Relation Between Mixed Venous Oxygen Saturation and Cerebral Oxygen Saturation Measured by Absolute and Relative Near-infrared Spectroscopy During Off-pump Coronary Artery Bypass Grafting.

University Hospital, Ghent42 enrolled

Overview

In this clinical study the investigators compared mixed venous oxygen saturation (SmvO2) with relative and absolute cerebral oxygen saturation (rScO2) measurements. They hypothesized that previously reported contradictory results regarding the equivalence of SmvO2 and rScO2 might be related to time delay issues and to the measurement technology. 42 consenting patients undergoing elective off-pump coronary artery bypass grafting were included. 4 disposable oxygenation sensors were applied bilaterally on the patient's forehead for continuous, non-invasive registration of rScO2. The sensors of one monitor were placed just above the eyebrows, and the sensors of the other monitor were placed just above the former sensors. The sensors placement was determined at random by a computerized randomization list. SmvO2 was measured continuously via a pulmonary artery catheter. All variables were recorded continuously. The study ended at the end of the operation.

Study Type

OBSERVATIONAL

Enrollment

Conditions

Elective Off-pump Coronary Artery Bypass Grafting

Interventions

Relative and absolute cerebral oxygen saturation (rScO2) measurements.

Eligibility

Sex: ALLMin age: 25 YearsMax age: 100 Years

Medical Language ↔ Plain English

Inclusion Criteria: * Patients undergoing elective off-pump coronary artery bypass grafting for at least 3-vessel coronary artery disease were eligible. Exclusion Criteria: * Patients with arteriovenous shunts, intracardiac shunts, a previous history of cerebrovascular accident, or stenosis of the internal carotid artery of \> 60% were excluded.

Outcomes

Primary Outcomes

Correlation and time delay between mixed venous and cerebral oxygen saturation during off-pump coronary artery bypass grafting.

Mixed venous oxygen saturation was measured continuously via a pulmonary artery catheter. Cerebral oxygen saturation was measured with near-infrared spectroscopy; the INVOS monitor to obtain relative measurements, and the Foresight monitor to obtain absolute data.

Time frame: 4 hours during an operation of average 5 hours (during off-pump coronary artery bypass grafting).

Secondary Outcomes

The response of cerebral oxygen saturation to major haemodynamic disturbances.

Percentage difference between the cerebral oxygen saturation value just before heart retraction and the value at the different time moments.

Time frame: 2 hours after start of operation (during placement of deep pericardial stitches).