Transcutaneous-Arterial Carbon Dioxide and Microcirculatory Dysfunction

Evaluation of the microcirculation is currently limited. Continual assessment of the tissue carbon dioxide-arterial carbon dioxide (PtC02-aCO2) offers a new, novel and noninvasive method of determining the state of the microcirculation. The investigators will apply two non-invasive devices, the Braedius sidesteam darkfield microscopy (SDF) microscopy device to the sublingual circulation and the transcutaneous PtC02 probe to the forehead in subjects undergoing cardiac surgery with cardiopulmonary bypass. The PtC02-aCO2 gradient will be determined and correlated with the videomicroscopic images of the sublingual microcirculation. Thereafter the incidence of postoperative organ failure and acute kidney injury will be determined and correlated with PtC02-arterial CO2 gradient and videomicroscopic images. Data will be analyzed by standard descriptive statistical methods.