AnesthesiaPhase 4NCT00146250
The Effect of N2O Administration on Arterial Oxygenation
A Phase 4 study testing Nitrous oxide in people with Anesthesia, run by Austin Health.
Trial summary
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… Read more about this study
- Who is it for?
- Ages 18 years and older
- Conditions the study is for
- Anesthesia
- What is being tested?
- Nitrous oxide
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 20 participants
- Where
- No sites listed yet
- Study dates
- 1 Mar 2005to 30 Sep 2005
- Phase
- Phase 4
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 years and older
- All sexes
- No healthy volunteers
- Adult, Older adult
Who may be able to join
- Patients undergoing elective coronary artery bypass surgery
Who cannot join
- Age under 18 years, emergency surgery
About this study
Official title: 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.
Read the 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.
- Conditions
- Anesthesia
- Being tested
- Nitrous oxide
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Nitrous oxideDrug
Also called N2O
Substitution of Nitrous oxide for Nitrogen as balance gas in inspired gas mixture
| Study group | Role | What they receive |
|---|---|---|
| Nitrous oxide | Experimental | Nitrous oxide 70% as balance gas in inspired mixture Receives: Drug: Nitrous oxide |
| Nitrogen | Experimental | Nitrogen instead of nitrous oxide 70% as balance gas in inspired mixture Receives: Drug: Nitrous oxide |
What is being measured
The primary outcome is the main question the study is designed to answer.
PaO2
Measured change in PaO2 after a minimum of 30 minutes of general anaesthesia, following sternotomy, in the two groups.
Measured: Minimum of 30 minutes after induction of anaesthesia
Secondary outcomes (1)
Change in pulmonary deadspace and shunt fractions
Change in pulmonary deadspace and shunt fractions, as calculated by the Bohr and shunt equations.
Measured: Minimum of 30 minutes after induction of anaesthesia
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted7 Sep 2005 (estimated)
- Study start1 Mar 2005
- Primary completion20 Jul 2005
- Study completion30 Sep 2005
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AnesthesiaStudies of the same condition, open and under way.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Interventional
- Phase
- Phase 4
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind
- Who is masked
- Participant
- Enrolment
- 20 participants (actual)
Sponsor and investigators
- Lead sponsor
- Austin Health
- Sponsor type
- Other government
- Collaborators
- Monash University, La Trobe University, The Alfred, University of Melbourne
- Responsible party
- Principal investigator, Dr Philip Peyton, Austin Health
- Investigators
- Philip J Peyton, MD FANZCA, Principal investigator, Dept of Anaesthesia, Austin Health
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00146250
- Sponsor's protocol ID
- H99/00835
- Status last verified
- Jan 2018
- First submitted
- 6 Sep 2005
- Last updated
- 11 Jan 2018
- Results posted
- No
- Data monitoring committee
- No
- FDA-regulated drug
- Yes
- FDA-regulated device
- No
Study at a glance
From the registry record, last updated by the sponsor on 11 Jan 2018. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Relationship of Oxygenation During Anaesthesia in the Presence of N2O or N2 to Mode of Ventilation
- ClinicalTrials.gov ID
- NCT00146250
- Acronym / sponsor ID
- H99/00835
- Conditions
- Anesthesia
- Phase
- Phase 4
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 20 participants (actual)
- Lead sponsor
- Austin HealthOther government
- Collaborators
- Monash University, La Trobe University, The Alfred, University of Melbourne
- Study start
- 1 Mar 2005 (actual)
- Primary completion
- 20 Jul 2005 (actual)
- Study completion
- 30 Sep 2005 (actual)
- First posted
- 7 Sep 2005 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
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 design
- Primary purpose
- Treatment
- Allocation
- Randomised
- Intervention model
- Parallel groups
- Masking
- Single blind (participant)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Nitrous oxide | Experimental | Drug: Nitrous oxideNitrous oxide 70% as balance gas in inspired mixture |
| Nitrogen | Experimental | Drug: Nitrous oxideNitrogen instead of nitrous oxide 70% as balance gas in inspired mixture |
Who may qualify
- Ages
- 18 years and older
- Sex
- All
- Healthy volunteers
- Not accepted
- Age groups
- Adult, Older adult
Key inclusion criteria (1 listed)
- Patients undergoing elective coronary artery bypass surgery
Key exclusion criteria (1 listed)
- Age under 18 years, emergency surgery
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| Nitrous oxideAlso: N2OSubstitution of Nitrous oxide for Nitrogen as balance gas in inspired gas mixture | Drug | Nitrogen, Nitrous oxide |
Primary outcome
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.
1 secondary outcome
Change in pulmonary deadspace and shunt fractions
Time frame: Minimum of 30 minutes after induction of anaesthesia
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 11 Jan 2018.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Philip J Peyton, MD FANZCA principal investigator
Dept of Anaesthesia, Austin Health
Questions about this trial
What is this clinical trial studying?
A Phase 4 study testing Nitrous oxide in people with Anesthesia, run by Austin Health.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 1 inclusion and 1 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: finished, as of the sponsor's last update on 11 Jan 2018. Status can change between updates, so confirm with the study contact before making plans.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
What does this phase mean?
Phase 4 studies take place after a treatment is approved, to learn more about its long-term benefits and risks in everyday use.
Not every study follows the same path, and some studies (observational studies, device studies) have no phase.
Are results available for this study?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
PaO2 (time frame: Minimum of 30 minutes after induction of anaesthesia). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Jan 2018.