Microcirculation During Extracorporeal Circulation

Overview

Digestive tract is supposed to be the motor of multiple organ failure. In ICU patients, mesenteric ischemia appears even when macrocirculatory parameters are controlled especially in our experience in patients coming in ICU after a cardiac surgery. The investigators suppose that microcirculatory failure develops and results in suffering of non major organs like muscle, skin and digestive tracts. In this study the investigators monitor digestive tract with plasmatic IFABP dosage and microcirculatory circulation with NIRS during a VOT and plasma glycocalyx measurements. The population is composed by patients having coronary artery bypass during cardiopulmonary bypass. The first aim of this study is to show that digestive tract is suffering with the use of extracorporeal circulation and will be assessed with Plasmatic Intestinal Fatty Acid Binding Protein when IFABP will more than 300 pg/ml ; and with citrullinemia when citrullinemia will be less than 20 micromol/L. The second aim is to investigate link between endothelial dysfunction and digestive tract. Endothelial dysfunction is assessed with tissular oxygen saturation before, during and after a vascular occlusion test of 3 minutes (measurement of basal value, desaturation curve, resaturation curve and hyperemic response by measurement of area under curve). Endothelial glycocalyx and NO pathway will be investigate (see under) Our objective is to enroll 100 patients. The same study will be done in a group of patients who benefit from coronary artery bypass without extracorporeal circulation to see the effects of extracorporeal circulation support.

Population study is patients who benefit from coronary artery bypass grafting under extracorporeal circulation support during intervention. Extracorporeal circulation result in SIRS. We aim to study digestive tract during this intervention. There are 5 times of measurements : under stable hemodynamic conditions and after beginning of anesthesia, just at the end of extracorporeal circulation, about 15 minutes following aortic unclamping and at the end of the Protamine perfusion, about 90 minutes after the end of extracorporeal circulation and the last time measurement 24 hours later. At each time measurement are done : blood samples to measure Intestinal Fatty Acid Binding Protein, Citrullinemia that are markers for digestive suffering ; blood samples for measurement of Syndecan 1 CD 138 and Heparan Sulfate, two markers of shedding of the endothelial glycocalyx; blood samples for measurement of NOx and GMPc to assess the NO pathway ; measurement of tissular oxygen saturation with a NIRS probe, before, during and after a vascular occlusion test of 3 minutes. Blood samples for hemoglobin, platelets, coagulation evaluation, urea, creatininemia, liver enzymes and pancreatic enzymes will be done at each time. The vascular occlusion test is done the day before the surgery when patient is awake without any exercise. This is a reference measurement.