The Effect of N2O Administration on Arterial Oxygenation

January 9, 2018 updated by: Dr Philip Peyton, Austin Health

Relationship of Oxygenation During Anaesthesia in the Presence of N2O or N2 to Mode of Ventilation

Nitrous oxide is a standard part of most anaesthetic breathing mixtures. It has often been assumed that it reduces the amount of oxygen reaching the lower parts of the lung. However the results of previous studies and of some computer modelling suggests the opposite may be true, and that oxygen levels in the blood are actually higher with nitrous oxide. This study seeks to determine whether nitrous oxide increases or decreases blood oxygen levels in anaesthetized patients.

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Detailed Description

The concentrating and second gas effects of nitrous oxide (N2O) uptake have been well described, and are produced by rapid uptake of N2O during the first several minutes of an inhalational anesthetic. This significantly increases alveolar and arterial O2 partial pressure. Theoretical modelling of alveolar gas exchange has predicted that these effects may not be transient but may be a persisting phenomenon. However, N2O is known to promote absorption atelectasis in poorly ventilated lung units.

This study, carried out pre-cardiopulmonary bypass in 20 patients undergoing coronary artery surgery, measures change in PaO2 after a minimum of 30 minutes of relaxant general anesthesia with a FIO2 of 30%. Patients are randomised to two groups. The intervention group has N2O introduced following baseline blood gas measurements, while the control group continued breathing an identical FIO2 in N2. The change in PaO2 in the two groups is the primary endpoint for comparison.

Study Type

Interventional

Enrollment (Actual)

20

Phase

  • Phase 4

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:

  • Patients undergoing elective coronary artery bypass surgery

Exclusion Criteria:

  • Age under 18 years, emergency surgery

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: TREATMENT
  • Allocation: RANDOMIZED
  • Interventional Model: PARALLEL
  • Masking: SINGLE

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
EXPERIMENTAL: Nitrous oxide
Nitrous oxide 70% as balance gas in inspired mixture
Drug: Nitrous oxide
Substitution of Nitrous oxide for Nitrogen as balance gas in inspired gas mixture
Other Names:
  • N2O
EXPERIMENTAL: Nitrogen
Nitrogen instead of nitrous oxide 70% as balance gas in inspired mixture
Drug: Nitrous oxide
Substitution of Nitrous oxide for Nitrogen as balance gas in inspired gas mixture
Other Names:
  • N2O

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
PaO2
Time Frame: Minimum of 30 minutes after induction of anaesthesia
Measured change in PaO2 after a minimum of 30 minutes of general anaesthesia, following sternotomy, in the two groups.
Minimum of 30 minutes after induction of anaesthesia

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Change in pulmonary deadspace and shunt fractions
Time Frame: Minimum of 30 minutes after induction of anaesthesia
Change in pulmonary deadspace and shunt fractions, as calculated by the Bohr and shunt equations.
Minimum of 30 minutes after induction of anaesthesia

Collaborators and Investigators

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

Sponsor

Austin Health

Collaborators

Monash University
The Alfred
University of Melbourne
La Trobe University

Investigators

  • Principal Investigator: Philip J Peyton, MD FANZCA, Dept of Anaesthesia, Austin Health

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 (ACTUAL)

March 1, 2005

Primary Completion (ACTUAL)

July 20, 2005

Study Completion (ACTUAL)

September 30, 2005

Study Registration Dates

First Submitted

September 6, 2005

First Submitted That Met QC Criteria

September 6, 2005

First Posted (ESTIMATE)

September 7, 2005

Study Record Updates

Last Update Posted (ACTUAL)

January 11, 2018

Last Update Submitted That Met QC Criteria

January 9, 2018

Last Verified

January 1, 2018

More Information

Terms related to this study

Additional Relevant MeSH Terms

Other Study ID Numbers

  • H99/00835

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

Yes

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

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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