support in paediatric intensive care units, there are no large randomised controlled trials comparing two commonly used non-invasive respiratory support modes, continuous positive airway pressure and high-flow nasal cannula therapy.
Objective: To evaluate the non-inferiority of high-flow nasal cannula, compared with continuous positive airway pressure, when used as the first-line mode of non-invasive respiratory support in acutely ill children and following extubation, on time to liberation from respiratory support, defined as the start of a 48-hour period during which the child was free of respiratory support (non-invasive and invasive).
Design: A master protocol comprising two pragmatic, multicentre, parallel-group, non-inferiority randomised controlled trials (step-up and step-down) with shared infrastructure, including internal pilot and integrated health economic evaluation.
Setting: Twenty-five National Health Service paediatric critical care units (paediatric intensive care units and/or high-dependency units) across England, Wales and Scotland.
Participants: Critically ill children assessed by the treating clinician to require non-invasive respiratory support for (1) acute illness (step-up randomised controlled trial) or (2) within 72 hours of extubation (step-down randomised controlled trial).
Interventions: High-flow nasal cannula delivered at a flow rate based on patient weight (Intervention) compared to continuous positive airway pressure of 7-8 cm H2O pressure (Control).
Main outcome measures: The primary clinical outcome was time to liberation from respiratory support. The primary cost-effectiveness outcome was 180-day incremental net monetary benefit. Secondary outcomes included mortality at paediatric intensive care unit/high-dependency unit discharge, day 60 and day 180; (re)intubation rate at 48 hours; duration of paediatric intensive care unit/high-dependency unit and hospital stay; patient comfort; sedation use; parental stress; and health-related quality of life at 180 days.
Results: In the step-up randomised controlled trial, out of 600 children randomised, 573 were included in the primary analysis (median age 9 months). Median time to liberation was 52.9 hours for high-flow nasal cannula (95% confidence interval 46.0 to 60.9 hours) and 47.9 hours (95% confidence interval 40.5 to 55.7 hours) for continuous positive airway pressure (adjusted hazard ratio 1.03, one-sided 97.5% confidence interval 0.86 to ∞). The high-flow nasal cannula group had lower use of sedation (27.7% vs. 37%) and mean duration of acute hospital stay (13.8 days vs. 19.5 days). In the step-down randomised controlled trial, of the 600 children randomised, 553 were included in the primary analysis (median age 3 months). Median time to liberation for high-flow nasal cannula was 50.5 hours (95% confidence interval, 43.0 to 67.9) versus 42.9 hours (95% confidence interval 30.5 to 48.2) for continuous positive airway pressure (adjusted hazard ratio 0.83, one-sided 97.5% confidence interval 0.70 to ∞). Mortality at day 180 was significantly higher for high-flow nasal cannula [5.6% vs. 2.4% for continuous positive airway pressure, adjusted odds ratio, 3.07 (95% confidence interval, 1.1 to 8.8)].
Limitations: The interventions were unblinded. A heterogeneous cohort of children with a range of diagnoses and severity of illness were included.
Conclusions: Among acutely ill children requiring non-invasive respiratory support, high-flow nasal cannula met the criterion for non-inferiority compared with continuous positive airway pressure for time to liberation from respiratory support whereas in critically ill children requiring non-invasive respiratory support following extubation, the non-inferiority of high-flow nasal cannula could not be demonstrated.
Future work: (1) Identify risk factors for treatment failure. (2) Compare protocolised approaches to post-extubation non-invasive respiratory support, with standard care. (3) Explore alternative approaches for evaluating heterogeneity of treatment effect. (4) Explore reasons for increased mortality in high-flow nasal cannula group within step-down randomised controlled trial.
Study registration: Current Controlled Trials ISRCTN60048867.
Funding: This award was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme (NIHR award ref: 17/94/28) and is published in full in Health Technology Assessment; Vol. 29, No. 9. See the NIHR Funding and Awards website for further award information.
Keywords: CONTINUOUS POSITIVE AIRWAY PRESSURE; HIGH-FLOW NASAL CANNULA THERAPY; NON-INVASIVE RESPIRATORY SUPPORT; PAEDIATRIC CRITICAL CARE.
Non-invasive forms of breathing support, mainly continuous positive airway pressure and high-flow nasal cannula, are used commonly in children’s intensive care units. High-flow nasal cannula is easier to use, requires less nursing input and is more comfortable for children. However, few clinical trials have compared their effectiveness in sick children. The aim of the FIRST-line support for Assistance in Breathing in Children clinical trials was to test if high-flow nasal cannula was non-inferior (not unacceptably worse) compared to continuous positive airway pressure in terms of how quickly children were able to come off breathing support, and whether high-flow nasal cannula provided value for money for the National Health Service. The trials were carried out in two groups of children in whom doctors usually start non-invasive breathing support: (1) acutely ill children and (2) children coming off a ventilator. A total of 1200 children (600 acutely ill and 600 following extubation) were entered into the trials. Half were randomly assigned to high-flow nasal cannula and the other half to continuous positive airway pressure. Complete information was available in 573 of 600 acutely ill children included in the trial. The average time taken to come off all breathing support was 5 hours longer with high-flow nasal cannula, judged as acceptable considering its benefits (fewer children on high-flow nasal cannula needed sedative medicines and developed pressure sores in the nose, and children spent a shorter time in hospital). Complete information was available in 553 children of 600 children needing breathing support following extubation. Average time taken to come off all breathing support was 8 hours longer with high-flow nasal cannula, not considered an acceptable difference, since there were few benefits of using high-flow nasal cannula. On average, high-flow nasal cannula saved a small amount of money for the National Health Service. The FIRST-line support for Assistance in Breathing in Children trials showed that high-flow nasal cannula was an acceptable first choice in acutely ill children needing breathing support, but continuous positive airway pressure was the most effective first choice in children needing breathing support after extubation.