Patent Application
20150068520
This disclosure relates generally to an interface device and method for supplying gas flow for subject breathing. The disclosure also relates to an apparatus for supplying anesthetic agent to the interface device.
On general inhalation anesthesia anesthetic drugs are used to keep patients experiencing surgical operation relaxed, motionless, unconscious, and free from pain. The anesthetic drugs interfere on the central nervous system for these effects. On inhalation anesthesia the anesthetic drugs are delivered with breathing gas to lungs where they get diffused to patient blood circulation. This circulation further carries the drug to the effect site in brains.
Inhalation anesthesia drugs are halogenated hydrocarbons that are delivered on administration site as liquids. These liquids are very volatile with vapor pressure at room temperature varying between 20-95 kPa. These liquids are vaporized for patient breathing in anesthesia vaporizer. The most common inhalation, anesthesia drugs are isoflurane, sevoflurane and desflurane. These have replaced the use of their predecessors, halothane and enflurane.
For various reasons preference of the agent to be used varies between patients and clinics. Conventional vaporizers are heavy devices to enclose thermal energy for the cooling caused by liquid vaporization. The devices are positioned for convenient use of the output concentration dial embedded on the device. Because of the weight and elevated position at anesthesia system, their installation may be laborious for clinical personnel. For this reason the anesthesia machines are equipped with functionality that enables easy selection of the agent to be used among those readily connected to the system. Anesthesia system accommodates therefore often two or three sockets to connect the vaporizer. Advantage of separate, anesthesia system independent module for vaporization, provides is to have functional redundancy against vaporizer failure.
In operation, vaporizer receives fresh gas, which is a mixture of oxygen, nitrogen, and nitrous oxide, and completes that with required percentage of the anesthetic drug vapor. On conventional passive vaporizers the completion occurs with vaporization of the liquid agent respective to its vapor pressure. Alternate technologies are active vaporization of liquid to gas and control of this gas flow, or controlling agent liquid flow and mixing to fresh gas stream. The prepared fresh gas is then delivered from vaporizer outlet to anesthesia breathing system for patient.
Arising from the operational principle of vaporizers, if two vaporizers would be active in anesthesia system they would both deliver the required concentration to the gas stream. Both of these drugs would then get delivered for patient breathing and circulation to effect-site both drug causing their effect resulting to doubled strength of the anesthesia effect. Clinically such situation is challenging to manage and may be dangerous. Therefore vaporizer constructional standards require mechanisms that prevents simultaneous opening of the vaporizers.
In vaporizer failure situation for provision of un-interrupted inhalation anesthesia delivery, the anesthesia system must have means to isolate the failing vaporizer from the pneumatic circuitry and continue the anesthesia with another vaporizer connected to the anesthesia system, or replace the damaged unit with an operational one. To achieve isolation, the components potentially endangered to fail are advantageously positioned to the exchangeable module and the anesthesia system has reliable means to isolate the vaporizer from the rest of the system. Isolating the vaporizer from anesthesia system pneumatic circuitry when the vaporizer is inactive also ensures that vaporizer not selected for use does not leak vapor for patient breathing. Current anesthesia systems have a valve at the vaporizer inlet connector and outlet connector. These valves can be switched to position allowing gas flow through vaporizer or bypassing the vaporizer.
One of the most sensitive components to invalidate vaporizer from use is leak of the seal between the vaporizer and the anesthesia system. Damage may occur when removing and installing the vaporizer on the anesthesia system. Identifying presence of such leak is difficult in the middle of anesthesia. Therefore the vaporizer connection is advantageously evaluated at the anesthesia system testing performed regularly. In such testing, identification of the site for observed leak is advantageous to ease problem solving. Valves on the anesthesia system isolating the seal between the vaporizer and anesthesia system provides advantage of controlled testing of the leak in this connection. In such testing one vaporizer at a time is connected to the pneumatic circuitry and the circuit leak is analyzed by pressurizing the circuit.
One particular undesired failure mode of anesthesia system is occlusion of the fresh gas line. When in use fresh gas is guided to vaporizer though inlet valve and out from the vaporizer through outlet valve. Would one of the valves connect vaporizer to fresh gas line but the other fails to make the connection, fresh gas occlusion occurs. Such failure to open only one of the valves may occur if one of the valves gets stuck or valve actuator gets broken to actuate the valve.
Modern anesthesia systems are electronic except the vaporizers where the mechanical actuation including connection valves and passive vaporization still dominates. These devices lack in performance what electronics can bring along regarding e.g. automatic therapy data storage to patient records, automated device diagnostics, drug usage measurement, monitoring remaining drug level and external control of the desired output from anesthesia system.
External electronic control of the vaporizer from anesthesia system allows positioning of the vaporizers away from the prime user interface area as well as anesthesia automation. Provision of electrical energy for vaporization miniaturizes size and weight. These enable anesthesia system use ergonomic development. Such electronic vaporizer must have also electronic control of the vaporizer connection valves to facilitate automatic vaporizer activation on user request of agent output and for automatic testing.
The above-mentioned shortcomings, disadvantages and problems are addressed herein which will be understood by reading and understanding the following specification.
In an embodiment an interface device for supplying a gas flow for subject breathing includes at least one socket for detachably connecting an apparatus for supplying anesthetic agent, and at least one gas output opening for the at least one socket for delivering the fresh gas to the apparatus. The interface device also includes at least one gas input opening for the at least one socket for receiving from the apparatus the fresh gas mixed with anesthetic agent to supply further for subject breathing, and a connection valve for the at least one socket. The interface device also includes at least four ports in flow communication with the connection valve, a first port receiving the fresh gas guided to the device, a second port providing a gas flow communication with the at least one gas output opening, a third port providing a gas flow communication with the at least one gas input opening, and a fourth port providing a gas flow communication for subject breathing, the connection valve having a first operational state disconnecting a gas flow communication between the first port and the second port, and a second operational state providing a gas flow communication besides between the first port and the second port, but also between the third port and the fourth port.
In another embodiment an apparatus for supplying anesthetic agent to an interface device, the device being configured to receive a fresh gas flow and to provide the gas flow for subject breathing, the apparatus being configured to connect detachably with the interface device, the apparatus includes a storage volume for a liquid anesthetic agent, and a space for vaporizing the liquid anesthetic agent. The apparatus also includes a gas inlet port for receiving from the device a fresh gas for mixing with vaporized anesthetic agent, and a gas outlet port for conducting the gas mixture including vaporized anesthetic agent out from the space to the interface device. The apparatus also includes an actuator for connecting the fresh gas flow through the gas inlet port and the gas outlet port and disconnecting this flow when required, the actuator being able to provide a control of the fresh gas flow through the gas inlet port and the gas outlet port by means of a single communication member extending between the apparatus and the interface device.
In yet another embodiment a method for supplying the gas flow from an interface device for subject breathing includes connecting detachably an apparatus for supplying anesthetic agent to at least one socket of the interface device, and delivering a fresh gas through at least one gas output opening of the at least one socket to the apparatus. The method also includes receiving through at least one input opening of the at least one socket from the apparatus the fresh gas mixed with anesthetic agent to provide further for subject breathing, and providing gas flow communication in the interface device between a connection valve and at least four ports, a first port receiving the fresh gas guided to the device, a second port providing a gas flow communication with the at least one gas output opening, a third port providing a gas flow communication with the at least one gas input opening, and a fourth port providing a gas flow communication for subject breathing, the connection valve having a first operational state disconnecting a gas flow communication between the first port and the second port, and a second operational state providing a gas flow communication besides between the first port and the second port, but also between the third port and the fourth port.
Various other features, objects, and advantages of the invention will be made apparent to those skilled in the art from the accompanying drawings and detailed description thereof.
Specific embodiments are explained in the following detailed description making a reference to accompanying drawings. These detailed embodiments can naturally be modified and should not limit the scope of the invention as set forth in the claims.
An anesthesia system 1 for supplying an inspiration gas to lungs of a subject shown in
In the breathing circuit 3 the fresh gas coming from the fresh gas mixer 5 and the apparatus 6 through a fresh gas outlet 18 is mixed with the re-circulated breathing gas at the circuit. During inspiration this mixture is guided through an inspiration line 8 to a branching unit 9 and further through a connection line 10 to subject lungs 4 expanding those. Expiration follows inspiration when the drive of the breathing gases into the lung is ceased. At this moment the compliant forces of the lungs pressurize the gas in the lungs. Expiration flow begins when the ventilator 2 opens an expiration control valve within the ventilator (not shown). Pressurized gas from the lungs 4 flows out through the connection line 10 to the branching unit 9 and further through an expiration line 11 to a ventilator limb 12 and to the ventilator 2. Within the ventilator the exhalation gas is advantageously at least partially preserved for the next inspiration. At the time of the next inspiration, the expiration control valve of the ventilator 2 is closed, the inspiration control valve of the ventilator (not shown) is opened to drive at least partly the previously exhaled breathing gas from the ventilator 2 back to the breathing circuit 3. Now the inspiration gas flows through a carbon dioxide (CO2) absorber 13 to remove the patient exhaled carbon dioxide before getting inhaled again and through the inspiration line 8 where the fresh gas is added along a fresh gas line 7. An expiration valve 14 and inspiration valve 15 guide the direction of rotation of the ventilation within the breathing circuit as indicated by arrows 16 and 17. The fresh gas outlet 18 may be upstream to the inspiration line, but the fresh gas outlet can be either downstream the inspiration valve 15 as presented or upstream.
The anesthesia system also includes an interface device 19 to supply the gas flow for subject breathing and to connect the apparatus 6 for supplying anesthetic agent to this interface device. The interface device 19 receiving fresh gas from the gas mixer 5 may comprise at least two sockets 20, each socket being for separate apparatus 6. Typically there is one socket for each apparatus for supplying anesthetic agent. The number of sockets is two in
The ventilator 2 may be of any type common for anesthesia ventilation. These include pressure driven ventilators where the ventilator is powered using the supply pressure guided from pressurized gas supply 28 through a line 32 as presented on
Each socket of the interface device 19 may comprise at least one gas input opening 38 to receive the gas flow from the apparatus 6 for supplying anesthetic agent to the interface device and at least one gas output opening 39 to allow the gas flow from the interface device to the apparatus 6 for supplying anesthetic agent. The interface device 19 provides for each socket 20 also a connection valve interface 40 for communication with a connection valve 70 in the interface device 19 as shown in
A schematic view of the apparatus 6 for supplying anesthetic agent vapor to breathing gas for subject breathing is shown in
The apparatus 6 may also comprise as explained hereinbefore a user interface 48, such as a dial, for entering desired targeted amount of anesthetic agent on the apparatus 6 outlet flow for controlling the operation. The user interface may also be common with other parts of the anesthesia system 1 and does not necessarily be in the same apparatus module. For this the apparatus 6 may have a communication connection 64 to communicate with corresponding connection 41 on the interface 19 of the anesthesia system 1. This connection between the apparatus and the anesthesia system may be also wireless and physical connections are then not needed. Further the apparatus 6 may comprise a logic circuit 49, such as a processing unit, to control the actuator 63 shown in
A detailed connection between the components of the interface device 19 and the components of the apparatus 6 is shown in
The interface device 19 also comprises at least four ports in flow communication with the connection valve. A first port 69 is for receiving the fresh gas flow guided to the interface device through the interface inlet 33 to the connection valve 70, a second port 80 is for providing a gas flow communication from the connection valve 70 to the at least one gas output opening 39, a third port 81 is for providing a gas flow communication from at least one gas input opening 38 to the connection valve 70 and a fourth port 82 is for providing a gas flow communication from the connection valve 70 typically through interface outlet 36 and along the fresh gas line 7 to the breathing circuit 3 for subject breathing.
As explained hereinbefore the connection valve 70 may comprise the valve member 67, such as a stem, and the valve spring 68 that forces the valve member to default position, but also it may comprise seals 72. These all may be assembled in a valve cavity 71, which is in this embodiment a longitudinal cavity, such as a tubular hole integral to the interface device 19. Each seal 72 is positioned into the valve cavity 71 crosswise to the longitudinal axis of the cavity and the seals follow with predetermined distance one after the other along a longitudinal axis of the valve cavity appropriately to provide the opening and closing of the aforementioned flow connections in both positions of the valve member 67. This positioning may be commenced using spacer rings 73 as presented in
The valve member 67 is advantageously circular stem or rod of variable thickness along its axis. The valve member, having a longitudinal axis parallel with its movement along the longitudinal axis of the valve cavity 71, may comprise at least three thick sections, which are a first thick section 85, second thick section 86 and third thick section 87. Further it may comprise at least two thin sections along the longitudinal axis of the valve member, which sections are a first thin section 88 and a second thin section 89. The first thin section 88 is between the first thick section 85 and the second thick section 86, while the second thin section 89 is between the second thick section 86 and the third thin section 87. Thus the thick and thin sections may occur alternately one after the other along the longitudinal axis of the valve member 67. Also thin and thick sections are crosswise to the longitudinal axis of the valve member 67.
The thick sections 85, 86, 87 seal against proper seals 72 when the valve member 67 is either in the first position where the connection valve is in the first operational state forced by the valve spring 68 as shown in
In the first operational state the first cavity bordering the first thin section 88 allows gas flow in the first cavity 90 from the first port 79 to the fourth port 82, when proper seals 72 are pressed towards the first thick section 85 and the second thick section 86 preventing or disconnecting the flow between the first port 79 and the second port 80 and advantageously also disconnecting the flow between the third port 81 and the fourth port 82. In the second operational state the first cavity 90 bordering the first thin section 88 allows gas flow through the first cavity 90 providing flow communication between the first port 79 and the second port 80, but the second cavity 91 bordering at least partly the second thin section 89 allows gas flow through a second cavity 91 providing flow communication between the third port 81 and the fourth port 82. The valve member movement to the direction forced by the valve spring 68 is limited with valve cap 74 having an opening for the connection valve interface 40 that the actuator mates when moving the valve member 67.
At the first operational state the gas connection from the third port 81 may be open to ambient through the leakage between the third thick section 87 and the valve cap 74 as presented on
For the apparatus logic circuit 49 it may be beneficial for proper functionality to have means to identify the position of the communication member 66. Such functionality may be needed e.g. to recognize failure to induce movement of the valve member 66 between the first operational position and the second operational position. The position may be identified with a position sensor 75. Such sensor may be optical, mechanical, or even electrical measuring the actuator current and drawing conclusion from that of the communication member movement.
In accordance with the embodiments shown hereinbefore the connection valve 70 of the apparatus 6 for supplying anesthetic agent is positioned on anesthesia system 1 outside the apparatus 6 for supplying anesthetic agent. This allows disconnection of the apparatus from the anesthesia system and also connection of the apparatus to the anesthesia system. In the embodiment the connection valve 70 is positioned on single axis of single valve member 67. This enables actuation of both the fresh gas flow from the interface device 19 to the apparatus 6 and from the apparatus to the interface device at the same time with single component movement. The valve member 67 defaults with spring-induced bias force to a position where the apparatus is disconnected from the anesthesia system pneumatic circuitry. Having both the inlet- and the outlet valve on same axis prevents the risk of fresh gas occlusion. Unifying two valves on single moving valve member 67 enables to have a single actuator 63 in the apparatus 6 with single communication member 66. This eliminates also risk of fresh gas occlusion due to failing actuator.
The written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to make and use the invention. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.
