Effect of Transpulmonary Pressure Guided Ventilation on Intraoperative Right Heart Function

The purpose of this clinical trial is to determine whether different types of ventilator settings during surgery change the relationship between the pressures in the lungs and the function of the heart. In this study, patients will be randomly assigned (like flipping a coin) to receive either standard or individualized (research) lung protective ventilator settings. Before surgery, patients will be given an 8-item verbal questionnaire about any respiratory symptoms. After patients are asleep for surgery, an ultrasound probe will be inserted into the esophagus (food pipe) and stomach to examine the heart and lungs and take ultrasound pictures. The ultrasound probe is then removed. Next, a small balloon catheter (a narrow tube smaller in diameter than a pencil lead) will be placed in the esophagus, where it will be used to measure the pressures in the chest and lungs. For patients who are assigned to standard ventilator settings, the ventilator settings and pressures during surgery will be recorded. For patients assigned to individualized (research) ventilator settings, the pressures from the balloon catheter will be used to adjust the ventilator settings every 30 minutes during surgery. A second ultrasound pictures of the heart and lungs will be obtained at the point at which the patient is placed into the Trendelenburg position. At the end of surgery and before the patient is awake, the balloon catheter will be removed, the ultrasound probe will be inserted, a third set of ultrasound pictures of the heart and lungs will be obtained, and the ultrasound probe then removed. Patients will be telephoned 30 days after surgery to ask about their recovery. The 8-item respiratory symptom questionnaire will be repeated at this time.