Condition category
Circulatory System
Date applied
Date assigned
Last edited
Prospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
High-risk patients with lung disease who have heart (cardiac) surgery are at significant risk of developing complications after surgery (postoperative complications) leading to a prolonged hospital stay. One way of reducing the risk of lung complications is to treat patients with non-invasive ventilation or continuous positive airways pressure after their surgery. However, this often requires admission to a high dependency unit or intensive care, and is uncomfortable because of the need for a tight fitting mask, as well as being labour intensive and costly. High-flow nasal oxygen is a new alternative as it provides warmed humidified oxygen at high flow, and also has been shown to assist breathing and improve recovery. It is comfortable during use and indeed may be more comfortable than standard (dry) oxygen via a facemask or nasal prongs. It may be given on a normal ward, however its routine use in high-risk patients with lung conditions such as asthma, chronic obstructive pulmonary disease, recent chest infections and heavy smokers has not been tested before. The primary aim of this study is to determine if prophylactic high-flow nasal oxygen therapy in cardiac surgical patients at high risk of developing postoperative pulmonary complications is associated with a shorter hospital stay.

Who can participate?
Adults (over 18) undergoing cardiac surgery and are at risk of developing respiratory complications after surgery.

What does the study involve?
Before surgery, each participant performs a six-minute walking test under the supervision of a physiotherapist. This simple tests measures how far patients can walk in six minutes. Additionally, patients have spirometry testing which is used to assess how well the lungs work by measuring how much air the patient inhales and exhales and how quickly they exhale. Patients then have their surgery under general anaesthesia. After the operation, they are looked after following the study recovery protocols, which includes pain relief, regular physiotherapy, early mobilisation and eating and drinking, and removal of chest drains and tubes as soon as possible. On arrival in the critical care area after their surgery, participants are randomly assigned to one of two groups. Those in group 1 are given supplemental oxygen via a soft facemask (control group). Those in group 2 are given supplemental oxygen via high-flow nasal cannulae (intervention group). Participants are given oxygen for at least 24 hours after surgery. Participants who develop breathing difficulty receive treatment based on their clinical need. On the fifth or sixth day after surgery, they all do the walking test and spirometry test again. A short questionnaire is used to determine if there is any difference in how the participants feel they have recovered before they leave hospital and how quickly they returned to normal activities after discharge, and also to evaluate how they tolerated either the facemask or high flow nasal cannulae.

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

Where is the study run from?
Papworth Hospital NHS Trust (UK)

When is the study starting and how long is it expected to run for?
September 2015 to February 2016

Who is funding the study?
Fisher & Paykel Healthcare Limited

Who is the main contact?
Miss Fiona Bottrill

Trial website

Contact information



Primary contact

Miss Fiona Bottrill


Contact details

Papworth Hospital NHS Trust
Clinical Trials
Papworth Hospital NHS Foundation Trust
Papworth Everard
CB23 3RE
United Kingdom

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

A randomised controlled trial of high-flow nasal oxygen (Optiflow™) and standard oxygen therapy in high-risk patients after cardiac surgery


Study hypothesis

Patients post cardiac surgery are at risk of respiratory complications, and consequently prolonged length of hospital stay, delayed recovery and poorer outcomes. The incidence of respiratory complications is increased in patients with previous respiratory disease such as asthma or chronic obstructive pulmonary disease (COPD), or current smokers. Our hypothesis is that prophylactic use of nasal high flow oxygen in high risk cardiac surgical patients for 24 hours after surgery will reduce the length of hospital stay and improve functional patient reported recovery. Improved functional recovery may be associated with fewer respiratory complications and may subsequently lead to earlier discharge from hospital.

Ethics approval

NRES Committee East Midlands – Derby, 15/06/2015, ref: 15/EM/0251

Study design

Randomised; Interventional; Design type: Treatment

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use contact details to request a participant information sheet


Topic: Cardiovascular disease; Subtopic: Cardiovascular (all Subtopics); Disease: Cardiac Surgery


Patients will be randomly assigned to receive high-flow nasal oxygen therapy or standard oxygen therapy (soft oxygen mask or nasal cannulae) for at least 24 hours postoperatively.

Intervention type



Phase II

Drug names

Primary outcome measures

Hospital length of stay (days)

Secondary outcome measures

1. Patients early postoperative functional recovery, as determined by 6 minute walk test (6MWT), compared with patients who receive standard oxygen therapy
2. Early postoperative lung function, tested by spirometry
3. Intensive care unit (ICU) length of stay (days)
4. Requirement for escalation of respiratory support and ICU re-admission

Overall trial start date


Overall trial end date


Reason abandoned


Participant inclusion criteria

1. They are aged over 18 years
2. They are undergoing elective cardiac surgery (coronary artery bypass grafting, valve surgery or both)
3. They have one or more patient related risk factor for postoperative pulmonary complications (COPD, asthma, lower respiratory tract infection in last 4 weeks, body mass index=35 kg/m2 current (last 6 weeks) heavy smokers (> 10 pack years))
4. They are capable of performing a 6MWT. The 6MWT is a clinical exercise test, and is popular in clinical practice because it aids clinical decision making, and because of the belief that it provides a better estimate of functional capacity than resting cardiorespiratory measurements. The 6MWT is the most popular clinical exercise test, which is used for postoperative evaluation after lung surgery and has also been validated in cardiac surgery

Participant type


Age group




Target number of participants

Planned Sample Size: 74; UK Sample Size: 74

Participant exclusion criteria

1. Contraindication to high flow nasal oxygen such as nasal septal defect
2. Not met extubation criteria by 10am the day after surgery (Day 1)
3. Need for CPAP preoperatively

Recruitment start date


Recruitment end date



Countries of recruitment

United Kingdom

Trial participating centre

Papworth Hospital NHS Trust
Clinical Trials Papworth Hospital NHS Foundation Trust Papworth Everard
CB23 3RE
United Kingdom

Sponsor information


Papworth Hospital NHS Trust

Sponsor details

Papworth Everard
United Kingdom

Sponsor type

Hospital/treatment centre



Funder type


Funder name

Fisher & Paykel Healthcare Limited

Alternative name(s)

Funding Body Type

Funding Body Subtype


Results and Publications

Publication and dissemination plan

We aim to publish our study results within 6 months from the end date.

Intention to publish date


Participant level data

Not provided at time of registration

Results - basic reporting

Publication summary

Publication citations

Additional files

Editorial Notes