Patent Description:
During some medical procedures, such as surgical procedures, a patient may be placed under general anesthesia by administration of an anesthetic agent. In some examples, the anesthetic agent may be a volatile anesthetic agent that is administered to the patient via an anesthetic vaporizer. For example, the anesthetic vaporizer may induce and control vaporization of the volatile anesthetic agent from a liquid form. A carrier gas (e.g., a mixture of oxygen and fresh air) may flow into the vaporizer and blend (e.g., mix and converge) with the anesthetic agent vapors generated by the vaporizer. An amount of carrier gas flowing into the vaporizer may be adjusted by an operator of the vaporizer (e.g., an anesthesiologist) in order to adjust a ratio of carrier gas to anesthetic agents within the vaporizer. The mixed gases may then flow to the patient, where they may be introduced via inhalation, for example. The concentration of the anesthetic agent in the mixed gases may be controlled to ensure sufficient anesthetic agent is provided for patient comfort without compromising patient safety.

In <CIT>, systems and methods are provided for delivering anesthetic agent to a patient. In one example, an anesthetic vaporizer includes a housing defining a sump, the sump configured to hold a self-contained supply of liquid anesthetic agent, a heating element electrically coupled to an electrical mating component, a gas inlet passage and a gas outlet passage, a manifold fluidically coupled to the gas inlet passage and the gas outlet passage, the manifold coupled to the housing and forming a gas-tight seal with the sump, and a quick disconnect pneumatic system coupled to the gas inlet passage and the gas outlet passage, sealing the gas inlet passage and the gas outlet passage from atmosphere.

The following documents are also disclosing anesthetic mixer, namely <CIT> and <CIT>.

In one aspect, a system for a vaporizer gas mixer may include a one-piece body; a gas inlet and a gas outlet; a first flow path fluidically coupled to the gas inlet and the gas outlet, the first flow path having a plurality of curves; and a second flow path fluidically coupled to the first flow path and a vaporizing chamber, wherein the first flow path and the second flow path merge after the gas inlet passage and before the plurality of curves. In this way, by using in-plane and out-of-plane mixing features, homogeneous gas mixing in a short distance is achieved.

It should be understood that the brief description above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the
detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.

The present disclosure will be better understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:.

Aspects of the present disclosure will now be described, by way of example, with reference to the <FIG>, which relate to mixing gas in an anesthetic vaporizer. Anesthetic gases of an anesthetic agent (also herein referred to as an agent or anesthetic gas) may be intentionally generated for delivery to a patient using an anesthetic vaporizer included in an anesthesia machine. Anesthesia vaporizers often mix with medical gas (e.g., purified fresh air, O<NUM> rich air) anesthetic gases having significantly larger molecular weights (e.g., <NUM> ~ <NUM> times heavier than air or O<NUM>). Additionally, anesthetic vaporizers often mix gases having a large dynamic flow range from very low laminar flow to high velocity turbulent flow. Dynamic and verifiable response to user adjustments and precise feedback control may constrain mixing the agent with the medical gas over short mixing lengths. Competing interests in achieving the desired operation include the preference for homogenous mixing, and mixing minimal pressure loss through the gas mixer to prevent error in reading anesthetic agent concentration, limited pressure available in the system, and limited packaging space including between a vaporizing chamber and vaporizer housing (the components above and below the mixture that limits space).

Some fluid (e.g., gas, liquid) mixing methods include corkscrew static mixing. Within a pipe for example, as the mixture of gases flow around a corner, the velocity on the outside radius increases causing the pressure to decrease to balance energy. When the flow reaches a <NUM> degree turn (e.g., a corner), a pressure difference between the inner radius and the outer radius of the pipe generates rotating flow and increases mixture. Corkscrew static mixing, however, may be less effective when one or more of the gases is very heavy, and in some examples, the heavier gas may centrifuge out of mixture. Another strategy for mixing fluids includes the use of serpentine flow paths (e.g., s-turns or s-curves). Serpentine flow paths include an advantage of attraction of heavier gases to the outside wall of the flow path (e.g., in a pipe). Following an s-turn, the heavier gas will cross through the center line of the flow path to get to the outside wall. Back and forth crossing through the center line mixes the gases of different densities. In some examples, s-turns may increase within layer mixing but not between layer mixing (e.g., stratified in a laminar flow regime). With enough length, heavier gases may mix by diffusion. However, in constrained space (e.g., short mixing length), additional strategies to provide homogenous mixing may be desirable. In some examples, introducing baffles (e.g., obstacles to flow) may increase gas mixing. However, baffles have a disadvantage of reducing pressure in a system.

Thus, according to the examples described herein, a gas mixer for an anesthetic vaporizer system that may be included in an anesthesia machine is provided. Examples of the gas mixer disclosed herein include a non-straight, sinuous three-dimensional mixing path to achieve efficient mixing over a short distance.

Examples disclosed herein may include a one-piece body. The one-piece body may include a gas inlet and a gas outlet. The one-piece body may also include a first flow path fluidically coupled to the gas inlet passage and the gas outlet passage, and a second flow path fluidically coupled to the first flow path. Further, the one-piece body may include a vaporizing chamber. According to other examples, the body may include two or more pieces that are rigidly attached.

The examples described herein may further include the first flow path and the second flow path having gas flows combined after the gas inlet and before a plurality of curves. In one example, the three-dimensional mixing path (or mixing path) uses in-plane mixing, out-of-plane mixing, and/or rotation to enable homogenous mixing over short mixing length. In an example with both in-plane and out-of-plane mixing, it may be advantageous to have a first set of curves in the passage only provide in-plane mixing, and a second set of curves in the passage only provide out-of-plane mixing. Such a configuration takes advantage of limited passage length to provide mixing of different gas density gasses in a more predictable way.

In-plane mixing may be encouraged by the use of a first mixing passage including at least two s-curves in-plane with respect to a gas inlet passage and a gas outlet passage of the system (e.g., X-Y plane in <FIG>). The first mixing passage includes a circular cross-section for generating rotational flow around the corner or turn to encourage out-of-plane mixing. Out-of-plane mixing is further encouraged by use of a second mixing passage including a curve configured as an out-of-plane turn with respect to the gas inlet passage and the gas outlet passage. The out-of-plane turn, incorporated in another plane (e.g., the Y-Z plane of <FIG>) perpendicular to the plane of the in-plane mixing, breaks up laminar layers that may form in the Y-Z plane such as in low flow fluids (e.g., low Reynolds number [RE] flows). The plurality of curves generated by the sinuous path of the mixing passages encourages anesthetic agent and medical gas mixture via momentum.

An amount of agent in a mixed gas may be controlled by adjusting a valve positioned between the vaporizing chamber and a valve seat of the gas mixer, the adjustment based on a signal difference measured at a first sensor assembly and a second sensor assembly. The examples described herein further include a method for operating feedback control for adjusting the agent concentration of mixed gas delivery based on sensor signals and generating an indication alerting an operator of the anesthetic vaporizer to detected difference in expected agent concentration.

The examples disclosed herein may provide several advantages. For example, the examples disclosed mix gases over a large dynamic flow range quickly, homogeneously, and with reduced pressure drop over a short mixing length. The thorough mixing with reduced pressure drop enables the use of point concentration sensors for determining agent concentration in the mixed gas. Point concentration sensors may be small, solid state devices, allowing for size reductions in package design. Given particular positioning and packaging constraints in the overall system, in-plane and out-of-plane mixing are provided in short distance while also still meeting packaging constraints and sensing requirements before and after the mixing. Moreover, achieving homogenous mixture over a short mixing length reduces system response lag allowing for more precise agent delivery and automatic feedback control.

<FIG> schematically shows an example of an anesthesia machine. <FIG> shows an example of an anesthetic vaporizer that may be included in the anesthesia machine of <FIG>. In particular, the anesthetic vaporizer includes a gas mixer in electronic communication with a control unit via a first sensor assembly and a second sensor assembly that determine an amount of agent in a mixed gas, and a valve for actuating a flow of agent from a vaporizing chamber to the gas mixer. <FIG> shows a perspective view of an exemplary embodiment of a gas mixer, which may be included in the anesthetic vaporizer of <FIG>. <FIG> is a first cross-section illustrating an example of a gas flow path for a gas mixer. <FIG> is a second cross-section illustrating an example of a seat for a valve and flow path access for point sensors for a gas mixer. <FIG> show a third cross-section illustrating an example of a gas flow path for a gas mixer. <FIG> schematically shows an example of a first mixing passage including in-plane s-curves. <FIG> schematically shows gas flow rotation around a circular bend, such as described with respect to an aspect of the first mixing passage. <FIG> schematically shows an aspect of a second mixing passage including a curve configured as an out-of-plane turn. <FIG> shows an example method for controlling an agent concentration of mixed gas in an anesthetic vaporizer based on a signal difference measured at a first sensor assembly and a second sensor assembly. Thus, methods and systems are provided for homogenous mixing of gases over a short mixing length enabling dynamic and precise feedback control.

Turning now to the figures, <FIG> schematically shows an example anesthesia machine <NUM>. The anesthesia machine <NUM> includes a frame (or housing) <NUM>. In some examples, the frame <NUM> may be supported by casters, where the movement of the casters may be controlled (e.g., stopped) by one or more locks. In some examples, the frame <NUM> may be formed of a plastic material (e.g., polypropylene). In other examples, the frame <NUM> may be formed of a different type of material (e.g., metal, such as steel).

The anesthesia machine <NUM> also includes an anesthesia display device <NUM>, a patient monitoring display device <NUM>, a respiratory gas module <NUM>, one or more patient monitoring modules, such as a patient monitoring module <NUM>, a ventilator <NUM> (explained in more detail below), an anesthetic vaporizer <NUM>, and an anesthetic agent storage bay <NUM>. The anesthesia machine <NUM> may further include a main power indicator <NUM>, a system activation switch <NUM> (which, in one example, permits gas flow when activated), an oxygen flush button <NUM>, and an oxygen control <NUM>. An aspect of the anesthetic vaporizer <NUM> will be described below with respect to <FIG>. The anesthetic vaporizer <NUM> may vaporize the anesthetic agent and combine the vaporized anesthetic agent with one or more medical grade gases (e.g., oxygen, air, nitrous oxide, or combinations thereof), which may then be delivered to a patient.

The anesthesia machine <NUM> may additionally include an integrated suction, an auxiliary oxygen flow control, and various other components for providing and/or controlling a flow of the one or more medical grade gases to the patient. In the example shown, the anesthesia machine <NUM> includes one or more pipeline connections <NUM> to facilitate coupling of the anesthesia machine to pipeline gas sources. Additionally, the anesthesia machine <NUM> includes a cylinder yoke <NUM>, via which one or more gas-holding cylinders <NUM> may be coupled to the anesthesia machine. Thus, through the pipeline connection and/or cylinder connections, gas may be provided to the anesthesia machine, where the gas may include (but is not limited to) medical air, oxygen, nitrogen, and nitrous oxide. The gas that enters the anesthesia machine may mix with the vaporized anesthetic agent at the anesthetic vaporizer <NUM>, as described above, before being supplied to a patient via ventilator <NUM>. The anesthesia machine may also include a serial port, a collection bottle connection, and a cylinder wrench storage area. Further, in some examples, the anesthesia machine may include an anesthesia gas scavenging system <NUM>.

The ventilator <NUM> may include an expiratory check valve at an expiratory port <NUM>, an expiratory flow sensor at the expiratory port <NUM>, an inspiratory check valve at an inspiratory port <NUM>, an inspiratory flow sensor at the inspiratory port <NUM>, an absorber canister, a manual bag port, a ventilator release, an adjustable pressurelimiting valve, a bag/vent switch, and a bellows assembly. When a patient breathing circuit is coupled to the ventilator <NUM>, breathing gases (e.g., air, oxygen, and/or nitrous oxide mixed with vaporized anesthetic agent) exit the anesthesia machine from the inspiratory port <NUM> and travel to the patient. Expiratory gases from the patient re-enter the anesthesia machine via expiratory port <NUM>, where carbon dioxide may be removed from the expiratory gases via absorber canister.

During operation of the anesthetic vaporizer <NUM>, an operator (e.g., an anesthesiologist) may adjust an amount of vaporized anesthetic agent that is supplied to the patient by adjusting a flow rate of gases from the gas source(s) (e.g., the pipeline gas supply) to the vaporizer. The flow rate of the gases from the gas source to the vaporizer may be adjusted by the operator via one or more flow adjustment devices. For example, the flow adjustment devices may include analog and/or digital adjustment dials and/or other user input devices configured to actuate one or more flow control valves of the anesthesia machine <NUM>. In some examples, a first flow control valve may be positioned between the gas source(s) and the anesthetic vaporizer <NUM> and may be actuatable via flow adjustment devices to a fully open position, a fully closed position, and a plurality of positions between the fully open position and the fully closed position.

The anesthesia machine <NUM> may additionally include one or more valves configured to bypass gases from the gas source(s) around the anesthetic vaporizer <NUM>. The valves may enable a first portion of gases to flow directly from the gas source to the inspiratory port <NUM> and a second portion of gases to flow from the gas source through the anesthetic vaporizer <NUM> to mix with the vaporized anesthetic agents prior to flowing to the inspiratory port <NUM>. By adjusting a ratio of the first portion of gases relative to the second portion of gases, the operator may control a concentration of vaporized anesthetic agent administered to the patient via inspiratory port <NUM>.

Further, the adjustments described above may be facilitated at least in part based on output from the respiratory gas module <NUM>. The respiratory gas module <NUM> may be configured to measure various parameters of the gases exiting the vaporizer and/or being provided to the patient. For example, the respiratory gas module <NUM> may measure the concentrations of carbon dioxide, nitrous oxide, and the anesthetic agent provided to the patient. Further, the respiratory gas module <NUM> may measure respiration rate, minimum alveolar concentration, patient oxygen, and/or other parameters. The output from the respiratory gas module <NUM> may be displayed via a graphical user interface on a display device (e.g., the anesthesia display device <NUM> and/or the patient monitoring display device <NUM>) and/or used by a controller to provide closed-loop feedback control of the amount of anesthesia provided to the patient.

The ventilator <NUM> may optionally be coupled to a breathing circuit (not shown) including a plurality of tubes (e.g., gas passages) <NUM>. The breathing circuit may be coupled between an airway of a patient (e.g., via a breathing mask positioned to enclose the mouth and/or nose of the patient or a tracheal intubation tube) and the inspiratory port <NUM>. Gases (e.g., the one or more medical gases, or a mixture of the one or more medical gases and vaporized anesthetic agent from the anesthetic vaporizer <NUM>) may flow from the inspiratory port <NUM>, through the breathing circuit, and into the airway of the patient, where the gases are absorbed by the lungs of the patient. By adjusting the concentration of vaporized anesthetic agent in the gases as described above, the operator may adjust a degree to which the patient is anesthetized.

During conditions in which the breathing circuit is coupled to the airway, the anesthetic agent and/or fresh gas (without the anesthetic agent) may flow into the airway of the patient (e.g., through inhalation) via inspiratory port <NUM> and the inspiratory check valve. As an example, the inspiratory check valve may open automatically (e.g., without input or adjustment by the operator) in response to inhalation by the patient and may close automatically in response to exhalation by the patient. Similarly, the expiratory check valve may open automatically in response to exhalation by the patient and may close automatically in response to inhalation by the patient.

In some examples, the operator may additionally or alternatively control one or more operating parameters of the anesthesia machine <NUM> via an electronic controller <NUM> of the anesthesia machine <NUM>. The controller <NUM> includes a processor operatively connected to a memory. The memory may be a non-transitory computerreadable medium and may be configured to store executable instructions, e.g., computer executable code, to be processed by the processor in order to execute one or more routines, such as those described herein. The memory may also be configured to store data received by the processor. The controller <NUM> may be communicatively coupled (e.g., via wired or wireless connections) to one or more external or remote computing devices, such as a hospital computing system, and may be configured to send and receive various information, such as electronic medical record information, procedure information, and so forth. The controller <NUM> may also be electronically coupled to various other components of the anesthesia machine <NUM>, such as the anesthetic vaporizer <NUM>, the ventilator <NUM>, the respiratory gas module <NUM>, the anesthesia display device <NUM>, and the patient monitoring display device <NUM>.

The controller <NUM> receives signals from the various sensors of the anesthesia machine <NUM> and employs the various actuators of the anesthesia machine <NUM> to adjust operation of the anesthesia machine <NUM> based on the received signals and instructions stored on the memory of the controller. For example, the flow of gases to the inspiratory port <NUM> may be controlled via an input device (e.g., keyboard, touchscreen, etc.) coupled to the electronic controller of the anesthesia machine <NUM>. The controller <NUM> may display operating parameters of the anesthesia machine <NUM> via anesthesia display device <NUM> and/or the patient monitoring display device <NUM>. The controller may receive signals (e.g., electrical signals) via input device and may adjust operating parameters of the anesthesia machine <NUM> in response (e.g., responsive) to the received signals.

As one example, the operator may input a desired concentration of the anesthetic agent to be delivered to the patient. A corresponding valve position of one or more valves of the anesthesia machine (e.g., a position of one or more bypass valves, as described above) may be empirically determined and stored in a predetermined lookup table or function in a memory of the controller. For example, the controller may receive the desired concentration of the anesthetic agent via an input device and may determine an amount of opening of the one or more valves corresponding to the desired concentration of the anesthetic agent based on the lookup table, with the input being the concentration of the anesthetic agent and the output being the valve position of the one or more valves. The controller may transmit an electrical signal to an actuator of the one or more valves in order to adjust each of the one or more valves to the corresponding output valve position. In some examples, the controller may compare the desired flow rate of gases to a measured flow rate of gases, such as measured by the inspiratory flow sensor, for example.

The controller <NUM> is shown in <FIG> for illustrative purposes, and it is to be understood that controller <NUM> may be located in various locations within, around, and/or remote from the anesthesia machine <NUM>. As an example, the controller <NUM> may include multiple devices/modules that may be distributed throughout the anesthesia machine <NUM>. As such, the controller <NUM> may include a plurality of controllers at various locations within the anesthesia machine <NUM>. As another example, additionally or alternatively, the controller <NUM> may include one or more devices/modules that are external to the anesthesia machine <NUM>, located proximate to (e.g., in a same room) or remote (e.g., at a remote server) from the anesthesia machine <NUM>. In each example, the multiple devices/modules may be communicatively coupled through wired and/or wireless connections.

Anesthetic vaporizers, such as the anesthetic vaporizer <NUM> shown in <FIG>, may employ various methods to vaporize a liquid anesthetic agent. For example, the anesthetic vaporizer <NUM> may use a flow-over method (in which a carrier gas flows over a top surface of a volatile liquid anesthetic agent), a bubble-through method (in which the carrier gas is bubbled up through the liquid anesthetic agent), or a gas/vapor blender (in which heat is used to vaporize the liquid anesthetic agent, and the vapors are injected into a fresh gas flow). Regardless of the vaporization method, in some examples, the anesthetic vaporizer <NUM> may include a sump for storing the liquid anesthetic agent before it is delivered to a vaporizing chamber.

<FIG> shows an aspect of an anesthetic vaporizer <NUM> including a vaporizer gas mixer or gas mixer <NUM>, which may be included in an anesthesia machine (e.g., the anesthesia machine <NUM> shown in <FIG>). As one example, the anesthetic vaporizer <NUM> may be the anesthetic vaporizer <NUM> of <FIG>. In the example, the anesthetic vaporizer <NUM> is a bubble-through anesthetic vaporizer, including an anesthetic source or vaporizing chamber <NUM> defined by a housing <NUM>. However, in other examples, the anesthetic vaporizer <NUM> may be another type of anesthetic vaporizer (e.g., flow-over, injector-based, wick-based, etc.) for use with a volatile liquid anesthetic agent, and the bubble-through architecture is shown for illustrative purposes.

A lower portion of the vaporizing chamber <NUM> is shown holding a liquid anesthetic agent <NUM> that is supplied from a sump <NUM> via a conduit <NUM> and a pump <NUM>. The liquid anesthetic agent <NUM> may be isoflurane, sevoflurane, or another liquid anesthetic agent of similar volatility, for example, that is stored in the sump <NUM>. The pump <NUM> may be a positive displacement pump, such as a reciprocating positive displacement pump, for example. The pump <NUM> may be selectively operated to deliver the liquid anesthetic agent <NUM> from the sump <NUM> to the vaporizing chamber <NUM> in response to a command signal from a controller <NUM>, as will be further described below. The controller <NUM> may be an electronic controller including a processor operatively connected to a memory <NUM>, which may be a non-transitory memory (e.g., read-only memory) that stores instructions executable by the processor. The controller <NUM> may be included in (e.g., a part of) or communicatively coupled to the controller <NUM> shown in <FIG>, for example.

The sump <NUM> is defined by a housing <NUM>. The housing <NUM> and the housing <NUM> may be integrated with or positioned with an external housing <NUM> of the anesthetic vaporizer <NUM>. For example, the pump <NUM>, the conduit <NUM>, etc. may be internal components within the external housing <NUM>. The sump <NUM> may be refilled via a filler apparatus <NUM> positioned on an exterior of the housing <NUM> and the housing <NUM>. The filler apparatus <NUM> includes a filler port <NUM>. In some examples, the filler apparatus <NUM> may further include a fill cap (not shown in <FIG>) configured to cover the filler port <NUM> when a refilling event is not occurring. For example, an operator of the anesthetic vaporizer <NUM> may remove the fill cap to refill the sump <NUM> with additional liquid anesthetic agent <NUM> (e.g., from a refill bottle) via the filler port <NUM> and then replace the fill cap to seal the sump <NUM>. The fill cap may be a screw cap, for example. Thus, in some examples, the sump <NUM> may be a sealed system when the fill cap is in place. In some examples, a sight glass <NUM> may enable the operator to evaluate a fill status of the sump <NUM>.

The conduit <NUM> may further include a shut-off valve <NUM> coupled between the pump <NUM> and the vaporizing chamber <NUM>. For example, the shut-off valve <NUM> may be an on-off valve, wherein the shut-off valve <NUM> is actuated to an open (e.g., fully open) position that allows the liquid anesthetic agent <NUM> to flow between and the pump <NUM> and the vaporizing chamber <NUM> or a closed (e.g., fully closed) position that prevents (e.g., blocks) the flow of the liquid anesthetic agent <NUM> between the pump <NUM> and the vaporizing chamber <NUM>. The shut-off valve <NUM> may be actuated between the open and closed positions in response to a command signal from the controller <NUM>, for example. A liquid return line <NUM> may be coupled to the conduit <NUM> between the shut-off valve <NUM> and the pump <NUM> to reduce a pressure build-up between the shut-off valve <NUM> and the pump <NUM>, such as when the shut-off valve <NUM> is closed. For example, an excess amount of the liquid anesthetic agent <NUM> provided by the pump <NUM> may be returned to the sump <NUM> via the liquid return line <NUM>. Further, the liquid return line <NUM> may include a restriction <NUM>, such as an orifice, to control flow through the liquid return line <NUM> such that the liquid anesthetic agent <NUM> preferentially flows through the shut-off valve <NUM> instead of the restriction <NUM> when the shut-off valve <NUM> is open.

The controller <NUM> may selectively activate the pump <NUM> to provide the liquid anesthetic agent <NUM> from the sump <NUM> to the vaporizing chamber <NUM>. In one example, the controller <NUM> may adjust operation of the pump <NUM> responsive to a measurement received from a level sensor coupled to the vaporizing chamber <NUM>. As one example, the controller <NUM> may be configured to maintain the level of liquid anesthetic agent at a target level or within a target range in order to prevent both underfilling and overfilling of the vaporizing chamber <NUM>.

In some examples, the pump <NUM> may include a positive displacement stepper motor, where each positive displacement step of the pump is equivalent to a specified volume of the liquid anesthetic agent <NUM>. In this manner, the pump may be used to precisely fill the vaporizing chamber <NUM> and prevent overfilling by recording the number of pump steps delivered. This approach may also be used to record a volume of anesthetic agent delivered to the vaporizing chamber <NUM>, which may be used for vaporizer run-time/maintenance analysis (e.g., service metrics), liquid leak detection, precise determination of an amount of liquid anesthetic remaining and available for delivery, vaporization efficiency calculations, etc..

An upper portion of the vaporizing chamber <NUM> (e.g., above a surface of the liquid anesthetic agent <NUM>) holds vapor, which may be a mixture of vaporized anesthetic agent and a carrier gas from a fresh gas flow (also herein referred to as a medical gas flow). The fresh gas flow, and thus the carrier gas, may include one or more medical grade gases, such as oxygen, air, nitrous oxide, and combinations thereof. The fresh gas flow may be provided via one or more gas pipelines (e.g., via the pipeline connections <NUM> shown in <FIG>) and/or one or more gas-holding cylinders (e.g., the gas-holding cylinder <NUM> of <FIG>). As shown in <FIG>, the fresh gas flow may enter anesthetic vaporizer <NUM> via a first gas passage <NUM>.

In the example, a second gas passage <NUM> branches off from first gas passage to provide carrier gas to the vaporizing chamber <NUM>. The first gas passage enters the gas mixer <NUM> to provide bypass gas to the gas mixer. In the example, the first gas passage <NUM> from the point of gas mixer entry to gas mixer exit may also be referred to as first flow path <NUM>. As used herein, "carrier gas" refers to a portion of the fresh gas flow that flows to the vaporizing chamber <NUM>, whereas "bypass gas" refers to a remaining portion of the fresh gas flow that does not flow through the vaporizing chamber <NUM>, as will be elaborated below. For example, the second gas passage <NUM> may pass through an opening in the housing <NUM>, which may include a gas-tight seal, to flow the carrier gas through a bottom of the vaporizing chamber <NUM>. However, in other examples, the anesthetic vaporizer <NUM> may not include the second gas passage <NUM>, and the carrier gas may not be delivered to the vaporizing chamber <NUM>. For example, the carrier gas may not be delivered to the vaporizing chamber <NUM> when the liquid anesthetic agent <NUM> has a relatively low boiling point (e.g., at or around room temperature), such as when the liquid anesthetic agent <NUM> is desflurane or another liquid anesthetic agent of similar volatility. Additionally or alternatively, the second gas passage <NUM> may not be included in examples where a different type of anesthetic vaporizer architecture is used (e.g., a flow over type or a gas/vapor blender). Thus, the anesthetic vaporizer shown in <FIG> is provided by way of example.

The carrier gas delivered to the vaporizing chamber <NUM> via the second gas passage <NUM> flows through the liquid anesthetic agent <NUM> to form a plurality of gas bubbles <NUM>. The plurality of gas bubbles <NUM> pass through the liquid anesthetic agent <NUM>, becoming saturated with vaporized anesthetic agent, as they rise to the surface of the liquid. In some examples, a heating element may be coupled to or within the vaporizing chamber <NUM> to increase a temperature of the liquid anesthetic agent <NUM> and provide energy for vaporization (e.g., latent heat of vaporization).

Vapor, such as the carrier gas that is saturated with vaporized anesthetic agent, may flow out of the vaporizing chamber <NUM> via a third gas passage <NUM> (e.g., a vapor delivery passage). For example, the third gas passage <NUM> may pass through an opening at or near a top of the housing <NUM>. The third gas passage may couple to the gas mixer via valve <NUM> (e.g., proportional valve) and form a junction with first flow path <NUM> to fluidically couple the upper portion of the vaporizing chamber <NUM> with the first gas passage <NUM> including the first flow path <NUM>. In the example, the third gas passage <NUM> from valve <NUM> to the junction with first flow path <NUM> may be referred to as second flow path <NUM> (e.g., within the gas mixer). Upstream of the junction with the second flow path <NUM> and downstream of the junction with the second gas passage <NUM>, the first gas passage <NUM> carries the bypass gas portion of the fresh gas flow. The bypass gas does not pass through the vaporizing chamber <NUM>. The bypass gas, containing no vaporized anesthetic agent, and the anesthetic gas from the vaporizing chamber <NUM>, containing the carrier gas saturated with the vaporized anesthetic agent, combine within gas mixer <NUM> at and downstream of the junction between the first flow path <NUM> and the second flow path <NUM>. The combined flow e.g., mixed gas, may then be delivered to the patient via an inspiratory limb of a breathing circuit (e.g., via the inspiratory port <NUM> described with respect to <FIG>).

In some examples, the gas mixer may include a first sensor assembly <NUM> coupled to first flow path <NUM> upstream of the junction with second flow path <NUM>. The gas mixer may include a second sensor assembly <NUM> coupled to first flow path <NUM> downstream of the junction with second flow path <NUM>. The first sensor assembly may include at least a first sensor and the second sensor assembly may include at least a second sensor, the first and second sensors configured to measure a concentration of the anesthetic agent in the mixed gas. As one example, the first and second sensor assemblies may include point sensors for detecting thermal conductivity of a gas mixture. A concentration of agent in the gas mixture may be determined based on a difference in thermal conductivity measured at the first sensor assembly compared to the second sensor assembly. As another example, the first and second sensor assemblies may include one or more optical sensors that transmits light of a suitable wavelength (e.g., infrared) through the mixed gas and determines a concentration of the anesthetic agent based on an absorption of the light by the mixed gas. In other examples, the first and second sensor assemblies may include one or more carbon dioxide or oxygen sensors that measure the concentration of the anesthetic agent based on a displacement of the carbon dioxide or oxygen relative to a supplied concentration of carbon dioxide or oxygen in the fresh gas flow. The first sensor assembly <NUM> and the second sensor assembly <NUM> may output signals to the controller <NUM> indicative of the measured concentration of the anesthetic agent (e.g., the concentration of the anesthetic agent vapor) in the mixed gas.

In addition to receiving signals output by the first sensor assembly <NUM> and the second sensor assembly <NUM>, the controller <NUM> may receive additional signals, including signals from one or more additional sensors <NUM> coupled in various locations throughout the anesthetic vaporizer <NUM>. The one or more additional sensors <NUM> may comprise pressure, temperature, and volatile organic compound (VOC) sensors.

The controller <NUM> receives the signals from the various sensors of <FIG>, processes the input data, and employs the various actuators of <FIG> to adjust operation of anesthetic vaporizer <NUM> based on the received signals and instructions stored on a memory of the controller. For example, based on signals received from the first sensor assembly <NUM> and the second sensor assembly <NUM>, valve <NUM> may be adjusted to control the flow of vaporized agent into the gas mixer. Additionally, the controller <NUM> may output an indication to the operator via a human-machine interface (HMI) <NUM> that is operationally connected to the controller (e.g., via wired or wireless communication) responsive to detecting an agent concentration outside of a threshold range. Further, data may be input to the controller <NUM> by the operator of anesthetic vaporizer <NUM> via the HMI <NUM>. Thus, the HMI <NUM> may include both a user input device and an output device. The user input device may include one or more of a mouse, a keyboard, a voice input device, a touch input device for receiving a gesture from the operator, a motion input device for detecting non-touch gestures and other motions by the operator, and other comparable input devices, as well as associated processing elements capable of receiving user input from the operator. The output device may include one or more of a display (e.g., the anesthesia display device <NUM> and/or the patient monitoring display device <NUM> of <FIG>) for providing visual alerts or text-based messages and a speaker for providing audible alerts or messages.

Lag time between adjusting an amount of agent and reliable detection of the adjustment may be decreased by homogenously mixing gases over a shorter mixing length. In one example, within gas mixer <NUM>, the first flow path <NUM> may be shaped into a plurality of curves, the curves downstream from the junction with the second flow path <NUM>. The plurality of curves shaping the flow path encourages vaporized agent and bypass gas mixture via momentum. In this way, homogeneous mixture may be achieved over very short mixing length and with reduced pressure drop, enabling close proximity sensor assemblies for rapid detection of agent concentration adjustments. Additionally, reliable gas mixing over a short distance may enable more compact vaporizer design.

<FIG> shows a perspective view of an example of a gas mixer <NUM> for an anesthetic vaporizer such as the anesthetic vaporizer <NUM> illustrated in <FIG>. Gas mixer <NUM> may be the same or similar to gas mixer <NUM> of <FIG>, which may be included in an anesthesia machine (e.g., the anesthesia machine <NUM> shown in <FIG>). Gas mixer <NUM> will be described herein with reference to the systems and components depicted in <FIG> and <FIG>, though it should be understood that the gas mixer may be applied to other systems without departing from the scope of this disclosure. Components of gas mixer <NUM> that are identical to components of gas mixer <NUM> in anesthetic vaporizer <NUM> are numbered the same and will not be introduced. An axis system <NUM> is given in <FIG> and the figures following. The x-axis may be referred to as a lateral axis, the z-axis may be referred to as a vertical axis, and the y-axis may be referred to as a longitudinal axis.

Gas mixer <NUM> may include a one-piece formed body without seams, without adhesives, and without connectors. In one example, the body be formed of a plastic material. The body may also be formed from a different type of material such as metal. In one example, one-piece construction achieves homogenous mixture in a compact design, which may be advantageous for meeting packaging constraints in the overall system. Additionally, one-piece construction may be advantageous by enabling manufacturing methods such as casting or 3D printing of the gas mixer.

The body of gas mixer <NUM> may be substantially rectangular, meaning that it would be understood to be rectangular by a person skilled in the art without being perfectly rectangular. The body of the gas mixer <NUM> may further include a length greater than the width and a height approximately half the width. An upper surface <NUM> is shown may be parallel to a matching lower surface (not shown). A first side surface <NUM> is shown may be parallel to a second side surface (not shown). A front surface <NUM> is shown may be parallel to a back surface (not shown). Gas mixer <NUM> may be substantially asymmetrical along a lateral center line and a longitudinal center line.

A gas inlet <NUM> and a gas outlet <NUM> may be formed in the front surface <NUM>. A flow path fluidically couples gas inlet <NUM> and gas outlet <NUM> (shown in <FIG>). Gas inlet <NUM> is a cavity with an opening formed by inner cylindrical surface <NUM>, outer cylindrical surface <NUM>, and annular surface <NUM>. Gas outlet <NUM> is a cavity with an opening formed by inner cylindrical surface <NUM>, outer cylindrical surface <NUM>, and annular surface <NUM>. Included in a system (e.g., vaporizer <NUM> in <FIG>, vaporizer <NUM> in <FIG>), gas inlet <NUM> may couple to a source of fresh air or blended medical gas (e.g., to a mixer or gas blender via first gas passage <NUM> in <FIG>) to provide a flow of bypass gas for mixing with vaporized agent. Gas outlet <NUM> may couple to a breathing circuit (shown as plurality of tubes <NUM> in <FIG>) to provide a flow of mixed gas to a patient. Mounting point <NUM> for the gas mixer may also be formed into the front surface <NUM>. Mounting point <NUM> may be a cylinder with a shallow recess formed by an inner cylindrical surface <NUM>, outer cylindrical surface <NUM>, and annular surface <NUM>. A through-hole <NUM> may be provided for mounting. The through-hole <NUM> may be formed by an inner cylindrical surface <NUM>, an opening on the upper surface <NUM> and an opening on the lower surface (not shown).

An inlet sensor assembly mount <NUM> and outlet sensor assembly mount <NUM> may be formed in the upper surface. As one example, in a vaporizer system, an inlet sensor assembly (e.g., first sensor assembly <NUM>) and an outlet sensor assembly (e.g., second sensor assembly <NUM>) including one or more point sensors may be integrated with gas mixer <NUM> via inlet sensor assembly mount <NUM> and outlet sensor assembly mount <NUM>, respectively. Inlet sensor assembly mount <NUM> may be formed by lip <NUM> with an inner cylinder surface <NUM>, a lip top surface <NUM>, and a lip side surface <NUM>. Lip <NUM> may encircle circular depression <NUM> and pair of through-holes <NUM>, <NUM>. The pair of through-holes <NUM>, <NUM> may be used for mounting the inlet sensor assembly to the gas mixer in vaporizer system. A plurality through-holes or inlet sensor access through-holes <NUM> may be provided in circular depression <NUM>. The inlet sensor access through-holes <NUM> provide routes for sensors (e.g., point sensors) for sampling gas within the flow path upstream from the junction where vaporized agent combines in the flow path. Outlet sensor assembly mount <NUM> may be formed similarly as inlet sensor assembly mount <NUM> including a plurality of through-holes or outlet sensor access through-holes <NUM> and pair of through-holes <NUM>, <NUM> for mounting. In the example, six outlet sensor access points and six inlet sensor access points are shown. Fewer or more sensor access points may be included in other examples.

In one example, gas mixer <NUM> may include a non-straight, three-dimensional flow path for mixing medical gas with a vaporized agent. In one example, the gas mixer system may include a plurality of s-curves including at least two s-curves in-plane and at least one s-curve out-of-plane. A first plane, herein referred to as plane <NUM>, indicates a vertical plane cross-section of gas mixer bisecting the body through the gas inlet <NUM> and the gas outlet <NUM>. The cross-section is shown in <FIG> to illustrate interior passages including two in-plane s-curves (e.g., with respect to the first plane). Plane <NUM> indicates a lateral plane cross-section of the gas mixer through the inlet sensor assembly and the outlet sensor assembly. The cross-section is shown in <FIG> to illustrate an inlet of a second flow path (<NUM> in <FIG>) and interior passages. Plane <NUM> indicates a longitudinal plane cross-section through the right third of the gas mixer. The cross-section is shown in <FIG> to illustrate an out-of-plane turn in a second mixing passage.

<FIG> shows a cross-section view of an example of a flow path for gas mixer <NUM>. Gas mixer <NUM> may be the same or similar to gas mixer <NUM> of <FIG> and gas mixer <NUM> of <FIG>. Components of gas mixer <NUM> of <FIG> that are identical to components of gas mixer <NUM> and <NUM> are numbered the same and will not be reintroduced. For example, gas mixer <NUM> includes first flow path <NUM>, gas inlet <NUM>, gas outlet <NUM>, through-holes <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, and mounting point <NUM>. Further, some components of gas mixer <NUM> may not be shown, although it may be understood that they may also be included in gas mixer <NUM>.

The cross-section view of gas mixer <NUM> is shown looking into the z axis to illustrate an example of first flow path <NUM>. First flow path <NUM> is fluidically coupled to the gas inlet <NUM> and the gas outlet <NUM>. The first flow path <NUM> includes a smooth internal wall <NUM> (e.g., without protrusions or baffles). As shown in <FIG>, the gas mixer <NUM> may include in-plane passages (e.g., incorporated in the xy plane) including gas inlet passage <NUM>, gas outlet passage <NUM>, and first mixing passage <NUM> comprising two s-curves. Gas inlet passage <NUM> may be the region of first flow path <NUM> from gas inlet <NUM> until junction <NUM> with the second flow path (<NUM> in <FIG>). First mixing passage <NUM> may be a region of first flow path <NUM> from junction <NUM> until curve <NUM> takes a substantially right angled turn out-of-plane into a second mixing passage <NUM> (e.g., detailed in <FIG> and <FIG>). Junction <NUM> indicates where gas flows from the second flow path may enter to mix with gas flows entering at gas inlet <NUM> (e.g., bypass gas). Gas flows from the second flow path is shown with arrow <NUM>. Gas outlet passage <NUM> may be the region of first flow path <NUM> from curve <NUM> until gas outlet <NUM>. In one example, the interior passages of the gas mixer, including first flow path <NUM>, gas inlet passage <NUM>, first mixing passage <NUM>, second mixing passage <NUM>, gas outlet passage <NUM>, and the second flow path may be a sinuous chamber formed into the one-piece body. In one example, the first mixing passage <NUM> may be formed within a first region <NUM> and the second mixing passage <NUM> is formed within a second region <NUM>. The first region <NUM> and second region <NUM> may be a central region <NUM> of the one-piece plastic body.

Following gas inlet <NUM>, the first flow path <NUM> may enter gas inlet passage <NUM>, turning upwards approximately <NUM> degrees at curve <NUM>. After length <NUM>, gas inlet passage <NUM> may turn back approximately <NUM> degrees at curve <NUM>. After length <NUM> which may be approximately twice as long as length <NUM>, gas inlet passage <NUM> takes a <NUM> degree turn at curve <NUM>.

Following junction <NUM>, first flow path <NUM> enters first mixing passage <NUM>. In one example, the first mixing passage includes first s-curve <NUM> and second s-curve <NUM> interposed by first perpendicular length <NUM> and second perpendicular length <NUM> (perpendicular lengths so-called with respect to gas inlet passage <NUM>). First perpendicular length <NUM> and second perpendicular length <NUM> may be similar. Lengths of passage between substantially <NUM> degree bends in the first s-curve <NUM> and second s-curve <NUM> may be similar. Following first perpendicular length <NUM>, at curve <NUM>, first mixing passage <NUM> may take a substantially <NUM> degree turn into first s-curve <NUM>. After length <NUM>, first mixing passage <NUM> may take another <NUM> turn at curve <NUM>. After length <NUM>, first mixing passage <NUM> may take another <NUM> turn at curve <NUM>. After another length <NUM>, first mixing passage <NUM> may take a <NUM> turn at curve <NUM>. After another length <NUM>, at curve <NUM>, first mixing passage <NUM> may take a <NUM> degree turn into second s-curve <NUM>. After length <NUM>, first mixing passage <NUM> may take a <NUM> degree turn at curve <NUM>. After length <NUM>, first mixing passage <NUM> may take a <NUM> degree turn at curve <NUM>. After another length <NUM>, first mixing passage <NUM> may take another <NUM> turn at curve <NUM> to finish the second s-curve <NUM>. After second perpendicular length <NUM>, first mixing passage <NUM> may take a <NUM> degree turn at curve <NUM>.

At curve <NUM>, the flow path may make a <NUM> degree turn out-of-plane turn or curve into second mixing passage <NUM>. Second mixing passage <NUM> may form a U-shaped bend incorporated in the yz plane between curve <NUM> and curve <NUM>. In the xyplane, the length <NUM> separates curve <NUM> and curve <NUM>. Second mixing passage <NUM> is described in more detail in <FIG> and <FIG>. After curve <NUM>, second mixing passage <NUM> may take an in-plane <NUM> degree turn at curve <NUM>. After length <NUM>, second mixing passage <NUM> passage may take a <NUM> degree turn at curve <NUM> to the gas outlet <NUM>.

The first flow path <NUM> between gas inlet passage <NUM> and junction <NUM> may have first diameter <NUM>. The radius of curvature <NUM> at curve <NUM> is similar to first diameter <NUM>. Between curve <NUM> and curve <NUM> the diameter of first flow path <NUM> may narrow to second diameter <NUM>. The radius of curvature <NUM> at curve <NUM> may be similar to second diameter <NUM>. Following curve <NUM>, the diameter of the gas outlet passage <NUM> may widen to first diameter <NUM>. The radius of curvature <NUM> at curve <NUM> may be similar to first diameter <NUM>.

In an example, upstream from junction <NUM>, e.g., in length <NUM> of gas inlet passage <NUM> between curve <NUM> and curve <NUM>, one or more point sensors inserted through sensor access points in body of the gas mixer (e.g. inlet sensor access through-holes <NUM> in <FIG>) may sample gas in first flow path <NUM>. Sampling upstream from junction <NUM> may provide a measurement of gas content before addition of a vaporized agent via the second flow path. Downstream from second mixing passage <NUM>, e.g., in length <NUM> of gas outlet passage <NUM> between curve <NUM> and gas outlet <NUM>, one or more point sensors inserted through sensor access points in body of the gas mixer (e.g. outlet sensor access through-holes <NUM> in <FIG>) may sample gas in first flow path <NUM>. Sampling in the gas outlet passage <NUM> may provide a measurement of gas content after addition of a vaporized agent via the second flow path.

In the example shown in <FIG>, gas flows through the in-plane s-curves of first mixing passage <NUM> before flowing through the out-of-plane turn in second mixing passage <NUM>. In other examples, one or more out-of-plane turns may precede one or more s-curves. For example, an additional or alternative flow path may include a first out-of-plane turn followed by one or more in-plane s-curves.

<FIG> shows a lateral section view of an example of a gas mixer <NUM> for an anesthetic vaporizer such as the anesthetic vaporizer <NUM> illustrated in <FIG>. Gas mixer <NUM> may be the same or similar to gas mixer <NUM> of <FIG> and gas mixer <NUM> of <FIG>. Therefore, components of gas mixer <NUM> of <FIG> that are identical to components of gas mixer <NUM> of <FIG> and gas mixer <NUM> of <FIG> are numbered the same and will not be reintroduced. For example, gas mixer <NUM> includes inlet sensor assembly mount <NUM>, inlet sensor access through-holes <NUM>, outlet sensor assembly mount <NUM> and outlet sensor access through-holes <NUM>. Further, some components of gas mixer <NUM> and gas mixer <NUM> may not be shown, although it may be understood that they may also be included in gas mixer <NUM>.

The lateral section view is shown looking into the y axis to illustrate an example of valve seat <NUM> formed into gas mixer <NUM>. The view further illustrates an example of interior passages of gas mixer <NUM> including access points for sensors within gas inlet passage <NUM> and gas outlet passage <NUM> of the first flow path (<NUM> in <FIG>) and sections through first mixing passage <NUM> and second mixing passage <NUM>. Wall <NUM> illustrates a thickness of portion of gas mixer <NUM> wherein the first flow path <NUM> is formed.

A section view of gas inlet passage <NUM> of the first flow path is shown under inlet sensor assembly mount <NUM>. The section view shows the shape <NUM> of gas inlet passage <NUM>. The shape may have an upper surface <NUM> parallel in the xy plane with a lower surface <NUM> and rounded sides <NUM>, <NUM> parallel in the yz plane. The shape <NUM> of first mixing passage <NUM> may be cylindrical. The shape <NUM> of gas outlet passage <NUM> is similar to shape <NUM>. In one example, one or more sensors may be inserted through the plurality of inlet sensor access through-holes <NUM>. Such sensors may sample the gas flows within the first flow path. For example, one or more sensors sampling within the first flow path may take gas measurements before agent is added via junction <NUM> (in <FIG>). A section view of gas outlet passage <NUM> of the first flow path is shown under outlet sensor assembly mount <NUM>. In one example, one or more sensors may be inserted through the plurality of outlet sensor access through-holes <NUM> for sampling the combined flow within the first flow path after agent is mixed with medical gas or air.

Valve seat <NUM> may be a substantially cylindrical void having an opening <NUM>. The interior of valve seat <NUM> comprises a first inner cylindrical void <NUM> that is concentric with and wider in diameter than a second inner cylindrical void <NUM>. The second inner cylindrical void <NUM> meets with an annular exterior face <NUM> of the second flow path <NUM>. The annular exterior face <NUM> of the second flow path <NUM> is parallel with an annular exterior face <NUM> of the second inner cylindrical void <NUM>. An interior surface <NUM> of second flow path is shown.

Valve seat <NUM> may be a threaded valve seat for a valve (e.g., valve <NUM> in <FIG>). As one example, valve seat <NUM> may be a seat for a proportional valve. In a vaporizer system, such a valve may control a flow of vaporized agent delivered from a vaporizing chamber (e.g., vaporizing chamber <NUM> of vaporizer <NUM> in <FIG>). The vaporized agent may flow into the gas mixer via second flow path <NUM> combining with bypass gas in first mixing passage <NUM> and second mixing passage <NUM> at and downstream from junction <NUM> (in <FIG>). The valve may be adjusted to target a threshold concentration of agent, the concentration determined by comparing sensor signals sampled in the passage before and after junction <NUM>.

<FIG> shows a longitudinal section view of an example of a gas mixer <NUM> for an anesthetic vaporizer such as the anesthetic vaporizer <NUM> illustrated in <FIG>. Gas mixer <NUM> may be the same or similar to gas mixer <NUM> of <FIG>, gas mixer <NUM> of <FIG>, and gas mixer <NUM> of <FIG>. Therefore, components of gas mixer <NUM> of <FIG> that are identical to components of gas mixer <NUM> of <FIG> gas mixer <NUM> of <FIG>, and gas mixer <NUM> of <FIG> are numbered the same and will not be reintroduced.

The longitudinal view is a section through second mixing passage <NUM> and looking into the x axis. Second mixing passage <NUM> is an out-of-plane turn incorporated into the yz plane. After length <NUM>, the out-of-plane turn begins at curve <NUM> where the second mixing passage makes a <NUM> degree turn downwards from the xy plane into the yz plane. Second mixing passage <NUM> forms a U-shaped bend incorporated in the yz plane and xy plane between curve <NUM> and curve <NUM>. After vertical length <NUM>, the U-shaped bend may be formed by a substantially <NUM> degree angled curve <NUM> followed by length <NUM> in the xy plane. After length <NUM>, the passage may make a substantially <NUM> degree angled curve <NUM> upwards into the yz plane of vertical length <NUM>, mirroring curve <NUM>. At curve <NUM>, the passage makes <NUM> degree turn back into the xy plane into length <NUM>. The second mixing passage <NUM> has a first diameter <NUM>. The radius of curvature <NUM> at curve <NUM> is similar to first diameter <NUM>.

The view further illustrates an example of second flow path <NUM>. Coupled in a vaporizer system with a vaporizing chamber (e.g., vaporizing chamber <NUM> in vaporizer <NUM> of <FIG>), vaporized agent may flow into second flow path <NUM> entering the lower passage <NUM> of the second flow path before flowing through the upper passage <NUM>.

<FIG> schematically shows an example of a first mixing passage <NUM> for in-plane gas mixing. First mixing passage <NUM> may be the same or similar to first mixing passage <NUM> of gas mixer <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> described with respect to the examples shown in <FIG>, <FIG>, <FIG>, <FIG>. Components of first mixing passage <NUM> of <FIG> that are identical to components of gas mixer <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are numbered the same and will not be reintroduced.

First mixing passage <NUM> includes a first s-curve <NUM> and a second s-curve <NUM>. First s-curve <NUM> includes a first outer radius <NUM>, a second outer radius <NUM>, a first inner radius <NUM>, and a second inner radius <NUM>. Second s-curve <NUM> includes a third outer radius <NUM>, a fourth outer radius <NUM>, a third inner radius <NUM>, and a fourth inner radius <NUM>.

A first gas stream <NUM> for a heavier gas (e.g., vaporized agent) indicated with a dashed line and a second gas stream <NUM> for a mixing gas (e.g., vaporized agent and medical gas) indicated with a solid line are shown combining in first mixing passage <NUM>. Due to the density of the heavier agent, the first gas stream <NUM> driven by centrifugal forces follows the outer radius of the first mixing passage <NUM>. The in-plane turn at corner or curve <NUM> causes the first gas stream <NUM> of heavier agent to cross through the second gas stream <NUM> to follow second outer radius <NUM>. The first gas stream <NUM> and the second gas stream <NUM> cross a second time at curve <NUM> as heavier gas is drawn from the second outer radius <NUM> to the third outer radius <NUM>. The first gas stream <NUM> and the second gas stream <NUM> cross again at curve <NUM> as heavier gas is drawn from the third outer radius <NUM> to fourth outer radius <NUM>. In one example, the effect of s-curved pathway in the first mixing passage is homogenous mixture of a heavier gas with a lighter gas.

<FIG> schematically shows an example of a flow path <NUM> in cross-section <NUM> illustrating gas flow rotation around a circular bend <NUM>. Circular bend <NUM> may be the same or similar to a curve in an in-plane s-curves described with respect to the example of gas mixer <NUM>, <NUM>, <NUM>, <NUM>, <NUM> and <NUM> in <FIG>. For example, circular bend <NUM> may be the same or similar to curve <NUM> in <FIG>. A bisecting line <NUM>.

As illustrated in <FIG>, cross-section <NUM> is taken across circular bend <NUM> from A to A. The use of circular cross-section for the s-curves (or serpentine) of first mixing passage results in rotational flow around the corner. Around the corner, gas stream <NUM> is mixed by rotational flow in the outer radius <NUM> and the inner radius <NUM>, the flow rotation being caused by the difference between the inner and outer radius pressure differences. To the left of bisecting line <NUM>, gas stream <NUM> rotates counter clockwise. To the right of bisecting line <NUM>, gas stream <NUM> rotates clockwise.

<FIG> schematically shows an example of second mixing passage <NUM> for out-of-plane gas mixing. Second mixing passage <NUM> may be the same or similar to second mixing passage <NUM> of gas mixer <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> described with respect to the examples shown in <FIG>, <FIG>, <FIG>, <FIG>. Components of second mixing passage <NUM> of <FIG> that are identical to components of gas mixer <NUM>, <NUM>, <NUM>, <NUM>, and <NUM> are numbered the same and will not be reintroduced.

In some examples, such as following a corkscrew or serpentine passage, a gas stream may be mixed in a laminar flow regime such that well mixed layers form in a gradient. Gas stream <NUM> is illustrated entering the second mixing passage. Gas stream is mixed in a laminar flow regime in a gradient of percent agent before curve <NUM>. Between curve <NUM> and curve <NUM>, second mixing passage <NUM> makes an out-of-plane turn incorporated in the yz plane. The out-of-plane turn forms U-shaped bend <NUM>. As gas stream <NUM> makes the turn through U-shaped bend <NUM>, the gradient layers are broken up, shown as crossing dashed lines. After curve <NUM>, gas stream <NUM> is homogenously mixed.

<FIG> shows a flow chart of an example method <NUM> for detecting a proportion of agent to medical gas in a gas mixture of an anesthetic vaporizer of an anesthesia machine. The anesthetic vaporizer may be the anesthetic vaporizer <NUM> of <FIG>, for example. The method <NUM> and the rest of the methods included herein may be executed by a controller, such as the controller <NUM> of <FIG>, according to instructions stored in a memory of the controller (e.g., the memory <NUM> of <FIG>) and in conjunction with one or more inputs, such as inputs received from one or more sensors (e.g., sensors of the first sensor assembly <NUM> and the second sensor assembly <NUM> of <FIG>) or as inputs received from an operator via a human-machine interface (e.g., HMI <NUM>). Further, the controller may output information to an operator of the anesthesia machine via a human-machine interface.

At <NUM>, the method <NUM> includes receiving sensor signals from the anesthetic vaporizer. As described above with respect to <FIG>, point sensors for detecting thermal conductivity of a gas mixture may be integrated into the first and second sensor assemblies. At least a first point sensor integrated into the first sensor assembly may sense bypass gas in the inlet of the gas mixer. At least a second point sensor integrated into the second sensor assembly may sense mixed gas (e.g., medical gas and agent) in the outlet of the gas mixer. In an additional or alternative example, the first and second sensor assemblies may include one or more optical sensors that transmits light of a suitable wavelength (e.g., infrared) through the mixed gas and determines a concentration of the anesthetic agent based on an absorption of the light by the mixed gas. In another example, the first and second sensor assemblies may include one or more carbon dioxide or oxygen sensors that measure the concentration of the anesthetic agent based on a displacement of the carbon dioxide or oxygen relative to a supplied concentration of carbon dioxide or oxygen in the fresh gas flow.

At <NUM>, the method <NUM> includes calculating an average thermal conductivity signal from gas inlet conductivity sensors. For example, the average thermal conductivity signal may be sampled over a duration and averaged. Additionally or alternatively, the average thermal conductivity signal may be sampled at more than one sensor.

At <NUM>, the method <NUM> includes calculating an average thermal conductivity signal from gas outlet conductivity sensors. As above, the average thermal conductivity signal may be sampled over a duration and averaged and may additionally or alternatively include outlet gas mixture sampling at more than one sensor.

At <NUM>, the method <NUM> includes determining a concentration of agent in the gas mixture based on a difference in average thermal conductivity of the gas flow measured at the first sensor assembly compared to the average thermal conductivity of the gas flow at second sensor assembly. In one example, by knowing the thermal conductivity of the gases (e.g., an intrinsic property), the proportion of gases (e.g., medical gas to vaporized agent) in the mixture may be determined. The signal difference in thermal conductivity between the inlet gas mixture and the outlet gas mixture is proportional to the amount of agent in the mixture.

At <NUM>, the method <NUM> includes determining if the proportion of agent to mixed gas is within a threshold range. For example, the controller may compare the signal difference to a threshold signal difference. As one example, the controller may compare the measured thermal conductivity difference to an expected conductivity for gas with the agent at the desired concentration. The expected conductivity may be determined by reference to a look-up table.

In response to the agent to mixed gas proportion being outside of the threshold range, or in other words greater than a threshold difference, the method <NUM> proceeds to <NUM> and includes generating an indication. The indication may be output by the HMI, for example, as an audible and/or visual alert (or alarm). For example, the audible alert may include an alarm sound that is output via speakers of the HMI. Additionally or alternatively, the audible alert may include a spoken message including the concentration of agent. Similarly, the visual alert may include the concentration of agent and other instructions.

At <NUM>, the method <NUM> includes automatic adjustment of the valve to vaporized agent. For example, the controller may adjust a throttle of the vaporizer tank valve to allow more or less vaporized agent into the second mixing passage using feedback control from the point sensors integrated into the gas mixer. In other examples of the method <NUM>, at <NUM> automatic adjustment may be omitted and an operator may give instructions to the controller to adjust the amount of anesthetic agent delivered to a patient. For example, the controller may receive the desired concentration of the anesthetic agent via input device and may determine an amount of opening of one or more valves corresponding to the desired concentration of the anesthetic agent based on the lookup table, with the input being the concentration of the anesthetic agent and the output being the valve position of the one or more valves. The controller may transmit an electrical signal to an actuator of the one or more valves in order to adjust each of the one or more valves to the corresponding output valve position.

The method <NUM> may then return. For example, the method <NUM> may be repeated at throughout vaporizer operation.

Thus, the systems and methods described herein provide for homogenous mixture of gases over a very short mixing length including over a large dynamic flow range and with reduced pressure drop. As one advantage, by achieving homogenous mixture over short mixing the use of point concentration sensors may be enabled, supporting more compact vaporizer design. Moreover, the systems and methods enable quick and verifiable changes in agent concentration of delivered gas and feedback control of anesthetic gas delivery.

A technical effect of using in-plane and out-of-plane mixing to achieve homogenous mixture over a very short mixing length is more responsive control of gas mixing in an anesthesia system and reduced likelihood of patient discomfort.

The disclosure also provides support for a system for a vaporizer gas mixer comprising: a one-piece body, a gas inlet passage and a gas outlet passage, a first flow path fluidically coupled to the gas inlet passage and the gas outlet passage, the first flow path having a plurality of curves, and a second flow path fluidically coupled to the first flow path and a vaporizing chamber, wherein the first flow path and the second flow path merge after the gas inlet passage and before the plurality of curves. In a first example of the system, the plurality of curves further comprises a first mixing passage and a second mixing passage, wherein the first mixing passage comprises an s-curve in-plane with respect to the gas inlet passage and the gas outlet passage. In a second example of the system, optionally including the first example, the first mixing passage comprises at least two s-curves in-plane with respect to the gas inlet passage and the gas outlet passage. In a third example of the system, optionally including one or both of the first and second examples, the second mixing passage comprises a curve out-of-plane with respect to the gas inlet passage and the gas outlet passage. In a fourth example of the system, optionally including one or more or each of the first through third examples, gas flows from the vaporizing chamber into the second flow path is actuated by a valve. In a fifth example of the system, optionally including one or more or each of the first through fourth examples, one or more sensors are positioned in the gas inlet passage to sense gas flows in first flow path before being combined with gas flows from the second flow path. In a sixth example of the system, optionally including one or more or each of the first through fifth examples, one or more point sensors are positioned in the gas outlet passage to sense gas flows in the first flow path after being combined with gas flows in the second flow path.

The disclosure also provides support for a system, comprising: an anesthetic source of anesthetic gas, a vaporizer gas mixer having a one-piece plastic body coupled with the anesthetic source, the one-piece plastic body having a gas inlet passage and a gas outlet passage in a first plane with a flow path therebetween, the flow path having a first region curving only in the first plane and a second region curving only out of the first plane. In a first example of the system, the one-piece plastic body further coupled with a source of medical gas. In a second example of the system, optionally including the first example, anesthetic gas enters the flow path through an opening in an internal wall of the flow path, the opening positioned in the flow path before the first region and the second region. In a third example of the system, optionally including one or both of the first and second examples, gas flows from the source of medical gas enter the vaporizer gas mixer through the gas inlet passage and combines flow with the anesthetic source of anesthetic gas at and downstream from the opening, the combined flow exiting the vaporizer gas mixer through the gas outlet passage. In a fourth example of the system, optionally including one or more or each of the first through third examples, curves of the first region and the second region are in a central region of the one-piece plastic body. In a fifth example of the system, optionally including one or more or each of the first through fourth examples, the vaporizer gas mixer further having a plurality of through-holes for at least a first sensor and at least a second sensor. In a sixth example of the system, optionally including one or more or each of the first through fifth examples, the first sensor is positioned in the gas inlet passage before medical gas combines with anesthetic gas and the second sensor is positioned in the gas outlet passage after the first region and the second region of the flow path. In a seventh example of the system, optionally including one or more or each of the first through sixth examples, the second region comprises a protrusion out-of-plane of the one-piece plastic body. In an eighth example of the system, optionally including one or more or each of the first through seventh examples, the gas flows between the anesthetic source of anesthetic gas and the one-piece plastic body are controlled by an actuator. In a ninth example of the system, optionally including one or more or each of the first through eighth examples, the flow path comprises a plurality of s-curves, the first region having at least two s-curves in-plane and the second region having at least one s-curve out-of-plane. In a tenth example of the system, optionally including one or more or each of the first through ninth examples, the flow path from the gas inlet passage to the gas outlet passage comprises a smooth internal wall. In an eleventh example of the system, optionally including one or more or each of the first through tenth examples, the flow path narrows after the opening in the internal wall of the flow path and before the plurality of s-curves. In a twelfth example of the system, optionally including one or more or each of the first through eleventh examples, the system further comprises: a controller storing executable instructions in non-transitory memory that, when executed cause the controller to: receive signals from the first sensor and the second sensor, compare a signal difference of the first sensor and the second sensor to a threshold signal difference, and, responsive to identifying signal difference greater than a threshold difference, adjust the actuator controlling the flow of anesthetic gas between the anesthetic source and the one-piece plastic body.

<FIG> are shown approximately to scale. As used herein, an element or step recited in the singular and preceded with the word "a" or "an" should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. The terms "including" and "in which" are used as the plainlanguage equivalents of the respective terms "comprising" and "wherein.

As used herein, the term "substantially" is construed to mean plus or minus five percent of the range unless otherwise specified.

Claim 1:
A vaporizer gas mixer (<NUM>) having a one-piece body arranged to be coupled with an anesthetic source of anesthetic gas (<NUM>), the one-piece body having a gas inlet passage (<NUM>) and a gas outlet passage (<NUM>) in a first plane with a flow path (<NUM>) therebetween, the flow path (<NUM>) having a first region (<NUM>) curving only in the first plane and a second region (<NUM>) curving only out of the first plane, wherein the gas inlet passage (<NUM>) is arranged to be coupled with a source of medical gas (<NUM>, <NUM>) and an internal wall of the flow path has an opening (<NUM>) arranged to allow anesthetic gas from the anesthetic source of anesthetic gas (<NUM>), to enter the flow path (<NUM>), the opening being positioned in the flow path before the first region (<NUM>) and the second region (<NUM>).