IRB-HSR# 14296 The Use of the Intrathoracic Pressure Regulator (ITPR) to Improve Systemic Blood Pressure in Patient Undergoing CABG Surgery

Briefly, after the induction of anesthesia and the placement of TEE, hemodynamic variables (pulmonary and systemic blood pressure, central and pulmonary venous pressure, cardiac output, calculated SVR, etc.) will be collected. In addition, left ventricular performance (including estimates of LVEDV, LVESV, EF, FAC, etc.) will be assessed using TEE. Once these baseline data are recorded, the ITPR will be inserted in the anesthesia circuit and activated to provide -9 mmHg ETP. After the ITPR has been active for at least two minutes, the same hemodynamic and TEE data obtained above will be gathered. After the data is recorded, the ITPR will be disconnected and no further interventions will be made. In addition to the hemodynamic and echocardiographic data described above, an arterial blood gas will be obtained from the pre-existing radial artery catheter during the on- and off- states.

Finally, the TEE examination will be recorded on videotape or DVD. A second echocardiographer, blinded to patient and ITPR status will review each echocardiogram and assess left ventricular performance. In addition to the data derived at the time of testing, the second echocardiographer will assess, if possible, changes in EF using Simpson's method of disks is used to calculate the LV volume.

This is a proof of concept/feasibility study designed to test the primary hypothesis that use of the ITPR will result in increased systemic blood pressure and cardiac output in patients undergoing CABG surgery. The effect of the ITPR on other secondary indicators of cardiac performance will also be examined. These include but are not limited to left ventricular end diastolic volume (LVEDV), ejection fraction (EF), left ventricular end systolic volume (LVESV), and fractional area change (FAC) as assessed by echocardiography, pulmonary artery pressure, and calculated systemic vascular resistance (SVR).