This study aims to investigate the effect of the pneumatic tourniquet technique on the patients' hemodynamics; heart rate (HR), systolic blood pressure (SBP) and diastolic blood pressure (DBP).

Coronary artery bypass graft surgery (CABG) is the most common cardiac surgical procedure. Radial artery of the non-dominant hand with better ulnar collaterals is preferred over the saphenous vein because of long term patency of the radial artery. Radial artery is the preferred second or third arterial conduits for vessels with sub occlusive stenosis.

There are two techniques of radial artery harvesting; open and endoscopic techniques. Endoscopic radial artery harvesting (ERAH) is increasing and it is possible but the evidence regarding its safety is scarce. ERAH is cosmetically better than the open technique.

ERAH technique is performed after applying a tourniquet over the distal arm proximally to the elbow. Allen test will be done first and if the hand has a good blood supply through the ulnar artery, the tourniquet pressure is increased 75-100 mmHg over the systolic pressure and the tourniquet time is kept under one hour and the left radial artery will be endoscopically harvested.

During the time of tourniquet inflation, there is ischemia of the forearm with subsequent cellular ischemic changes like; cellular acidosis, cellular edema, and activation of cellular apoptosis. On deflating the tourniquet, there is reperfusion of the limb and development of ischemic / reperfusion injury with a subsequent increase of inflammatory mediators and reactive oxygen species (ROS). These changes may be associated with some hemodynamic instability that might be dangerous, especially in patients with ischemic heart disease (IHD).

Inclusion Criteria:

• Listed for CABG surgery with the use of ERAH technique.

Exclusion Criteria:

• Emergency CABG surgery.
• CABG plus any other cardiac surgery.
• The use of inopressor drugs before ERAH

Patients who are listed for CABG surgery with the use of ERAH technique at cardiothoracic and vascular surgery center (Mansoura University Hospitals, Mansoura University) are eligible for this study.

The individual participant data will be available (including data dictionaries).

Individual participant data that underlie the results reported in this article, after deidentification (text, tables, figures, and appendices) will be shared.

The data will be available immediately following publication and no end date.

The data will be shared with anyone who wishes to access the data. To achieve the aims in the approved proposal. Data will be available indefinitely at my research gate account under the name (Elsayed Abdelkarime)