This is a proof of concept/feasibility study designed to test the primary hypothesis that use of the ITPR will result in decreased intracranial pressure and increased cerebral perfusion pressure. The effect of the ITPR on secondary indicators of cardiac performance will also be examined. These include but are not limited estimates of ventricular end diastolic volume and pressure (LVEDV/P), ejection fraction (EF), left ventricular end systolic volume and pressure (LVESV/P), fractional area change (FAC), all of which will be assessed by transthoracic echocardiography (TTE) or transesophageal echocardiography (TEE).