BR102012028313B1 - ANESTHESIA APPLIANCE - Google Patents

Abstract

breathing circuit for anesthesia machines and anesthesia machine. the present invention relates to an anesthesia circuit, used in inhalation anesthesia machines, which does not have gas stagnation points, since it uses a turbine (18) and a pressure control valve (14), in addition to a long duct (19) of laminar flow in contact with the external air.

Description

[001] The present invention relates to an anesthesia circuit, used in inhalation anesthesia devices, which does not have gas stagnation points, since it uses a turbine and a pressure control valve, in addition to a tube reservoir long in contact with outside air.

Description of the State of the Art

[002] In several types of surgery, the patient must be curarized, to avoid muscle contractions that can hinder or cause accidents during the operation. Thus, in modern medicine, it is essential to use respiratory circuits in anesthesia machines, as these allow the breathing of anesthetized patients with total paralysis of the muscles, and, therefore, without control of their respiratory system.

[003] Anesthesia devices generally comprise a part called a continuous flow section and another part called a respiratory 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 subsequently conducted to the calibrated vaporizer, where the anesthetic is added, thus forming a flow of fresh gas. The respiratory circuit is the place where the patient's respiratory cycle is generated.

[004] In this way, a continuous flow section generally comprises rotameters and an anesthetic vaporizer, while the respiratory circuit generally comprises an inspiratory valve connected to an inspiratory branch, an expiratory valve connected to an expiratory branch, a piece in Y in contact with the inspiratory branch and the expiatory branch, as well as with the patient's respiratory system, a balloon / ventilator switch, a balloon, a soda lime filter, a pressure limit valve, a bell comprising a moved bellows by an external fan.

[005] Thus, the gas flow is intermittent, so that the patient must 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 his lungs.

[006] At the beginning of the anesthesia process, the patient is induced to the state of anesthesia, usually manually, with the balloon / fan switch in the "balloon" position. This process is called induction, in which the anesthesiologist pumps the gas mixture through the balloon, with a high concentration of anesthetic (which can reach 8% volumetric), until the patient is unconscious. After disagreeing with the patient, the concentration of anesthetic is reduced to a level of maintenance of the anesthetic plan (usually to about 2%, depending on the patient and the anesthetic agent), and breathing controlled by devices is initiated by changing the position of the balloon / fan switch to the "fan" position.

[007] During the process of controlled breathing, the gas expired by the patient must be filtered to remove carbon dioxide, and to the rest of the gas mixture, fresh gas must be added, replacing the oxygen consumed by the patient's breathing, for later be sent back to the patient's lung, thus taking advantage of anesthetic gases and residual oxygen from breathing.

[008] Thus, conventional anesthesia systems generally use a cyclic breathing circuit, called a circular breathing circuit with rebreathing, in which the carbon dioxide from the gas mixture that is inside the circuit is removed through the soda lime filter, and the rest of the gas mixture is recirculated.

[009] In this circuit, the gas expired by the patient is directed into the bellows, which is a passive element, mounted inside the bell. During exhalation a mixture of gases leaves the patient's lungs, the bellows inflates (rises) with the entry of the exhaled gas. During inspiration, a renewed mixture of gases inflates the patient's lungs, by injecting a propulsion gas into the bell, outside the bellows, by means of the external fan, consequently deflating the bellows (impelling the gas from the inside of the bellows. downwards) 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, the presence of an external fan is necessary in these systems, which generates the propulsion gas to propel the bellows.

[010] US patent 5,673,688, for example, describes a conventional anesthesia breathing circuit as described, which still monitors the concentration of carbon dioxide (CO2) to control the flow of fresh gas by feedback, so that mixture of gases that is sent to the patient's lungs is CO2-free.

[011] Another type of anesthesia device uses, in place of the bell and bellows, a cylinder and piston system, which has a plunger coupled to a spindle and a motor (linear actuator). This system generates the respiratory cycle, using electricity as an energy source for the movement of the engine. Thus, this system does not include an external fan, as the respiratory cycle is generated by the piston.

[012] US patent 4,989,597 describes a breathing circuit in which, instead of the bellows and bell, it uses a pressure transmission system, named by the changer inventor, made of corrugated tube, between the external fan and the gases of the anesthesia circuit, avoiding the dilution of anesthetic gases. This system, however, does not eliminate the need for an external fan.

[013] The prior art document US 2005/0103338 describes an anesthesia device comprising measuring devices for respiratory gas components, with a first and a second gas analyzer installed so that the difference between a predetermined concentration and a concentration measurement on the patient connection is minimized.

[014] The prior art document WO 00/78380 describes an anesthesia machine comprising an electrically actionable pressure intensifier in the form of a blower, the blower being selected and energized to assist inflation of the lungs, but without interfering with spontaneous breathing. of the patient.

[015] In addition, the prior art document DE 20 2011 102 764 describes an anesthesia machine comprising a reservoir connected to a rebreathing line, the reservoir being in the form of a manual respiratory bag.

[016] The major disadvantage of the anesthesia devices described is the immense amount of elements used, such as bellows, bellows and an external fan. In addition, these devices are complex and require extreme precision, having a high manufacturing cost, which makes the final price of anesthesia devices too expensive.

[017] Also, as there is not a continuous flow of gases in all the elements involved (only the bellows, for example, usually comprises 2 liters of volume), the volume of anesthetic gases stagnant in the circuit is large, and there is a long delay renewing the anesthetic gas mixture in the circuit. For example, when the anesthetist changes the concentration of anesthetic in the vaporizer, the gas stagnation points due to the presence of large residual volumes of the bellows, such as; reservoir balloon or piston liner, this change does not occur immediately in the gases inspired by the patient. In these stagnation points, fresh gas enters, mixes by diffusion with the gas stopped inside the residual volumes, and a new mixture of gases leaves, in the same amount of the mixture that entered, however, with the composition very similar to the old mixture of interior of the stagnant volume, keeping in the stagnation points, thus, a mixture very similar to the old mixture. In this way, the renewal of the composition at the gas stagnation points is carried out cycle by cycle, extremely slowly, including delaying the moment when the patient must be awakened. Mathematically, it is predicted that the time of equalization of the old concentration with the new concentration is infinite, that is, even if anesthesia changes the concentration of the gas mixture, the concentration of gases in these elements will never be the modified concentration and, therefore, the mixture will be continuously modified by the system that controls it.

[018] The importance of eliminating all points of stagnation in the circuit stems from the possibility and need to carry out the renewal of the internal content of the anesthesia circuit in a single respiratory cycle, so that, in the event of any change in the composition of the gas mixture , the patient immediately receives the new composition. In general inhalation anesthesia, the high concentration of anesthetic, which is generally used in induction, cannot remain high for a very long time, in the order of a few minutes, as it can cause irreversible damage to the patient's brain or even lead to death.

[019] On the other hand, a decrease in anesthetic concentration may cause anesthesia to become superficial, which is usually detected by an increase in blood pressure and heart rate, being signs of stress caused by the pain felt by the patient, which can bring irreversible consequences as post-surgical neurological disorders, which manifest themselves in different ways. The decrease in the concentration of anesthetic in the circuit, therefore, is desirable, but a superficialization of anesthesia should be corrected as soon as possible, given the first sign of stress. In the state of the art, however, such correction is carried out by increasing the concentration of fresh gas anesthetic in the vaporizer, however the result is only appreciated after a long period of stabilization of the new level.

[020] An attempt to solve this problem is the US patent US 6,216,690, which describes an anesthesia device that comprises an anesthetic agent concentration monitor, located in the inspiratory branch, to act on the vaporizer concentration, changing the concentration of the vaporizer. anesthetic in fresh gas to very high values, trying to quickly reach the new level. This is a way to improve the response time of the concentration adjustment, however it requires a monitor of anesthetic agent, of high cost. In addition, changing the concentration of anesthetic in the vaporizer above the necessary can exceed the ideal point and enter an oscillation, which is a very risky operation, where the reliability of the system is critical.

[021] Finally, another major disadvantage of the described anesthesia machines is the lack of exact control of the residual pressure in the lung, that is, the lack of control of the positive end-expiratory pressure (PEEP), caused by the need for an escape valve for excess anesthetic gases, which is opened by the action of residual pressure in the circuit. This pressure must be controlled exactly, so that the patient does not show carbon dioxide retention during a long surgery.

[022] Therefore, in the state of the art, there is no breathing circuit for simple anesthesia devices, with few construction elements, low production and maintenance cost, and which also includes an easy exchange of gases, allowing greater control of the concentration of gases, as well as the exact control of residual pulmonary pressure.

Objectives of the invention

[023] A first objective of the present invention is to provide a breathing circuit for anesthesia devices that has few construction elements, reducing the costs of production and maintenance.

[024] It is another objective of the present invention to provide a breathing circuit for anesthesia devices that comprises a continuous flow without stagnation points in the entire path of the circuit, allowing greater control of the concentration of gases.

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

Brief Description of the Invention

[026] The objectives are achieved by means of an anesthesia device comprising at least one rotameter, connected to an anesthetic vaporizer, which is connected to elements in contact with a patient's respiratory system. The elements in contact with the respiratory system are connected to a switch 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 machine also comprises a turbine connected to the carbon dioxide filter, the balloon and a long tube reservoir, which is connected to the switch. The anesthesia device according to the present invention is configured to create a flow of a mixture of gases towards the patient's respiratory system.

[027] Another embodiment of the present invention that achieves the stated objectives is a breathing circuit for an anesthesia device comprising elements of contact 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 mixture of gases towards the patient's respiratory system.

Brief Description of Drawings

[028] The present invention will be described in greater detail below, with reference to the accompanying drawings, in which: Figure 1 - is a representation of the state-of-the-art anesthesia machines; Figure 2 - is a representation of a preferred construction of the present invention, showing the inspiration cycle in the induction phase; Figure 3 - is a representation of a preferred construction of the present invention, showing the expiration cycle in the induction phase; Figure 4 - is a representation of a preferred construction of the present invention, showing the inspiration cycle in the breathing phase controlled by devices; and Figure 5 - is a representation of a preferred construction of the present invention, showing the expiration cycle in the apparatus-controlled breathing phase.

Detailed Description of the Figures

[029] Figure 1 shows a representation of the state-of-the-art anesthesia machines. As previously explained, state-of-the-art anesthesia machines comprise a part called a continuous flow section and another part called a respiratory circuit.

[030] As can be seen in 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 that allow the adjustment and measurement of the flow of each one gases, plus the anesthetic vaporizer 2, which adds the vaporized anesthetic to the mixture.

[031] The respiratory circuit section comprises tubes or ducts that connect a bell 13 comprising a bellows 12, a soda lime filter 11, and contact elements 3, 4, 5, 6, 7 with a patient's respiratory system, which are preferably an inspiratory valve 3 connected to an 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 respiratory circuit section comprises an external ventilator 14, configured to generate the inspiratory and expiratory cycles that drive the bellows 12 when inserting air in the hood 13.

[032] The breathing circuit section also includes a manual breathing system, which has a balloon 10, a pressure limit valve 9 and a switch switch 8, also called the balloon / fan switch.

[033] During operation, the gas mixture passes through vaporizer 2, which can be a simple anesthetic evaporator that vaporizes a predetermined amount of liquid to the quantity of gases, in order to provide the respiratory circuit with the exact concentration of anesthetic, adjusted by the anesthetist, in the form of a flow of a mixture of gases, or a flow of fresh gases 23.

[034] In this circuit, the gas exhaled by the patient is directed into the bellows 12, which is a passive element, mounted inside the bell 13. During exhalation, the gases from the patient's lungs are expelled by the Y 5 piece to the expiatory branch 6, also passing through the expiratory valve 7 and thus reaching the bellows 12, which inflates (rises) with the entry of the expired gas. During inspiration, a propulsion gas is injected into the bell 13 outside the bellows 12 by means of the external fan 14, deflating the bellows 12 (driving the gas from the inside of the bellows 12 downwards), thus forming the flow of the mixture of gases that passes through the carbon dioxide filter 11, for the removal of carbon dioxide, and is then directed to the patient through the inspiratory valve 3, the inspiratory branch 4 and the Y-piece 5. Depending on the position of the switch 8, the flow of the gas mixture can also be created through the manual actuation of inflating or deflating the balloon 10. In this way, the entire flow of the gas mixture is created and directed by the balloon 10 or the external fan 14.

[035] Figures 2 to 5 illustrate a representation of the preferred embodiment of the present invention, which still comprises at least one rotameter 1, connected to the anesthetic vaporizer 2, the elements of contact 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 switch switch 8, the pressure limit valve 9, the balloon 10 and the soda lime filter 11, preferably a soda lime filter soda lime. Unlike the state of the art, the present invention comprises a turbine 18, which can be a turbine used in respirators, and a long laminar flow tube 19, in addition to possibly comprising 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.

[036] Thus, the anesthesia device according to the present invention continues to have two modes of operation: the first being the balloon mode 10 (switch switch 8 in the "balloon" position), which is used in the induction phase, ie , to perform manual ventilation, and the turbine 18 mode (switch 8 in the "turbine" position), for automatic mechanical ventilation, in which the turbine 18 creates the flow of gases containing a specific gas mixture towards the respiratory system of the patient, and is used in the phase of maintaining the patient's state of anesthesia. Obviously, the switch 8 can be a simple control valve, which directs the flow to the balloon 10, interrupting the flow through the turbine 18, and vice versa.

[037] Figure 2 illustrates the inspiratory phase of ventilation in balloon 10 mode, where switching valve 8 is open for balloon 10. In this phase, the anesthesiologist compresses balloon 10, and the contents of balloon 10 are propelled towards the filter. carbon dioxide 11. It is also provided for a one-way valve 17, which prevents the flow of air to the turbine 18. Additionally, the expiratory 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 rest of the gas is propelled towards the patient, passing through the inspiratory valve 3 and entering the lung through the expiatory branch 4 and the part in Y 5. As the expiratory valve 7 remains closed, air enters the patient's lung due to the pressure generated by the compression of the balloon 10.

[038] Figure 3 illustrates the expiatory phase of ventilation in balloon mode, where switching valve 8 is still open for balloon 10. In this phase, the anesthetist releases the balloon 10, allowing the air flow containing the mixture of gases to enter the balloon 10. It is also foreseen the existence of a one-way valve 22, so that the lung gas flows directly to the balloon 10 and remains there. In this phase, the expiratory valve 7 remains open and the inspiratory valve 3 remains closed, and the expired gas goes towards the expiratory valve 7 through the Y-piece 5 and the expiatory branch 6.

[039] Additionally, a pressure relief valve 9 is provided, which opens when reaching the adjusted inspiratory pressure at each cycle. In addition, there is an increase in gas volume, through the addition of more gas mixture from rotameter 1 and anesthetic vaporizer 2, as a fresh gas flow 23. Thus, the fresh gas flow 23 enters the circuit respiratory tract, both in the inspiratory and expiratory phases. In part, this increase in gas volume compensates for the reduction in volume due to the absorption of carbon dioxide by the carbon dioxide filter, however, for safety, the flow of fresh gas 23 is adjusted to be slightly higher than the absorption of carbon dioxide, and the excess is eliminated by the pressure relief valve 9.

[040] Figure 4 illustrates the inspiratory phase in turbine 18 mode. In this mode, switching valve 8 is open for turbine 18 and closed for balloon 10. In this inspiration 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 the flow of fresh gas is added 23. In this way, the air flow it goes through the inspiratory branch 4 until it reaches the Y-5 piece, inflating the patient's lung. It is also provided that the turbine mode 18 is controlled by a microprocessor, which remains on, and keeps a linear actuator 16 energized, closing a pressure control valve 15, configured in order to prevent the flow of gases through the expiratory branch 6 at a pressure greater than a pressure determined by the linear actuator 16, that is, the pressure control valve 15 determines that the positive pressure in the lung rises until it reaches a limit pressure value adjusted by the anesthesiologist.

[041] Figure 5 illustrates the expiratory phase in turbine mode 18. In this mode, switching valve 8 is open for turbine 18 and closed for balloon 10. In this phase, the microprocessor can reduce the electric current in actuator 16, and the valve pressure controller 15 opens, letting the lung gas out, thus limiting the pressure. The expired gas exits through the expiratory branch 6, and, as the turbine 18 is turned off, the gas flows through the long duct 19 of laminar flow, displacing the remaining gas in the duct until it exits through the mouthpiece of an anti-pollution system 24, for disposal of the excess gas.

[042] After this phase, the cycle is repeated, and on the new inspiration the turbine 18 is turned on, and the gas accumulated in the long duct 19 of laminar flow is aspirated. To prevent external air from entering the circuit by diluting the anesthetic gas, the long laminar flow duct 19 is dimensioned in such a way that the tidal volume is always less than the volume accumulated in the long laminar flow duct 19, and the volume increased by the the amount of fresh gas entering continuously is sufficient to expel the excess gas volume from the circuit with a speed greater than the diffusion of the gas mixture in the anesthetic gas, inside the long laminar flow duct 19. It is worth remembering that the lung volume of patients varies with their height and weight, having on average a tidal volume of less than 1 liter. Thus, the volume of the long duct 19 of laminar flow can be of the order of 1.5 liters, being greater than the tidal volume of the lung, but without allowing the stagnation of the gas mixture. In this way, the long duct 19 of laminar flow presents the role of a reservoir in contact with the external air, allowing the exchange of gases, in which, within the long duct 19 of laminar flow, an exact point for the exchange of gases, which is displaced upwards during inspiration, but should not reach the end of the long laminar flow duct 19, as this would enter the respiratory circuit.

[043] Thus the present invention describes a breathing circuit for anesthesia devices that with few construction elements, decreasing the production and maintenance costs. In addition, the anesthesia device according to the present invention can be built in a small physical space, increasing the useful space of the operating rooms.

[044] Anesthesia devices constructed in accordance with the present invention also comprise an easy gas exchange, that is, a continuous flow of the gas mixture without stagnation points in the entire path of the circuit, allowing greater control of the concentration of gases and an improvement in the control of residual pressure in the lungs of anesthetized patients.

[045] Another advantage of the invention is that the unique volume in the respiratory circuit, derived from the long tube reservoir 19 of laminar flow, is located at the outlet of the excess gas so that, at the end of the anesthesia section, the entire contents of the mixture of gases containing the anesthetic substance can be replaced by a gas completely without anesthetic, in a single respiratory cycle, starting very quickly the process of leaving the patient from general anesthesia.

[046] 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 possible equivalents therein.

Claims (4)

1. Anesthesia device comprising at least one rotameter (1) connected to an anesthetic vaporizer (2), which is connected to contact elements (3, 4, 5, 6, 7) with a patient's respiratory system, which are connected to a switch 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 device being characterized by the fact that it also comprises a turbine (18) connected to the carbon dioxide filter (11), the balloon (10) and a long tube reservoir (19), which is connected to the switch switch (8), the switch switch (8 ) being configured to select between the balloon (10) and the turbine (18) in order to create a flow of a mixture of gases towards the patient's respiratory system, the long tube reservoir (19) being in contact with external air . 2. Anesthesia device according to claim 1, characterized in that the contact elements (3, 4, 5, 6, 7) of 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 (5) in contact with the inspiratory branch (4), the expiatory branch (6) and the patient's respiratory system. 3. Anesthesia device according to claim 1, characterized by the fact that it also comprises a linear actuator (16) that controls a pressure control valve (15), the pressure valve (15) being configured in order to prevent the flow of the gas mixture flows through the expiratory branch (6) at a pressure greater than a pressure determined by the linear actuator (16). 4. Anesthesia device according to claim 1, characterized in that the carbon dioxide filter (11) is a soda lime filter.

Images