September 23, 2014 - The "area under the curve of oxygen desaturation" (AUCDesat) may provide a more sophisticated approach to monitoring blood oxygen levels during procedures using sedation, according to a study published in Anesthesia & Analgesia.
The AUCDesat provides information not only whether blood oxygenation has dropped too low--but also on the depth, duration, and rate of episodes of oxygen desaturation. The new study by Paul Niklewski, PhD, of University of Cincinnati and colleagues reports on the development of the AUCDesat as a potentially useful new approach to monitoring patient during sedation.
Four-Component Desaturation Measure Better Reflects Patient Risks
In the study, 13 Board-certified anesthesiologists reviewed a total of 204 records, including information on a wide range of physiological measures, of procedures performed in sedated patients. After review, each anesthesiologist assigned a risk score for that procedure, based on their perceptions of the patient's risk of complications related to oversedation.
The risk scores were then analyzed in depth to determine their relationship to oxygen saturation levels. Oxygen saturation is typically measured by pulse oximetry--the familiar "finger clip" test. Levels of less than 95 percent are typically defined as desaturation--meaning that the red blood cells aren't at or near their maximum oxygen-carrying capacity.
The researchers were interested in finding out how anesthesiologists' perceptions of patient risk were affected not only by the presence or absence of desaturation, but also by the duration, depth, and number of desaturation events. They also assessed the value of the AUCDesat, which incorporates all four components into a single number.
Overall, the anesthesiologists ranked arterial blood oxygen level as the most important factor in assessing patient risk, with an average rank of 4.69 out of 5. The respiratory rate was the second most important factor.
Of the oxygen saturation measures analyzed, the AUCDesat was the best predictor of the anesthesiologists' rankings--better than the mere presence of desaturation or the other individual components. Using the data, the researchers were able to define AUCDesat scores identifying groups of patients at low, medium, and high perceived risk of complications during sedation.
Sedation is essential for many types of medical procedures. But even though it has an excellent safety profile, sedation is not risk-free. Anesthesiologists play an important role in monitoring patient safety during sedation.
Since adverse clinical outcomes are rare, surrogate indicators of possible safety problems are used. Oxygen saturation is a common and important measure, reflecting the potential for harm related to low blood oxygenation.
The new study suggests that the AUCDesat, providing more complete information on the characteristics of desaturation episodes, could be a useful new tool for monitoring patient risk during procedures. "AUCDesat, given it is a single numerical variable, is an ideal endpoint for assessment of risk of adverse clinical outcomes in sedation studies," Dr Niklewski and coauthors conclude. They plan further studies to further define the role of oxygen desaturation--including how well AUCDesat corresponds to actual physiological outcomes during procedures.
Conflict of interest statement: Dr. Niklewski is also an employee of Sedasys, which developed the SEDASYS SystemTM used to measure AUCDesat in this study.
About Anesthesia & Analgesia
Anesthesia & Analgesia was founded in 1922 and was issued bi-monthly until 1980, when it became a monthly publication. A&A is the leading journal for anesthesia clinicians and researchers and includes more than 500 articles annually in all areas related to anesthesia and analgesia, such as cardiovascular anesthesiology, patient safety, anesthetic pharmacology, and pain management. The journal is published on behalf of the IARS by Lippincott Williams & Wilkins (LWW), a division of Wolters Kluwer Health.
About the IARS
The International Anesthesia Research Society is a nonpolitical, not-for-profit medical society founded in 1922 to advance and support scientific research and education related to anesthesia, and to improve patient care through basic research. The IARS contributes nearly $1 million annually to fund anesthesia research; provides a forum for anesthesiology leaders to share information and ideas; maintains a worldwide membership of more than 15,000 physicians, physician residents, and others with doctoral degrees, as well as health professionals in anesthesia related practice; sponsors the SmartTots initiative in partnership with the FDA; and publishes the monthly journal Anesthesia & Analgesia in print and online.
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