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ℒ1-adaptive methods for control of patient response to anesthesia

ℒ1-adaptive methods for control of patient response to anesthesia,M. Ralph,C. L. Beck,M. Bloom

ℒ1-adaptive methods for control of patient response to anesthesia  
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In this paper, we discuss the first application of recently developed L1-adaptive control methods for closed- loop control of anesthesia delivery during surgery. Our initial objective, described herein, is to design controllers that are robust to inter-patient variability, such that patients follow a prespecified Bispectral Index profile. The controllers are designed from identification-based models constructed from clinical trial data. I. INTRODUCTION During surgery, the anesthesiologist constantly monitors and adjusts the delivery of anesthesia to the patient in an attempt to maintain a desired level of sedation, analgesia and muscle relaxation. At the same time, the anesthesiologist maintains ventilation parameters and monitors cardiovascular and respiratory functions Additionally, intra-operative blood samples are often taken and used to observe gas concentra- tions, blood-sugar levels, electrolyte concentrations and co- agulation parameters. In short, the anesthesiologist performs an extremely complex role, namely, that of a multivariable feedback controller. A common long term research goal in this area is thus to incorporate partially automated anesthesia delivery into the process, allowing the anesthesiologist to concentrate on urgent safety-critical events that arise during surgery. In order to implement model-based feedback control of anesthesia delivery, two primary needs are (1) adequate and appropriate means of sensing the patient's level of sedation, analgesia and muscle relaxation, and (2) mathematical mod- els capturing the patient response to anesthetic agents. Over the past two decades, the bispectral index (BIS), a statistical index based on phase and frequency relations between the component frequencies in the electroencephalograph (EEG) recordings, has found significant acceptance as a measure of sedation level (see (13), (34), (14) and the references therein). The adequacy and extent of muscle relaxation or neuromus- cular blockade can be evaluated effectively using different modes of electrical stimulation ((20), (28)). Whereas the means and methods for establishing and monitoring adequate sedation and NMB levels are by now fairly well-accepted, there is no standardized or generally accepted method for
Published in 2011.
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