Measurement of the Second Gas Effect on Sevoflurane in Anaesthetised Patients

Anesthesia Clinical Trial

Official title:

Measurement of the Second Gas Effect on Sevoflurane in Anaesthetised Patients

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00321191
• Other study ID #: 02531
• Status: Completed
• Phase: Phase 4
• First received: May 2, 2006
• Last updated: June 23, 2015
• Start date: May 2006
• Est. completion date: September 2006

Study information

• Verified date: August 2008
• Source: Austin Health
• Contact: n/a
• Is FDA regulated: No
• Health authority: Australia: National Health and Medical Research Council
• Study type: Interventional

Clinical Trial Summary

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.

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.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 14
• Est. completion date: September 2006
• Accepts healthy volunteers: No
• Gender: Both
• Age group: 18 Years and older

Eligibility

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.

Study Design

Allocation: Randomized, Endpoint Classification: Pharmacokinetics Study, Intervention Model: Crossover Assignment, Masking: Open Label

Related Conditions & MeSH terms

• Anesthesia

Intervention

Drug:
• No nitrous oxide

• Administration of N2O

Locations

Country	Name	City	State
Australia	Austin Hospital	Melbourne	Victoria

Sponsors (1)

Lead Sponsor	Collaborator
Austin Health

Country where clinical trial is conducted

Australia, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Fa/FI sevoflurane in 100% O2 vs in 70% N2O and 30% O2 during 1st 60 min anaesthesia
Primary	Change in Fa/FI sevoflurane in 100% O2 vs in 70% N2O and 30% O2 after 60 minutes anaesthesia
Secondary	Fa/FI and FA/FI for N2O will also be recorded.