Using high flow moist oxygen early to treat acute severe asthma in children
| ISRCTN | ISRCTN86214145 |
|---|---|
| DOI | https://doi.org/10.1186/ISRCTN86214145 |
| Integrated Research Application System (IRAS) | 344459 |
| Central Portfolio Management System (CPMS) | 62634 |
| National Institute for Health and Care Research (NIHR) | 208869 |
| Sponsor | University Hospitals Sussex NHS Foundation Trust |
| Funder | National Institute for Health and Care Research |
- Submission date
- 16/02/2026
- Registration date
- 20/02/2026
- Last edited
- 20/02/2026
- Recruitment status
- Not yet recruiting
- Overall study status
- Ongoing
- Condition category
- Respiratory
Plain English summary of protocol
Background and study aims
Asthma is common in children, and many come to hospital with severe attacks. Most children get better after high‑dose inhaler treatment, but some do not and may need medicines given into a vein, which can be unpleasant. The study aims to find out whether giving high flow humidified oxygen early helps children recover more quickly and reduces the need for intravenous therapy.
Who can participate?
Children aged 2 to 18 years who come to hospital with a severe asthma attack and still have breathing problems after receiving usual high‑dose inhaler treatment may be able to take part. Children will not be able to join if they have pneumonia, very severe life‑threatening asthma, reduced consciousness, conditions that make high flow oxygen unsafe, other major illnesses, or if they have taken part in this study before.
What does the study involve?
Children who join the study will receive either early high flow humidified oxygen or usual care. The treatment will start straight away because asthma attacks need urgent care. There are no extra blood tests. Families will be asked to give consent for the use of their child’s data once the emergency has passed, usually the next working day. The study team will compare how quickly children recover, whether they need intravenous treatment, how long they stay in hospital, and how they feel during recovery.
What are the possible benefits and risks of participating?
Children receiving early high flow oxygen may recover more quickly and may be less likely to need intravenous treatment. High flow oxygen is already used for other breathing problems in children and has a good safety record. Risks are low but, as with any treatment, there may be minor discomfort or side effects.
Where is the study run from?
The study is being carried out in hospitals across England and Scotland, including Brighton, Canterbury, Middlesbrough, Edinburgh, Oxford, Blackburn, Dartford, Salisbury and Stoke‑on‑Trent.
When is the study starting and how long is it expected to run for?
The first participants are expected to join the study on 16 March 2026. Recruitment is planned to continue until 31 December 2027, with the whole study expected to finish by 30 June 2028
Who is funding the study?
The study is funded by the National Institute for Health and Care Research (NIHR).
Who is the main contact?
Dr Akshat Kapur, akshat.kapur@nhs.net
Brighton and Sussex Clinical Trials Unit, CTU-HOPSA@bsms.ac.uk
Contact information
Principal investigator
Royal Alexandra Children's Hospital
Brighton
BN2 5BE
United Kingdom
 ORCID ID |
0000-0003-1772-9300 |
|---|---|
| Phone | +44 1273696955 |
| akshat.kapur@nhs.net |
Principal investigator, Scientific
Royal Alexandra Children's Hospital
Brighton
BN2 5BE
United Kingdom
| ORCID ID |
0000-0003-2136-958X |
|---|---|
| Phone | +44 7714777361 |
| paul.seddon@nhs.net |
Scientific, Public
Brghton and Sussex Clinical Trials Unit
Brighton
BN1 9PH
United Kingdom
| ORCID ID |
0000-0001-7817-8720 |
|---|---|
| Phone | +44 1273 641469 |
| CTU-HOPSA@bsms.ac.uk |
Study information
| Primary study design | Interventional | |
|---|---|---|
| Allocation | Randomized controlled trial | |
| Masking | Open (masking not used) | |
| Control | Active | |
| Assignment | Parallel | |
| Purpose | Treatment | |
| Scientific title | High flow humidified oxygen as an early intervention in children with acute severe asthma: a randomised controlled trial (High flow humidified oxygen in paediatric severe asthma) | |
| Study acronym | HOPSA | |
| Study objectives | To determine whether early HiFlo (commenced within 4 hours of starting high dose inhaled “burst” therapy) reduces the need for escalation to intravenous bronchodilator therapy. | |
| Ethics approval(s) |
Approved 01/12/2025, Nottingham Research Ethics Committee 1 (2 Redman Place, London, E20 1JQ, United Kingdom; +44 207 104 8115; Nottingham1.rec@hra.nhs.uk), ref: 25/EM/0236 | |
| Health condition(s) or problem(s) studied | Acute severe asthma in children | |
| Intervention | Eligible children will be randomised using an online software application to the HiFlo or usual care arm. This will be performed by clinical staff using a computer desktop link and administered by the Clinical Trials Unit, as successfully piloted in the feasibility study. The randomisation list will be pre-generated by the Brighton and Sussex Clinical Trials Unit and uploaded to the randomisation system. The list will be block randomised with random block sizes, and stratified by age (2-4 years, 5-10 years, 11-18 years) and severity at study entry (oxygen saturation less than 92%, 92-94%). Randomised treatment will apply during the hospital admission, and follow-up will be for 48 hours after discharge from hospital (and only to measure the outcome of Readmission within 48 hours) HiFlo (Intervention) arm Children randomised to the HiFlo arm will be commenced on HiFlo by the clinical team immediately after randomisation (within a window of 30 minutes), and flow will be gradually increased to a target flow determined by body weight, using the targets published in the FIRST-ABC Study [36]. Inspired oxygen concentration will be adjusted to the minimum required to maintain oxygen saturation (by pulse oximeter) at 92% or higher. Other treatment for acute asthma will continue during HiFlo therapy. Inhaled bronchodilators will be administered via in-line vibrating mesh nebuliser (Aerogen Ltd), since this is the only effective way of administering inhaled bronchodilator on HiFlo. Children who have not already received an oral corticosteroid dose during burst therapy will receive a single dose of prednisolone or dexamethasone (according to local guidelines) at randomisation – further doses of oral corticosteroids during admission will be at the discretion of the clinical team. All treatment options will be allowed as clinically indicated, and further escalations of treatment will occur as judged necessary by the treating clinical team. These can include intravenous bronchodilators (magnesium, salbutamol, aminophylline), and respiratory support with continuous positive airway pressure (CPAP), bi-level airway pressure (BiPAP) or invasive ventilation. Once the child’s condition stabilises, HiFlo will be weaned according to clear guidelines based on those used in the FIRST-ABC study [36]. In brief, clinicians will be encouraged to reduce flow will once the inspired oxygen required is below 40%, and to discontinue HiFlo once below 30%. Once HiFlo is discontinued, inhaled bronchodilator therapy will continue by metered dose inhaler and spacer or by nebuliser. As the child improves, the frequency of inhaled bronchodilator doses will be gradually tapered until the point of clinical readiness for discharge is reached. This is defined as no longer requiring additional oxygen or respiratory support, and not requiring inhaled bronchodilators more often than 4-hourly. Below is the weight banded starting flow rate of Hiflo and weaning flow rate we will use in our study adapted from the First ABC study. Active weaning of Hiflo in children with reduced respiratory distress is really important and we will provide adequate training for it. Weight (kg) ≤12 13-15 16-30 31-50 >50 Starting flow rate 2L/kg/min 25-30L/min 35L/min 40L/min 50L/min Weaning flow rate 1L/kg/min 13-15L/min 18L/min 20L/min 25L/min During administration of inhaled bronchodilators on HiFlo (in-line mesh nebulisation via Aerogen Solo device) Hiflo should be reduced to weaning flow rate as in the table. If already on weaning flow rate, then no adjustment is needed. Once Hiflo stops, standard inhaled or nebulised bronchodilators will be administered as per usual protocol for the unit. Usual care arm Children randomised to the usual care arm will continue with treatment for acute asthma as indicated by local procedures and clinical assessment. Inhaled bronchodilator therapy will continue as required according to clinical assessment, and may be administered by metered dose inhaler and spacer or by nebuliser. Children who have not already received an oral corticosteroid dose during burst therapy will receive a single dose of prednisolone or dexamethasone (according to local guidelines) at randomisation – further doses of oral corticosteroids during admission will be at the discretion of the clinical team. All treatment options will be allowed as clinically indicated, and further escalations of treatment will occur as judged necessary by the treating clinical team. These may include intravenous bronchodilators (magnesium, salbutamol, aminophylline), and respiratory support with continuous positive airway pressure (CPAP), bi-level airway pressure (BiPAP) or invasive ventilation. Use of HiFlo as an escalation is permitted, but with the stipulation that starting HiFlo should not be the first escalation of therapy – this corresponds to current clinical practice. Oral corticosteroid therapy will be administered according to local practice and clinical assessment. | |
| Intervention type | Procedure/Surgery | |
| Primary outcome measure(s) |
| |
| Key secondary outcome measure(s) |
| |
| Completion date | 30/06/2028 |
Eligibility
| Participant type(s) | |
|---|---|
| Age group | Mixed |
| Lower age limit | 2 Years |
| Upper age limit | 18 Years |
| Sex | All |
| Target sample size at registration | 218 |
| Key inclusion criteria | 1. CYP aged 2-18 years (up to and including the day before 19th birthday) 2. Acute severe asthma (ASA) presenting to hospital, defined as respiratory distress and documented wheeze – formal prior diagnosis of asthma not required 3. Required high dose “burst” inhaled bronchodilator therapy – 3 doses of salbutamol ± ipratropium ± nebulised magnesium 4. Failure to respond, defined as persisting hypoxaemia (pulse oxygen saturation less than 95% in air) with moderate or severe respiratory distress, at any point 1 to 4 hours after commencing burst. |
| Key exclusion criteria | 1. Clinical/radiological evidence of bacterial pneumonia: fever >38.5oC plus focal signs on auscultation or chest X-ray 2. Life-threatening asthma: signs of impending respiratory failure warranting imminent intubation 3. Impaired consciousness (AVPU score P or worse) 4. Contraindications to use of high flow humidified oxygen (HiFlo): air leak (pneumothorax, pneumomediastinum or subcutaneous emphysema), , recent (within 6 weeks) bowel surgery, intractable vomiting 5. Other major respiratory, cardiovascular or neurological condition 6. Previous participation in this study |
| Date of first enrolment | 16/03/2026 |
| Date of final enrolment | 31/12/2027 |
Locations
Countries of recruitment
- United Kingdom
- England
- Scotland
Study participating centres
Brighton
BN2 5BE
England
Ethelbert Road
Canterbury
CT1 3NG
England
Marton Road
Middlesbrough
TS4 3BW
England
Edinburgh
Lothian
EH9 1LF
Scotland
Headley Way
Headington
Oxford
OX3 9DU
England
Haslingden Road
Blackburn
BB2 3HH
England
Darenth Wood Road
Dartford
DA2 8DA
England
Odstock Road
Salisbury
SP2 8BJ
England
Stoke-on-trent
ST4 6QG
England
Results and Publications
| Individual participant data (IPD) Intention to share | No |
|---|---|
| IPD sharing plan summary | Not expected to be made available |
| IPD sharing plan |
Editorial Notes
16/02/2026: Trial's existence confirmed by NHS HRA.
