Fuzzy Logic Control of Blood Pressure during Anesthesia.pdf

Summarize and understand the work intitled "Fuzzy Logic Control of
Blood Pressure during
Anesthesia" from :
@inproceedings{MeierFuzzyLC,
title={Fuzzy Logic Control of Blood Pressure during Anesthesia},
author={R. Meier and J. Nieuwland and Alex M. Zbinden and Selim S. Hacisalihzade},
url={https://api.semanticscholar.org/CorpusID:169809}
}

1. Fuzzy Logic Control of
Blood Pressure during
Anesthesia

2. Outline
INTRODUCTION
PROBLEM STATEMENT:Depth of Anesthesia

ANESTHESIA CONTROLLER Design:A FUZZY CONTROL
ANESTHESIA CONTROLLER study simulation
Fuzzy Linguistic Variables
Fuzzy Linguistic Values
Fuzzy rules : Rule Bases Table
Results

3. Introduction
In the medical field, during a surgical operation, the anesthetic plays a
mandatory role in controlling important patient parameters such as
blood pressure, heart rate, temperature, blood oxygenation and
exhaled CO2 within acceptable limits.
Anesthesia must be maintained throughout the surgical procedure.
The goal is to develop automated control systems to regulate the
depth of anesthesia using fuzzy logic techniques.

4. KEY CONCEPTS : Depth of Anesthesia

Anesthesia is a balance between the amount of anesthetic drug(s)
administered and the awake state of the patient.
The depth of anesthesia(DoA) is the degree to which the central
nervous system (CNS) is depressed by a general anesthetic agent.
The ideal depth of DoA is one in which the risk of patient awareness
of the operation is as low as possible .

5. KEY CONCEPTS: Depth of Anesthesia

Quality of drug delivery
Possibly reduce costs
Improve patient outcomes.
Advanced monitoring of DoA drug effect might help to optimize :

6. PROBLEM STATEMENT:Depth of Anesthesia

The depth of anesthesia is not readily measurable.
In clinical practice, the depth of anesthesia is evaluated by measuring :
Blood Pressure EEG signal
Face muscles
Anesthesiologists still use blood pressure as the most reliable guide
for controlling depth of anesthesia(dosing inhaled anesthetics).

7. ANESTHESIA CONTROLLER Design:A FUZZY CONTROL

The Anesthesia Controller mainly aim to automate the control
of depth of anesthesia and to release the anesthetist so that
he can devote his attention to other tasks which cannot yet be
adequately automated, thus increasing the patient's safety.

8. ANESTHESIA CONTROLLER Design:A FUZZY CONTROL

DoA is Controlled by using a mixture of drugs which are injected
intravenously(IV) or inhaled as gases (mixture of isoflurane in
oxygen O2 and/or nitrous oxide N2O.)
Depth anesthesia Administration
The primary role of anesthesiologists is to control the
administration of isoflurane concentration inspired , thus
adjusting the patient breathing circle .

9. semi-closed circle
breathing system
Finf :Inflowing isoflurane concentration
Fins :Inspired isoflurane concentration
Fend : isoflurane concentration at the end
of each expiratory cycle

10. ANESTHESIA CONTROLLER DESIGN:A FUZZY CONTROL

The controller should mimic the control actions of the anesthetist ,
to do so we should develop a fuzzy controllers .
The fuzzy controller is designed to automate how a human
expert who is successful at this task would control the system.
Fuzzy controller

11. control of depth of
anesthesia
u : isoflurance concentration
y : Blood pressure

12. The step response if the input is a unit step,is given by :
where:
First order systems
Z transform of the transfer function of the step response :

13. ANESTHESIA CONTROLLER study simulation

ERROR :e(t)
change in ERROR : ce(t)
Integral ERROR : ie(t)
The Expert provides a description of how best to control the plant in
some natural language . We seek to take this “linguistic” description and
load it into the fuzzy controller.

14. ANESTHESIA CONTROLLER study simulation

negsmall(NS)
zero (ZR):0
possmall (PS, positive small in size):1
posbig(Pb)
posVeryBig(
posmedium(pm)
Linguistic values :Values that linguistic variables take on over
time change dynamically.

15. ANESTHESIA CONTROLLER study simulation
Linguistic rule :are simply abstract ideas about how to achieve
good control .
Linguistic Rules General form:
If premise Then consequent
The premises (antecedents) are associated with the fuzzy
controllers inputs.
The consequents (actions) are associated with the fuzzy controllers
outputs.

16. ANESTHESIA CONTROLLER study simulation

Linguistic Rules General form:
If premise Then consequent
if the endtidal concentration sinks below 0.4% ( danger of
awakening ) , the inflow concentration in increased by 0.1%
if the endtidal concentration is still under 0.4% the process is
repeated .
if endtidal concentration exceeds 2.5% (toxic limit) ,concentration
is decreased by 0.2% and the controller is switched off .

17. Tabular
representation of
linguistic rules

18. Rule Bases (Table)

19. Membership
Functions for Inputs
and Output

20. Results
Fuzzy controler was measurably more
accurate in keeping the blood
pressure within a small range of its set
value of 85 mmHg .
The L1 norm of the difference
between the desired and the actual
blood pressure during manual control
is 40% more than during fuzzy
control (blood pressure devided more
than 15 mmHg from desired value ).

21. THANK YOU