The purpose of this study is to investigate the impact of supraphysiologic oxygen (hyperoxia) on myocardial function in anaesthetized patients with coronary artery disease.
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.
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
SINGLE
Enrollment
106
Two FIO2 settings during stable general anaesthesia resulting in normoxaemic and hyperoxic arterial oxygen partial pressures.
Bern University Hospital, Inselspital
Bern, Switzerland
Difference in myocardial peak strain between oxygen levels
Percent (%), a measure of systolic function (shortening and thickening) of the myocardium
Time frame: Through study completion, within 1hour post-induction
Difference in myocardial time to peak strain between oxygen levels
Milliseconds (ms)
Time frame: Through study completion, within 1hour post-induction
Difference in myocardial strain rate between oxygen levels
Change in strain over time (/second)
Time frame: Through study completion, within 1hour post-induction
Difference in myocardial strain rate ratio between oxygen levels
Change in E/A ratio
Time frame: Through study completion, within 1hour post-induction
Difference in myocardial displacement between oxygen levels
Millimeters (mm)
Time frame: Through study completion, within 1hour post-induction
Difference in myocardial time to peak displacement between oxygen levels
Milliseconds (ms)
Time frame: Through study completion, within 1hour post-induction
Difference in myocardial velocities between oxygen levels
Change in displacement over time (millimeters/second)
Time frame: Through study completion, within 1hour post-induction
Difference in myocardial velocity ratio between oxygen levels
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Change in E/A ratio
Time frame: Through study completion, within 1hour post-induction
Difference in peak twist
Degrees (°)
Time frame: Through study completion, within 1hour post-induction
Difference in peak torsion
Degrees/centimeter (°/cm)
Time frame: Through study completion, within 1hour post-induction
Difference in ejection fraction (EF)
Percent (%)
Time frame: Through study completion, within 1hour post-induction
Difference in chamber volumes
Millilitres (ml)
Time frame: Through study completion, within 1hour post-induction