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

Status

Completed

Phases

Unknown

Study type

Observational

Source

ClinicalTrials.gov

Registry ID

NCT02003300

Enrollment

Registered

2013-12-06

Start date

2005-04-30

Completion date

2006-11-30

Last updated

2013-12-06

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

E03.155.197, E03.155.253

Keywords

Oxygen uptake, Anesthetic gas uptake

Brief summary

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.

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.

Interventions

None listed

Study design

Time perspective

PROSPECTIVE

Eligibility

Sex/Gender

ALL

Age

18 Years to 18 Years

Healthy volunteers

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

Design outcomes

Primary

Measure	Time frame
oxygen uptake	During surgery

Countries

Australia

Outcome results