Measurement of intracerebral oxygen pressure: practicalities and pitfalls.
Two probes, using different technologies, are currently available to measure tissue oxygen pressure. One of these also measures oxygen pressure, carbon dioxide pressure, pH and temperature. Research has delineated normal brain tissue oxygen pressure as 25-45 mmHg and ischemic thresholds of less than 10 mmHg that are related to ischemic injury. Oxygen pressure measures are correlated with other indicators of brain oxygenation such as jugular bulb oxygen saturation and near infrared spectroscopy, but are more reliable for detecting regional ischemic events. Oxygen pressure is correlated with local blood flow in the brain, and treatments that enhance tissue perfusion improve oxygenation.
Hoffman
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Department of Anesthesiology, University of Illinois at Chicago, Chicago, IL 60612, USA. whoffman@uic.edu