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| |  Low Brain Oxygen Saturation Before Cardiac Surgery Predicts Cognitive Dysfunction TROY, MI -- May 10, 2000 -- A 156-patient study from the Weill Medical College of Cornell University demonstrated that cardiac surgery patients with low regional brain blood oxygen saturation before their surgery, as monitored by Somanetics' INVOS(R) Cerebral Oximeter, are more likely to suffer post-operative frontal lobe and cognitive dysfunction after their surgery than patients with higher brain oxygen saturation before their surgery, announced Somanetics Corporation. The study also demonstrated that low regional brain blood oxygen saturation before cardiac surgery is associated with prolonged intensive care unit and hospital stays. The study results were presented today by Fun-Sun Yao, M.D., professor of anesthesia, Cornell University, at the Society of Cardiovascular Anesthesiologists' annual meeting in Orlando. The cardiac surgery patients were monitored with Somanetics' INVOS Cerebral Oximeter, the only commercially-available patient monitoring system which noninvasively and continuously monitors changes in the regional blood oxygen saturation in the adult brain. The Cerebral Oximeter provides information by noninvasively transmitting and detecting visible and near- infrared light through SomaSensors(R), single-use sensors that are placed on both sides of a patient's forehead. Use of the patient monitoring system can help medical professionals monitor changes in regional brain blood oxygen saturation and take corrective action. Such action can potentially prevent or reduce neurological injuries related to surgery and in other critical care situations and reduce the associated cost of care. "Previously, we reported that low regional brain blood oxygen saturation during surgery is associated with frontal lobe injury after cardiac surgery, so we believe that maintaining brain oxygen saturation at adequate levels is vitally important to the patient's health. And, we evaluated the relationship between brain blood oxygen saturation levels and lengths of ICU and hospital stay following cardiac surgery, and discovered that patients with the lowest regional brain oxygen saturation during surgery, of less than 45 as monitored by the INVOS Cerebral Oximeter, stayed in the ICU 2.8 days longer and in the hospital 3.1 days longer on average, than those whose brain oxygen did not fall below this threshold," said Dr. Yao. The latest study demonstrated that patients with the lowest baseline oxygen saturation levels, under 50 before surgery as monitored by the INVOS Cerebral Oximeter, had statistically significantly longer ICU and hospital stays than those with brain oxygen saturation levels over 50 pre-operatively (p<0.001). "These low pre-op brain oxygen levels may help to identify patients who cannot tolerate even moderate desaturation and who are at higher risk to go on to exhibit frontal lobe and cognitive dysfunction, resulting in longer intensive care unit and hospital stays. Therefore, we believe special attention should be paid to maintain adequate cerebral oxygen saturation during cardiac surgery in patients with low pre-operative cerebral oxygen saturation," said Dr. Yao. An associated study of 137 patients undergoing cardiac surgery demonstrated correlations between low oxygen saturation levels during surgery and the number of times oxygen saturation levels were low, and the incidence of severe adverse neurologic outcome. In this study, nine (6.6 percent) of the patients sustained adverse neurologic events including coma or delirium, for more than 24 hours, or frank stroke. The patients suffering neurologic injury had significantly lower values of the lowest oxygen saturation during surgery (p=0.021) and more significant desaturation events below 30 (p=0.04), than patients without adverse neurologic outcome. "Cerebral oxygen desaturation was associated with neurologic complications following the cardiac surgery. Therefore, it is prudent to monitor and maintain adequate cerebral oxygen saturation during cardiac surgery," said Dr. Yao. Related Link: Somanetics Corporation.
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