FIO2 Influences Accuracy of Fick-based Cardiac Output

Chang Gung Medical Foundation

Status: Completed

Conditions: Cardiac Output

Treatments: Other: fraction of inspired oxygen (FIO2)

Study type: Interventional

Funder types: Other

Identifiers

NCT03970980

201900558B0

Details and patient eligibility

About

Cardiac output (CO) monitoring is often required for clinical evaluation and management in critically ill patients and during anesthesia. There are many methods to measure CO. Fick-based CO estimation (Fick-CO) is one of the most commonly used methods, while thermodilution (TD-CO) is viewed as golden standard. But Fick-CO is still widely used, especially in catheterization laboratories and pediatric cardiologic department, whose patients often with congenital heart disease. Multiple studies from the 1960s find a strong correlation between TD-CO and Fick-CO. However, more recent studies reject the conclusion. Since Fick-CO is the ratio of oxygen consumption (V'O2) to the arteriovenous difference in oxygen content, many parameters are included in the Fick equation, such as V'O2, hemoglobin (Hb), arterial oxygen saturation (SaO2), mixed venous oxygen saturation (SvO2), partial pressure of arterial oxygen (PaO2), and mixed venous oxygen tension (PvO2). Any changes of each parameter may influence the accuracy of Fick-CO calculation. This may be the reason why it remains controversial whether Fick-CO and TD-CO are interchangeable or not. Although there are lots of studies comparing Fick-CO and TD-CO, discussing the impact of V'O2 on Fick-CO, how the other parameters influence the final CO estimation are rarely focused. Therefore, the purpose of this study was to assess the influence of FIO2 on PaO2, SvO2, PvO2, and the accuracy of Fick-CO in cardiac surgery patients.

Full description

Patients who are aged ≥20 years, are undergoing planned elective cardiac surgery, and provided signed informed consent are included in the present study. Any patients with cardiac arrhythmia or an intra-cardiac shunt are excluded.

The patients are randomly assigned to 2 groups: FIO2 <70% or FIO2 >90%. And during the surgery, the oximeter values are kept ≥98%. Intra-operatively, FIO2, PaO2, SvO2, PvO2, Hb, and TD-CO are recorded.

Enrollment: 24 patients

Sex: All

Ages: 20+ years old

Volunteers: No Healthy Volunteers

Inclusion criteria

• undergoing planned elective cardiac surgery
• agree to sign informed consent

Exclusion criteria

• cardiac arrhythmia
• intra-cardiac shunt

Trial design

Primary purpose: Other

Allocation: Randomized

Interventional model: Parallel Assignment

Masking: Single Blind

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24 participants in 2 patient groups

FIO2 >90% group

Experimental group

Description:

This group receives FIO2 \>90% during the surgery.

Treatment:

Other: fraction of inspired oxygen (FIO2)

FIO2 <70% group

Active Comparator group

Description:

This group receives FIO2 \<70% during the surgery.

Treatment:

Other: fraction of inspired oxygen (FIO2)