Effects of Electrical Impedance Tomography-Guided Positive End-Expiratory Pressure on Postoperative Cardiopulmonary Exercise Capacity in Elderly Patients: Study Protocol for a Randomized Controlled Trial

BACKGROUND Mechanical ventilation can lead to cardiopulmonary complications in elderly patients undergoing abdominal surgery plus general anesthesia. The cardiopulmonary exercise test (CPET) is a dynamic and noninvasive evaluation method for assessing the cardiopulmonary system function under rest and stress. Positive end-expiratory pressure (PEEP) titration guided by electrical impedance tomography (EIT) can individualize lung protection strategies and may be beneficial in postoperative cardiopulmonary exercise capacity for these patients. MATERIAL AND METHODS This study is a prospective, single-center, randomized, and controlled trail that will include 80 elderly patients scheduled for major abdominal surgery. The patients will be divided into 2 groups: (1) intervention group: using individualized PEEP ventilation; and (2) control group: using fixed PEEP ventilation (3-5 cmH₂O). RESULTS The primary outcome is the change of postoperative cardiopulmonary exercise capacity. CONCLUSIONS In this study, we will evaluate if EIT-guided PEEP titration can improve postoperative cardiopulmonary exercise capacity and reduce postoperative complications in elderly patients undergoing open abdominal surgery plus general anesthesia. If the result is in accordance with the hypothesis, it would provide evidence to aid the perioperative management for these patients.