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Trial registered on ANZCTR

Registration number

ACTRN12618000949280

Ethics application status

Approved

Date submitted

23/05/2018

Date registered

6/06/2018

Date last updated

14/07/2024

Date data sharing statement initially provided

12/11/2018

Date results provided

24/06/2024

Type of registration

Prospectively registered

Titles & IDs

Public title

High flow oxygen for children's airway surgery

Scientific title

Effect of high flow oxygen on rescue oxygenation use for hypoxic events during children's airway surgery: A randomised controlled trial

Secondary ID [1]

Nil known

Universal Trial Number (UTN)

U1111-1214-5246

Trial acronym

HAMSTER

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Airway surgery

Condition category

Condition code

Anaesthesiology

Anaesthetics

Respiratory

Other respiratory disorders / diseases

Surgery

Other surgery

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

Intervention: High flow nasal oxygen insufflation

From induction until the completion of surgery (duration of procedure)

Description: High-Flow Nasal Oxygen Insufflation (HFNOI) is insufflation of heated (37 degrees Celsius) and humidified (100%) oxygen at weight related flow rates matching peak inspiratory flow thereby allowing a known inspired fraction of inspired oxygen.

HFNOI will be delivered via the Optiflow™ device at weight specific flow rates as per table below delivering a FiO2 of 1.0.

Weight HFNOI Flow rates
0-12 kg 2L/kg/min
13-15kg 30L/min
15-30 kg 35L/min
30-50 kg 40L/min
>50 kg 50L/min

Jaw thrust will be applied to ensure a patent airway until airway instrumentation begins.
Anaesthesia will be maintained via a Total Intravenous Venous Anaesthesia (TIVA) using a combination of dexmedetomidine, propofol +/- an opioid (either remifentanil or alfentanil) at the discretion of the attending anaesthetist. Anaesthetists may wish to omit opioids in certain circumstances and this will be at the discretion of the anaesthetist e.g. neonates. Anaesthesia infusions will be adjusted to maintain both adequate depth of anaesthesia and spontaneous ventilation during procedure.

Intervention code [1]

Treatment: Devices

Intervention code [2]

Prevention

Comparator / control treatment

Comparator: Nasopharyngeal low flow oxygen

From induction until the completion of surgery (duration of procedure)

Description: Nasopharyngeal low flow oxygen provides oxygen into the nasopharynx using a nasopharyngeal catheter at flow rates up to 2L/min for infants ( up to 12 months of age) and maximal 6L/min for larger children.

Jaw thrust will be applied to ensure a patent airway until airway instrumentation begins, and after airway instrumentation is complete. Anaesthesia will be maintained at the discretion of the anaesthetist, via inhalational anaesthesia, intravenous agents, or a combination of both. Anaesthetists may wish to omit opioids in certain circumstances and this will be at the discretion of the anaesthetist e.g. neonates.

Control group

Active

Outcomes

Primary outcome [1]

The primary outcome is defined as successful anaesthesia without any rescue oxygenation attempt for a hypoxic event.

This outcome will be observed and recorded on the case report form by the clinical research nurse during the airway surgery.

Definitions
Normally hypoxia for anaesthesia is defined as an oxygen saturation of 90% or less. However dependent of the patient’s physiology, age and starting saturation levels prior to the procedure, the anaesthetist can accept transiently lower oxygen levels if required to allow an uninterrupted surgical procedure. For the purpose of this study we will not define a specific threshold for acceptable oxygen saturations as these are defined case by case. Similarly, the surgical procedure can contribute to hypoxia and acceptance of this is again at the discretion of the anaesthetist and surgeon or proceduralist. The investigators’ view is that a hypoxic event that requires rescue intervention irrespective of the cause is the true and important outcome measure for this study.

Rescue Oxygenation: The surgical procedure is interrupted and the anaesthetist attempts to improve oxygenation of the child using either bag mask ventilation, insertion of an endotracheal tube or laryngeal mask followed by positive pressure ventilation_

Timepoint [1]

Duration of surgical procedure

Secondary outcome [1]

Total length of time patient experiences hypoxia.

This outcome will be observed and recorded on the case report form by the clinical research nurse during the airway surgery.

Timepoint [1]

Measurement: seconds
Time point: At any time during airway surgery

Secondary outcome [2]

Adverse events

This outcome will be observed and recorded on the case report form by the clinical research nurse during the airway surgery.

Minor adverse events_ occurrence of epistaxis, laryngospasm, bronchospasm, coughing at any time during procedure.
Major adverse events_ occurrence of hypotension requiring treatment, bradycardia requiring treatment, cardiac arrest with or without return of spontaneous circulation at any time during procedure_

Timepoint [2]

Time point: At any point during airway surgery.

Secondary outcome [3]

Requirement for unexpected paediatric intensive care admission

This outcome will be observed and recorded either the clinical research nurse during the airway surgery or on follow up assessment using electronic medical records. .

Timepoint [3]

Yes/No
From surgery commencement until discharge from the hospital

Secondary outcome [4]

Requirement for assisted positive pressure ventilatory support

Timepoint [4]

Y/N
Type of support: mechanical ventilation, non-invasvie ventilation or high flow nasal oxygen,
From surgery commencement until discharge from the hospital

Secondary outcome [5]

Length of paediatric intensive care unit stay

Timepoint [5]

Duration of PICU admission, days
Ascertained through electronic medical records.

Secondary outcome [6]

Length of hospital stay

Timepoint [6]

Duration of hospital admission, days
Ascertained through electronic medical records.

Eligibility

Key inclusion criteria

• 0 (>37 weeks gestational age) – 16 years of age (15 years + 364 days)
• Elective microlaryngoscopy (where a tubeless airway management technique is required for the procedure)

Minimum age

0 Weeks

Maximum age

16 Years

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

• Tracheostomy in situ
• Requirement for laser surgery
• Known choanal atresia
• HFNOI contraindication (recent cranial and/or mid-face surgery/trauma; CSF leak)
• Emergency airway cases out of hours (after hours during week and weekend)

Study design

Purpose of the study

Prevention

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Central randomisation via computer will be used to achieve allocation concealment.

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

Patients will be allocated to a treatment arm using a computer based randomisation schedule and an allocation of 1:1 per treatment arm. Randomisation will be stratified by age (<1 year, 1-5 year and 5-16 year of age), with randomly varied block sizes within each stratum.

Masking / blinding

Open (masking not used)

Who is / are masked / blinded?

Intervention assignment

Parallel

Other design features

Phase

Phase 3

Type of endpoint/s

Safety

Statistical methods / analysis

Descriptive statistics will be utilised to report on the baseline characteristics of the total study cohort and each subgroup, as well as by site. The primary and secondary outcome measure investigating clinical treatment failure will be compared using a chi-square test, and the absolute difference between treatment groups will be reported as the risk difference, 95% confidence interval and p-value. Analysis will be by intention-to-treat. For continuous parameters, an independent t-test will be used assuming normal data distribution. Statistical significance will be set at the 0.05 level. A multiple regression model will be used to conduct an analysis of the primary outcome adjusting for baseline variables. Post-hoc power analyses may be undertaken to determine if results found in sub-group analyses are reliable particularly for age groups (<1 year and older). A pre-planned secondary analysis of the outcome data will be reported for patients with SpO2 < 80% during rescue attempt.

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

2/07/2018

Actual

3/09/2018

Date of last participant enrolment

Anticipated

2/07/2020

Actual

12/04/2021

Date of last data collection

Anticipated

31/07/2020

Actual

31/05/2021

Sample size

Target

496

Accrual to date

Final

530

Recruitment in Australia

Recruitment state(s)

NSW,QLD,SA,WA,VIC

Recruitment hospital [1]

Lady Cilento Children's Hospital - South Brisbane

Recruitment hospital [2]

Perth Children's Hospital - Nedlands

Recruitment hospital [3]

The Royal Childrens Hospital - Parkville

Recruitment hospital [4]

Womens and Childrens Hospital - North Adelaide

Recruitment hospital [5]

The Children's Hospital at Westmead - Westmead

Recruitment postcode(s) [1]

4101 - South Brisbane

Recruitment postcode(s) [2]

6009 - Nedlands

Recruitment postcode(s) [3]

3052 - Parkville

Recruitment postcode(s) [4]

5006 - North Adelaide

Recruitment postcode(s) [5]

2145 - Westmead

Funding & Sponsors

Funding source category [1]

Other Collaborative groups

Name [1]

Paediatric Critical Care Research Group

Address [1]

Centre for Children's Health Research
62 Graham St
South Brisbane 4101

Country [1]

Australia

Primary sponsor type

Hospital

Name

Queensland Childrens Hospital

Address

501 Stanley St, South Brisbane QLD 4101

Country

Australia

Secondary sponsor category [1]

Other Collaborative groups

Name [1]

Paediatric Critical Care Research group

Address [1]

Centre for Children's Health Research
Level 7
62 Graham St
South Brisbane QLD 4101

Country [1]

Australia

Secondary sponsor category [2]

University

Name [2]

University of Queensland

Address [2]

288 Herston Road
Herston QLD 4006, Australia

Country [2]

Australia

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

Children's Health Queensland Human Research Ethics Committee

Ethics committee address [1]

Children's Health Queensland HREC
Level 7 Centre for Children's Health Research
62 Graham St
South Brisbane, QLD 4101

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

30/04/2018

Approval date [1]

02/07/2018

Ethics approval number [1]

HREC/18/QRCH/130

Summary

Brief summary

Infants and children with airway abnormality often require surgery of their upper airway to improve their breathing; a procedure called microlaryngoscopy. During this procedure the child is anaesthetised and the anaesthetist controls the child’s breathing. In these situations, known as ‘shared airway’ cases, both the surgeon and anaesthetist require simultaneous access to the child’s airway. The anaesthetist needs to maximise oxygen delivery and provide adequate depth of anaesthesia while the surgeon requires direct access to the airway and an unobstructed view to perform the procedure. In these circumstances it is often impractical for the anaesthetist to place an artificial breathing (endotracheal) tube to deliver oxygen and inhaled anaesthetic gases, therefore oxygen delivery must be achieved by other means. 

During this kind of surgery it is not uncommon for blood oxygen levels to fall (hypoxia). Surgery may need to be interrupted by the anaesthetist to correct this, potentially compromising patient safety, prolonging the procedure, increasing exposure to anaesthesia and reducing surgical efficiency. At Lady Cilento Children’s Hospital (LCCH), we recently conducted a clinical audit of the anaesthetic care of children undergoing airway surgery and found that 32% of children experienced one or more hypoxemic events (low oxygen levels). A further 23% of surgeries required interruption to apply rescue oxygenation. The method the anaesthetist chooses to oxygenate the child may help prevent this type of serious complication. Traditionally, anaesthesia technique has involved the delivery of low flow oxygen via a ‘Nasopharyngeal Low Flow Oxygen’ (NLFO) system, in which oxygen is delivered at flow rates of 2-6L/min, typically via an oxygen catheter tube placed in the nose. Our research team at LCCH has been investigating the use of a new mode of oxygenation for children undergoing anaesthesia called ‘High-Flow Nasal Oxygen Insufflation’ (HFNOI). In HFNOI, warm and humidified oxygen is delivered to the airway via nasal cannulae at weight-specific flow rates. For example, HFNOI can be delivered at rates of 2L/kg therefore a 10 kg infant the child would receive 20L/min. Matching flow to the patient’s breathing demand this allows the anaesthetist to deliver oxygen to the child at the required concentration. Recent studies conducted in anaesthetised children at LCCH, have demonstrated HFNOI is an effective alternative oxygen delivery technique that can be safely used in infants and children with abnormal airways. The choice of oxygenation method may have significant ramifications for the child, and for surgical efficiency. However, to date there have been no high-quality studies evaluating HFNOI in comparison to other oxygenation techniques during paediatric airway surgery. Therefore, we would like to test the two techniques to determine whether HFNOI is superior to traditional anaesthesia oxygenation methods during paediatric airway surgery. We will achieve this aim using a randomised controlled trial to compare HFNOI with NLFO as the mode of oxygen delivery, during microlaryngoscopy in infants and children. The investigators hypothesise that HFNOI will confer advantages over the alternative techniques when used as an airway management and oxygenation technique during anaesthesia of spontaneously breathing infants or children undergoing microlaryngoscopy surgery. It is important to determine which mode or modes of oxygenation confer the lowest incidence of hypoxia and rescue oxygenation during these surgeries. If we can demonstrate that HFNOI reduces the risk of hypoxia and surgical interruption, this has the potential to both improve both the safety and the operating efficiency of these surgeries for children.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Dr Susan Humphreys

Address

Centre for Children's Health Research
Level 7
62 Graham St
South Brisbane
QLD, 4101

Country

Australia

Phone

+617 3068 1135

Fax

susan.humphreys@uq.edu.au

Contact person for public queries

Name

Susan Humphreys

Address

Centre for Children's Health Research
Level 7
62 Graham St
South Brisbane
QLD, 4101

Country

Australia

Phone

+61 7 3069 7480

Fax

susan.humphreys@uq.edu.au

Contact person for scientific queries

Name

Susan Humphreys

Address

Centre for Children's Health Research
Level 7
62 Graham St
South Brisbane
QLD, 4101

Country

Australia

Phone

+61 07 30697480

Fax

susan.humphreys@uq.edu.au

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

No/undecided IPD sharing reason/comment

This will be discussed with the team closer to reporting

What supporting documents are/will be available?

Doc. No.	Type	Citation	Link	Email	Other Details	Attachment
13855	Statistical analysis plan					375166-(Uploaded-19-01-2022-11-32-02)-Study-related document.pdf

Results publications and other study-related documents

Documents added manually

No documents have been uploaded by study researchers.

Documents added automatically

Source	Title	Year of Publication	DOI
Embase	High-flow oxygen for children's airway surgery: Randomised controll edtrial protocol (HAMSTER).	2019	https://dx.doi.org/10.1136/bmjopen-2019-031873
Embase	Apneic oxygenation in pediatric anesthesia.	2022	https://dx.doi.org/10.1097/ACO.0000000000001127

N.B. These documents automatically identified may not have been verified by the study sponsor.

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