Myocardial Strain Analysis in Anaesthetized Coronary Artery Disease Patients During Hyperoxia and Normoxaemia

Study Overview
=================
Brief Summary
-----------------
The purpose of this study is to investigate the impact of supraphysiologic oxygen (hyperoxia) on myocardial function in anaesthetized patients with coronary artery disease.

Detailed Description
-----------------
Up to 106 patients with coronary artery disease undergoing elective coronary artery bypass graft (CABG) surgery will be recruited to undergo this single visit study. In the timeframe shortly after the induction of anaesthesia and prior to the start of surgery, myocardial strain as a marker of cardiac function will be measured by transesophageal echocardiography (TEE). Echocardiography measurements will be acquired at two different oxygen states for each patient. The fraction of inspired oxygen (FiO2) will be adjusted to reach a normoxaemic state (FiO2=0.3) and a hyperoxic state (FiO2=0.8). Patients will be randomized to which oxygen level is investigated first. Thereafter, the study intervention is completed and anaesthesia and surgery will be performed as planned by the treating team. Echocardiography images will be analyzed in a blinded manner for cardiac function and systolic and diastolic strain parameters. The results will help anaesthesiologists to better weigh risks and benefits when selecting an inspired oxygen fraction in such patients, and will help to evaluate hyperoxia as a risk factor for myocardial injury.

Official Title
-----------------
Myocardial Strain Analysis in Patients With Coronary Artery Disease at Hyperoxia and Normoxaemia Prior to Coronary Artery Bypass Graft Surgery - a Randomized Crossover Study

Conditions
-----------------
Coronary Artery Disease, Anesthesia

Intervention / Treatment
-----------------
* Drug: Oxygen


Participation Criteria
=================
Eligibility Criteria
-----------------
Inclusion Criteria: Elective CABG surgery (with or without other cardiac surgery) Ability to give and sign informed consent Age >18 years. Exclusion Criteria: Absolute contraindication for TEE Emergency surgery, including but not limited to patients with instable CAD: ST- and Non-ST-elevation myocardial infarction (STEMI, NSTEMI) and instable angina (instable AP) Atrial fibrillation or significant arrhythmia Pacemaker, CRT, left bundle branch block Severe-grade valvular disease Pericardial disease Previous cardiac or thoracic aortic surgery Previous chest radiation therapy or cardiotoxic or bleomycin chemotherapy Severe pulmonary hypertension, cor-pulmonale, or right ventricular dysfunction, i.e., where high FIO2 might reduce pulmonary vascular resistance and right ventricular afterload Patients where study explanation and informed consent cannot been performed/obtained at the latest on the day before scheduled surgery Females of child-bearing potential

Ages Eligible for Study
-----------------
Minimum Age: 18 Years

Sexes Eligible for Study
-----------------
All

Accepts Healthy Volunteers
-----------------
No

Study Plan
=================
How is the study designed?
-----------------

Design Details

Primary Purpose: Other
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Other: Normoxaemia First<br>Patients will undergo TEE imaging at normoxaemia (FiO2=0.3) first, and hyperoxia (FiO2=0.8) will be targeted second. | Drug: Oxygen<br>* Two FIO2 settings during stable general anaesthesia resulting in normoxaemic and hyperoxic arterial oxygen partial pressures.<br>* Other names: Medical gas;|
| Other: Hyperoxia First<br>Patients will undergo TEE imaging at hyperoxia (FiO2=0.8) first, and normoxaemia (FiO2=0.3) will be targeted second. | Drug: Oxygen<br>* Two FIO2 settings during stable general anaesthesia resulting in normoxaemic and hyperoxic arterial oxygen partial pressures.<br>* Other names: Medical gas;|

What is the study measuring?
-----------------
Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in myocardial peak strain between oxygen levels | Percent (%), a measure of systolic function (shortening and thickening) of the myocardium | Through study completion, within 1hour post-induction | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Difference in myocardial time to peak strain between oxygen levels | Milliseconds (ms) | Through study completion, within 1hour post-induction | 
| Difference in myocardial strain rate between oxygen levels | Change in strain over time (/second) | Through study completion, within 1hour post-induction | 
| Difference in myocardial strain rate ratio between oxygen levels | Change in E/A ratio | Through study completion, within 1hour post-induction | 
| Difference in myocardial displacement between oxygen levels | Millimeters (mm) | Through study completion, within 1hour post-induction | 
| Difference in myocardial time to peak displacement between oxygen levels | Milliseconds (ms) | Through study completion, within 1hour post-induction | 
| Difference in myocardial velocities between oxygen levels | Change in displacement over time (millimeters/second) | Through study completion, within 1hour post-induction | 
| Difference in myocardial velocity ratio between oxygen levels | Change in E/A ratio | Through study completion, within 1hour post-induction | 
| Difference in peak twist | Degrees (°) | Through study completion, within 1hour post-induction | 
| Difference in peak torsion | Degrees/centimeter (°/cm) | Through study completion, within 1hour post-induction | 
| Difference in ejection fraction (EF) | Percent (%) | Through study completion, within 1hour post-induction | 
| Difference in chamber volumes | Millilitres (ml) | Through study completion, within 1hour post-induction | 

 Terms related to the study
=================
Keywords Provided by Centre Hospitalier Valida
-----------------
Myocardial Deformation, CABG, Normoxaemia, Coronary artery disease, Transesophageal Echocardiography (TEE), Hyperoxia, Strain, Anaesthesia