An Improved Method for the Measurement of Oxygen and Anaesthetic Agent Uptake in Patients Using the Foldes-Biro Equation
The Modified Foldes-Biro Equation Used in Patients Under General Anaesthesia for the Measurement of Oxygen and Anaesthetic Agent Uptake
The primary aim is to confirm the efficacy of a new non-invasive method for measuring the oxygen uptake during general anesthesia of patients undergoing surgery under cardiopulmonary bypass. The method has already been successfully tested in the laboratory under controlled conditions. In the patient group chosen, oxygen uptake is simultaneously calculated, for comparison purposes, from monitoring measurements made routinely as part of normal patient care in these cases, using a pulmonary artery catheter - an invasive technique from which severe complications occasionally arise, including death.
A secondary aim is to elucidate the time course of uptake of the anaesthetic vapor, isoflurane, during this kind of surgery.
Study Overview
Status
Conditions
Detailed Description
In a series of 30 patients undergoing cardiopulmonary bypass, the change in nitrogen concentration between fresh gas entering the anesthetic breathing system and the exhaust gas leaving it in an otherwise closed system is used to determine total gas uptake by the principle of insoluble gas dilution. Oxygen and anaesthetic agent uptakes are then automatically determined by a computer directly linked to a rapid gas analyzer, every 15 seconds.
As a control, oxygen is calculated using the reverse Fick method. Measured arterial and mixed venous oxygen saturations were used to do this, and the cardiac output which was determined by thermodilution.
Study Type
Enrollment (Actual)
Contacts and Locations
Study Locations
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Victoria
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Melbourne, Victoria, Australia, 2004
- The Alfred
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Participation Criteria
Eligibility Criteria
Ages Eligible for Study
Accepts Healthy Volunteers
Genders Eligible for Study
Description
Inclusion Criteria:
- Patients undergoing non-emergency procedures using cardiopulmonary bypass in whom pulmonary artery catheterization was to be performed for routine monitoring purposes, including mixed venous oxygen determinations and thermodilution cardiac output determinations.
Exclusion Criteria:
- High risk patients (ASA 4+)
- Acute lung injury, sepsis
- Tricuspid regurgitation
- Patients under 18 years of age
- Patients unable to give informed consent
Study Plan
How is the study designed?
Design Details
What is the study measuring?
Primary Outcome Measures
Outcome Measure |
Time Frame |
|---|---|
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oxygen uptake
Time Frame: During surgery
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During surgery
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Collaborators and Investigators
Sponsor
Investigators
- Study Director: Brian J Lithgow, MESc BE BSc, Monash University Department of Electrical Engineering
- Principal Investigator: Gavin JB Robinson, MB BS FANZCA, The Alfred, Bayside Health
- Study Director: Philip J Peyton, MB BS FANZCA, The Austin Hospital
Publications and helpful links
Study record dates
Study Major Dates
Study Start
Primary Completion (Actual)
Study Completion (Actual)
Study Registration Dates
First Submitted
First Submitted That Met QC Criteria
First Posted (Estimate)
Study Record Updates
Last Update Posted (Estimate)
Last Update Submitted That Met QC Criteria
Last Verified
More Information
Terms related to this study
Keywords
Other Study ID Numbers
- 177/03
- GE/ASA Research Grant, 2004 (Other Grant/Funding Number: GE/ASA Research Grant, 2004)
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