FIO2 Influences SvO2 Interpretation and Fick-based Cardiac Output Assessment

Study Overview
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Brief Summary
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In this study, the investigators sought to clarify the influence of FIO2 levels on the variables in the Fick equation and then assessed the influence of each variable on the accuracy of Fick-CO measurements in patients undergoing cardiac surgery.

Detailed Description
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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 an intra-cardiac shunt are excluded. The patients are randomly assigned to 2 groups: FIO2 <0.7 or FIO2 >0.85. And during the surgery, the oximeter values are kept ≥98%. Intra-operatively, FIO2, PaO2, SaO2, SvO2, PvO2, Hb, blood pH values, body temperature and TD-CO are recorded.

Official Title
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Increased FIO2 Influences SvO2 Interpretation and Accuracy of Fick-based Cardiac Output Assessment in Cardiac Surgery Patients

Conditions
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Cardiac Output

Intervention / Treatment
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* Other: fraction of inspired oxygen (FIO2)


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: undergoing planned elective cardiac surgery agree to sign informed consent Exclusion Criteria: intra-cardiac shunt

Ages Eligible for Study
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Minimum Age: 20 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: >0.85 FIO2 group<br>This group receives FIO2 >0.85 during the surgery. | Other: fraction of inspired oxygen (FIO2)<br>* The fraction of inspired oxygen (FIO2) is given accordingly (>0.85 for the >0.85 group, and <0.7 for the <0.7 group) to the patients during the surgery.<br>|
| Active Comparator: <0.7 FIO2 group<br>This group receives FIO2 <0.7 during the surgery. | Other: fraction of inspired oxygen (FIO2)<br>* The fraction of inspired oxygen (FIO2) is given accordingly (>0.85 for the >0.85 group, and <0.7 for the <0.7 group) to the patients during the surgery.<br>|

What is the study measuring?
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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 >0.85 or <0.7) during the surgery. We will collect hemoglobin data in each patient. | under general anesthesia but before surgical incision | 
| The Oxygen Consumption in Different FIO2 Groups during Cardiac Surgeries | The patients were divided into two FIO2 groups (FIO2 >0.85 or <0.7) during the surgery. We will use the LaFarge equation to calculate oxygen consumption (ml/min/m^2) in each patient. | under general anesthesia but before surgical incision | 
| The Blood PH Values in Different FIO2 Groups during Cardiac Surgeries | The patients were divided into two FIO2 groups (FIO2 >0.85 or <0.7) during the surgery. We will calculate oxygen consumption in each patient. | under general anesthesia but before surgical incision | 
| The Body Temperatures in Different FIO2 Groups during Cardiac Surgeries | The patients were divided into two FIO2 groups (FIO2 >0.85 or <0.7) during the surgery. We will calculate oxygen consumption in each patient. | under general anesthesia but before surgical incision | 
| The SaO2 in Different FIO2 Groups during Cardiac Surgeries | The patients were divided into two FIO2 groups (FIO2 >0.85 or <0.7) during the surgery. We will calculate oxygen consumption in each patient. | under general anesthesia but before surgical incision | 
| The SvO2 in Different FIO2 Groups during Cardiac Surgeries | The patients were divided into two FIO2 groups (FIO2 >0.85 or <0.7) during the surgery. We will calculate oxygen consumption in each patient. | under general anesthesia but before surgical incision | 
| The PaO2 in Different FIO2 Groups during Cardiac Surgeries | The patients were divided into two FIO2 groups (FIO2 >0.85 or <0.7) during the surgery. We will calculate oxygen consumption in each patient. | under general anesthesia but before surgical incision | 
| The PvO2 in Different FIO2 Groups during Cardiac Surgeries | The patients were divided into two FIO2 groups (FIO2 >0.85 or <0.7) during the surgery. We will calculate oxygen consumption in each patient. | under general anesthesia but before surgical incision | 

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. | under general anesthesia but before surgical incision |