Hemoglobin Saturation in Superior Vena Cava and Right Atrium

The aim of the study is to compare oxygen saturation of blood samples collected from the superior vena cava, the right atrium, and the pulmonary artery. A secondary target was to assess whether positioning the tip of central venous catheters in the right atrium causes more arrhythmias than positioning it in the superior vena cava. The study is carried out in patients that undergo central venous and pulmonary artery catheterization for surgical coronary revascularization. In the interventional group (atrium, A), the tip of the central venous catheter (CVC) is placed in the right atrium; in the control group (control, C), the tip is placed in the superior vena cava. In both groups, CVC position is confirmed with transesophageal echocardiography (TEE). At fixed times during surgery and in the following 72 hours, heparinized blood samples are collected from the proximal and distal CVC lumens and from the distal lumen of the pulmonary catheter (PC) and oxygen saturation is measured by an oximeter. Besides, mechanical and electrical complications potentially influenced by CVC position are registered. 1. The primary aim of the study will be achieved by performing the following analysis on values from CVC proximal and distal lumens: 1. a Bland Altman analysis between proximal and distal oxygen saturation in group A, in order to evaluate if the two measures are equivalent 2. a comparison of the difference between proximal and distal oxygen saturation in groups A and C in order to rule out random errors 2. In addition: 1. differences in oxygen saturation between proximal or distal CVC and distal PC will be compared in order to evaluate whether distal saturation is more indicative of mixed venous saturation 2. differences between proximal and distal oxygen saturation will be correlated with cardiac index and PCWP to investigate if low cardiac output and hypovolemia increase differences 3. The secondary aim of the study will be achieved by comparing the incidenc