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Trial registered on ANZCTR

Registration number

ACTRN12617001385336p

Ethics application status

Submitted, not yet approved

Date submitted

24/09/2017

Date registered

29/09/2017

Date last updated

31/01/2018

Type of registration

Prospectively registered

Titles & IDs

Public title

Intraoperative nitrous oxide and its role in surgery of the middle ear:

Scientific title

Intraoperative nitrous oxide and its role in surgery of the middle ear:
A randomized control trial

Secondary ID [1]

NONE

Universal Trial Number (UTN)

U1111-1201-3482

Trial acronym

Linked study record

Health condition

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

Tympanic Membrane Retraction

Condition category

Condition code

Ear

Other ear disorders

Anaesthesiology

Other anaesthesiology

Surgery

Other surgery

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

All patients from both cohorts will be pre-oxygenated (100 % O2) prior to induction of anaesthesia via an open circuit for 3mins. At the discretion of the anaesthetist, patients will undergo an inhalation or intravenous induction. Inhalational induction is performed with a spontaneously breathing patient with sevoflurane in 100% oxygen. Intravenous induction is performed with propofol and preferred adjuncts. A Laryngeal mask airway or endotracheal tube is then introduced, avoiding positive pressure ventilation until the establishment of an airway device.

Once the airway has been secured, the tympanic membrane will be visualised by the surgeon, its state recorded & wide band absorbance tympanometry performed.

Following initial review, patients are randomised into 2 groups, single blinded to the Surgeon

Interventional group:
Inhale 30% O2 and 70 % Nitrous Oxide at a total flow rate of 6L for 10 mins.
The surgeon will return at 10 mins post exposure repeat tympanography and visualisation of the tympanic membrane will be performed and recorded.

Following second review, nitrous oxide will be discontinued and the anaesthetic will be conducted at the discretion of the anaesthetist. Risk of increasing rates of PONV are low due to the limited exposure to nitrous oxide 5 mins as shown by Peyton and Wu 2014.

Intervention code [1]

Treatment: Drugs

Comparator / control treatment

Controlled Group:
Inhale 30% O2 and 70% Air at a total flow rate of 6L for 10 mins.
The surgeon will return at 10 mins post exposure repeat tympanography and visualisation of the tympanic membrane will be performed and recorded.
Following second review, nitrous oxide will be discontinued and the anaesthetic will be conducted at the discretion of the anaesthetist.

Control group

Placebo

Outcomes

Primary outcome [1]

Tympanic Membrane Retraction vs No Tympanic Membrane Retraction
- This will be assessed under microscopy by the consultant surgeon
- The tympanic membrane will be reported as retracted, and graded according to Sade 1-5.

Timepoint [1]

Following intubation the consultant will review the tympanic membrane this will be considered 0 mins (prior to intervention). 10 minutes post conduction of intervention the surgeon will again eyeball the tympanic membrane.

Secondary outcome [1]

Tympanometry will be conducted using a portable instrument, results will be graphed accordingly admittance over air pressure.

Timepoint [1]

Following intubation the consultant will review the tympanic membrane, after this tympanometry will be performed this will be considered 0 mins (prior to intervention). 10 minutes post conduction of intervention the surgeon will again eyeball the tympanic membrane and tympanometry will again be repeated.

Secondary outcome [2]

Surgeon Satisfaction:
- Three-point linkert scale will be used

Timepoint [2]

Post-operatively

Secondary outcome [3]

Acute Post-operative complications:
- Nausea as reported by the patient Y/N
- Vomiting Y/N
- Antiemetic use - all anti-emetics used post-operatively will be documented.

Timepoint [3]

within 24 hours post-operatively

Secondary outcome [4]

Post-operative outcomes:
Tympanometry will be conducted using a portable instrument, results will be graphed accordingly admittance over air pressure.

Timepoint [4]

3 months post surgery

Eligibility

Key inclusion criteria

Patients aged 2-80 with Sade stage 2 tympanic membrane retraction or higher undergoing surgery to the outer or middle ear at the Townsville Hospital or Mater Health Service North Queensland.

Minimum age

2 Years

Maximum age

80 Years

Sex

Both males and females

Can healthy volunteers participate?

Key exclusion criteria

Any condition where there is potential pathological gas fluid space - post-op recent bowel surgery; pneumoperitoneum, pneumocranium.

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

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

Using computer generated sealed envelopes patients were allocated to one of two treatment groups; those receiving nitrous oxide as part of operative procedure versus those receiving a standardized anaesthetic regime with equal persons to both cohorts.

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

Computerised sequence generation

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

The people receiving the treatment/s

The people assessing the outcomes

Intervention assignment

Factorial

Other design features

Phase

Phase 3

Type of endpoint/s

Efficacy

Statistical methods / analysis

• Sample Size: Sample size was based upon findings from Koivenen et al. 1996. Thirty patients are required to have a 95% chance of detecting, as significant at the 5% level, an increase in the primary outcome measure from 25% in the control group to 90% in the experimental group with a 10% adjustment for non-compliance.
• Data Analysis: Data will be collected using SPSS database. Pearson’s chi-squared test for independence will be used to assess the relationship between Nitrous versus the control group on normalization of the tympanic membrane. Analysis of covariance will be used to assess if there is a significant difference in the middle ear pressure in participants receiving Nitrous Oxide versus the control group while controlling for their pre-intervention scores.

Recruitment

Recruitment status

Not yet recruiting

Date of first participant enrolment

Anticipated

1/02/2018

Actual

Date of last participant enrolment

Anticipated

1/09/2019

Actual

Date of last data collection

Anticipated

1/12/2019

Actual

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

QLD

Recruitment hospital [1]

The Townsville Hospital - Douglas

Recruitment hospital [2]

Mater Hospital Pimlico - Pimlico

Recruitment postcode(s) [1]

4814 - Douglas

Recruitment postcode(s) [2]

4810 - Pimlico

Funding & Sponsors

Funding source category [1]

Hospital

Name [1]

The Townsville Hospital

Address [1]

The Townsville Hospital
100 Angus Smith Drive
Douglas, Townsville QLD 4814

Country [1]

Australia

Primary sponsor type

Hospital

Name

The Townsville Hospital

Address

The Townsville Hospital
100 Angus Smith Drive
Douglas, Townsville QLD 4814

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Submitted, not yet approved

Ethics committee name [1]

The Townsville Health Service District Institutional Ethics Committee

Ethics committee address [1]

The Townsville Hospital 
100 Angus Smith Drive
Douglas, Townsville QLD 4814

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

25/09/2017

Approval date [1]

Ethics approval number [1]

Summary

Brief summary

Tympanic membrane retraction can lead to increased technical difficulties for surgeons when conducting tympanoplastic procedures. Nitrous Oxide is a commonly used inhaled anaesthetic agent that has a solubility 35 times higher than Nitrogen. Its diffusion into the middle ear has been well reported and the effects on middle ear pressure and effusions have previously been investigated. Currently, at the discretion of the anesthetist and surgeon the use of Nitrous Oxide as part of anesthetic prior to surgery to the middle ear is conducted at our hospital. It has been noted that in patients with a retraction, normalization of the tympanic membrane can occur thereby allowing for ease of surgery. This study aims to assess the effect of Nitrous Oxide on retracted tympanic membranes, in a controlled manner to see if this practice should be implemented as a standard of care. It is hypothesized that the use of Nitrous Oxide at the time of induction on patients with tympanic membrane retraction will result in normalization of positioning of the membrane thereby allowing for ease of surgery.

A multicenter randomized prospective control trial will be conducted at the Townsville Hospital and the Mater Health Service North Queensland. All patients undergoing middle ear surgery with a retracted tympanic membrane graded Sade 2 or higher will be assessed for suitability for participation. Patients will be randomized via random number generator into two groups of either 30% Oxygen and 70 % Nitrous Oxide vs 30% Oxygen and Air. At time of surgery following the insertion of airway device, the tympanic membrane will be visualized by the surgeon, its state recorded and tympanography will be performed. Single blinded to the Surgeon; who will leave the operating room to prepare for surgery, the maintenance gases will be commenced at 6L/min for 10 minutes. Following cessation, the surgeon will return and again visualize the tympanic membrane and repeat tympanography will be performed allowing for comparison. The operation will then commence. Following the surgery the surgeon will document his personal experience or ease of surgery using a standardized system. Postoperative nausea or vomiting will be documented as well as use of antiemetic’s. Patients will be followed up at 3 months as per our hospitals standard procedures and any complications will be noted.

Trial website

Trial related presentations / publications

Public notes

Contacts

Principal investigator

Name

Dr Jemma Porrett

Address

The Townsville Hospital
100 Angus Smith Drive
Douglas, Townsville QLD 4814

Country

Australia

Phone

+61, 7, 44331111

Fax

[email protected]

Contact person for public queries

Name

Jemma Porrett

Address

The Townsville Hospital
100 Angus Smith Drive
Douglas, Townsville QLD 4814

Country

Australia

Phone

+61, 7, 44331111

Fax

[email protected]

Contact person for scientific queries

Name

Jemma Porrett

Address

The Townsville Hospital
100 Angus Smith Drive
Douglas, Townsville QLD 4814

Country

Australia

Phone

+61, 7, 44331111

Fax

[email protected]

No information has been provided regarding IPD availability

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

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Documents added automatically

No additional documents have been identified.

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