Physiological Effects of Nitrous Oxide on Anaesthesia

NCT01092923 | Completed Phase 4 Results DMC

• 1 other identifier: 03749
• Study Type: interventional
• Target: 20
• Locations: 1 country
• Sites: 1

Brief Summary

Nitrous oxide is the oldest anaesthetic agent still in routine use today. Despite huge changes in the pharmacology of volatile anaesthetic agents and intravenous anaesthetics, the unique properties of nitrous oxide have maintained its place in modern practice, where it is used in combination with other, more powerful inhaled agents, such as sevoflurane. It has useful analgesic properties, unlike the other agents used today, and its inclusion reduces the concentration of other agents required to maintain an adequate depth of anaesthesia for surgery. In particular, its low solubility in body tissues gives it a unique pharmacokinetic profile, with rapid washin and washout from the body. It has been shown to have a similar effect on the speed of uptake of accompanying agents like sevoflurane (the "second gas effect"), which have much slower pharmacokinetics. A recent study by us suggested that this promotes faster and smoother onset of anaesthesia, as measured using the standard monitor of depth of anaesthesia (the BIS monitor). This finding requires confirmation prospectively in a larger group of patients. The investigators further hypothesise that a similar effect also exists on washout of sevoflurane at the end of the procedure, promoting quicker recovery (emergence) from anaesthesia. This has never been previously demonstrated. This information will help better define the place of nitrous oxide in achieving optimal outcomes in modern anaesthetic practice. The investigators propose to conduct a simple study to measure the effects of nitrous oxide washin and washout on exhaled concentrations of accompanying sevoflurane during both induction of anaesthesia and emergence, and identify any accompanying effect on the rate of change in depth of anaesthesia using BIS. The investigators hypothesise that the rate of fall of exhaled sevoflurane concentration at the end of anaesthesia will be more rapid in the group of patients breathing a gas mixture containing nitrous oxide, and that the rate of fall of BIS on induction and the rate of rise of BIS on emergence will be faster in the nitrous oxide group.

Conditions

Anesthesia

Keywords

Nitrous Oxide; washin; washout; second gas effect; sevoflurane; induction; emergence

Outcome Measures

Primary Outcomes (2)

• Pa t/Pa0 Sevo (Arterial Partial Pressure of Sevoflurane), t=Time(Minutes)

  Rate of fall in the arterial partial pressure of sevoflurane relative to baseline at 2 minutes (Pa 2/Pa0 Sevo), 5 minutes (Pa 5/Pa0 Sevo, and 30 minutes (Pa 30/Pa0 Sevo)

  Baseline, 2 minutes, 5 minutes, and 30 minutes after emergence

• PA t/PA0 Sevo (End Tidal Partial Pressure of Sevoflurane), t=Time (Minutes)

  Rate of fall in the end-tidal partial pressure of sevoflurane relative to baseline at 2 minutes (PA2/PA0 sevo) and 5 minutes (PA5/PA0 sevo)

  Baseline, 2 minutes, and 5 minutes after emergence

Secondary Outcomes (1)

• Time to Eye Opening

  20 Minutes

Study Arms (2)

Air/Oxygen

EXPERIMENTAL

Sevoflurane with Air/Oxygen Mix

Drug: sevoflurane on air/O2

sevoflurane in N2O/O2

EXPERIMENTAL

Drug: sevoflurane in N2O/O2

Interventions

sevoflurane on air/O2 DRUG

sevoflurane on air/O2

Air/Oxygen

sevoflurane in N2O/O2 DRUG

sevoflurane in N2O/O2

sevoflurane in N2O/O2

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• Adult patients undergoing elective general or orthopaedic surgery under relaxant general anaesthesia anticipated to take \>1 hour

You may not qualify if:

• Age under 18 years
• Morbid obesity BMI \> 35
• Severe or moderately severe lung disease (FEV1 \< 1.0L, FEV1/FVC \< 50%)
• Past history of severe post-operative nausea and vomiting
• Pregnancy

Sponsors & Collaborators

• Austin Health: lead

Study Sites (1)

Austin Health

Melbourne, Victoria, 3084, Australia

Location

MeSH Terms

Interventions

Sevoflurane

Intervention Hierarchy (Ancestors)

Methyl Ethers; Ethers; Organic Chemicals; Hydrocarbons, Fluorinated; Hydrocarbons, Halogenated; Hydrocarbons

Results Point of Contact

• Title: Dr Phil Peyton
• Organization: Austin Health

phil.peyton@austinhealth.org.au

9496 5000

Study Officials

• Phil Peyton, MBBS

  Austin Health

  PRINCIPAL INVESTIGATOR

Publication Agreements

• PI is Sponsor Employee: Yes

Study Design

• Study Type: interventional
• Phase: phase 4
• Allocation: RANDOMIZED
• Masking: SINGLE
• Who Masked: PARTICIPANT
• Purpose: TREATMENT
• Intervention Model: PARALLEL
• Sponsor Type: OTHER GOV
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Staff Anaesthetist

Study Record Dates

• First Submitted: March 10, 2010
• First Posted: March 25, 2010
• Study Start: October 1, 2009
• Primary Completion: July 1, 2010
• Study Completion: October 1, 2010
• Last Updated: October 12, 2012
• Results First Posted: October 12, 2012

Record last verified: 2012-09

Locations

AU (1)