1994 Fiscal Year Final Research Report Summary
Development of a closed loop control system for total intravenous anesthesia
| Project/Area Number |
04454387
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| Research Category |
Grant-in-Aid for General Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Research Field |
麻酔学
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| Research Institution | Hamamatsu University School of Medicine |
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Principal Investigator |
IKEDA Kazuyuki Hamamatsu University School of Medicine Professor, 医学部, 教授 (00010215)
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| Co-Investigator(Kenkyū-buntansha) |
MORITA Koji Hamamatsu University School of Medicine Research Associate, 医学部, 助手 (30115513)
DOI Matsuyuki Hamamatsu University School of Medicine Assistant Professor, 医学部, 講師 (10155616)
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| Project Period (FY) |
1992 – 1994
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| Keywords | Total Intravenous Anesthesia / Computer Control / Simulation |
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| Research Abstract |
The purpose of this study was to develop a closed loop control system for total intravenous anesthesia. This system was divided into four subsystems as follows ;
(1) Subsystem to quantify anesthesia depth
To quantify anesthesia depth, a real time spectral analyzer of the heart rate variability and a computer program to analyze power spectra of electroencephalograph were developed. A precise method for carbon dioxide tension measurement in expiratory gas was also studied.
(2) Subsystem to estimate concentrations of anesthetic agents in blood within brief duration
Concentrations of anesthetic agents ; midazolam, thiopental, pentazocine and vecuronium, were estimated using high performace liquid chromatography. An interval between blood sampling and estimation of blood concentration was less than twenty minutes.
(3) Subsystem to simulate concentrations of anesthetic agents in blood and effect sites
A computer program to simulate anesthetic agents in blood and effect sites was studied. To calculate the concentrations, the Euler method or the Runge-Kutta-Gill method was applied. Influences of aging on pharmacokinetics and pharmacodynamics of midazolam were studied to improve the precision of the simulation.
(4) Subsystem to control syringe pumps using a computer
A computer program to simultaneously control three syringe pumps was studied. This system enabled estimation of the time required for reaching the presetting concentrations of the agents in blood.
Muscle relaxants were able to be infused by a closed loop control method using a neuromuscular junction monitor. Since methods for estimation of effects of analgesics and hypnotics have not been completed, it is impossible to infuse those agents using a closed loop control method. Analgesics and hypnotics were infused by an open loop control method according to values of concentrations of the agents simulated. The differences between actual and simulated concentrations were corrected by the values measured in blood.
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