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.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
TREATMENT
Masking
SINGLE
Enrollment
50
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.
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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: 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.
Time frame: under general anesthesia but before surgical incision
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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.
Time frame: 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.
Time frame: under general anesthesia but 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.
Time frame: under general anesthesia but before surgical incision