The Application and Validation of Triple Drug Response Surface Models on Density Spectral Array in Clinical Anesthesia

Precision anesthesia is the current trend. The benefits including faster recovery, earlier return to normal activity, increased patient satisfaction and shorter length of stay. In order to avoid unnecessarily deep or too light anesthesia, processed electroencephalogram (EEG) monitors are applied for accurate assessment of the depth of anesthesia (DoA). Bispectral index (BIS) and PSI monitor are among the most widely used. Recently, density spectral array (DSA) has been developed to facilitate the interpretation of EEG signals. Real-time DSA EEG monitoring helps in detecting even subtle changes in the depth of anesthesia and provides more comprehensive information then simple digits. An emerging field of pharmacodynamics in anesthesia is the response surface models. They describe the interaction of different anesthetics during sedation or anesthesia. Our research team has developed the first comprehensive two-drug response surface models for midazolam and alfentanil during gastrointestinal procedural sedations. However, adequate anesthesia is often achieved with multiple drugs. Two-drug models thus have limited applications. We aim to extend the models into three-drug interactions where it can be used for a broader range of clinical scenarios. The main goal of the study is to establish and validate the three-drug response surface model by collecting and analyzing EEG parameters (BIS or PSI values, DSA, SEF95 (95% spectral edge frequency) and MF (Median frequency) ) from 60 patients undergoing general anesthesia for thoracic surgeries. We aim to establish the models that help anesthesiologist to achieve rapid emergence, appropriate analgesia, adequate DoA, and patient safety. The secondary aim is to apply this model to provide a guideline for drug dosage adjustment and improve the quality of anesthesia.