The response of arterial pressure to halothane: A systems analysis

Nt, Smith; Ho, Schwede

doi:10.1007/bf02474111

Cited by 23 publications

(2 citation statements)

References 2 publications

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“…Smith and Schwede (25) were among the first to employ more effective control system analysis methods to the problem of anesthetic control, using the mean arterial blood pressure (MAP) as a measure of the effect of the anesthetic. They first measured the dynamics of the response of the MAP to the anesthetic halothane, using sine wave inputs.…”

Section: Introductionmentioning

confidence: 99%

Automatic control of anesthesia using two feedback variables

1987

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A new controller of an ON/OFF type was implemented for halothane anesthesia. A proportional-plus-integral controller with time-delay compensation proved not to be robust enough for the known clinical situation, as shown both in computer simulations and in animal trials. The ON/OFF controller proved to be less sensitive to parameter mismatches, and repeated animal trials showed a short response time and acceptable steady-state tracking. A method for switching the controlled effect of the drug was also developed, since anesthetic agents have multiple effects. Mean arterial blood pressure and a measure of EEG frequency were chosen as controlled variables, both being depressed by halothane. A coordinator forces the system state as near the desired values of these variables as possible, given that only one drug is used.

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Section: Introductionmentioning

confidence: 99%

Automatic control of anesthesia using two feedback variables

1987

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“…Automatic control using arterial pressure as a measure of depth of anaesthesia was achieved by Fukui, Smith and Fleming [3], Robb and colleagues [4,5] and Monk and colleagues [6] and by Suppan [7] using heart rate. Arterial pressure was controlled automatically using sodium nitroprusside by Smith and colleagues [8,9], Meline and co-workers [10] and others. Today, feedback controlled pumps are commercially available [11].…”

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confidence: 99%

Arterial pressure control with isoflurane using fuzzy logic

Zbinden¹,

Feigenwinter²,

Petersen-Felix³

et al. 1995

British Journal of Anaesthesia

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Arterial pressure is still one of the most important measures in estimating the required dose of inhaled anaesthetics. It is measured easily and reacts rapidly which makes it suitable as a variable for feedback control of depth of anaesthesia. Fuzzy logic, a novel approach to feedback control, was used to control arterial pressure in 10 patients during intraabdominal surgery by automatic adjustment of the concentration of isoflurane in fresh gas. During anaesthesia, fuzzy control periods of 45-min duration were alternated randomly with human control periods of equal duration. During the skin incision period (-3 to + 12 min) 48.2% of all fuzzy control pressure values were within +/- 10% of the desired mean arterial pressure compared with 40.4% of the human control values (P < 0.05). The corresponding values for the remainder of the operation were 78.3% and 83.2%, respectively. Thus fuzzy out-performed human control at skin incision, but was slightly inferior during the rest of the operation. We conclude that fuzzy logic is a promising new technique for control of isoflurane delivery during routine anaesthesia.

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