Intraoperative Oxygen Concentration and Neurocognition After Cardiac Surgery

Study Overview
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Brief Summary
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This is a randomized, prospective controlled trial in patients undergoing cardiac surgery, specifically on-pump coronary artery bypass grafting, comparing level of administered oxygen and partial pressure of arterial oxygen in the operating room and its impact on a widely-used and validated neurocognitive score, the telephonic Montreal Cognitive Assessment (t-MoCA), throughout the hospital stay and at 1 month, 3 months, and 6 postoperatively. It is hypothesized that cardiac surgical patients who undergo normoxic conditions throughout the intraoperative period will have better neurocognitive function than those with maintenance of hyperoxia.

Official Title
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The Relationship Between Administered Oxygen Levels and Arterial Partial Oxygen Pressure to Neurocognition in Post-operative Mechanically Ventilated Cardiac Surgical Patients

Conditions
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Hyperoxia, Normoxic, Delirium

Intervention / Treatment
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* Other: Normoxic oxygenation
* Other: Hyperoxic oxygenation


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Males and females aged 65 years and older Undergoing elective or urgent on-pump Coronary Artery Bypass Graft (CABG) only Exclusion Criteria: Off-pump or any other procedure in addition to CABG Emergent procedure One-lung ventilation Non-English speaking Baseline tMoCA score <10 Preoperative inotrope use Preoperative vasopressor use Intra-aortic balloon counterpulsation Mechanical circulatory support (Intra-aortic balloon pump (IABP)/ Ventricular assisted devices (VAD)/Extracorporeal membrane oxygenation (ECMO)) Active cardiac ischemia Acute decompensated arrhythmia O2 sat < 90% on supplemental oxygen Use of continuous vasopressor or inotrope infusion medications Significant physician or nurse concern Cessation Criteria Development of significant intraoperative hemodynamic compromise as a result of cardiac surgery Oxygen desaturation <90% for > 3 min Significant physician or nurse concern

Ages Eligible for Study
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Minimum Age: 65 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: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Normoxic group<br>To standardize key aspects of ventilator support, tidal volume will be set to 6-8ml/kg and PEEP levels will be set to 0-5cm H2O, allowing flexibility for provider preference. For normoxic oxygenation FiO2 will be set at 0.35 (35%) ideally to maintain PaO2 above 70mmHg (or saturations greater than or equal to 92%), and titrated up if need be to prevent potentially injurious hypoxemia (saturations below 92%). During cardiopulmonary bypass, blended air/ oxygen mixture will be titrated to arterial blood gas analysis with maintenance of PaO2 between 100mmHg and 150mmHg. | Other: Normoxic oxygenation<br>* FiO2 set at 0.35 to maintain PaO2 > 70 mmHg or oxygen saturation greater than or equal to 92%.<br>|
| Active Comparator: Hyperoxic group<br>To standardize key aspects of ventilator support, tidal volume will be set to 6-8ml/kg and PEEP levels will be set to 0-5cm H2O, allowing flexibility for provider preference. For hyperoxic oxygenation FiO2 will be set at 1.0 (100%) throughout the intraoperative period, including cardiopulmonary bypass. | Other: Hyperoxic oxygenation<br>* FiO2 set at 1.0 throughout the procedure<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Telephonic-MoCA (t-MoCA) | t-MoCA will be performed baseline, daily starting POD#1 as well as at 1, 3 and 6 months post-operatively. In previous studies, testing through month 6, has been shown to accurately reflect more longitudinal follow-up. t-MoCA results are on a 22 point scale and will be used as a marker for cognitive function and has been validated. Blinded study staff trained in administering the assessments will collect the data. | Change from baseline tMoCA score through 6 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Confusion Assessment Method for the ICU | CAM and CAM-ICU as a marker of delirium post-operatively will be administered and measured at the same time as the t-MoCA. This is a validated test to measure delirium. There is much data to support an increased reduction in cognitive ability in patients exhibiting post-operative delirium. | Post-operative day 1 through discharge from hospital (3-5 days on average) | 
| Days of mechanical ventilation |  | Post-operative day 1 through discharge from hospital (3-5 days on average) | 
| Length of stay in hospital |  | Post-operative day 1 through discharge from hospital (3-5 days on average) | 
| Time to extubation |  | Post-operative day 1 through discharge from hospital | 
| Patient mortality |  | 30 days and 6 months post-operatively | 
| Biomarkers of oxidative stress, IL-6, IL-8 and others |  | Intraoperatively at cardiopulmonary bypass (CPB) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Hyperoxia, Delirium, Normoxic, t-MoCA