The goal of this randomised controlled, cross-over clinical trial is to compare High Flow Nasal Cannulas (HFNC) and Continuous Positive Airways Pressure (CPAP) in neonates over 34 weeks' amenorrhoea (SA) up to children weighing less than 20 kg with respiratory failure.

The main question it aims to answer is the non-inferiority of high flows of high-flow nasal cannula compared with CPAP by analysis of diaphragmatic contraction (EAdi (Electrical activity of diaphragm)).

Participants with respiratory failure and need of non invasive ventilation and nasogastric tube will receive 4 different increasing flows of HFNC and Positive End-Expiratory Pressure of 7 cmH2O with CPAP during 30 minutes for each flow rate and CPAP. The electrical activity of diaphragm and clinical data of the patient upon each flow and support will be collected. According to the cross-over procedure, the patients will change groups (increasing flows of HFNC or CPAP) in order to perform the remaining analysis.

With this research protocol, the investigators aim to demonstrate the non-inferiority of high flows of HFNC compared with CPAP on work of breathing (based on the intensity of contraction of diaphragmatic fibres and clinical aspects) in paediatric and neonatal patients. The investigators will also study the clinical tolerance and safety of these practices.

Objectives :

Main objective: To demonstrate the non-inferiority of high-flow nasal cannula flow rates compared with CPAP by analysis of diaphragmatic contraction (EAdi (Electrical activity of diaphragm)) in neonates over 34 weeks' amenorrhoea (SA) up to children weighing less than 20 kg in respiratory failure.

Secondary objectives:

• To compare different flows of HFNC (2 L/kg/min, 3 L/kg/min, 4 L/kg/min, 5 L/kg/min) with each other by analysing diaphragmatic contraction.
• Compare the clinical effectiveness of different flow rates of HFNC with CPAP in young children in respiratory distress.
• To compare the tolerability of different flow rates of HFNC with CPAP in the population of young children suffering from respiratory distress.
• To compare the incidence of minor (digestive discomfort, digestive bloating, non-damaging skin lesions) and major (thoracic barotrauma, damaging skin lesions) side effects of different flow rates of HFNC with CPAP in young children in respiratory distress.
• To describe the choice of support and settings (flow rates or PEEP levels) made by the practitioners in charge of the child after the study period.
• To describe the epidemiological data from the paediatric intensive care and monitoring units and the neonatal intensive care unit.

Type of study: Randomised controlled, cross-over, single-centre, non-inferiority trial of a medical device.

Number of centres: 1

Study design:

Upon admission to the department, if the eligibility criteria are met and the parents agree to the research , a wash-out period will be performed under low-flow oxygen therapy at 1 L/min to achieve SpO2 ≥ 94% for 15 minutes.

The included patients will then be randomized into two separate groups: a CPAP group with PEEP at 7 cmH2O for 30 minutes and an HFNC group with increasing flow rates for up to 2 hours.

The patients included will be their own controls and at the end of the first analysis, according to the cross-over procedure, the patients will change groups in order to perform the remaining analysis.

A recourse procedure has been foreseen in case of failure of ventilatory support.

Medical devices :

Concerning HFNC ventilation:

The nasal cannulas used are Optiflow® cannulas (Fisher and Paykel Laboratory) which will be adapted to the size of each patient's nostrils. The following sizes are available:

• NICU patient: Optiflow Junior 2®.
• PICU patient: Optiflow Junior 2®, Optiflow +®.

Concerning CPAP ventilation:

• For the neonatal population:

  • Medin Sindi® CPAP masks, caps and ties
  • Medin Miniflow® CPAP generators

• For the paediatric population :

  • Medin Sindi® CPAP masks, caps and ties
  • Fisher and Paykel Healthcare CPAP masks, cannulas and caps
  • Miniflow® CPAP generators from Medin
  • Fisher and Paykel Healthcare CPAP generators

Expected benefits :

If it is shown that a reduction in the work of breathing is observed (EAdi and usual clinical signs) when HFNC flow rates are gradually increased, and that this increase to flow rates of 3 to 5 L/kg/min is well tolerated and does not increase the risk of barotrauma, HFNC ventilation at flow rates greater than 2 L/kg/min could be more widely proposed and accepted in the various units using it, as it is unanimously accepted in terms of tolerance and comfort for the patient compared with CPAP.

Recruitment procedures The patients eligible for this study will be those admitted to the neonatal and paediatric intensive care unit of the Clermont-Ferrand University Hospital by a doctor on the unit and who meet the various inclusion criteria for the study.

An information note has been drawn up and will be presented and explained to the child's legal representative(s) by an investigating doctor during their usual care, as well as to the child if his or her level of understanding is adequate, within 2 hours of admission to the department. The parents and the child will have a maximum of 1 hour to reflect (and a maximum of 3 hours from admission to the ward) between the time they are given the information and the time they sign the consent form.

Legal representative(s) will then be asked to sign the written consent. The child's inclusion in the DiaworkHFNC protocol will be recorded in the child's computerised medical record (ICCA software).

Inclusion Criteria:

• Newborns over 34 SA and paediatric patients weighing less than 20 kg.
• Need for ventilatory support by HFNC or CPAP for respiratory failure
• Need for enteral feeding via nasogastric tube
• Hospitalized in PICU or NICU at Clermont-Ferrand University Hospital,
• Covered by Social Security.
• Whose parents or guardians are able to provide informed consent to participate in the research.

Exclusion Criteria:

• Respiratory failure requiring immediate intubation.
• Use of HFNC or CPAP as a relay to extubation.
• Acquired or congenital abnormality of the gastrointestinal tract.
• Diaphragmatic paralysis and/or neuromuscular pathology
• Failure of central ventilatory control (e.g. intra-ventricular haemorrhage, anoxic-ischaemic encephalopathy, massive vascular accident, intracranial process, cerebral edema and/or intracranial hypertension).
• Contraindications listed in the CPAP and HFNC user manuals: absence of spontaneous ventilation, choanal atresia, diaphragmatic hernia, tracheo-oesophageal fistula, nasal trauma, severe deformity likely to be aggravated by the nasal mask or nasal cannula, pneumothorax, pneumencephaly, Cerebrospinal Fluid leak, hypotension.
• Refusal by parents or guardians.