WO2014066969A1

WO2014066969A1 - Breathing circuit for an anesthesia apparatus

Info

Publication number: WO2014066969A1
Application number: PCT/BR2013/000465
Authority: WO
Inventors: Toru MIYAGI KINJO; Wataru Ueda; Tatsuo Suzuki
Original assignee: Magnamed Tecnologia Médica S/A
Priority date: 2012-11-05
Filing date: 2013-11-05
Publication date: 2014-05-08
Also published as: BR102012028313A2; WO2014066969A8; BR102012028313B1

Abstract

The present invention relates to an anesthesia circuit used on inhalation anesthesia apparatus, which does not have gas stagnation points, since it uses a turbine (18) and a pressure controlling valve in addition to a laminar-flow long-tube reservoir (19) in contact with external air.

Description

RESPIRATORY CIRCUIT FOR ANESTHESICS

The present invention relates to an anesthesia circuit used in inhalation anesthesia apparatus having no gas stagnation points as it utilizes a turbine and a pressure control valve in addition to a long tube reservoir. in contact with outside air.

Description of the prior art

In various types of surgery, the patient should be cured to avoid muscle contractions that may hinder or cause accidents during the operation. Thus, in modern medicine, the use of respiratory circuits in anesthesia devices is indispensable, since they allow the breathing of anesthetized patients with total paralysis of the muscles, and therefore without control of their respiratory system.

Anesthesia devices generally comprise a part called the continuous flow section and another part called the breathing circuit. The continuous flow section is the section of the circuit in which gases, usually oxygen, nitrous oxide or air, are dosed and mixed, and then conveyed to the calibrated vaporizer, where anesthetic is added, thereby forming a fresh gas flow. The breathing circuit is the place where the patient's breathing cycle is generated.

Thus, the continuous flow section generally comprises rotameters and an anesthetic vaporizer, whereas the respiratory circuit generally comprises an inspiratory valve connected to an inspiratory branch, an expiratory valve connected to an expiratory branch, a Y-piece in contact. with the inspiratory branch and the expiatory branch, as well as the patient's respiratory system, a balloon / ventilator toggle switch, a balloon, a soda lime filter, a pressure limit valve, a bell comprising a ventilator-operated bellows external.

Thus, the gas flow is intermittent, so that the patient You should inhale a mixture of anesthetic gases with oxygen, and exhale a mixture of residual oxygen, residual anesthetic in addition to the carbon dioxide produced in your lungs.

At the beginning of the anesthesia process, the patient is induced to the anesthesia state, usually manually, with the balloon / ventilator switch in the "balloon" position. This process is called induction, in which the anesthesiologist pumps the gas mixture through the balloon with a high anesthetic concentration (up to 8% volumetric) until the patient is unconscious. After disagreeing the patient, the anesthetic concentration is reduced to a maintenance level of the anesthetic plane (usually to about 2%, depending on the patient and anesthetic agent), and device-controlled respiration is initiated upon modification. the position of the balloon / fan switch switch to the "fan" position.

During the controlled breathing process, the patient's exhaled gas should be filtered to remove carbon dioxide, and fresh gas should be added to the remainder of the gas mixture, replenishing the oxygen consumed by the patient's breath, to be subsequently returned to the gas. patient's lung, thus taking advantage of anesthetic gases and residual breathing oxygen.

Thus, conventional anesthesia systems generally utilize a cyclic breathing circuit, called the rebreathing circular breathing circuit, wherein the carbon dioxide from the gas mixture within the circuit is withdrawn via the soda lime filter and the rest - te of the gas mixture is recirculated.

In this circuit, the gas exhaled by the patient is directed into the bellows, which is a passive element mounted within the bell. During exhalation a gas mixture exits the patient's lungs, the bellows inflates (rises) as the exhaled gas enters. During inhalation a renewed gas mixture inflates the patient's lungs by injecting propellant gas into the bell, outside the bellows, through the external ventilator, thereby deflating the bellows (pushing the gas from the bellows downward) and forming a flow of the gas mixture, which passes through the soda lime filter, where the carbon dioxide is absorbed, and is then directed to the patient. For this reason, in these systems an external fan is required, which generates the propulsion gas to propel the bellows.

US 5,673,688, for example, describes a conventional anesthetic breathing circuit as described which further monitors carbon dioxide (CO ₂ ) concentration to control the flow of fresh gas by feedback, so that the mixture of gas that is sent to the patient's lungs be free of C0 _2.

Another type of anesthesia device uses, instead of the bell and bellows, a cylinder and piston system, which has a piston coupled to a spindle and a motor (linear actuator). This system generates the breathing cycle, using electricity as a source of energy for motor movement. Thus, this system does not comprise an external fan, as the breathing cycle is generated by the piston.

U.S. Patent 4,989,597 discloses a breathing circuit in which instead of bellows and bell uses a pressure transmission system, called the inventor of a exchanger, made of corrugated tube, between the external fan and the gases of the circuit. anesthesia, avoiding dilution of anesthetic gases. This system, however, does not eliminate the need for an external fan.

The major disadvantage of the anesthetic devices described is the huge amount of elements used, such as bell rings, bellows and external ventilator. Additionally, these devices are complex and need extreme precision, having a high cost of manufacture, which makes the final price of anesthesia devices too expensive.

Also, since there is no continuous flow of gases in all the elements involved (only the bellows, for example, generally comprises 2 liters of volume), the volume of anesthetic gases stagnant in the circuit is large, and there is a long delay in the renewal of the gas. anesthetic gas mixture co in the circuit. For example, when the anesthetist changes the anesthetic concentration in the vaporizer, the gas stagnation points due to the presence of large residual bellows volumes such as; reservoir or piston jacket, this change does not occur immediately in patient-inspired gases. At these stagnation points, fresh gas enters, diffusion mixed with standing gas within the residual volumes, and a new gas mixture exits, in the same amount as the incoming mixture, but with a composition very similar to the old mixture of inside the stagnant volume, thus maintaining at the stagnation points a mixture very similar to the old mixture. Thus, the renewal of the composition at the gas stagnation points is carried out cycle by cycle extremely slowly, including delaying the time when the patient must be awakened. Mathematically, it is predicted that the equalization time of the old concentration with the new concentration is infinite, that is, even if anesthesia changes the gas mixture concentration, the gas concentration in these elements will never be the modified concentration and therefore The mixture will be continuously modified by the system that controls it.

The importance of eliminating all circuit stagnation points derives from the possibility and need to renew the internal content of the anesthesia circuit in a single respiratory cycle, so that, if any change in the gas mixture composition occurs, the patient receive the new composition immediately. In general inhalation anesthesia, the high anesthetic concentration, which is usually used in induction, cannot remain high for a very long time, on the order of a few minutes, as it can cause irreversible damage to the patient's brain or even lead to death.

On the other hand, a decrease in anesthetic concentration may cause anesthesia superficialization, which is usually detected by the increase of blood pressure and heart rate, being signs of stress caused by the pain felt by the patient, which can have irreversible consequences such as post-neurological disorders. -surgists who manifest in various ways. Decreasing anesthetic concentration in the circuit is therefore desirable, but a superficial anesthetic should be corrected as soon as possible given the first sign of stress. In the prior art, however, such correction is performed by increasing the anesthetic concentration of fresh gas in the vaporizer, however the result is only appreciated after a long period of stabilization of the new plateau.

An attempt to solve this problem is US 6,216,690, which describes an anesthesia apparatus comprising an anesthetic agent concentration monitor located on the inspiratory branch to act on vaporizer concentration by altering anesthetic concentration. in fresh gas to very high values, trying to quickly reach the new level. This is a way to improve the response time of concentration adjustment, but it requires a high cost anesthetic agent monitor. Additionally, changing the anesthetic concentration in the vaporizer above the required level may exceed the optimum point and enter an oscillation, which is a very risky operation where system reliability is critical.

Finally, another major disadvantage of the described anesthesia devices is the lack of exact control of residual lung pressure, ie the lack of positive end-expiratory pressure (PEEP) control, caused by the need for of an excess anesthetic gas relief valve, which is opened by the action of residual pressure in the circuit. This pressure should be precisely controlled so that the patient does not have carbon dioxide retention during long surgery.

Thus, there is no state of the art breathing circuit for simple anesthesia apparatus with few building elements, low production and maintenance costs, and easy gas exchange, allowing greater control of gas concentration. as well as accurate control of residual pulmonary pressure. Objectives of the invention A first object of the present invention is to provide a breathing circuit for anesthesia apparatus which has few building elements, reducing production and maintenance costs.

It is another object of the present invention to provide a breathing circuit for anesthesia apparatus comprising a continuous flow with no stagnation points throughout the circuit path, allowing greater control of gas concentration.

Finally, it is a third object of the present invention to improve the control of residual pressure in the lung of anesthetized patients.

Brief Description of the Invention

The objectives are achieved by means of an Anesthesia Apparatus comprising at least one rotameter, connected to an anesthetic vaporizer, which is connected to contact elements with a patient's respiratory system. The breathing system contact elements are connected to a toggle switch, which in turn is connected to a balloon connected to a carbon dioxide filter. This carbon dioxide filter is also connected to the anesthetic vaporizer. The anesthesia apparatus further comprises a turbine connected to the carbon dioxide filter, the balloon and a long tube reservoir, which is connected to the toggle switch. The anesthesia apparatus according to the present invention is configured to create a flow of a gas mixture towards the patient's respiratory system.

Another embodiment of the present invention that achieves the stated objectives is a respiratory circuit for an anesthesia apparatus comprising contact elements with a patient's respiratory system, and further comprising a turbine, connected to a long tube reservoir. The breathing circuit is configured to create a flow of a gas mixture toward the patient's respiratory system.

Brief Description of the Drawings

The present invention will be described in more detail below with reference to the accompanying drawings in which: Figure 1 is a representation of the state of the art anesthesia apparatus;

Figure 2 is a representation of a preferred embodiment of the present invention showing the inspiration cycle in the induction phase;

Figure 3 is a representation of a preferred embodiment of the present invention showing the expiration cycle in the induction phase;

Figure 4 is a representation of a preferred embodiment of the present invention showing the inspiratory cycle in the apparatus controlled breathing phase; and

Figure 5 is a representation of a preferred embodiment of the present invention showing the expiration cycle in the apparatus controlled breathing phase.

Detailed Description of the Figures

Figure 1 presents a representation of the state of the art anesthesia apparatus. As previously explained, state-of-the-art anesthesia devices comprise a part called a continuous flow section and a part called a respiratory circuit.

As can be seen from figure 1, in the conventional system, in the continuous flow section the gases, preferably nitrous oxide and oxygen or air and oxygen, are dosed by rotameters 1 which allow the adjustment and measurement of the flow of each gas, plus anesthetic vaporizer 2, which adds the vaporized anesthetic to the mixture.

The breathing circuit section comprises tubes or ducts that interconnect a bell 13 comprising a bellows 12, a soda lime filter 11, and contact elements with a patient's breathing system, which are preferably an inspiratory valve 3 connected to a bell. inspiratory branch 4, an expiratory valve 7 connected to an expiratory branch 6 and a Y-piece 5 in contact with the inspiratory branch 4, the expiatory branch 6, and the patient's respiratory system. Additionally, the breathing circuit section comprises an external ventilator 14 configured for generate the inspiratory and expiratory cycles that propel the bellows 12 by inserting air into the bell 13.

The breathing circuit section further comprises a manual breathing system having a balloon 10, a pressure limit valve 9 and a toggle switch 8, also called a balloon / ventilator switch.

During operation, the gas mixture passes through vaporizer 7, which may be a simple anesthetic evaporator which vaporizes a predetermined amount of liquid to the amount of gases to provide the respiratory circuit with the exact anesthetic concentration adjusted by the anesthetist, in the form of a gas mixture flow, or fresh gas flow 23.

In this circuit, the gas exhaled by the patient is directed into the bellows 12, which is a passive element, mounted within the bell 13. During exhalation, the gases from the patient's lungs are expelled by the Y 5 piece into the ramus. 6, passing also through the expiratory valve 7 and thus reaching the bellows 12, which inflates (rises) with the inlet of the expired gas. During inspiration, a propellant gas is injected into bell 13 outside the bellows 12 via the external fan 14, deflating the bellows 12 (pushing the gas from the bellows 12 downwards), thereby forming the flow of the mixture. which passes through the carbon dioxide filter 11 for carbon dioxide removal and is then directed to the patient via the inspiratory valve 3, inspiratory branch 4 and Y-piece 5. Depending on the position of the toggle switch 8, The gas mixture flow can also be created by manually inflating or deflating the balloon 10. Thus, the entire gas mixture flow is created and directed by the balloon 10 or the external fan 14.

Figures 2 to 5 illustrate a representation of the preferred embodiment of the present invention which further comprises at least one parameter 1, connected to the anesthetic vaporizer 2, the contact elements with the patient's respiratory system (the inspiratory valve 3). , the inspiratory branch 4, the Y-piece 5, the expiatory branch 6, the expiratory valve 7), the toggle switch 8, pressure limit valve 9, balloon 10 and soda lime filter 11, preferably a soda lime filter. Unlike the prior art, the present invention comprises a turbine 18, which may be a respirator turbine, and a long laminar flow tube 19, and possibly comprises an electronically controlled pressure control valve, one-way valves, and a pressure plate. microprocessor control, arranged to minimize the volume of anesthetic gases and eliminate all gas stagnation points within the circuit.

Thus, the anesthesia apparatus according to the present invention continues to have two modes of operation: the first being the balloon mode (toggle switch 8 in the "balloon" position), which is used in the induction phase, ie to perform manual ventilation, and turbine mode (toggle switch 8 in the "turbine" position), for automatic mechanical ventilation, where the turbine creates the gas flow containing a specific gas mixture toward the patient's respiratory system and is used in the maintenance phase of the patient's anesthetic state. Of course, the toggle switch 8 may be a simple control valve which directs flow to balloon 10, interrupting flow through turbine 18, and vice versa.

Figure 2 illustrates the inspiratory phase of balloon mode ventilation, where the switch valve 8 is open to balloon 10. At this stage the anesthetist compresses balloon 10, and the contents of balloon 10 are pushed towards carbon dioxide filter 11 Also provided is a one-way valve 17 which prevents air flow to turbine 18. In addition, the exhalation valve 7 is closed and the inspiratory valve 3 is opened. The gas mixture thus passes through the carbon dioxide filter 11, where the carbon dioxide is absorbed and the remainder of the gas is propelled toward the patient, passing the inspiratory valve 3 and entering the lung through the expiatory branch 4 and the part in question. Y 5. As the expiratory valve 7 remains closed, air enters the patient's lung by the action of pressure generated by balloon compression 10. Figure 3 illustrates the expiatory phase of balloon mode ventilation, where the switch valve 8 is still open to balloon 10. In this phase the anesthetist releases balloon 10, allowing air flow containing the gas mixture to enter balloon 10. It is also envisaged to have a one-way valve 22 so that lung gas flows directly into the balloon 10 and remains there. At this stage, the exhalation valve 7 remains open and the inspiratory valve 3 remains closed, and the exhaled gas goes towards the expiratory valve 7 through the Y-piece 5 and the expiatory branch 6.

Additionally, a pressure relief valve 9 is provided, which opens when the set inspiratory pressure is reached each cycle. In addition, there is an increase in gas volume by adding more gas mixture from rotameter 1 and anesthetic vaporizer 2 as a fresh gas stream 23. Thus, fresh gas stream 23 enters the circuit. continuously, both in the inspiratory phase and in the expiratory phase. In part this increase in gas volume offsets the reduction in volume due to carbon dioxide absorption by the carbon dioxide filter, but for safety, fresh gas flow 23 is adjusted to be slightly higher than carbon dioxide absorption, and the excess is eliminated by pressure relief valve 9.

Figure 4 illustrates the inspiratory phase in turbine mode. In this mode switch valve 8 is open for turbine 18 and closed for balloon 10. In this inspiratory phase, turbine 18 is turned on, and the gas mixture is propelled towards the carbon dioxide filter 11, where the carbon dioxide is absorbed, and the flow of the gas mixture goes towards the inspiratory valve 3, in which way fresh gas flow 23 is added. Thus, the air flow follows the inspiratory branch 4 until it reaches the Y 5 piece, inflating the patient's lung. It is further envisaged that the turbine mode is controlled by a microprocessor, which remains on, and maintains a linear actuator 16, closing a pressure control valve 15, configured to prevent gas flow through the expiratory branch 6 at a greater than a pressure determined by linear actuator 16, ie pressure control valve 15 determines The lung pressure rises to a limit pressure value set by the anesthetist.

Figure 5 illustrates the expiratory phase in turbine mode. In this mode switch valve 8 is open for turbine 18 and closed for balloon 10. At this stage, the microprocessor can reduce the electric current in actuator 16, and pressure control valve 15 opens, letting the lung gas out thus limiting the pressure. Exhaled gas exits through the expiratory branch 6, and as turbine 18 is off, the gas flows through the long laminar flow duct 19, displacing the remaining gas in the duct until it exits through the mouth of an anti-pollution system 24, for disposal of surplus gas.

At the end of this phase, the cycle repeats, and in the new inspiration the turbine 18 is turned on, and the accumulated gas in the long laminar flow duct 19 is drawn. To prevent external air from entering the circuit by diluting the anesthetic gas the laminar flow long duct 19 is dimensioned such that the tidal volume is always smaller than the accumulated volume in the laminar flow long duct 19, and the volume increased by the amount of fresh gas entering continuously is sufficient to expel excess gas volume from the circuit at a rate greater than the diffusion of the gas mixture into the anesthetic gas within the long laminar flow duct 19. It is worth remembering that the lung volume of patients varies with their height and weight, with an average tidal volume of less than 1 liter. Thus, the volume of laminar flow long duct 19 can be of the order of 1.5 liters, being larger than the tidal volume of the lung, but without allowing the stagnation of the gas mixture. Thus, the long laminar flow duct 19 plays the role of a reservoir in contact with the external air, enabling the exchange of gases, whereby an exact point for the exchange of laminar flow is created within the long laminar flow duct 19. gas, which is shifted upwards during inspiration, but should not reach the end of the long laminar flow duct 19 as this would enter the breathing circuit.

Thus the present invention describes a breathing circuit for anesthesia apparatus which has few building elements, reducing production and maintenance costs. In addition, the Anesthesia according to the present invention may be constructed in a small physical space, increasing the useful space of the operating rooms.

Anesthesia apparatus constructed in accordance with the present invention also comprises easy gas exchange, ie a continuous flow of gas mixture without stagnation points throughout the circuit path, allowing for greater control of gas concentration and an improvement in the control of residual lung pressure in anesthetized patients.

Another advantage of the invention is that the single volume in the breathing circuit, derived from the laminar flow long tube reservoir 19, is located at the outlet of the excess gases so that at the end of the anesthesia section the entire contents of the gas mixture containing The anesthetic substance can be replaced by a completely anesthetic-free gas in a single respiratory cycle, very quickly starting the patient's exit from general anesthesia.

Having described examples of preferred embodiments, it should be understood that the scope of the present invention encompasses other possible variations, being limited only by the content of the appended claims, including the possible equivalents thereof.

Claims

1. Anesthesia apparatus comprising at least one rotameter (1) connected to an anesthetic vaporizer (2), which is connected to contact elements with a patient's respiratory system, which are connected to a toggle switch (8). which is connected to a balloon (10), which is connected to a carbon dioxide filter (11), which is connected to the anesthetic vaporizer (2), the anesthesia apparatus further comprising a turbine (18) connected to the carbon dioxide filter (11), the balloon (10) and a long tube reservoir (19), which is connected to the toggle switch (8), the anesthesia apparatus being configured to create a flow of a gas mixture towards the patient's respiratory system.

Anesthesia apparatus according to claim 1, characterized in that the connections between the elements are ducts which allow the flow of the gas mixture to pass through.

Anesthesia apparatus according to claim 1, characterized in that the toggle switch (8) is configured to select between the balloon (10) and the turbine (18) as a gas mixture flow creating element. .

Anesthesia apparatus according to claim 1, characterized in that the contact elements in the patient's respiratory system are an inspiratory valve (3) connected to an inspiratory branch (4), an expiratory valve (7) connected to a expiratory branch (6) and a Y-piece (11) in contact with the inspiratory branch (4), the expiatory branch (6) and the patient's respiratory system.

Anesthesia apparatus according to claim 4, characterized in that it further comprises a linear actuator (16) controlling a pressure controlling valve (15), the pressure valve (15) being configured to prevent the flow of the gas mixture flows through the expiratory branch (12) at a pressure greater than a pressure determined by the linear actuator (16).

Anesthesia apparatus according to claim 1, capable of characterized by the fact that the long tube reservoir (19) is in contact with atmospheric air.

Anesthesia apparatus according to claim 6, characterized in that the long tube reservoir (19) is configured to eliminate excess gas from the gas mixture flow.

Anesthesia apparatus according to claim 1, characterized in that the carbon dioxide filter (1) is a soda lime filter.

9. Respiratory circuit for an anesthesia apparatus comprising elements of contact with a patient's respiratory system, the respiratory circuit being characterized by the fact that it comprises a turbine (18) connected to a long tube reservoir (19), the circuit respiratory system being configured to create a flow of a gas mixture toward the patient's respiratory system.

Respiratory circuit for an anesthesia apparatus according to claim 10, characterized in that the connections between the elements are ducts which allow the flow of the gas mixture to pass through.

Respiratory circuit for an anesthesia apparatus according to claim 10, characterized in that it further comprises a toggle switch (8) which is connected to a balloon (10), the turbine (18) and the tube reservoir. Long (19), the toggle switch (8) is configured to select between the balloon (10) and the turbine (18) as the gas mixture flow creating element.

Respiratory circuit for an anesthesia apparatus according to claim 10, characterized in that the contact elements in the patient's respiratory system are an inspiratory valve (3) connected to an inspiratory branch (4), an expiratory valve (7 ) connected to an expiratory branch (6) and a Y-piece (11) in contact with the inspiratory branch (4), the expiatory branch (6) and the patient's respiratory system.

Respiratory circuit for an anesthesia apparatus according to claim 13, characterized in that it further comprises a linear actuator (16) controlling a pressure controlling valve (15), the pressure valve (15) being configured to prevent the flow of the gas mixture from flowing through the exhalation branch (12) at a pressure greater than one. pressure determined by the linear actuator (16).

Respiratory circuit for an anesthesia apparatus according to claim 10, characterized in that the long tube reservoir (19) is in contact with atmospheric air.

Respiratory circuit for an anesthesia apparatus according to claim 10, characterized in that the long tube reservoir (19) is configured to eliminate excess gas from the gas mixture flow.