Modeling and Application of Triple Drug Response Surface Models

Demand for anesthesiologists outside the operating rooms is increasing. Surgeons, radiologists, endoscopists and other interventionists are performing procedures with greater complexity, sometimes accompanied by greater pain and therefore require some sedation. This growing need place a pivotal role on careful handling the delivered drugs. Specifically, the investigators wish to know how different classes of drugs interact in order for us to titrate the effects more precisely. Early studies used isobolograms and concentration effect curves as their tools but these methods are limited and incapable of making continuous bedside monitoring. Researchers integrated these methodologies mathematically and developed response surface models. It's becoming a very convenient tool to assess drug interactions. Drug interactions are visualized with a three dimensional graph, or a surface. Users will only need the calculated drug concentrations and a predicted loss of response probability will be given after a model is built. The process of model construction is complex and time demanding process. Our team has successfully built a dual-drug model for midazolam and alfentanil and several works have been published in renowned anesthesia journals. Dual-drug models are simple but their use is very limited. The investigators often use more than two drugs during practice and a three-drug model will be a great leap to monitor clinical pharmacodynamics. The investigators will collect vital signs, anesthestic depth (BIS=bispectral index, analgesia nociception index (ANI)), drug dosing (propofol, midazolam and alfentanil), and the MOAA/S (modified observer's assessment/alertness score) scores in patient who are receive routine general anesthesia under laryngeal mask or sedation for TEE (transesophageal echocardiography) examinations. Patient's consent will be obtained prior to enrollment. These recordings will be pooled into computer program for model construction. A novel model in the fiel