ENIGMA - Evaluation of Nitrous Oxide In the Gas Mixture for Anaesthesia: a Randomised Controlled Trial

July 29, 2009 updated by: Bayside Health

Evaluation of Nitrous Oxide In the Gas Mixture for Anaesthesia: a Randomised Controlled Trial

We aim to investigate the effectiveness and safety of nitrous oxide (N2O) in anaesthesia.

Hypothesis In patients undergoing anaesthesia for major surgery, avoidance of N2O will reduce hospital length of stay when compared with otherwise identically managed surgical patients receiving N2O as a component of their anaesthesia.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

There are some compelling reasons to question the routine use of nitrous oxide (N2O), also known as "laughing gas". Despite being the first anaesthetic drug introduced, and still widely used, there is sufficient doubt as to the risk-benefit profile.

There is strong evidence that N2O is a major risk factor for postoperative nausea and vomiting. It is clear that (even) brief exposure to N2O impairs methionine synthetase, an enzyme required for DNA production, red and white blood cell formation. Tissue hypoxia may be more common. These adverse effects are enhanced in "sick" patients (ie. those at highest risk, increased hospital length of stay and healthcare expenditure), and will be more likely in longer surgery. The extent of wound infection and cardiac morbidity associated with N2O is not known.

Large outcome trial data are lacking. When considering its widespread use in about 90% of all surgery around the world, small differences in outcome would have major implications for healthcare delivery. A large randomised controlled trial is necessary to answer this question.

We have recruited 2000 patients from about 25 centres around the world (mostly Australasia), who are undergoing major surgery.

Study Type

Interventional

Enrollment (Anticipated)

2070

Phase

  • Phase 4

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Australia
    • Victoria
      • Melbourne, Victoria, Australia, 3004
        • Alfred Hospital

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years and older (ADULT, OLDER_ADULT)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  1. Males and females, age 18 years and over
  2. Planned general anaesthesia for surgery that includes a skin incision and expected to exceed two hours, and the patient is expected to be in hospital for at least three days

Exclusion Criteria:

  1. Endoscopic or radiological procedures
  2. Cardiac surgery
  3. Marked impairment of gas-exchange (requiring Fi02> 0.3)
  4. Thoracic surgery requiring one-lung ventilation (requiring Fi02> 0.3)
  5. Specific circumstances where N2O is contraindicated (eg. volvulus, pulmonary hypertension, raised intracranial pressure)
  6. Lack of provision of N2O.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: PREVENTION
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: SINGLE

What is the study measuring?

Primary Outcome Measures

Outcome Measure
The primary endpoint is hospital length of stay (LOS), defined from the start of surgery until actual hospital discharge. Patients transferred to another hospital will be tracked until final discharge to home (or other final destination). LOS is likely

Secondary Outcome Measures

Outcome Measure
Secondary endpoints will be detected by a research assistant who will be masked to Group identity, using chart review up to 30 days postoperatively; confirmation of each will be sought by an independent member of the Endpoint Committee:
Wound infection - if associated with purulent discharge or a positive microbial culture (46)
Myocardial infarction - confirmed by ECG and/or troponin or CK-MB enzyme rise
Venous thromboembolism - symptomatic DVT or PE, confirmed by venography, duplex ultrasonography, V-Q scan or spiral CT, or autopsy
Stroke - a new neurological deficit persisting for 24 hours, confirmed by neurologist assessment and/or CT scan or MRI
Awareness - postoperative recollection of intraoperative events
Blood transfusion - any red cell transfusion within 30 days of surgery
Pneumothorax, atelectasis, or pneumonia - confirmed by chest x-ray; for pneumonia: also 2 or more of temp> 38oC, white cell count >12,000/ml, positive sputum culture
Severe vomiting - at least 2 episodes >6 hrs apart, or if requiring >2 doses of antiemetic medication
Quality of recovery on the morning after surgery -using the validated QoR Score instrument (14), a 9-item patient-orientated measure of early postoperative health status. This is associated with patient satisfaction.
30-day mortality - for safety analysis only (study not powered for this rare event).

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Bayside Health

Collaborators

National Health and Medical Research Council, Australia
Australia: Theapeutic Goods Administration

Investigators

  • Principal Investigator: Paul S Myles, MB BS MPH MD, The Alfred

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start

April 1, 2003

Primary Completion (ACTUAL)

December 1, 2004

Study Completion (ACTUAL)

December 1, 2004

Study Registration Dates

First Submitted

September 13, 2005

First Submitted That Met QC Criteria

September 13, 2005

First Posted (ESTIMATE)

September 14, 2005

Study Record Updates

Last Update Posted (ESTIMATE)

July 31, 2009

Last Update Submitted That Met QC Criteria

July 29, 2009

Last Verified

July 1, 2009

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • 204/02
  • NHMRC 236956

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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