Participants undergoing Off-CABG will be randomized 1:1 to one of the following groups:

• treatment with CirQlator TM Intrathoracic Pressure Regulator (ITPR)
• no ITPR .Anesthesia will be standardized for both groups. The groups will be compared based on the differences in vasopressor use, the number and amount (in milliliters) of intravenous fluid boluses required and hemodynamic changes noted, including systemic blood pressure, pulmonary arterial pressure, pulse pressure, heart rate (recorded most reliably from the arterial line), cardiac output (CO), cardiac index (CI), mixed venous oxygen saturation (SVO2), SVR, pulmonary vascular resistance (PVR), and stroke volume (SV).

Specifically, we will compare the groups based on the mean number of intravenous fluid boluses, mean amount of norepinephrine and epinephrine infusion required, the number of recorded systolic blood pressures < 90 mmHg, and number of CI < 2.0 L/min/m2. We will also compare the number of times the surgeon must reposition the heart for treatment of hypotension, and ascertain whether the ITPR will help patients tolerate the cardiac displacement better, thus decreasing the time required to complete the bypass graft anastamosis. ECG will be monitored intraoperatively for signs of ischemia including ST changes, greater than 1mm depression or elevation. Postoperatively, we will record the need for and amount of diuretic required.

We hypothesize that in this pilot study, patients undergoing OPCAB who are treated with CirQlator TM Intrathoracic Pressure Regulator (ITPR) will achieve higher blood pressures and cardiac output and require less intravenous fluids and vasopressor administration than patients managed without the ITPR.

A new method to improve cardiac performance during OPCAB surgery is needed in order to avoid the administration of large amounts of intravenous volume, reduce vasopressor medications, and thus improve cardiac function and reduce the need for postoperative diuresis.

The CirQlator TM Intrathoracic Pressure Regulator (ITPR) is an FDA-approved device intended to increase circulation and blood pressure in hypovolemic and cardiogenic shock. The device is inserted within a standard respiratory circuit between the patient and the ventilator. It functions by decreasing intrathoracic pressure during the expiratory phase to subatmospheric levels after each positive pressure ventilation. The decrease in intrathoracic pressure creates a vacuum within the thorax relative to the rest of the body thereby enhancing blood return to the heart and consequently increasing cardiac output and blood pressure. Activation of the device is also accompanied by a decrease in systemic vascular resistance (SVR). The end result is a device that simultaneously improves cardiac output by increasing preload and decreasing systemic vascular resistance (SVR) while increasing coronary perfusion pressure by increasing blood pressure and decreasing left ventricular end systolic pressure and volume (LVESP/LVESV).7-14

Inclusion Criteria:

• patients presenting for elective off-pump CABG age 18 years of age and older informed consent has been obtained

Exclusion Criteria:

• Patients with planned on pump CABG patients requiring IABP or VAD pre-operatively emergent CABG pneumothorax hemothorax uncontrolled bleeding uncontrolled hypertension defined as SBP > 180 mmHg at the time of surgery