Patent Description:
During some medical procedures, such as surgical procedures, a patient may be placed under general anesthesia by administrating 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 before flowing to the patient, where they may be introduced via inhalation, for example, via a mask or breathing tube.

It may be desirable to ensure that the anesthetic vaporizer does not unintentionally emit anesthetic gases to the surrounding environment during operation and during storage. For example, anesthetic gases may escape from various coupling locations within the anesthetic vaporizer. Similarly, it may be desirable to ensure that the anesthetic vaporizer functions as intended so that a dosage of the anesthetic agent provided to the patient is controlled.

"<NPL> relates to a portable medical vaporizer and to a technique for detecting excessive physical shock to portable medical vaporizer.

<NPL> describes that inhalational anaesthetic agents are used for induction and maintenance of general anaesthesia. Inhalational agents have been developed and refined to suit changing anaesthetic requirements.

In one aspect, a method for an anesthetic vaporizer comprises determining a quantitative acceleration of the anesthetic vaporizer based on acceleration vectors measured by an accelerometer coupled within the anesthetic vaporizer, and outputting an alert responsive to the quantitative acceleration exceeding an acceleration threshold. In this way, drop-related degradation may be more easily identified, thus reducing usage of anesthetic vaporizers that may have degraded functionality.

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:.

Embodiments of the present disclosure will now be described, by way of example, with reference to the <FIG>, which relate to various embodiments for detecting drop-related degradation of an anesthetic vaporizer. Anesthetic gases of an anesthetic agent may be intentionally generated for delivery to a patient using an anesthetic vaporizer included in an anesthesia machine. However, in some examples, the anesthetic vaporizer may become degraded due to mishandling, for example, or not being properly secured during transport. As a result, the anesthetic vaporizer may not be able to connect appropriately to the anesthesia machine and/or may not be able to deliver the anesthetic gases at an intended concentration. As another example, the degradation may result in the anesthetic vaporizer emitting the anesthetic agent while the anesthetic vaporizer is not in use, such as when the anesthetic vaporizer is unpowered.

Currently available anesthetic vaporizers do not have the capability to actively monitor for degradation that may be caused by drops or falls of the anesthetic vaporizer. As a result, healthcare professionals using or storing the anesthesia machine may not be alerted to leaks or other functional issues. Because the anesthetic gases may diffuse into the environment surrounding the anesthesia machine, healthcare professionals may be unintentionally exposed to the anesthetic agent. Overall, the anesthetic gases may decrease air quality in the environment surrounding the anesthesia machine. Further, the patient may not receive an intended dose of the anesthetic gases.

Thus, embodiments described herein include a method and system for alerting an operator of the anesthetic vaporizer to detected drops and impacts of the anesthetic vaporizer that may result in degradation of the anesthetic vaporizer. For example, the system may include an accelerometer that records acceleration vectors even while the anesthetic vaporizer is unpowered. While the anesthetic vaporizer is powered, a controller may receive the recorded acceleration vectors and trigger an alert (e.g., alarm) if the anesthetic vaporizer has experienced unacceptable acceleration that may result in degradation of the anesthetic vaporizer.

The embodiments disclosed herein may provide several advantages. For example, the alert may enable medical personnel to identify and isolate potentially degraded equipment, allowing the medical personnel to proactively manage air quality in the clinical environment as well as effectively provide anesthetic gases to a patient. As an example, the alarming anesthetic vaporizer may not be used until it is evaluated for degradation by a qualified technician. Further, by actively monitoring a direction of the acceleration, anesthetic vaporizer repair may be expedited. Further still, by actively monitoring for drops that may result in anesthetic vaporizer degradation, unwanted vapors may be removed from the clinical environment, increasing air quality. Overall, by providing an active alerting system, the medical personnel may have increased confidence that a non-alarming anesthetic vaporizer has not undergone an unacceptable fall.

<FIG> schematically shows an embodiment of an anesthesia machine. <FIG> shows an embodiment of an anesthetic vaporizer that may be included in the anesthesia machine of <FIG>. In particular, the anesthetic vaporizer includes a battery-operated accelerometer that records acceleration vectors even while the anesthetic vaporizer is powered off. <FIG> shows an exemplary method for identifying unacceptable drops and rough handling of the anesthetic vaporizer of <FIG> based on the acceleration vectors recorded by the accelerometer and outputting an alarm in response. Thus, methods and systems are provided for reducing unidentified drop-related anesthetic vaporizer degradation, thereby reducing inadvertent healthcare professional exposure to anesthetic gases and increasing patient anesthetic dosage accuracy.

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 embodiments, 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 example embodiment 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 embodiment 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 embodiments, 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 pressure-limiting 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 embodiments, 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 embodiments, 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 computer-readable medium and may be configured to store computer executable code (e.g., instructions) 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 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 embodiments, 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 exemplary embodiment of an anesthetic vaporizer <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 embodiment shown in <FIG>, the anesthetic vaporizer <NUM> is a bubble-through anesthetic vaporizer, including a vaporizing chamber <NUM> defined by a housing <NUM>. However, in other embodiments, the anesthetic vaporizer <NUM> may be another type of anesthetic vaporizer (e.g., flow-over, inj ector-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 (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 embodiments, 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 embodiments, the sump <NUM> may be a sealed system when the fill cap is in place. In some embodiments, 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 embodiment, 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 embodiments, 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. 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 exemplary embodiment of <FIG>, a second gas passage <NUM> branches off from first gas passage to provide carrier gas to the vaporizing chamber <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 embodiments, 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 embodiments where a different type of anesthetic vaporizer architecture is used (e.g., a flow over type or a gas/vapor blender). Thus, the embodiment 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> and form a junction with the first gas passage <NUM> to fluidically couple the upper portion of the vaporizing chamber <NUM> with the first gas passage <NUM>. Upstream of the junction with the third gas passage <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 vapor from the vaporizing chamber <NUM>, containing the carrier gas saturated with the vaporized anesthetic agent, mix at and downstream of the junction between the first gas passage <NUM> and the third gas passage <NUM>. The 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 embodiments, a concentration sensor <NUM> may be coupled to first gas passage <NUM> downstream of the junction with third gas passage <NUM>. The concentration sensor <NUM> may be any suitable sensor that is configured to measure a concentration of the anesthetic agent in the mixed gas. As one example, the concentration sensor <NUM> may be an optical sensor 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 concentration sensor may be a carbon dioxide or oxygen sensor that measures 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 concentration sensor <NUM> may output a signal 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.

The anesthetic vaporizer <NUM> further includes an accelerometer <NUM> coupled within the external housing <NUM>. The accelerometer <NUM> may comprise a three-axis accelerometer, which may provide information about the orientation and motion of the anesthetic vaporizer <NUM>. The accelerometer <NUM> may be rigidly affixed to a surface within the anesthetic vaporizer <NUM> (e.g., within the external housing <NUM>) so that the accelerometer <NUM> does not move independently from the anesthetic vaporizer <NUM> as a whole. The accelerometer <NUM> may be used to calculate an orientation of the anesthetic vaporizer <NUM> as well as acceleration. For example, the three axes of the accelerometer <NUM> may generate an acceleration vector that will be resolved within the controller <NUM> to determine a quantitative acceleration that the anesthetic vaporizer <NUM> experienced as well as the direction of the acceleration, as will be elaborated below with respect to <FIG>.

The accelerometer <NUM> includes a power source <NUM>. The power source <NUM> may be a battery, such as a coin battery. The power source <NUM> provides continuous electrical power to the accelerometer <NUM> independently from the other components of the anesthetic vaporizer <NUM>. That is, the power source <NUM> only powers the accelerometer <NUM>, and thus the accelerometer <NUM> remains powered on and active even while the remaining components of the anesthetic vaporizer <NUM>, including the controller <NUM>, are powered off. For example, the controller <NUM>, the pump <NUM>, and other electronic components of the anesthetic vaporizer <NUM> receive electrical power from a system power source <NUM>, which is distinct from and not electrically coupled to the power source <NUM>, when the anesthetic vaporizer <NUM> is powered on. For example, at least a portion of the system power source <NUM> may be exterior to the external housing <NUM>. When the anesthetic vaporizer <NUM> is not powered on, the anesthetic vaporizer <NUM> may be powered off and may not be receiving electrical power from the system power source <NUM>. The system power source <NUM> may be a battery (e.g., a rechargeable battery), an electrical grid (e.g., accessed via a plug), a solar power grid, etc. The controller <NUM> may receive acceleration vectors that were recorded by the accelerometer <NUM> while the controller <NUM> was powered off upon power up (e.g., in response to a start-up operation of the anesthetic vaporizer <NUM>), for example.

In addition to receiving signals output by the concentration sensor <NUM> and the accelerometer <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. Additionally or alternatively, the one or more additional sensors <NUM> may comprise a gyroscope, a level sensor, a touch sensor, and an ultrasonic leak sensor. For example, the gyroscope may measure an angular velocity of the anesthetic vaporizer <NUM>, which may be used by the controller <NUM> in combination with data from the accelerometer <NUM> to determine tilt. Combining information from the gyroscope with information from the accelerometer <NUM> may result in a more accurate quantification of tilt, for example. As another example, in addition to using the level sensor to determine agent levels in the sump <NUM> during use, the level sensor may be activated in response to an acceleration measured by the accelerometer <NUM> exceeding a drop threshold in order to monitor the agent level in the sump <NUM> after the drop has occurred. Doing so may help identify if the drop caused degradation to components holding the liquid anesthetic agent <NUM>. Identifying the drop based on the output of the accelerometer <NUM> will be further described below with respect to <FIG>. As still another example, the touch sensor may be positioned on the external housing <NUM> and may be used to identify if and where the anesthetic vaporizer <NUM> was being held prior to the drop. For example, the touch sensor may detect that the anesthetic vaporizer <NUM> is being held on two opposing faces when the drop occurs, suggesting that a user was carrying the anesthetic vaporizer <NUM> when it was dropped. As yet another example, the ultrasonic leak detector may be used to listen for ultrasonic leaks within the anesthetic vaporizer <NUM> following a detected drop. For example, in response to the acceleration measured by the accelerometer <NUM> exceeding the drop threshold, the anesthetic vaporizer <NUM> may be pressurized (e.g., via a blower), and the ultrasonic leak detector may be activated to listen for leakage of the pressurized air from the anesthetic vaporizer <NUM>. Doing so may help identify if degradation of the anesthetic vaporizer <NUM> has occurred during the drop.

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. Additionally, the controller <NUM> may output an alert 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 unacceptable drop or fall. 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.

The controller <NUM> may further communicate with an inventory management system <NUM> that is external to the anesthetic vaporizer <NUM>. For example, the inventory management system <NUM> may be remote from the anesthetic vaporizer <NUM>, such as in a different location within a hospital. The inventory management system <NUM> may track a maintenance status, usage statistics, etc. of the anesthetic vaporizer <NUM> as well as other medical equipment within a medical facility. As one example, the controller <NUM> may communicate with the inventory management system <NUM> via wireless communication, such as via WiFi, Bluetooth, or near-field communication (NFC) protocols. For example, the controller <NUM> may transmit information regarding unacceptable drop detections to the inventory management system <NUM>, as will be elaborated below with respect to <FIG>.

The conduit <NUM>, the shut-off valve <NUM>, the pump <NUM>, the first gas passage <NUM>, the second gas passage <NUM>, the third gas passage <NUM>, and the liquid return line <NUM> may all include seal sites that may potentially become degraded during drops or mishandling. For example, the conduit <NUM>, the shut-off valve <NUM>, the pump <NUM>, and the liquid return line <NUM> may be included in a pneumatic coupling system between the sump <NUM> and the vaporizing chamber <NUM>. As an example, degradation of the seal sites may result in unintended emission of the anesthetic agent into the surrounding environment. As another example, degradation may result in decreased functionality of the anesthetic vaporizer. As still another example, the sight glass <NUM> may shatter or crack. As such, it may be desired to preemptively identify events such as falls and drops that may result in the degradation of the anesthetic vaporizer <NUM> so that timely inspection and any repairs may be performed before the vaporizer is attempted to be used for patient care.

Thus, <FIG> shows a flow chart of an example method <NUM> for detecting unacceptable acceleration and impact 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., the accelerometer <NUM> of <FIG>). Further, the controller may output information to an operator of the anesthesia machine via a human-machine interface (e.g., the HMI <NUM> of <FIG>).

At <NUM>, the method <NUM> includes receiving measurements from the accelerometer of the anesthetic vaporizer upon start-up. As described above with respect to <FIG>, the accelerometer may be a three-axis accelerometer that includes a separate power source from the anesthetic vaporizer. Thus, the accelerometer may record measurements in each of the three axes while the anesthetic vaporizer is powered down and then send the recorded measurements to the controller during a starting operation of the anesthetic vaporizer (e.g., in response to the anesthetic vaporizer being powered on from an unpowered state).

At <NUM>, the method <NUM> includes calculating a quantitative acceleration from the measurements received from the accelerometer. For example, the acceleration measurements from the three axes may be resolved into an acceleration vector that has a magnitude and a direction. As one example, the controller may resolve the quantitative acceleration using a root sum squared method. That is, the three-axis accelerometer may acquire acceleration measurements in each axis (x, y, z) of three-dimensional space, and the resulting quantitative acceleration may be calculated by inputting the three acceleration measurements into a root sum squared equation: <MAT> where x is the x-axis acceleration, y is the y-axis acceleration, and z is the z-axis acceleration. As an illustrative example, the measured x-axis acceleration may be <NUM> milligravities (mG), the measured y-axis acceleration may be <NUM>, and the measured z-axis acceleration may be <NUM>, resulting in a resolved vector magnitude of <NUM>.

The angle of each measurement from the origin of the accelerometer axes may be determined by: <MAT> where axis measurement is the measured acceleration for a single axis (x, y, or z) and resolved vector is determined using the root sum squared equation, as shown above. Continuing the illustrative example, the x-axis angle would be <NUM> degrees, the y-axis angle would be <NUM> degrees, and the z-axis angle would be <NUM>. The three angles enable the overall direction of the resolved acceleration vector to be defined in three-dimensional space.

At <NUM>, the method <NUM> includes determining an orientation of the anesthetic vaporizer during the acceleration from the measurements. For example, the direction of the resolved acceleration vector may be used to determine the orientation of the anesthetic vaporizer during the acceleration. For example, the origin of the accelerometer may be associated with a known orientation of the anesthetic vaporizer. Further, the controller may have pre-programmed knowledge of the direction of each axis of the accelerometer with respect to the faces of the anesthetic vaporizer. As such, the controller may infer which face (e.g., side, top, or bottom) of the anesthetic vaporizer may have impacted with another surface, such as the ground.

At <NUM>, the method <NUM> includes selecting an acceleration threshold based on the determined orientation. For example, some surfaces of the anesthetic vaporizer may become more easily degraded than others, such as where a sight glass is positioned. As another example, fragile internal components (or those more easily degraded) may be positioned more toward one surface of the anesthetic vaporizer relative to others. As such, the acceleration threshold may vary based on the determined orientation. As one example, the controller may select from a plurality of acceleration thresholds stored in memory, with each of the plurality of acceleration thresholds corresponding to a different direction of the acceleration (and thus, a different surface and orientation of the anesthetic vaporizer that undergoes impact). For example, the plurality of acceleration thresholds may be stored as an array or matrix, and the controller may input the determined orientation (or direction of the acceleration vector) into the array or matrix, which may output the corresponding acceleration threshold to use. As another example, the controller may adjust the acceleration threshold by a pre-determined amount based on the determined orientation, such as by increasing the acceleration threshold for orientations that are less prone to degradation and/or decreasing the acceleration threshold for orientations that are more prone to degradation.

Each acceleration threshold corresponds to a pre-determined acceleration value (e.g., in g-force) above which drop-related degradation is expected. For example, each acceleration value may further correspond to a threshold drop height above which evaluation for impact-related degradation is recommended before the anesthetic vaporizer is used for patient care. As discussed above, the threshold drop height may vary for each possible orientation of the anesthetic vaporizer at impact.

At <NUM>, the method <NUM> includes determining if the quantitative acceleration is greater than the selected acceleration threshold. For example, the controller may directly compare the quantitative acceleration (e.g., the magnitude of the resolved acceleration vector, as determined at <NUM>) to the selected acceleration threshold (e.g., as selected at <NUM>) to determine if the quantitative acceleration is greater than the selected acceleration threshold.

In response to the quantitative acceleration being greater than the selected acceleration threshold, the method <NUM> proceeds to <NUM> and includes outputting a drop alert. The drop alert 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 regarding the detected drop, including the quantitative (e.g., total) acceleration experienced and the determined orientation off the anesthetic vaporizer during the acceleration. In some examples, the drop alert may further include information regarding each individually measured acceleration vector comprising the quantitative acceleration, a number of the individually measured acceleration vectors comprising the quantitative acceleration, etc. For example, multiple smaller accelerations may result in a same quantitative acceleration as a single larger acceleration, and an amount of degradation expected may be different for the multiple smaller accelerations relative to the single larger acceleration. Similarly, the visual alert may include a drop alert symbol output via a display screen of the HMI, flashing lights, and/or a text-based message. For example, the text-based message may include information regarding the detected drop, including the determined orientation off the anesthetic vaporizer during the acceleration.

At <NUM>, the method <NUM> includes communicating the drop alert to an inventory management system, which may be the inventory management system <NUM> of <FIG>, for example. For example, the controller may communicate the drop alert to the inventory management system via WiFi, NFC, or another wired or wireless communication protocol. The inventory management system may track drop statistics, a maintenance status, a usage status, etc. of the anesthetic vaporizer as well as settings of the anesthetic vaporizer during use.

At <NUM>, the method <NUM> optionally includes disabling the anesthetic vaporizer. For example, the controller may prevent the anesthetic vaporizer from being operated so that the anesthetic vaporizer may not be used until maintenance or inspection is performed and logged with the controller. As such, a likelihood that a degraded anesthetic vaporizer is used for patient care may be reduced. As a result, unintentional emission of the anesthetic agent to the environment may be reduced, and an accuracy of anesthetic agent delivery to a patient may be increased. However, in other embodiments of the method <NUM>, <NUM> may be omitted, and a user may instead voluntarily choose to not use the anesthetic vaporizer based on the drop alarm.

At <NUM>, the method <NUM> optionally includes outputting maintenance guidance based on the determined orientation. For example, the controller may communicate the maintenance guidance to the operator via the HMI and may further output the maintenance guidance to the inventory management system. In some embodiments, the maintenance guidance may include an audible message. In other embodiments, the maintenance guidance may additionally or alternatively include a visual message. The message may include information regarding particular components that are the most likely to be degraded due to the orientation of the anesthetic vaporizer at impact. For example, the maintenance guidance may include an inspection checklist so that the anesthetic vaporizer may be more efficiently inspected and/or repaired, thus reducing a down-time of the anesthetic vaporizer. As one example, the inspection checklist may be selected from a plurality of pre-determined inspection checklists based on the determined orientation of the anesthetic vaporizer at impact. However, in other embodiments of the method <NUM>, <NUM> may be omitted.

The method <NUM> may then end. For example, the method <NUM> may be repeated at every start-up of the anesthetic vaporizer and at a pre-determined frequency while the anesthetic vaporizer is powered "on" in order to continue checking for drops and mishandling of the anesthetic vaporizer.

Returning to <NUM>, in response to the quantitative acceleration not being greater than the selected acceleration threshold (e.g., the quantitative acceleration is less than or equal to the selected acceleration threshold), the method <NUM> proceeds to <NUM> and includes not outputting the drop alert. For example, even if non-zero acceleration was experienced, it is not expected to degrade the anesthetic vaporizer because it is less than the selected acceleration threshold. As such, the operator may not be alerted.

At <NUM>, the method <NUM> includes receiving measurements from the accelerometer during anesthetic vaporizer usage. As such, the accelerometer may record data not only while the anesthetic vaporizer is powered down, but while the anesthetic vaporizer is in use. The accelerometer may transmit the measurements to the controller in real-time while the anesthetic vaporizer is powered on. As used herein, the term "real-time" may refer to simultaneous or substantially simultaneous detection and processing. As another example, the term "real-time" may refer to a process executed without intentional delay.

At <NUM>, the method <NUM> includes determining a tilt of the anesthetic vaporizer in real-time from the received real-time measurements during the anesthetic vaporizer usage. For example, the measurements received from the accelerometer may be used to determine a real-time orientation of the anesthetic vaporizer, which may be used to determine the real-time tilt. In embodiments where a gyroscope is included in the anesthetic vaporizer, the controller may also receive real-time measurements of angular velocity from the gyroscope and determine the real-time tilt based on both of the real-time orientation determined from the accelerometer measurements and the angular velocity. The tilt of the anesthetic vaporizer may be an angle of the anesthetic vaporizer relative to a desired position defined as <NUM>° of tilt. For example, the desired position may be an orientation where a bottom surface of the anesthetic vaporizer is parallel to (e.g., level with) a ground surface and closer to the ground surface than a top surface of the anesthetic vaporizer. As an example, the anesthetic vaporizer may become tilted during use during patient transport.

At <NUM>, the method <NUM> includes determining if the tilt is greater than a tilt threshold. The tilt threshold may be a non-zero value stored in the memory of the controller above which the anesthetic vaporizer may not function as intended. As a non-limiting example, the tilt threshold may be <NUM>° from the desired position. However, in other examples, the tilt threshold may be less than or greater than <NUM>° from the desired position.

If the tilt is not greater than the tilt threshold, the method <NUM> proceeds to <NUM> and includes not outputting a tilt alert. As such, even if the anesthetic vaporizer is moved or jostled, the operator will not be alerted because the movement is not expected to affect anesthetic vaporizer function. The method <NUM> may then end.

Returning to <NUM>, in response to the tilt being greater than the tilt threshold, the method <NUM> proceeds to <NUM> and includes outputting a tilt alert. The tilt alert may be output by the HMI, for example, as an audible and/or visual alert. 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 regarding the detected tilt, including a direction or degree of the tilt. Similarly, the visual alert may include a tilt alert symbol output via the display screen of the HMI, flashing lights, and/or a text-based message. For example, the text-based message may include the information regarding the detected tilt mentioned above. Further, the tilt alert may be a second type of alert that is different than the drop alert, which may be a first type of alert. The tilt alert may be further communicated to the inventory management system. The method <NUM> may then end.

Thus, the methods and systems described herein provide for detecting unacceptable drops, falls, and mishandling of an anesthetic vaporizer. As a result, an air quality in the environment surrounding the anesthetic vaporizer, such as in a surgical suite or other medical facility, may be increased. Further, inadvertent exposure of medical professionals to anesthetic gases may be decreased, and silent leaks within the anesthetic vaporizer may be determined, enabling maintenance of the anesthetic vaporizer to be prompted. Further still, an accuracy of anesthetic agent delivery to a patient may be increased by alerting operators to potential fall-related degradation as well as when the anesthetic vaporizer becomes tilted during use. Additionally, servicing of the anesthetic vaporizer may be expedited, resulting in reduced down-time of the anesthetic vaporizer.

A technical effect of measuring acceleration vectors of an anesthetic vaporizer and outputting an alert in response to a quantitative acceleration exceeding a threshold is that an operator may be alerted to impact-related degradation of the anesthetic vaporizer that may be otherwise unnoticed.

The disclosure also provides support for a method for an anesthetic vaporizer, comprising: determining a quantitative acceleration of the anesthetic vaporizer based on acceleration vectors measured by an accelerometer coupled within the anesthetic vaporizer, and outputting an alert responsive to the quantitative acceleration exceeding an acceleration threshold. In a first example of the method, the method further comprises: determining an orientation of the anesthetic vaporizer during the quantitative acceleration based on the acceleration vectors, and wherein the acceleration threshold is selected from a plurality of acceleration thresholds based on the determined orientation. In a second example of the method, optionally including the first example, each of the plurality of acceleration thresholds corresponds to a threshold drop height for each possible orientation of the anesthetic vaporizer. In a third example of the method, optionally including one or both of the first and second examples, the method further comprises: outputting maintenance guidance based on the determined orientation in response to the quantitative acceleration exceeding the acceleration threshold. In a fourth example of the method, optionally including one or more or each of the first through third examples, the alert includes information regarding the determined orientation and the quantitative acceleration. In a fifth example of the method, optionally including one or more or each of the first through fourth examples, the accelerometer is powered by a separate power source from the anesthetic vaporizer, and wherein determining the quantitative acceleration of the anesthetic vaporizer based on the acceleration vectors measured by the accelerometer coupled within the anesthetic vaporizer is responsive to the anesthetic vaporizer being powered on. In a sixth example of the method, optionally including one or more or each of the first through fifth examples, the acceleration vectors measured by the accelerometer coupled within the anesthetic vaporizer are measured while the anesthetic vaporizer is unpowered, and wherein the alert includes one or both of an audible alert and a visual alert. In a seventh example of the method, optionally including one or more or each of the first through sixth examples, the method further comprises: disabling usage of the anesthetic vaporizer in response to the quantitative acceleration exceeding the acceleration threshold and communicating the alert to an inventory management system. In an eighth example of the method, optionally including one or more or each of the first through seventh examples, the method further comprises: communicating the alert and a magnitude of each of the acceleration vectors to an inventory management system via a wireless communication protocol in response to the quantitative acceleration exceeding the acceleration threshold. In a ninth example of the method, optionally including one or more or each of the first through eighth examples, the method further comprises: determining a tilt of the anesthetic vaporizer during usage based on measurements received in real-time from the accelerometer coupled within the accelerometer, and outputting a tilt alert in response to the tilt of the anesthetic vaporizer exceeding a threshold tilt.

The disclosure also provides support for a system for an anesthetic vaporizer, comprising: an accelerometer positioned within an external housing of the anesthetic vaporizer, and a controller storing executable instructions in non-transitory memory that, when executed, cause the controller to: receive measurements from the accelerometer recorded while the anesthetic vaporizer is powered off, resolve a quantitative acceleration from the received measurements, determine an orientation of the anesthetic vaporizer from the received measurements, and output a first type of alert in response to the quantitative acceleration exceeding an acceleration threshold. In a first example of the system, the controller includes further instructions stored in the non-transitory memory that, when executed, cause the controller to: select the acceleration threshold from a plurality of different acceleration thresholds stored in the non-transitory memory based on the determined orientation. In a second example of the system, optionally including the first example, the system further comprises: a first power source that provides continuous electrical power to the accelerometer and a second power source that provides electrical power to the controller while the anesthetic vaporizer is powered on and not while the anesthetic vaporizer is powered off. In a third example of the system, optionally including one or both of the first and second examples, the controller includes further instructions stored in the non-transitory memory that, when executed, cause the controller to: receive real-time measurements from the accelerometer while the anesthetic vaporizer is powered on, determine a real-time tilt of the anesthetic vaporizer based on the real-time measurements received from the accelerometer, and output a second type of alert in response to the real-time tilt exceeding a tilt threshold.

The disclosure also provides support for a method for detecting a fall of an anesthetic vaporizer, comprising: upon start-up of the anesthetic vaporizer, receiving acceleration measurements recorded by an accelerometer coupled within the anesthetic vaporizer while the anesthetic vaporizer is powered off, determining a magnitude and direction of an acceleration vector from the acceleration measurements, selecting an acceleration threshold based on the direction of the acceleration vector, and outputting a drop alert in response to the magnitude of the acceleration vector exceeding the acceleration threshold. In a first example of the method, selecting the acceleration threshold based on the direction of the acceleration vector comprises inputting the direction of the acceleration vector into an array storing a plurality of acceleration thresholds, each of the plurality of acceleration thresholds corresponding to a different direction of the acceleration vector. In a second example of the method, optionally including the first example, the drop alert comprises an audible alarm. In a third example of the method, optionally including one or both of the first and second examples, the method further comprises: disabling the anesthetic vaporizer in response to the magnitude of the acceleration vector exceeding the acceleration threshold, and not disabling the anesthetic vaporizer in response to the magnitude of the acceleration vector not exceeding the acceleration threshold. In a fourth example of the method, optionally including one or more or each of the first through third examples, the method further comprises: outputting an inspection checklist in response to the magnitude of the acceleration vector exceeding the acceleration threshold. In a fifth example of the method, optionally including one or more or each of the first through fourth examples, the inspection checklist is selected from a plurality of different inspection checklists based on the direction of the acceleration vector, and wherein both of the drop alert and the inspection checklist are communicated to an inventory management system via wireless communication.

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.

Claim 1:
A method for an anesthetic vaporizer (<NUM>), comprising:
determining (<NUM>) a quantitative acceleration of the anesthetic vaporizer (<NUM>) based on acceleration vectors measured by an accelerometer (<NUM>) coupled within the anesthetic vaporizer (<NUM>),
determining (<NUM>) an orientation of the anesthetic vaporizer (<NUM>) during the quantitative acceleration based on the acceleration vectors; and
outputting (<NUM>) an alert responsive to the quantitative acceleration exceeding an acceleration threshold, wherein the acceleration threshold is selected (<NUM>) from a plurality of acceleration thresholds based on the determined orientation.