FIO2 Influences Accuracy of Fick-based Cardiac Output

Increasing FIO2 Influences Accuracy of Fick-based Assessments of Cardiac Output in Cardiac Surgery Patients

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.

Study Overview

• Status: Completed
• Conditions: Cardiac Output
• Intervention / Treatment: Other: fraction of inspired oxygen (FIO2)

Detailed 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.

• Study Type: Interventional
• Enrollment (Actual): 24
• Phase: Not Applicable

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 20 years and older (ADULT, OLDER_ADULT)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

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

Exclusion Criteria:

• cardiac arrhythmia
• intra-cardiac shunt

Study Plan

How is the study designed?

Design Details

• Primary Purpose: OTHER
• Allocation: RANDOMIZED
• Interventional Model: PARALLEL
• Masking: SINGLE

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
EXPERIMENTAL: FIO2 >90% group; This group receives FIO2 >90% during the surgery.	Other: fraction of inspired oxygen (FIO2); Different group receives different (70% vs. 90%) fraction of inspired oxygen (FIO2) during the surgery.
ACTIVE_COMPARATOR: FIO2 <70% group; This group receives FIO2 <70% during the surgery.	Other: fraction of inspired oxygen (FIO2); Different group receives different (70% vs. 90%) fraction of inspired oxygen (FIO2) during the surgery.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The Hemoglobin Values in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will collect hemoglobin data in each patient.	5 minutes before surgical incision
The Hemoglobin Values in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will collect hemoglobin data in each patient.	5 minutes after finishing protamine infusion
The Oxygen Consumption in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will calculate oxygen consumption in each patient.	5 minutes before surgical incision
The Oxygen Consumption in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will calculate oxygen consumption in each patient.	5 minutes after finishing protamine infusion
The SaO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record SaO2 data in each patient.	5 minutes before surgical incision
The SaO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record SaO2 data in each patient.	5 minutes after finishing protamine infusion
The SvO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record SvO2 data in each patient.	5 minutes before surgical incision
The SvO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record SvO2 data in each patient.	5 minutes after finishing protamine infusion
The PaO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record PaO2 data in each patient.	5 minutes before surgical incision
The PaO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record PaO2 data in each patient.	5 minutes after finishing protamine infusion
The PvO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record PvO2 data in each patient.	5 minutes before surgical incision
The PvO2 in Different FIO2 Groups during Cardiac Surgeries	The patients were divided into two FIO2 groups (FIO2 >90% or <70%) during the surgery. We will record PvO2 data in each patient.	5 minutes after finishing protamine infusion

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
The Precision of Fick-based Cardiac Output in Different FIO2 Groups during Cardiac Surgeries	After collecting the elements data included in the Fick eqaution (oxygen consumption, hemoglobin, SaO2, SvO2, PaO2, and PvO2), we can calculate the Fick-based cardiac output in each patient. And the pulmonary artery thermodilution is adopted as the standard cardiac output monitoring method. We will calculate the correlation and level of agreement between Fick-based cardiac output and pulmonary artery thermodilution in the two groups.	5 minutes before surgical incision
The Precision of Fick-based Cardiac Output in Different FIO2 Groups during Cardiac Surgeries	After collecting the elements data included in the Fick eqaution (oxygen consumption, hemoglobin, SaO2, SvO2, PaO2, and PvO2), we can calculate the Fick-based cardiac output in each patient. And the pulmonary artery thermodilution is adopted as the standard cardiac output monitoring method. We will calculate the correlation and level of agreement between Fick-based cardiac output and pulmonary artery thermodilution in the two groups.	5 minutes after finishing protamine infusion

Collaborators and Investigators

• Sponsor: Chang Gung Memorial Hospital

Study record dates

Study Major Dates

• Study Start (ACTUAL): January 1, 2015
• Primary Completion (ACTUAL): January 1, 2017
• Study Completion (ACTUAL): January 1, 2017

Study Registration Dates

• First Submitted: May 20, 2019
• First Submitted That Met QC Criteria: May 29, 2019
• First Posted (ACTUAL): June 3, 2019

Study Record Updates

• Last Update Posted (ACTUAL): June 5, 2019
• Last Update Submitted That Met QC Criteria: June 3, 2019
• Last Verified: May 1, 2019

More Information

Terms related to this study

• Keywords: Fick Principle
• Other Study ID Numbers: 201900558B0

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: UNDECIDED

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No