ES2343496A1 - Anesthesia machine simulator (Machine-translation by Google Translate, not legally binding) - Google Patents

Abstract

Anesthesia machine simulator. The present invention relates to an anesthesia machine simulator that enables anesthesiologists to have a better understanding of the elements and parameters that govern a common anesthesia workstation. In addition, this device allows reproducing the different critical situations that may occur during the ventilation of patients, in order that anesthesiologists are able to handle them in the most appropriate manner for the patient. (Machine-translation by Google Translate, not legally binding)

Description

Anesthesia machine simulator.

The present invention relates to a simulator of anesthesia machine that allows mainly anesthesiologists may have a better knowledge of the elements and parameters that govern a common anesthesia workstation. In addition, this device allows to reproduce the different situations criticisms that may occur during patient ventilation, in order for anesthesiologists to be able to handle them in the most appropriate way for the patient.

Prior art

Current anesthesia devices have evolved considerably since in 1903 Harcourt used valves unidirectional for the application of chloroform and facilitate its supply to the patient by applying heat to increase their vaporization. Between 1910 and 1930, scientists revolutionized the design of anesthesia machines, which from from the thirties they began to have characteristics very similar to the ones they currently have.

Anesthesia devices are equipment of precision with details of mechanics, engineering and electronics for be able to ensure an accurate predictable gas volume. The teams of Anesthesia consist of four important characteristics: a source of O_ {2} and a form of CO 2 removal, a source of anesthetic liquids or gases, and an inhalation system for what require cylinders and their yokes, adjustment valves, flow meters, pressure gauges and other systems to manage the mixture anesthetic to the patient's airways.

Become familiar with these anesthesia devices for the anesthesiologist it is one of his basic tasks, for which it requires not only knowing how it works, but that main features of its components agree with the safety standards published by the American National Standard Institute in the norm Z 79.8. This tool allows the specialist choose and combine measured gases, vaporize volumes exact anesthetic gases and therefore administer controlled concentrations of anesthetic mixture through the respiratory tract.

However, this work of familiarization with anesthesia devices are performed very superficially by most anesthesiologists, who generally do not have a deep knowledge of the machine they are working with, due to the complexity of them.

Currently, an anesthesia machine is composed, on the one hand of a fan designed with a circuit circular for the use of exhaled gases by the sick and, on the other hand, of a monitoring set hemodynamic and respiratory for the control of the low patient operating room anesthesia.

Fans designed with circular circuit they are totally different from those used for ventilation of patients outside the operating room in critical care areas They are always open circuit fans. The circuit open at each breath always take fresh new gases to ventilate the patient, and in the expiratory phase the patient pulls All gases used abroad. On the contrary, the circuit circular allows the anesthesiologist to take advantage of the gases expirations of the patient, once the CO2 has been removed, and return to use them to ventilate the patient over and over again. This fact determines economic and environmental cost savings by reducing the consumption and release of anesthetic gases. This type of ventilation, that by default should be done with the dosing technique in Under flow, it is referred to as mechanical controlled ventilation.

Therefore, unlike what happens with open circuit fans (critical care), Circular circuit fans should be known in depth so as not to have problems ventilating patients in special circumstances (severe obese, pregnant, children premature infants, healthy infants, patients with laparoscopy, etc.) and especially in children (under 10 kg of weight), where clinical incidents arising from improper use of the machine anesthesia is 1: 10,000, being barotrauma, hypoxemia and hypercapnia complications with a higher incidence reported and which are usually the cause of serious neurological lesions and permanent and even of the death of the patients of cause or anesthetic origin

On the other hand, the machines or stations of circular circuit anesthesia have the capacity, as it has been indicated above, to take advantage of the anesthetic gases that the patient exhales to later reuse them. To carry efficiently perform this ventilation and take advantage of advantages offered by circular cycle anesthesia stations, anesthetists should guide the patient the minimum consumption metabolic oxygen that it needs (usually between 200 and 300 ml of O2 per minute - under flow-), and at the same time Increase the concentration of anesthetic gas. In this way, the total volume of anesthetic gas that reaches the patient is the same that the one that would arrive if the flow of O_ {2} was greater and the lower anesthetic gas concentration (high flow), as It happens in open circuits. Surprisingly, when consult anesthesiologists, who use anesthesia machines circular circuit, by anesthetic gas concentrations and O_ {2} flows that contribute to patients, it is decided that in a very high percentage of cases the interventions are made with high flow dosing. This circumstance gives place to that, when the gas with dosage in high flows is mixing with the exhaled gas of the patient, there is an increase in the concentration and pressure of the gas, which should be reduced to through an overflow valve, no economizing anesthetic gases.

The main difference between a circuit circular and an open circuit is that the circular circuit has have to have the following components and parameters of which the Open circuit lacks:

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Patient circuit with branch inspiratory and expiratory branch and "Y" piece for connection with the patient

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Unidirectional valves (inspiratory and expiratory).

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Entry point of the flow of fresh gas

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Vaporizer for anesthetic gas administration.

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An internal volume of circuit.

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A reservoir of gases. (bag, concertina, etc.).

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A valve overflow or valve "pop-off"

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APL or opening valve by pressure release

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A canister or absorber of CO 2.

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Flow generator independent of the gas intake (concertina, piston or turbine).

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These components condition that the circuit circular have a series of elements and parameters that must also be considered when handling this type of stations anesthesia:

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Time constant.

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Compliance (volume / pressure) (from English " Complience ").

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Compensation systems of " complience " or distensibility.

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Rate of flow utilization of fresh gas.

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Leaks

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Low dosage flows.

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All this series of specific features of circular circuits, which do not have open circuits, they cause anesthesiologists to have many more problems ventilation clinics, than any other specialist who ventilates with open circuit. Thus, if an open circuit is used to it is not necessary to ventilate the internal design of the fan, since they do not generate adverse circumstances in clinic. But nevertheless, given the different design of the different circular circuits, a Anesthesiologist who does not know and understand, perfectly, all characteristics of the anesthesia station with which it is working may have complications when ventilating patients on All in special circumstances.

Brief Description of the Invention

The author of the present invention has developed a circular circuit anesthesia simulator that reproduce each and every part of which it is composed An anesthesia machine. This simulator allows you to reproduce the different clinical situations, fundamentally adverse, that can occur during the patient ventilation process and help users of anesthesia machines that take it to cape.

Definitions

The terms "table, machine, device, Anesthesia station, ventilator or equipment "means the set of elements used to manage gases anesthetic and fresh to the patient during anesthesia, both in spontaneous ventilation as controlled.

The term "controlled ventilation" makes reference to situations in which the patient is ventilated from according to the control variables preset by the operator of the anesthesia machine. In the absence of an inspiratory effort of the patient, the ventilator provides controlled breathing. This ventilation will be called mechanical when performed using the mechanical pressure generation system, known as piston, bellows, concertina, etc., and manual when carried out using the manual pressure generation system.

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The term "anesthesia simulator" makes reference to a device capable of reproducing the different situations that occur during the ventilation process with an anesthesia workstation, as well as tests or checkups that these machines perform. Consequently, this device does not must necessarily have all the elements that constitute a circular circuit anesthesia machine and is not useful for ventilating patients

The term "pressure generating system" refers in the description to a bellows, piston, concertina, turbine or any other type of device that allows generating a positive pressure in the anesthetic circuit, in order to favor gas inlet in the inspiratory branch.

The term "canister or filter" makes reference in the description to a container filled with soda lime or bary whose purpose is to absorb the CO2 from the patient expirations ("exhaled gas") so that the patient does not inspire in the next inhalation.

The term "vaporizer" refers to apparatus whose function is to give rise to the vaporization of volatile liquids within an adjustable concentration. In others words, are responsible for controlling the gas concentration of anesthesia that is given to the patient along with oxygen.

The term "valve pop-off "or over-flow does reference to devices that eliminate the excess pressure generated by the excess gas present in the circular circuit. That term It is closely related to the "gas flow utilization rate fresh ", which is explained later.

The term "internal circuit volume" refers to the sum of the volumes of all components Internal anesthesia machine. This internal volume determines of the speed with which the gas is mixed with the exhaled gas, and It is represented in the simulated, together with the gas reservoir, by the container.

The term "gas reservoir" makes reference in the description to a container or container where collects the flow of "gas" that enters the anesthetic circuit and mixed with the exhaled gas, to be driven to the patient by compression. This gas reservoir is hidden in the inside the anesthesia stations, and in the simulator is represented by the container.

The term "time constant" makes reference to the time it takes to fill or empty the machine anesthesia with new gases. In the open circuit this is verified It is practically null, since there is no internal volume of the significant circuit, the time that elapses since the gas pressure is exerted until it reaches the patient is insignificant. In the circular circuit, depending on how it is built, this constant is more or less high.

The term "APL valve" (in English " adjustable pressure limiting valve ") refers to a valve whose function is to regulate the pressure supplied to the circular circuit through the manual pressure generation system. This valve is usually confused in the literature with the " pop-off " valve.

The term "tidal volume or stream" is the volume of air that penetrates the patient in each inspiration. If you take into account that a person makes a certain number of inspirations per minute, this data allows to know the volume of air inspired per minute ("minute volume"). This volume minute is approximately 200 ml / kg for children under 10 kilos and 100 ml / kilo for children over 10 kilos and for Adults.

The term "machine compliance anesthesia "refers to the compressible volume that remains compressed inside the anesthesia machine for every cm of H2O of positive pressure that is generated in mechanical ventilation. This volume is retained inside the anesthesia machine and if not the tidal volume of the current is compensated, subtracted and decreased patient.

The term "compressible volume" refers to the property of gases to reduce their volume when subjected to a certain pressure, this concept is governed by the Boyle Gas Compressibility Law, which says that when " a gas is subjected to a given pressure acquires a new smaller volume, and that the initial pressure x volume product is equal to the final pressure x volume product (P x V = P 'x V') ". The compressible volume is increased the higher the internal volume of the anesthesia machine and the circuit tubing and the greater the maximum pressure reached during mechanical ventilation at positive pressure. To know it, proceed to place a known volume of gas and measure the pressure with the pressure gauge. The volume divided by the pressure will give us the compliment of the circuit, with which the volume of gas must be calculated must be introduced into the piston.

The term "compensation systems of the Anesthesia machine compliance "refers to systems designed to minimize the effect explained above. According to effective they are lost more or less tidal volume in each patient ventilation

The term "flow utilization rate of fresh gas "expressed as a percentage of the total gas volume fresh administered to the anesthesia machine just coming from true to the patient. Due to the way in which they are designed different circular circuits not all take 100% advantage of fresh gases that enter but part are expelled to the atmosphere even before reaching the sick. This circumstance never occur in open circuit fans whose rate of Fresh gas flow utilization is always 100%.

The term "machine leaks" refers to to the gas losses that occur along the circuit Anesthesia machine circular through the different present connections between its components.

The term "patient leakage" refers to to the gas losses that occur when used for mechanical ventilation of the patient endotracheal tubes without pneumotropic or supraglottic devices, in this circumstances gas leaks may occur between the supraglottic device or tube and glottis or trachea of the sick, these leaks that occur within the patient are variables and also subtract volume for the next ventilation with circular circuit Throughout the description the terms leaks machine and patient leaks will be generally referred to as leaks

The term "low flow dosage" refers to the dosage mode that can and should be used with circular circuit anesthesia machines by default. This system consists in supplying the machine with anesthesia the minimum flow of fresh gas to cover the consumption of patient oxygen (minimum metabolic consumption of O2) plus total leaks and thus be able to save a great cost by saving anesthetic gases

The term "Mapleson system" makes reference to a manual continuous flow ventilation system that It is incorporated in the anesthesia stations. These circuits were designed to perform spontaneous and manual ventilation without the need for any anesthesia machine from just a continuous and constant source of fresh gas. These circuits are optional in anesthesia machines but highly recommended, since that allow the patient to ventilate if the anesthesia machine stops function or breaks down, even with these circuits we can continue administering anesthetic gases.

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Brief description of the figures

Figure 1. This figure shows a machine or anesthesia station

Figure 2. This figure shows a view full overview of the anesthesia simulator with the main elements that compose it.

Figure 3. This figure shows the system of gas outlet and return.

Figure 4. This figure shows the system of overflow removal.

Figure 5. This figure shows the system of manual ventilation

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Detailed description of the invention

Due to the large existing differences between open-circuit critical care fans, and the current circular circuit anesthesia fans, the anesthesia workstations (Fig. 1) when turned on they need to carry out a series of preliminary checks to check that they work correctly and provide information to anesthesiologist, who should know how to interpret so as not to have ventilation problems during the intervention.

The author of the present invention has developed an anesthesia simulator (Fig. 2) of circular circuit which reproduces each and every part of which it is Composed an anesthesia machine. In addition, this simulator allows reproduce the different clinical situations, fundamentally adverse effects that may occur during the ventilation process of patients Similarly, this device helps the anesthesiologist to have a deeper understanding of the elements, functioning and variables that govern an anesthesia machine, thus allowing, at all times, know the problems that may arise and how to solve them, to avoid problems derived from ventilation with patients under anesthesia.

Next, it will be illustrated as the simulator of anesthesia helps the anesthesiologist to know all the elements which constitute the circular circuit of an anesthesia machine, its location and the way they are interconnected, so that the specialist can get to have a better knowledge of the machine you work with. In addition, the simulator allows a better understanding of those difficult to understand parameters, which are intrinsic to these devices. This better knowledge will allow not just get more proper handling of the stations anesthesia, resulting in cost savings, but also avoid adverse clinical situations during the processes of anesthesia that generate avoidable damage to the patient.

Thus, a first aspect of the present invention refers to an anesthesia simulator (hereinafter, the simulator -Fig 2-) comprising a sealed container (1), preferably transparent, and more preferably of variable volume, to which they go connected the selected elements of the group comprising:

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A device or system of gas inlet (2) that introduces gases, preferably O2, in the sealed container (1).

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A system or system capable of generate flow and pressure (3) inside the sealed container (1) ("mechanical flow generation system"). This system, which comprises flow or pressure generating means, is capable of press the gas introduced by the gas inlet system (2), to direct it to the gas outlet and return system (4). Preferably, the flow generating means may comprise, without any limitation, a piston, a turbine, a bellows, a bag, a syringe or a concertina.

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A device or system of gas outlet and return (4) ("patient circuit") through from which the gases pushed by the mechanical system of flow generation (3), to be returned back to the container tight (1) when the pressure exerted by the system (3) ceases

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In a preferred embodiment the circuit patient or gas outlet and return device (4) comprises (Fig 3):

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An inspiratory branch or of gas outlet (5), inside which is a valve unidirectional that allows the entry of gas from the container waterproof (1), but prevents its return by this same route. In a preferred embodiment this inspiratory branch (5) would have an entry of auxiliary gases (8) that allows to reproduce a special type of anesthesia machine (see example 3).

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An expiratory branch (6), connected to the inspiratory branch (5), inside which is a unidirectional valve that prevents the entry of gas from the airtight container (1), and allows the gas coming from the inspiratory branch (5). In an even more preferred embodiment, to the outlet of the expiratory branch is connected to a canister or CO2 filter (26).

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In another preferred embodiment of this aspect of the invention, the connection between the inspiratory branch and the expiratory is carried out through a duct (7) that would simulate the patient or the patient's airways ("patient simulator"). Preferably, the conduit (7) has connected a valve (27) that allows the opening and closing of the same, allowing the total or partial exit of the gas that penetrates through the inspiratory branch, to simulate leak situations patient of variable magnitude. Additionally, this valve (27) can be used as a gas inlet to simulate the processes of gas capitation

In practice the patient simulator (conduit (7)) an element may also be connected at its free end inflatable (9) (Fig. 3) that serves as the patient's lungs ("lung simulator"), increasing in size when exercised pressure inside the circuit and decreasing when said pressure ceases or leaks are simulated.

In a preferred embodiment of this aspect of the invention the gas inlet device (2) would be constituted by an inlet conduit (10) connected to a supply source of O_ {2} or any other gas ("the source") (11). In a even more preferred embodiment this device (2) would comprise an inlet conduit (10) that is connected to the source (11) and to a vaporizer (12). In an even more preferred embodiment, the inlet duct (10) connects or forks in a duct auxiliary (13) at whose end a bag (14) is attached, or any another type of element that allows to generate pressure, and along the which is arranged an APL valve (16) or any other type of valve capable of regulating the pressure provided by the bag (14). This system comprising the elements (13 and 14), and that parallel to the piston, bellows, etc., allows to exert pressure on The interior of the circuit is known in the field of anesthesia as "Mapleson auxiliary circuit".

In an even more preferred embodiment of this aspect of the invention the simulator has connected, preferably the stake vessel 1, a pressure gauge (15) that It allows to measure the pressure inside the circuit.

In an even more preferred embodiment of this aspect of the invention the simulator comprises a device of elimination of over-flow or excess pressure (19) (Fig. 4), which comprises a pop-off valve or overflow (17). Preferably, said valve is connected to a duct of elimination of overflow or overpressure (18) at the end of which find the excess gas outlet, which connects to media for the extraction or evacuation of gases introduced in excess in the circuit. Said extraction system comprises preferably a tubing (20) that connects to a bag reservoir (21). This reservoir bag could also include a connector to communicate its interior with the environment, and another connector that can be connected to an external vacuum outlet.

In a also preferred embodiment of this aspect of the invention to the sealed container (1) a second device (22) (Fig. 5) capable of exerting a pressure positive inside ("manual system for generating pressure "). In a preferred embodiment this system (22) would be consisting of at least: a conduit (23) along which connect an APL valve (24) or any other type of valve capable of regulating the air pressure that passes through the duct (23), to be transmitted to the patient circuit (3), and a bag of manual ventilation or any other means of exerting pressure (25), connected to the free end of the duct (23).

In an even more preferred embodiment of this aspect of the invention the simulator would have connected along its circuit at least one valve (27) for the opening and closing of conduits or of the sealed container in order to simulate leaks of the machine or the patient circuit, in addition to valves unidirectional that allow direct gas flows.

Finally, indicate that some of the elements that will be part of the simulator are likely to be replaced by non-functional elements that mimic the real ones, just as it could happen with the canister, the vaporizer or the pop-off and APL valves. This is because these elements are not essential for the simulator, since this It does not have the function of ventilating a patient.

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Detailed statement of embodiments Example 1 Leak test

When an anesthesia machine is completely waterproof, that is, it does not leak through any of the interconnections of its components, the pressure exerted on its Interior remains constant over time.

To carry out this check, the machine of anesthesia introduces into the circuit, through the piston (3), a known pressure, as a general rule of thumb, 30 cm H2O, and once the machine is pressurized at this pressure, it interrupts the flow and calculate what pressure loss occurs for one minute and so Calculate the leaks of the anesthesia machine in one minute. Other what they do is calculate the gas flow they need continue to contribute during that minute to get the pressure to hold at 30 cm H2O for one minute, reaching it calculation.

This same essay can be simulated very simple in the simulator allowing the entry of gases through from the flow generator (2) to the container (1), exerting pressure with the piston (3) and measuring the pressure variations in the circuit with the pressure gauge (15). If the container and the interconnections between the simulator elements are tight not they will cause leaks (constant pressure on the gauge), although these they can be simulated from the valves (27). In this way, a complicated process of understanding when explained about a machine of common anesthesia, where you cannot visualize what the machine, it becomes very simple to understand. In practice These checks are performed by the machine operators, the which are limited to the repetition of a series of steps preset, without actually knowing what implications or foundation they have.

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Example 2 Compressible volume

In an open circuit the gas pressure that is supplies a patient is transmitted directly to him. By against, in a circular circuit the volume of gas in its interior has the ability to compress when a pressure on the piston (3), as happens when in a syringe is exerted pressure on the plunger, while its end Open stays locked.

To carry out this check, the machine of anesthesia introduced into the circuit, through the piston, concertina, turbine or other flow generator, an air volume known, which results in an increase in the internal pressure of the circuit that is measured by the pressure gauge. If the pressure is maintained, the machine calculates, from volume and pressure, the compliance (volume / pressure) of the circuit, which in most cases ranges from 5 to 7 (ml / cm H2O), depending on the internal volume of each machine If this compliance value matches the one at machine corresponds to its internal volume, this indicates that no there are leaks and that it can continue to work safely. In case on the contrary, the compliarice would increase, because the pressure decreases, its value would not match the one the machine has expected and would alert to be out of range and insecurity for use

This same test can be performed using the elements that configure the simulator, making it very simple for the anesthesia machine operator understanding the process, especially if the gas used is not colorless.

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Example 3 Time constant

The time constant is the time it takes to fill or empty 63% of a given container, this being An exponential process. Thus, for a time constant there will be produced 63% of the filling or emptying of the container, for two 86% time constants, and for three time constants the 95%

The time constant of a machine anesthesia depends on the internal volume of the circuit and the flow of Fresh gas used, less circuit leakage. Also influences in the time constant the efficiency of the system or percentage of Fresh gas flow utilization.

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There are currently different ways of introduce the flow of fresh gas into the anesthesia machine; (i) one of these systems provides air through the duct of inlet (10) together with the anesthetic gases, coming from the vaporizer (13) and mixed with O2 from the source (eleven). This fresh gas is taken to a reservoir chamber (represented in the simulator by the watertight container (1)), for be pushed by the concertina (3). (ii) The other system too introduce the anesthesia gas through the inlet duct (10), but the fresh gas enters directly at the height of the branch inspiratory (5). Thus, for the first of the systems there will be a time constant much higher than the time constant of the second system. To play the second of the systems mentioned (ii) it would be enough to disconnect the auxiliary conduit (13) of the inlet duct (10) and attach its free end to the inlet of gases (8) of the inspiratory branch (5).

In situations of hypoxia (lack of O2), hypercapmia (excess of CO2), or bronchospasm (closure of the bronchi), where if the patient remains without O2 during a time exceeding 3 minutes brain damage is irreversible, the anesthesiologist quickly resortes, in most cases, to manual ventilation system or Mapleson (circuit independent inside the machine) to recover the patient as soon as possible and give him the O_ {2} he needs. This way of acting, which has sense when using the first of the systems (i), mentioned in the previous paragraph, it is inappropriate when the second one is used (ii) (decrease in the effectiveness of patient care), due to to which the anesthesiologist dedicates his efforts to ventilate the patient, instead administer a series of drugs that it needs immediate way.

Therefore, adequate knowledge of the typology and design of the anesthesia machine with which you are Working would help avoid these kinds of situations.

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Example 4 Pop-off or valve overflow

Overflow valves (17) Eliminate the excess flow of fresh gas from the circular circuit, to prevent the excess pressure that occurs is not transmitted to the patient and can cause a barotrauma or rupture of the lungs due to airway pressure These valves are also subject to check when the anesthesia machine is turned on.

Sometimes the valves of overflow (17) may become clogged during course of an operation and produce a barotrauma in the patient, especially in those who have the airways little elastic This circumstance is more common when patients They are anesthetized at high flows.

To explain this situation in the simulator, we supplies gas at high flow, through the gas inlet (2), and seconds later, by means of the piston (3), a circuit is provided volume of air similar to what would normally be contributed to a patient. If everything works correctly, the gas will enter the branch inspiratory (5), will inflate the inflatable element (9) and return to enter the expiratory branch (6). Now, through the entrance of gas continues to enter gas at the pressure set at the beginning, which at mixing with the expired gas would increase the pressure inside of the container. If the overflow valve (17) works correctly, the gas output can be seen through of it and also the entry of gas through the branch inspiratory (5) towards the globe (9). This process will be even more Appreciable if the gas is colored.

If instead we perform the same operation but somehow the pop-off valve clogged, excess pressure would be transmitted quickly to the element inflatable (9) and can even break it. If in addition, the patient is a newborn, a premature child, a pregnant woman or has a poorly flexible respiratory system (fibrous lung, patient with laparoscopy, with severe obesity or respiratory distress), the result can be deadly.

These simple experiments help the anesthetist to have a better knowledge of the machines of anesthesia with which they work, thus avoiding this type of situations.

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Example 5 Mapleson or direct controlled flow ventilation system continuous

Anesthesia machines usually have in the most cases of a Mapleson auxiliary circuit (elements 13, 14, 16), which may be optional, but which in most cases its incorporation is recommended as security, in case the circular main circuit of the anesthesia machine and, of this mode, have an alternative to ventilate the patient.

However, many specialists do not understand well the usefulness of using in certain critical situations for the patient as bronchospasms (bronchial closure) and desaturations (lowering of blood oxygen) this circuit of Mapleson in front of the circular in manual ventilation. This is so important that in some countries and hospitals to reduce costs request that anesthesia machines not incorporate this circuit, being sold without this accessory circuit.

With the anesthesia simulator it is very easy visualize all the differences between ventilation manual with the circular circuit of the anesthesia machine, starting of the manual pressure generation system (22), and ventilation manual with the Mapleson circuit. They can thus be easily appreciated all connections of both systems, and how the Mapleson is primed of the flow of fresh gas that the anesthesiologist directly programs, and as instead, the circular circuit is primed from the mixture between the fresh gas that guides the anesthesiologist and gas that machine receives from the patient, which delays the time to get Change the concentration of the gas the patient receives.

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Example 6 Low flow dosage

This is the primary purpose for which it they designed the circular circuits in anesthesia, the gas saving anesthetics The way to dose in open circuit is very easy, since what is scheduled for fresh gases in the machine is what It reaches the patient in each ventilation. However, in circuit the same does not happen, since if we use low gas flows fresh these are mixed with the gases that return from the patient, and from the mixture of the two types of gases is what is vented to sick in the next ventilation. Therefore, the concentration of anesthetic gas that is scheduled in fresh gas does not have to be the same that reaches the sick. This is what determines that the Dosing of gases in low flows and circular circuit, either Technically more complex and not easy to understand.

The evidence of the little knowledge that exists of this type of systems is found when checking that, in a high percentage, anesthesiologists use high flows when driving circular circuit machines, where they should use flows low.

To visualize this process in the simulator, you supplies high flow gas, through the inlet system of gases (2), and seconds later, by means of the piston (3), it is contributed to the circuit a volume of air similar to what would normally be provided to a patient If everything works correctly, the gas in the container (1) will enter the inspiratory branch (5), inflate the balloon (9) and will enter again through the expiratory branch (6) to the container (1), passing through the unidirectional valve of this branch and through the canister (26), where the CO2 would be trapped. Now through from the gas inlet continues to enter gas at the pressure set at start, which when mixed with exhaled gas would increase the pressure inside the container. If the valve overflow (17) works correctly, you can appreciate the gas outlet through it and a second gas inlet through the inspiratory branch (5), which ends by cause the balloon volume to increase again (9).

To show the low dosing technique flows, the same process as described in the paragraph would be carried out previous but using a low flow dosage. The only one difference that could be seen in this case is that it does not occur no gas leakage through the overflow valve (17) with the second gas inlet by the inspiratory branch (5) and, consequently, there would be no waste of the anesthetic gases

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Example 7 Manual controlled ventilation through the machine anesthesia

When faced with a problem with the flow generator of the anesthesia machine (2), the anesthesiologist can choose different systems to continue ventilating the patient. One of these systems it is the Mapleson, explained above, and the other consists of a manual ventilation incorporating the machine's circular circuit of anesthesia and which in the simulator has been called as a system pressure generation manual (22). This system unlike the Mapleson takes advantage of the circular circuit of the machine.

From the simulator it is easy to observe how by means of the bag (25) it is possible to exert a positive pressure on the circuit. This pressure is transmitted through the duct (23), passing to through the APL valve (24) that regulates and releases it, so that I finally ended up pushing the gas in the container (one). This mechanism, like the rest of the comments, is difficult to understand when working with an anesthesia machine common, where it is also possible to pass to the ventilation system manual controlled, usually by simply turning a lever (28) (Figure 1). The simulator thus allows to know in depth, and especially when colored gases are used, which is what happens when you pass the controlled ventilation system Mechanical to manual.

Claims (13)

1. Anesthesia simulator characterized in that it comprises:

to.

a waterproof container (1),

b.

a gas inlet device (2) that introduces gases into the tight container (1) to which it is connected,

C.

a gas outlet and return device (4) from which they leave gases from a tight container (1) to which it is connected,

d.

pressure generating means (3) connected to the tight container that exert pressure inside of said sealed container (1).

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2. Anesthesia simulator according to the preceding claim characterized in that the gas outlet and return device (4) comprises:

to.

a inspiratory branch (5) connected to the sealed container (1), which includes a unidirectional valve that prevents gas recoil towards the sealed container (1)

b.

a expiratory branch (6), connected to the inspiratory branch (5) and the tight container (1), which conducts the gases that circulate through the inspiratory branch (5) towards the sealed container (1) and which includes a unidirectional valve that prevents the entry of gases from the waterproof container (1).

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3. Anesthesia simulator according to any of the preceding claims, characterized in that the inspiratory branch additionally comprises an auxiliary gas inlet (8) with a valve (27) that allows its opening and closing. 4. Anesthesia simulator according to any of the preceding claims characterized in that the gas inlet device (2) comprises a gas supply source (11) and an inlet conduit (10) that connects the source with the sealed container (1) ). 5. Anesthesia simulator according to any of the preceding claims characterized in that the pressure generating means (3) are selected from the group comprising a piston, a turbine, a bellows, a syringe or a concertina. 6. Anesthesia simulator according to any of the preceding claims characterized in that the inlet duct (10) is branched off or connected to an auxiliary duct (13) associated with a bag (14) or any other type of means capable of generating pressure. 7. Anesthesia simulator according to any of the preceding claims, characterized in that the inspiratory branch (5) is connected to the expiratory branch (6) by means of a conduit (7) comprising a valve (27) that regulates the gas outlet from the inspiratory branch (3) outwards and the sealed container (1) through the expiratory branch (4). 8. Anesthesia simulator according to claim 7 characterized in that it incorporates an inflatable element (9) connected to the free end of the duct as a simulator element of the patient's lungs. 9. Anesthesia simulator according to any of the preceding claims characterized in that it additionally comprises a pressure gauge (15) connected to the sealed container (1) and which measures the pressure inside it. 10. Anesthesia simulator according to any of the preceding claims characterized in that it comprises an overflow elimination device connected to the sealed container (1). Anesthesia simulator according to the preceding claim characterized in that the overflow elimination device comprises an overpressure valve (17) connected to the sealed container (1) and an overflow elimination conduit (18) at whose end extraction devices are coupled or gas evacuation (19). 12. Anesthesia simulator according to any of the preceding claims characterized in that it comprises a device capable of generating pressure (25) connected to the sealed container (1) through an inlet conduit (23), along which it is connected with a APL valve (24), which regulates the air pressure that is auxiliaryly introduced with the device (25) to the sealed container (1). 13. Anesthesia simulator according to any of the preceding claims, characterized in that, connected along its circuit, it has at least one valve (27) that allows the release of pressure.