Cerebral oximetry provides new way to identify patient risk levels prior to cardiac surgery

Covidien (NYSE: COV), a leading global provider of healthcare products and recognized innovator in mechanical ventilation and respiratory care devices, today announced that its INVOS^™ Cerebral/Somatic Oximeter can provide a simple, noninvasive way to help cardiac surgeons assess patients at risk for poor outcomes prior to surgery.

The new evidence, published in Anesthesiology, showed that INVOS System cerebral regional oxygen saturation (rSO₂*) values, which reflect brain oxygenation, measured prior to cardiac surgery, were independent predictors of 30-day and one-year morbidity and mortality. This is the first adult study to link decreased preoperative cerebral rSO₂ with postoperative morbidity and mortality.

“Our finding suggests that low, presurgical cerebral rSO₂ might serve as a refined physiological marker for preoperative risk stratification in cardiac patients,” said lead investigator Matthias Heringlake, M.D., Universitaet zu Luebeck, Germany. “This enhanced assessment may also enable physicians to proactively consider adding or tailoring care therapies per patient.”

The study, published in the January 2011 issue of Anesthesiology, assessed cerebral rSO₂ readings from the INVOS System in 1,178 adult patients about to undergo on-pump cardiac surgery. The analysis showed that baseline cerebral rSO₂ values ≤50% were independent predictors of 30-day and one-year morbidity and mortality.

The study also showed a statistically significant correlation between cerebral rSO₂ values and traditional measures of cardiopulmonary function such as left ventricular ejection fraction, pro-B natriuretic peptide and kidney filtration rate, among others.

“Consistent with these new findings, earlier studies showed that rSO₂ not only reflects cerebral oxygenation, but also a patient’s overall cardiopulmonary function and systemic oxygen needs,” added John M. Murkin, M.D., F.R.C.P.C., of the Schulich School of Medicine at the University of Western Ontario, whose earlier INVOS System trial showed a connection between adequate rSO₂ and improved patient outcomes. “If non-cardiac researchers confirm similar benefits of  cerebral rSO₂ monitoring, then it could be employed as a simple, sensitive and noninvasive way to enhance the preoperative risk assessment of non-cardiac patients as well.”

“This large clinical study further augments the clinical value of cerebral oximetry utilizing the INVOS System,” said Scott Kelley, M.D., Vice President, Medical Affairs, Respiratory and Monitoring Solutions, Covidien. “To date, the INVOS System is backed by more than 600 peer-reviewed articles reporting a variety of clinical benefits that enhance decision-making, rapid response, patient safety and clinical outcomes.”

Other recent research found that cerebral rSO₂ monitoring provides a first alert to changes in oxygenation that could potentially lead to an adverse patient outcome. Cerebral oximetry data, such as that from the INVOS System, were registered from January 2008 through December 2009 in the Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database, which is the gold standard for specialty outcomes databases. Initial findings were released in July 2010 and showed that in nearly one in four (23%) cardiac surgery procedures (n=36,548) “cerebral oximetry provided the first indication of a technical problem or physiologic change that could potentially lead to an adverse patient outcome.”²

“Oxygen deficiencies that lead to neurological injury or other complications often have no initial outward signs; they can brew silently and go undetected until damage has already been done,” Dr. Kelley continued. “Use of preoperative rSO₂ could augment anesthesiologists’ already robust practices for vigilance and patient safety.”

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