“…Russo et al demonstrated that headdown positioning was capable of increasing the venous return, enlarging left ventricular end-diastolic volume, and elevating the SV in normal and elevated IAP (21). Hirvonen et al demonstrated that the Trendelenburg position in awake and anesthetized patients increased pulmonary arterial pressures, CVP and pulmonary capillary wedge pressures, and these pressures further increased at the beginning of IAH (22). The elevated IAP influences the intrathoracic pressure by pushing the diaphragm upward, thus decreasing respiratory system compliance (23).…”