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

Study Results

Results pending

The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.

Basic Information

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Recruitment Status

COMPLETED

Clinical Phase

PHASE4

Total Enrollment

2070 participants

Study Classification

INTERVENTIONAL

Study Start Date

2003-04-30

Study Completion Date

2004-12-31

Brief Summary

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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.

Detailed Description

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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.

Conditions

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Quality of Recovery From Anaesthesia Effects of Nitrous Oxide Following Anaesthesia Induced Endothelial Dysfunction

Keywords

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Nitrous Oxide Anaesthesia Anesthesia Recovery Quality

Study Design

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Allocation Method

RANDOMIZED

Intervention Model

PARALLEL

Primary Study Purpose

PREVENTION

Blinding Strategy

SINGLE

Interventions

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Nitrous Oxide

Intervention Type DRUG

Eligibility Criteria

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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.

Minimum Eligible Age

18 Years

Eligible Sex

ALL

Accepts Healthy Volunteers

No

Principal Investigators

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Paul S Myles, MB BS MPH MD

Role: PRINCIPAL_INVESTIGATOR

The Alfred

Locations

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Alfred Hospital

Melbourne, Victoria, Australia

Site Status

Countries

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Australia

References

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Myles PS, Leslie K, Silbert B, Paech MJ, Peyton P. A review of the risks and benefits of nitrous oxide in current anaesthetic practice. Anaesth Intensive Care. 2004 Apr;32(2):165-72. doi: 10.1177/0310057X0403200202. No abstract available.

Reference Type BACKGROUND

PMID: 15957712 (View on PubMed)

Myles PS, Leslie K, Chan MT, Forbes A, Paech MJ, Peyton P, Silbert BS, Pascoe E; ENIGMA Trial Group. Avoidance of nitrous oxide for patients undergoing major surgery: a randomized controlled trial. Anesthesiology. 2007 Aug;107(2):221-31. doi: 10.1097/01.anes.0000270723.30772.da.

Reference Type RESULT

PMID: 17667565 (View on PubMed)

Leslie K, Myles PS, Chan MT, Paech MJ, Peyton P, Forbes A, McKenzie D; ENIGMA Trial Group. Risk factors for severe postoperative nausea and vomiting in a randomized trial of nitrous oxide-based vs nitrous oxide-free anaesthesia. Br J Anaesth. 2008 Oct;101(4):498-505. doi: 10.1093/bja/aen230. Epub 2008 Aug 5.

Reference Type DERIVED

PMID: 18682411 (View on PubMed)

Other Identifiers

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NHMRC 236956

Identifier Type: -

Identifier Source: secondary_id

204/02