Cerebral Energy State in Cardiac Surgery

Study Overview
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Brief Summary
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Impaired cerebral function remains an important complication of cardiopulmonary bypass (CPB) during cardiac surgery. The aim of the present study is to investigate whether the lactate to pyruvate (LP) ratio obtained by microdialysis (MD) of the cerebral venous outflow reflects a derangement of global cerebral energy state during cardiopulmonary bypass.

Detailed Description
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Patients undergoing primary, elective coronary artery bypass grafting were blindly randomized to usual range MAP (40 to 60 mmHg; n = 5) or intervention group MAP (60 to 80 mmHg; n = 5) during CPB. MD catheters were positioned in a retrograde direction in the internal jugular vein and a reference catheter was inserted into the brachial artery. The relations between LP ratio, MAP, data obtained from bi-frontal NIRS and neurological outcome measures were assessed.

Official Title
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Continuous Monitoring of Cerebral Energy State During Cardiac Surgery - A Novel Approach Utilizing Intravenous Microdialysis

Conditions
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Postoperative; Dysfunction Following Cardiac Surgery

Intervention / Treatment
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* Procedure: Microdialysis


Participation Criteria
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Eligibility Criteria
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Inclusion criteria: Elective CABG on CPB Exclusion criteria: Acute patients or reoperations Patients with epidural catheter Previous stroke Stenotic carotids Ejection fraction (EF) < 50 % Estimated per operative risk > 5%

Ages Eligible for Study
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Minimum Age: 60 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: Diagnostic
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Low mean arterial perfusion pressure<br>5 patients undergoing primary, elective coronary artery bypass grafting were randomized to usual range MAP (40 to 60 mmHg) during CPB. Microdialysis catheters were positioned in a retrograde direction in the internal jugular vein. | Procedure: Microdialysis<br>* Extracerebral MD catheters were positioned in a retrograde direction in the internal jugular vein.<br>* Other names: NIRS;|
| Experimental: High mean arterial perfusion pressure<br>5 patients undergoing primary, elective coronary artery bypass grafting were blindly randomized to intervention group MAP (60 to 80 mmHg) during CPB. Microdialysis catheters were positioned in a retrograde direction in the internal jugular vein. | Procedure: Microdialysis<br>* Extracerebral MD catheters were positioned in a retrograde direction in the internal jugular vein.<br>* Other names: NIRS;|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Extracerebral microdialysis parameters | Does the LP ratio of cerebral venous blood increase significantly during CPB indicating compromised cerebral oxidative metabolism.The analyses included the variables routinely monitored during intracerebral microdialysis: glucose, pyruvate, lactate, glutamate, glycerol and lactate to pyruvate ratio. | MD parameters were measured intraoperatively and for two hours postoperatively | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Mini mental state examination (MMSE) | Patients were assessed preoperatively and postoperatively day two after surgery | Neurological complications with in 2 days after surgery | 
| Near-infrared spectroscopy (NIRS) | Right and left frontal rSO2 values were recorded simultaneously pre- and intraoperatively and for two hours postoperatively. Cerebral desaturation was defined as a decrease in the relative rSO2 value of 20 % compared with the individual pre-induction baseline value | one day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Microdialysis, Cardiac surgery, Lactate to pyruvate ratio, Cardiopulmonary bypass, Neurological complications