Condition category
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting
Publication status
Results overdue

Plain English Summary

Background and study aims
Very premature babies (those of less than 32 weeks gestation or weighing less than 1500g) are born with lungs that have not yet fully developed. These babies may need help to breathe with the support of machines (mechanical ventilation) until their lungs are developed enough to do the work on their own. Traditionally, mechanical ventilation has been provided by controlling the pressure or volume of air delivered by these machines (ventilators). Recent studies have shown that controlling the volume works better than controlling pressure and has fewer side effects. The volume controlled ventilation works by controlling the amount of air/oxygen delivered at each breath (tidal volume). However, the tidal volume delivered by ventilators in clinical practice varies considerably, from 4-8ml/kg. This is important as, although lower tidal volumes can prevent the lungs from being damaged, they can also make the baby work harder at their breathing than they should. Some new advances in the technology means that there are now better ventilators that can deliver more accurate tidal volumes than before. We have therefore decided to take a closer look at what may be the best tidal volume to use in terms of performance and preventing side effects. Here, we are comparing the effects of the lower end of what is considered a normal tidal volume (4-5 ml/kg) to those of a higher normal tidal volume (7-8 ml/kg) delivered by mechanical ventilation to premature babies.

Who can participate?
Premature babies needing mechanical ventilation, weighing between 500-1500g or of no more than 32 weeks gestation at birth.

What does the study involve?
The babies are randomly allocated into one of two groups. Those in group 1 are given the lower normal tidal volume of air (4-5 ml/kg) via mechanical ventilation. Those in group 2 are given the higher normal tidal volume of air (7-8 ml/kg). We then compare the two groups to see which babies come of the ventilator first.

What are the possible benefits and risks of participating?
Not provided at registration.

Where is the study run from?
University Hospital of North Tees (UK)

When is the study starting and how long is it expected to run for?
July 2013 to February 2015

Who is funding the study?
North Tees and Hartlepool Hospitals NHS Foundation Trust (UK)

Who is the main contact?
Prof Samir Gupta

Trial website

Contact information



Primary contact

Prof Samir Gupta


Contact details

Consultant Neonatologist
Department of Paediatrics
University Hospital of North Tees
Hardwick Road
Stockton on Tees
TS19 8PE
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number

IRAS Project ID: 126072

Study information

Scientific title

HILO Trial - A comparative pilot study of HIgh versus LOw tidal volume for mechanical ventilation in very low birth weight preterm babies with respiratory distress syndrome. A randomised controlled trial


HILO Trial

Study hypothesis

The time to achieve a 25% reduction in peak pressure in very premature babies receiving mechanical breathing support using volume-targeted ventilation is less using high normal tidal volume (7-8 ml/kg) as compared to low normal tidal volume (4-5 ml/kg).

Null hypothesis: There is no difference in time to achieve 25% reduction in peak pressure using either 7-8 ml/kg or 4-5 ml/kg tidal volume.

Ethics approval

Sunderland Ethics Committee; ref. 13/NE/0110

Study design

Randomised controlled trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use the contact details below to request a patient information sheet


Respiratory distress syndrome


The study would involve randomising the babies to low tidal volume (4-5 ml/kg) or high tidal volume (7-8 ml/kg) at birth using volume guarantee mode of ventilation. We would also collect tracheal aspirate before surfactant. The babies would then have a standard management on ventilation without altering the tidal volume.

Intervention type



Not Applicable

Drug names

Primary outcome measure

The time to achieve 25% reduction in peak pressure

Secondary outcome measures

1. Duration of intubation
2.Incidence of pulmonary and non-pulmonary complications i.e., pneumothorax, bronchopulmonary dyplasia, intraventricular haemorrhage
3. Impact on inflammatory markers in tracheal aspirate
4. Survival to discharge

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Preterm babies weighing 500-1500g or ≤32 weeks of gestation at birth
2. Requirement of intubation and mechanical ventilation

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Serious underlying congenital anomaly
1.1. Congenital diaphragmatic hernia
1.2. Cyanotic congenital heart disease
1.3. Airway anomalies
1.4. Abdominal wall defects
2. Multiple pregnancies – only the first-born were enrolled and randomized; the others received the same strategy but were not be enrolled
3. Babies initiated on ventilation after 12 hours of life or transferred from other centres

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Consultant Neonatologist
Stockton on Tees
TS19 8PE
United Kingdom

Sponsor information


North Tees and Hartlepool Hospitals NHS Trust (UK)

Sponsor details

c/o Jane Greenaway
Research and development Manager
Hardwick Road
Stockton on Tees
TS19 8PE
United Kingdom

Sponsor type

Hospital/treatment centre



Funder type

Hospital/treatment centre

Funder name

North Tees and Hartlepool Hospitals NHS Foundation Trust (UK); ref.: CH-087

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

Not provided at time of registration

2019 thesis in (added 25/06/2020)

Intention to publish date

Participant level data

Not provided at time of registration

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

25/06/2020: Link to thesis added to publication and dissemination plan. 18/04/2017: No publications found in PubMed, verifying study status with principal investigator.