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 the journal 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.
In the study, 13 Board-certified anaesthesiologists reviewed a total of 204 records, including information on a wide range of physiological measures, of procedures performed in sedated patients. After review, each anaesthesiologist assigned a risk score for that procedure, based on their perceptions of the patient’s risk of complications related to over-sedation. The risk scores were then analysed in depth to determine their relationship to oxygen saturation levels.
The researchers were interested in finding out how anaesthesiologists’ 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 4 components into a single number.
Overall, the anaesthesiologists 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 analysed, the AUCDesat was the best predictor of the anaesthesiologists’ 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. Anaesthesiologists 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 current 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,” wrote Paul Niklewski, PhD, University of Cincinnati, Cincinnati, Ohio, and colleagues.
They plan further studies to further define the role of oxygen desaturation, including how well AUCDesat corresponds to actual physiological outcomes during procedures.