Non-invasive Measurement of Regional Intracerebral Tissue Oxygenation in Elective Cardiac Surgeries

Overview

Patients after cardiac surgical operations often exhibit neuropsychological complications. In particular, the post-operative delirium is associated with a significantly increased morbidity and mortality. Intracerebral microembolization in addition to inadequate cerebral perfusion during surgery was verified as the main cause of this. The aim of the study is to demonstrate a correlation between intraoperative low measured cerebral oxygen levels and a loss neurological outcome, especially the development of postoperative delirium, using non-invasive cerebral oximetry (RSO2).

Before the operation, the parameters required for the collection of the EURO-scores are recorded, allowing an assessment of perioperative risk (age, gender, type of planned surgery, concomitant diseases). After the patient arrives in the operating room the required electrodes to measure the intracerebral oxygenation are stuck bitemporal on the patient´s head. The measurement of oxygenation begins before induction of anaesthesia (while the patient is still awake) and will continue until 24 h postoperatively. The measurement of cerebral oxygenation is not intended to serve as a replacement for the collection of routine peripheral oxygen saturation, but will be performed additionally.Therefore the anaesthesiological management depends primarily on the peripheral oxygen saturation and arterial blood gases according to our clinical routine. If, however, intracerebral oxygenation shows an ominous decline, this change can be corrected by targeted measures very early (such as increasing the inspiratory oxygen concentration). At the specified test points following additional parameters are determined: Mean arterial blood pressure, central venous blood pressure, cardiac output, serum lactate, venous oxygen saturation, arterial blood gas analysis, fluid balance. These parameters are collected as part of a routine cardiac surgery. To measure these parameters no additional punctuation or blood draws are therefore necessary. To determine the cytokines IL-6 and IL-10, procalcitonin (PCT) and the S-100 protein, however, it is necessary to take 5ml blood to the respective measuring points from an already existing venous access. In the ICU the collection of the above mentioned parameters occurs at admission, after 6h and 12h, and on the morning of the first postoperative day (and possibly on further ICU-treatment-days). Additionally, each 12 h after surgery, the SOFA and the CAM-ICU-Score are recorded. An already before surgery performed CAM-ICU questionnaire serves as a direct comparison with the post-operative acquired CAM-ICU score. In case the patient is still be ventilated, the test cannot be performed and will be documented correspondingly. The treatment, monitoring of vital signs including intermittent blood gas analysis and other diagnostic measures (clinical chemistry, radiology, etc.) corresponds to the standard surgical procedure for heart surgery of the University Hospital Aachen.