THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
NATURE OF THE INVENTION

SIMULATION TOOL FOR ANESTHESIA AS MONITORING AND CARBON-DI-OXIDE MONITORING SYSTEM
A) TECHNICAL FIELD
[001] The present invention generally relates to an AGM (Anesthesia gas machine) and CO2 test bench to simulate various normal as well as abnormal conditions of a patient. The present invention relates more particularly to an AGM and CO2 test bench to simulate various normal as well as abnormal conditions of the patient which can be used to calibrate and verify various measuring equipments.
B) BACKGROUND AND PRIOR ART
[002]A test bench is used for measuring the specific amounts of gases in a mixture for various purposes. One of the important fields where this test bench can be used is for simulating real life conditions of a patient. The concentration of gases being administered to a patient is of prime importance for the safety and life of the patient. Various test benches have been designed in the past for measuring various patient parameters. A few of the patents citing the same are listed below.
[003]In US patent numbered 4,881,183, a method and apparatus for emission testing has been described. A computerized emissions tester determines concentrations of HC, CO, and CO2 in exhaust emissions. An IR test bench assembly develops an analog voltage representative of the concentration of a particular gas in a sample gas of known concentration. Data related to calibration pressure, voltage offset and voltage gain is stored in non-volatile memory EEPROM. Algorithms relating voltage and

Concentration of the particular gases are included in software. The pressure of an exhaust emission is compared with the calibration pressure data in memory and a correction is applied to the tester output. The data relating to the voltage offset and gain factor are also used to compensate the tester output.
[004] In US patent numbered 4,314,344, a method and apparatus for selected gas concentration has been explained. A method and apparatus for generating an adjustable concentration of a selected gas within a carrier gas flow including a gas generator which is responsive to a drive signal. A gas analyzer detects the selected gas concentration within the carrier gas flow from the gas generator and provides a signal proportional to the measured concentration to a comparator. A gas concentration selector provides a second signal to the comparator, the signal being proportional to a desired concentration of the selected gas. In response to these signals, the comparator adjusts the drive signal to correct the gas generator output for the difference between the signals and to thereby substantially adjust the concentration of the selected gas within the carrier gas flow to the desired concentration. The method and apparatus automatically corrects for drift or other inaccuracies associated with the generation of the selected gas.
[005]The above mentioned patents describe various types of test benches for the measurement of concentration of gases in a mixture. The patents however do not discuss about the test bench which can be used for the simulation of the various normal and abnormal conditions of a patient. The present invention solves this problem by simulating the normal and abnormal conditions for a patient and checks the patient's response to the applied condition. The present invention also reveals a method for calibrating and testing CO2 and AGM test bench for various measurement modules.

C) OBJECTS OF THE PRESENT INVENTION
a. A primary object of the present invention is to have an AGM (Anesthesia Gas
Machine) and CO2 test bench for simulating the various normal and abnormal
conditions for a test patient.
b. Another object of the present invention is to simulate the various normal and
abnormal conditions of a test patient, by setting a ventilator system comprising
of inspiration valve, expiration valve and a control system.
c. Another object of the present invention is to control the simulation of various
normal and abnormal conditions of a test patient by a control system, where
control system controls the pressure of various gases, expiration valve and
inspiration valve.
d. Another object of the present invention is to safely dispose the lethal gases
disposed from the system by scavenges system.
D) STATEMENT OF THE INVENTION
[006] Accordingly the present invention provides a test bench for simulation of various normal as well as abnormal conditions of a patient. The setup has got O2 CO2 supply, and a pressure regulator for compressing the gas and regulating the amount of pressure of each gas. The mixture of these gases is then passed to a rotameter which show the flow rates of individual gas which can be adjusted precisely.

[007]The mixture of gases is collected in an ambu type reservoir which acts as an input to the ventilator system. The ventilator system consists of inspiration valve, expiration valve and the control system.
[008] Initially, the inspiration and expiration valves are closed which maintains the reservoir at high pressure. The expiration valve is then opened to allow the mixture of gases to the test lung. The pressure inside the test lung and the ventilator system increases. The measuring equipment measures the quantity of the gases and displays the measurement.
[009] According to the requirement, the amount of various gases can be changed by the control system. Hence, the modules can be verified according to the reading of the rotameter.
[010]The expiration valve is then closed and the inspiration valve opened, which lets the gas mixture through circle absorbers which are filled with pink color soda lime. The soda lime will absorb the CO2 from the gas mixture. When the soda lime is saturated with CO2 the pink color fades, indicating the need for replacement.
[011]The gas mixture is then passed through a vaporizer. The vaporizer is designed to allow liquid anesthetics to become vapors to regulate the amount of vapor entering the breathing circuit.
[012]The volatile halogenated agents used for inhalation of anesthesia will vaporize from the liquid state in to a closed container to produce lethal gaseous concentrations. These are discarded safely by scavenger system.
E) BRIEF DESCRIPTION OF DIAGRAM

[013] FIG.l shows a complete setup of AGM and CO2 bench which is used for simulation of normal and abnormal conditions of a patient.
[014] FIG.2 shows a detailed block diagram of the control system.
F) DETAILED DESCRIPTION OF THE INVENTION
[015] FIG.l shows a setup for an AGM(Anesthesia Gas Machine) and CO2test bench for simulation of various normal as well as abnormal conditions of patient. CO2 and AGM are important parameters and can be monitored only in big hospitals and in critical conditions. The CO2 gives the amount of carbon dioxide being released from patient, which in turn gives an indication of the metabolic activity and stability of the person. The lung of a person stops when the person is under anesthesia. The functioning of the body under these and other related conditions have to be administered. The present day test benches can view the condition of the patient under normal conditions. The patient's response under abnormal conditions, such as hyper ventilation, hypo ventilation or respiratory adiosis cannot be produced in real life as they can be fatal. The present invention solves the above problem by simulating the normal and abnormal condition of a patient and checks the patient's response according to these conditions.
[016]The invention comprises of a CO2 and AGM test bench which can simulate all normal and abnormal conditions of a patient.
[017]The invention consists of O2 and CO2 supply (103 and 104 respectively) which are combined with compressed air supply. Compressed air is supplied from a centralized air compressor (105). The centralized air compressor (105) is a machine that presses or squeezes together gases. The pressure released from gases during compression is brought to safe working pressure using pressure regulators (102)

Comprising of pressure reducing valves, one for each compressed gas source. The pressure reduced gases are sent through flow meter which controls the flow of CO9, or air. One flow meter is needed for each gas as medical gases vary in their densities and viscosities.
[018]The gases are then passed through a multiple tube rotameter (101), which gives an indication of the individual flow rates of the gases and it can be adjusted precisely by the control system (107). Rotameter is a gravity-type flow meter because it is based on the opposition between the downward force of gravity and the upward force of flowing gas. The rotameter consists of metal float and a conical glass tube, constructed such that the diameter increases with height. When there are no gases passing through the rotameter, the float rests at the bottom of the tube. As gas enters the tube, the higher density of the float causes the float remains on the bottom. The space between the float and the tube allows for flow past the float. As the flow increases in the tube, the drop in the pressure increases. When the pressure drop is sufficient, the float will rise to increase the amount of flow. The higher the flow rate the greater the pressure drop. The higher the pressure drops the farther up the tube the float rise. The float should stay at a constant position at a constant flow rate.
[019]The gas mixture which comes out of the rotameter is collected in an ambu type reservoir (108). This acts as an input to the ventilator system. A ventilator module consists of an inspiration valve (111), expiration valve (106) and a control system (107). The inspiration to expiration time ratio (I:E) is correctly maintained by the control system.
[020]The inspiration and expiration valves (111 and 106 respectively) are closed initially, which maintains the reservoir at a higher pressure. The expiration valve (106) is then opened which passes the gases to the test lung (114) via the unidirectional valve (115). The pressure inside the ventilator system which is a combination of inspiration valve, expiration valve and control system, and test lung (114) increases. The OEM

Module (112) measures the quantity of the gases and displays it. According to the requirement, the various measurements such as EtCO2 (End tidal CO2), EtAA (End tidal Anesthesia Agent) and RR can be simulated. The modules can hence be verified against the readings from the rotameter.
[021]The expiration valve (106) is then closed and the inspiration valve (111) is opened, which lets out the gas through circle absorbers (113) filled with soda lime. Soda lime absorbs the CO2 from the gas mixture. When soda lime is saturated with CO2 it causes the pink color to fade indicating the need to change the soda lime.
[022]The vaporizer (AGM) (110) present in the system allows liquid anesthetics to become vapors and to regulate the amount of vapor entering the breathing circuit. Volatile halogenated agents used for inhalation will vaporize from liquid state in the air of a closed container to produce lethal gaseous concentrations. This lethal gaseous concentration is disposed by scavenges system (109).
[023]The control system can change various parameters like the quantity of CO2 and O2 or increasing or decreasing the rate of flow of gases to the test lung.
[024]The diagram in FIG.2 shows the block diagram of the control system. The diagram shows a pressure gauge 202, which is being used to control the pressure of gases entering and being expired by the test lung.
[025]The expiration cycle as discussed above is controlled by the expiration valve driving circuit 203. The inspiration valve as described above is controlled by the inspiration valve driving circuit 204.

[026]The person operating the test bench can view the various parameters using the computer 201. The various parameters can be changed according to the simulation desired by the user.
G) SCOPE OF THE INVENTION
[027]The present invention has several advantages:
a. A primary advantage of the present invention is that the need for field trials
for verification and validation of the OEM modules can be minimized to
maximum.
b. Another advantage of the present invention is that the values of CO2 and
AGM can be changed according to the requirement of user and the results
can be obtained for any condition.
c. Another advantage of the present invention is that the various normal as well
as abnormal conditions of the patient can be simulated to check working of
modules under different conditions.
d. Another advantage of the present invention is that initial verification of the
OEM module using the test bench will minimize post launch complaints.
e. Another advantage of the present invention is that the reliability can be
ensured for the range of CO2and AGM modules.
Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention.

WE CLAIM:
1) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a patient comprising of:
a. an O2 supply ,
b. a CO2 supply ,
c. plurality of pressure regulators connected to individual supply,
d. flow meters,
e. a rotameter,
f. a control system,
g. an expiration valve,
h. an inspiration valve,
i. a circle absorber, and
j. a scavenges system for disposing lethal gases.
2) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a patient as claimed in claim 1, where the flow meter are used to control flow rate of individual gases.

3) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a
patient as claimed in claim 1, where the rotameter has multiple tubes, a metal float and a
conical glass tube for displaying flow rate of individual gases.
4) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a
patient as claimed in claim 1, where the control system has a pressure gauge.
5) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a
patient as claimed in claim 1, where the control system has an expiration valve driving
circuit.
6) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a
patient as claimed in claim 1, where the control system has an inspiration valve driving
circuit.
7) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a
patient as claimed in claim 1, where the expiration valve is connected to the test lung by a
unidirectional valve.
8) A CO2 and AGM test bench for simulation of normal and abnormal conditions of a
patient as claimed in claim 1, where the scavenger system has a vaporizer.
9) A method for simulating normal and abnormal condition of a patient which comprises of:
a. regulating the pressure of O2 and CO2,
b. control the flow rate of individual gases,
c. opening the expiration valve for passing the gases to the test lung from the
expiration valve,

d. measuring the quantity of various gases coming to the test lung,
e. closing the expiration valve and opening the inspiration valve, and
f. vaporizing the liquid anesthetics.
10) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the pressure of O2 and CO2 are brought to safe working conditions by the pressure
regulator.
11) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the pressure of individual gases is varied by the control system.
12) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the flow rates of individual gases is controlled by the flow meter.
13) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the expiration valve is used as a simulation for expiration cycle.
14) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the inspiration valve is used as a simulation for inspiration cycle.
15) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the test lung is used as a simulation of human compliance.
16) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the gases are passed from the expiration valve to the test lung to simulate expiration
cycle.

17) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the expiration valve is closed and inspiration valve is opened for initiating the
inspiration cycle.
18) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the gases coming out of the test lung is passed through circle absorbers which
absorb the amount of CO2 from the gaseous mixture coming from the test lung.
19) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the liquid anesthetics are converted to vapors by the vaporizer to regulate the
amount of vapors entering the breathing circuit.
20) A method for simulating normal and abnormal condition of a patient as claimed in claim
9, where the vapors from vaporizer are safely disposed by the scavengers system
Date: September 27, 2006 Place: Bangalore