Measurement of the Second Gas Effect on Sevoflurane in Anaesthetised Patients

This study has been completed.
Sponsor:
Information provided by:
Austin Health
ClinicalTrials.gov Identifier:
NCT00321191
First received: May 2, 2006
Last updated: August 18, 2008
Last verified: August 2008
  Purpose

This study is investigating the "second gas effect", a phenomenon produced by the uptake of nitrous oxide (N2O) by the lungs, during the course of a typical anaesthetic. The effect is to increase the concentration of other breathed gases in the lung. These include oxygen and volatile anaesthetic agents such as sevoflurane, which are also normally administered along with N2O. We wish to i) measure the magnitude of the second gas effects on both blood and expired concentrations of sevoflurane (Part 1), and ii) see if a demonstrable difference exists between the effects on blood and expired concentrations.


Condition Intervention Phase
Anesthesia
Drug: No nitrous oxide
Drug: Administration of N2O
Phase 4

Study Type: Interventional
Study Design: Allocation: Randomized
Endpoint Classification: Pharmacokinetics Study
Intervention Model: Crossover Assignment
Masking: Open Label
Official Title: Measurement of the Second Gas Effect on Sevoflurane in Anaesthetised Patients

Resource links provided by NLM:


Further study details as provided by Austin Health:

Primary Outcome Measures:
  • Fa/FI sevoflurane in 100% O2 vs in 70% N2O and 30% O2 during 1st 60 min anaesthesia
  • FA/FI sevoflurane in 100% O2 vs in 70% N2O and 30% O2 during 1st 60 min anaesthesia
  • Change in Fa/FI sevoflurane in 100% O2 vs in 70% N2O and 30% O2 after 60 minutes anaesthesia
  • Change in FA/FI sevoflurane in 100% O2 vs in 70% N2O and 30% O2 after 60 minutes anaesthesia

Secondary Outcome Measures:
  • Fa/FI and FA/FI for N2O will also be recorded.

Enrollment: 14
Study Start Date: May 2006
Study Completion Date: September 2006
Arms Assigned Interventions
Experimental: N2O Drug: Administration of N2O
No Intervention: No N2O Drug: No nitrous oxide

Detailed Description:

This study is investigating the "second gas effect", a phenomenon produced by the uptake of nitrous oxide (N2O) by the lungs, during the course of a typical anaesthetic. The effect is to increase the concentration of other breathed gases in the lung. These include oxygen and volatile anaesthetic agents such as sevoflurane, which are also normally administered along with N2O.

While the second gas effect has been demonstrated previously, by measuring the concentration of volatile anaesthetic in the expired breath, no study has yet shown that it has a significant effect on the concentrations in the blood. The blood concentration is in fact more important, as it directly determines the concentration of anaesthetic reaching the brain, and therefore the effect on the depth of anaesthesia. The second gas effect on blood concentrations may be more powerful than that on expired concentrations, due to the detrimental effect of anaesthesia on the evenness of distribution of ventilation and blood flow in the lung.

The proposed study will have two parallel components or Parts. We wish to i) measure the magnitude of the second gas effects on both blood and expired concentrations of sevoflurane (Part 1), and ii) see if a demonstrable difference exists between the effects on blood and expired concentrations.

  Eligibility

Ages Eligible for Study:   18 Years and older
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   No
Criteria

Inclusion Criteria:

  • Patients scheduled for elective surgery requiring relaxant general anaesthesia with arterial blood pressure monitoring via an arterial line.

Exclusion criteria:

  • Patients with moderately or severely impaired respiratory disease (FEV1 < 1.5L, or FVC < 2.0L).
  • Patients under 18 years of age.
  • Morbidly obese patients: BMI > 30
  • Patients unable to give informed consent.
  Contacts and Locations
Choosing to participate in a study is an important personal decision. Talk with your doctor and family members or friends about deciding to join a study. To learn more about this study, you or your doctor may contact the study research staff using the Contacts provided below. For general information, see Learn About Clinical Studies.

Please refer to this study by its ClinicalTrials.gov identifier: NCT00321191

Locations
Australia, Victoria
Austin Hospital
Melbourne, Victoria, Australia, 3084
Sponsors and Collaborators
Austin Health
Investigators
Principal Investigator: Philip J Peyton, MD FANZCA Austin Health
  More Information

No publications provided

ClinicalTrials.gov Identifier: NCT00321191     History of Changes
Other Study ID Numbers: 02531
Study First Received: May 2, 2006
Last Updated: August 18, 2008
Health Authority: Australia: National Health and Medical Research Council

Additional relevant MeSH terms:
Sevoflurane
Nitrous Oxide
Platelet Aggregation Inhibitors
Hematologic Agents
Therapeutic Uses
Pharmacologic Actions
Anesthetics, Inhalation
Anesthetics, General
Anesthetics
Central Nervous System Depressants
Physiological Effects of Drugs
Central Nervous System Agents
Analgesics, Non-Narcotic
Analgesics
Sensory System Agents
Peripheral Nervous System Agents

ClinicalTrials.gov processed this record on September 18, 2014