Study on the Relationship of Arterial-venous Oxygen Difference and Postoperative Complications After Cardiac Surgery.

Study Overview
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Brief Summary
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Avoidance of unnecessary blood transfusions has always been a focus of clinical research. The rate of perioperative red blood cell transfusion in patients undergoing cardiac surgery under cardiopulmonary bypass reaches between 50-70%, and the intraoperative red blood cell transfusion rate is 30-50%. Regarding whether and when to perform a blood transfusion, it is necessary to comprehensively consider the benefits and risks brought by blood transfusion. Previous studies on blood transfusion strategies have mainly focused on the hemoglobin threshold, but the hemoglobin level does not fully reflect the level of tissue oxygenation. Mixed venous blood oxygen saturation has been widely studied as a valuable indicator reflecting the balance of oxygen delivery and oxygen consumption. But due to the difficulty of placing a pulmonary artery floating catheter for monitoring, its clinical application is limited. Central venous oxygen saturation requires only a small collection of blood samples, which can reflect the oxygen saturation of the superior vena cava, and studies have shown that it can effectively guide the blood transfusion of patients undergoing cardiac surgery. Existing studies have shown that in critically ill patients, the use of arterial-venous oxygen difference > 3.7 mL as an indicator to guide blood transfusion can lead to a higher 90-day survival rate. However, the relationship between the arterial-venous oxygen difference and the incidence of adverse events in cardiac surgery patients under CPB remains unclear. Whether increasing the arterial-venous oxygen difference during surgery can reduce the incidence of postoperative adverse events remains to be clarified. This study intends to collect intraoperative arterial blood and central venous blood samples from cardiac surgery patients undergoing CPB, and analyze the relationship between arterial-venous oxygen difference and the incidence of postoperative adverse events.

Detailed Description
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The >18 y/o patients who undergo cardiac surgery with cardiopulmonary bypass and with a preoperative additive EuroSCORE I≥ 6 are enrolled. Blood samples will be collected through arteries and central venous at the following intraoperative time points: before CPB, during CPB, after CPB, before transfusion, and after transfusion. The observation will end by hospital discharge or 28 days after surgery, whichever came first. The follow-up will continue to one year after surgery.

Official Title
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Study on the Relationship of Arterial-venous Oxygen Difference and Postoperative Complications After Cardiac Surgery.

Conditions
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Patient Blood Management, Cardiac Surgery, Transfusion

Intervention / Treatment
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* Other: No intervention


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Over 18 years old Cardiovascular surgery patients with cardiopulmonary bypass Preoperative EuroSCORE I≥6（European System for Cardiac Operative Risk Evaluation) Obtained informed consent Exclusion Criteria: Patients who cannot accept blood products Patients who refuse to accept transfusion Patients with autologous blood reserve before surgery Patients who are going to receive heart transplantation or have undergone heart transplantation Patients who have undergone ventricular assist device implantation surgery Patients who refuse to participate in this trial

Ages Eligible for Study
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Minimum Age: 18 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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Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Patients undergoing cardiac surgery with CPB<br>>18 y/o patients who undergo cardiac surgery with cardiopulmonary bypass and with a preoperative additive EuroSCORE I≥ 6 | Other: No intervention<br>* No intervention<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Composite outcome of mortality and serious morbidity (cardiac, renal, and neurological events) | Composite incidence of any one of the following events occurring during the hospitalization : (1) all-cause mortality; (2) myocardial infarction; (3) new renal failure requiring dialysis; or (4) new focal neurological deficit (stroke) | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Incidence of any independent component of the primary outcome | Incidence of any independent component of the primary outcome (all-cause mortality, myocardial infarction, new renal failure requiring dialysis, and new focal neurological deficit (stroke)) | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Blood product transfusion | Time, category, and volume of blood product transfusion | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Length of stay in ICU | Length of stay in ICU after surgery | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Total length of hospital stay after surgery | Total length of hospital stay after surgery | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Duration of mechanical ventilation after surgery | Total length of hospital stay after surgery | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Occurrence of low cardiac output after surgery | Need for two or more inotropes for 24 hours or more, intra-aortic balloon pump postoperatively or ventricular assist device | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Infection | Infection will be defined as septic shock with positive blood cultures; pneumonia defined as autopsy diagnosis or roentgenographic infiltrate and at least two of the following three criteria: fever, leukocytosis, and positive sputum culture; and/or deep sternal or leg wound infection requiring intravenous antibiotics and/or surgical debridement | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Gut infarction | confirmed by imaging, autopsy, or through surgical means | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Acute kidney injury | AKI defined by the KDIGO | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Seizures | Defined as generalized or focal tonic-clonic movements consistent with seizure; or EEG demonstrating epileptiform discharges; or diagnosis of seizures by neurologist or neurosurgeon consultation | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Delirium | Based on one of the following criteria: CAM-ICU/ CAM (even on 1 occasion) or ICDSC > 3 or more than one dose of haloperidol or similar antipsychotic drug or documented delirium by neurologist or neurosurgeon or psychiatrist consultation | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Encephalopathy | Defined as unexpected delayed awakening or severely altered mental status (unconscious despite no sedative medication for more than 5 days), or encephalopathy documented by neurologist or neurosurgeon or psychiatrist consultation | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 
| Reoperation rate | The rate of reoperation | From the start of surgery until hospital discharge or postoperative day 28, whichever comes first | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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arterial-venous oxygen difference, Patient blood management