Mechanical ventilator apparatuses and methods thereof

A ventilator apparatus includes a linear electro-mechanical actuator that interfaces with a self-inflating bag including an inlet configured to receive air and an outlet configured to expend the air. A three-way valve is coupled to the outlet via a first flowmeter, an ambient environment via a second flowmeter, and a patient via an endotracheal tube. The first and/or second flowmeters are coupled to pressure transducer(s). A control unit is coupled to the linear electro-mechanical actuator and the first and second flowmeters and includes a control panel, memory including programmed instructions stored thereon, and processor(s) configured to execute the stored programmed instructions to set an inhalation time and an exhalation time. A current inspiratory pressure and a current tidal volume are obtained from the pressure transducer(s) and/or the first flowmeter. A stroke of the linear electro-mechanical actuator is then controlled to facilitate inspiratory and expiratory phases of a respiratory cycle.

FIELD

This technology generally relates to ventilator devices and, more particularly, to mechanical ventilator apparatuses with reduced complexity for emergency deployments in clinical environments and methods thereof.

BACKGROUND

Currently available mechanical ventilators are complex medical devices that pump air and oxygen into the lungs and remove carbon dioxide, assisting patients whose lungs otherwise cannot function adequately. The most critically ill COVID-19 patients, for example, develop severe pneumonia, and often need ventilators to survive and recover. There is a dire need for ventilators in many developing countries where demand can quickly exceed limited supply.

However, current ventilators are relatively expensive, complex, and difficult and time-consuming to manufacture. In particular, current ventilators have more modes than necessary for treating limited conditions often seen in viral infections (e.g., COVID-19). Additionally, current ventilators have many parts and associated supply chain dependencies. Accordingly, current ventilators are unable to effectively meet current needs, particularly for emergency deployments to treat severe patient conditions in underserved and geographically remote populations.

SUMMARY

A ventilator apparatus is disclosed that in some examples includes a linear electro-mechanical actuator configured to operatively interface with a self-inflating bag that comprises an inlet configured to receive air and an outlet configured to expend the received air. The ventilator apparatus in these examples further includes a three-way valve coupled to the outlet of the self-inflating bag via at least a first flowmeter, an ambient environment via at least a second flowmeter, and a patient via at least an endotracheal tube. One or more of the first or second flowmeters are coupled to one or more pressure transducers. A control unit is communicably coupled to the linear electro-mechanical actuator and the first and second flowmeters and includes a control panel, memory comprising programmed instructions stored thereon, and one or more processors configured to execute the stored programmed instructions to set an inhalation time and an exhalation time based on parameter values obtained via the control panel. At least a current inspiratory pressure and a current tidal volume are obtained from one or more of the pressure transducers or the first flowmeter. A stroke of the linear electro-mechanical actuator is then selectively controlled, based on the inhalation and exhalation times and a comparison of the current inspiratory pressure and the current tidal volume with one or more of the parameter values, to facilitate inspiratory and expiratory phases of a respiratory cycle for the patient.

In another example, a method for facilitating a respiratory cycle, and implemented by a control unit of a ventilator apparatus, is disclosed that includes setting an inhalation time and an exhalation time based on obtained parameter values comprising at least an inspiratory pressure limit and a required tidal volume. At least a current inspiratory pressure and a current tidal volume are obtained from one or more pressure transducers or a first flowmeter. The first flowmeter is disposed between a self-inflating bag and a three-way valve and is coupled to one or more of the pressure transducer. A stroke of a linear electro-mechanical actuator is selectively controlled, based on the inhalation and exhalation times and a comparison of the current inspiratory pressure and the current tidal volume with one or more of the parameter values, to facilitate inspiratory and expiratory phases of a respiratory cycle for the patient.

In yet other examples, a method of making a ventilator apparatus is disclosed that includes placing a self-inflating bag into a cradle disposed within an enclosure. The self-inflating bag includes an inlet configured to receive air and an outlet configured to expend the received air. A three-way valve is coupled to the outlet of the self-inflating bag via at least a first flowmeter in an inspiratory flow path, an ambient environment via at least a second flowmeter in an expiratory flow path, and a patient via at least an endotracheal tube in the inspiratory flow path. One or more pressure transducers are inserted into one or more of the first or second flowmeters. A linear electro-mechanical actuator is then attached to the enclosure proximate the self-inflating bag. The linear electro-mechanical actuator is configured to operatively engage with, and disengage from, the self-inflating bag. A control unit is communicably coupled to the linear electro-mechanical actuator and one or more of the pressure transducers or first or second flowmeters. The control unit is configured to selectively control a stroke of the linear electro-mechanical actuator to facilitate inspiratory and expiratory phases of a respiratory cycle for a patient.

The technology disclosed herein provides an elegant, efficient, and cost-effective mechanical ventilator that requires reduced complexity and a reduced number of parts. Accordingly, the mechanical ventilator is less reliant on extensive supply chains and can be manufactured more quickly and in more remote and other environments and geographic regions in which parts may be more difficult to obtain. The mechanical ventilator can operate using ventilator circuits already in hospitals and other clinical environments to facilitate respiration for patients in emergency conditions and respiratory distress, such as due to significant viral infection.

DETAILED DESCRIPTION

Referring toFIGS.1-2, a perspective view of an exemplary ventilator apparatus100, and a flow diagram of an exemplary operation of the ventilator apparatus100, according to some examples of this technology are illustrated, respectively. The ventilator apparatus100described and illustrated by way of the examples herein is configured to operate with ventilator circuits already in hospitals and other medical environments. Examples of the ventilator apparatus100are focused on the typical need in COVID-19 and other patients with respiratory distress: operating in continuous mandatory ventilation (CMV) mode, with controllable inspiration/expiration (I/E) ratio, breaths per minute (BPM), tidal volume (TV), and inspiratory pressure limit. However, in some examples, other modes of operation can also be utilized, as described in more detail below.

The operation of the ventilator apparatus100includes mechanically compressing a self-inflating bag102(e.g., an artificial manual breathing unit (AMBU™) bag or bag included in a bag-valve-mask (BVM) device with an electro-mechanical linear actuator104. Medical grade valves, including 3-way valve200, regulate both the inspiration and expiration flow rates and ensure minimum pressures. Flowmeters202and204are used with a control unit106that can include a microcontroller programmed to regulate the flow. The control unit106permits a clinician to select key parameters via a manual control panel. A display device108is integrated into the control unit106for essential parameters as well as a graphical flow-volume diagram that serves as valuable input to the clinician to assess the performance of the ventilator apparatus100, and to gauge the current condition of the patient.

Accordingly, the ventilator apparatus100of this technology is a microcontroller-driven actuating system configured to be mated to a ventilator circuit (e.g., an FDA-approved ventilator circuit). The ventilator apparatus100includes a self-inflating bag102connectable to a ventilator hose that connects to an endotracheal tube (ETT) (not shown). The ventilator apparatus100is configured to operate in a volume control mode and can be provided to a patient who is in a sedated mode and/or a mode in which the patient is not breathing on their own. The ventilator apparatus100of this technology can advantageously operate in an emergency mode providing urgent ventilation when so indicated, as well as other modes and explained in more detail below.

The ventilator apparatus100is configured to be deployed in a monitored hospital or other clinical environment and its operation can be managed by trained clinical personnel with supportive ancillary services, for example, although other types of deployments can also be used. Traditional sensors (such as pulse oximeters, cardiac monitors, oxygen concentration, carbon dioxide concentration, etc.) are generally available in a clinical setting and could be used in conjunction with the control unit106and display device108of the ventilator apparatus100to make clinical decisions.

The ventilator apparatus100includes a housing110or enclosure that supports the self-inflating bag102in a cradle112or other types of supporting structure. The self-inflating bag102is compressed by a curved plate114, which is connected to a linear actuator104, although other types or shapes of the plate114can be used in other examples. The signal of the actuator104is determined through the control unit106that includes a microcontroller (e.g., an Arduino microcontroller). Additionally, a reservoir bag206can be disposed upstream of the self-inflating bag102.

At least one check valve208is provided (e.g., between the reservoir bag206and the self-inflating bag102) to ensure correct flow direction. A pressure relief valve210disposed proximate an outlet of the self-inflating bag102is configured to ensure that the ventilator apparatus100does not exceed a specified pressure (e.g., 35 cm of water). Flowmeters202and204are provided in the inspiratory and expiratory flow paths, respectively, to measure inspired and expired air flow, which are used by the control unit106to manage the respiratory cycle of a patient.

In this example, the ventilator apparatus100also includes pressure transducers212,214, and215, whose readings are collected for control and/or display via the display device108. An exhalation pipe (not shown) also vents to the ambient through a positive end-expiratory pressure (PEEP) valve216. The PEEP valve216is set to a particular value in order to help prevent a pneumothorax condition. The inspired flow rate is used to compute the total volume inspired for each breath and is checked against the set value of the PEEP valve216.

According, the ventilator apparatus100includes the self-inflating bag102that is “squeezed” or compressed using a linear electromechanical actuator104that depresses the constrained self-inflating bag102from one side. The length and speed of the actuator104stroke is controlled by the control unit106that allows the operator to set ventilator parameters, such as BPM and TV, as described and illustrated in more detail below. The air volume delivered to and expired from the patient is measured with flowmeters202and204, respectively.

In this example, a 3-way valve (not shown) (e.g., a 3-way-Duck valve) located on the self-inflating bag102is implemented as a flow exit with the relief valve210to prevent over-pressuring. The expiratory port (also referred to herein as an outlet or exit) on the self-inflating bag102that normally leads to a PEEP valve is plugged. A ventilator hose (not shown) can be attached to the self-inflating bag102flow exit and connects on the other end to a 3-way valve200that branches in two directions.

In particular, the 3-way valve200allows the passage of flow towards the inspiratory (i.e., patient) branch through a high-efficiency particulate air (HEPA) filter218. The expired flow from the patient is directed towards the expiratory branch via the 3-way valve200. The 3-way valve200passively opens the inspiratory flow path and closes the expiratory flow path when the vent hose delivers slightly pressurized flow from the self-inflating bag102to the 3-way valve200during the inspiratory phase. During the expiratory phase, the 3-way valve200passively opens the expiratory flow path and closes the inspiratory flow path, allowing patient exhalation.

In this particular example, the ventilator apparatus100also includes carbon dioxide (CO2) concentration and oxygen (O2) concentration sensors, referred to inFIG.2as CO2/O2 sensors220. The CO2/O2 sensors220and flowmeters202and204collectively measure and provide feedback on instantaneous inspiratory and expiratory volumetric flow rate, absolute pressure at the vent line in relatively close proximity to the patient, CO2 concentration in the expiratory flow, and O2 concentration in the expiratory flow. The CO2/O2 sensors220and flowmeters202and204in some examples are integrated into a relatively compact electronic package connected to the control unit106via a wire harness that facilitated exchange of both signals to the control unit106and power to the CO2/O2 sensors220and flowmeters202and204.

Accordingly, volumetric flow sensors or flowmeters are placed in the inspiratory and expiratory vent hoses. One or more of the flowmeters202or204can be a modified Venturi flowmeter designed to allow measurement of the flow in either direction (i.e., a bi-directional flow sensor). Flow is determined by measuring the static pressure drop from inlet to throat. The absolute pressure at the inlet and the pressure drop can be measured with pressure micro-sensors.

CO2 concentration in the expiratory vent hose is measured with a sensor that is based on principles of measuring light absorption by the CO2 in the air mixture, although other approaches for measuring CO2 concentration can be used. Operationally, it is necessary to draw a sample of air into the CO2 concentration sensor for measurement, which can be performed in real-time with a micro-pump attached to the exit of the CO2 concentration sensor. An O2 concentration sensor is also placed in the expiratory vent hose for measuring the O2 concentration.

Referring toFIG.3, a control schematic illustrating a relationship between measured pressures and temperatures and actuator control is illustrated. The thinner black lines are signal wires for transmitting control and sensor signals and the double black and white arrows represent the conversion of a physical quantity (such as air flow) into a signal. Signals can be displayed or otherwise output (e.g., to the display device108) for observation by a clinician.

Starting in the upper left corner ofFIG.3, external air enters the ventilator apparatus100. The external air flows along the line to the right, then down and to the right through an inlet check valve208, and continues to the right toward the 3-way valve located at the exit or outlet of the self-inflating bag102. A pressure relief valve210, which ensures that inspiratory air pressure does not exceed a prescribed level, is connected in parallel at this point. In one example, the pressure relief valve210is contained within a 3-way valve whose other end is plugged. The ventilator apparatus100utilizes a self-inflating bag102or BVM with the mask removed and the components of this device, such as the bulb, are connected between the inlet check valve208and the 3-way valve as illustrated inFIG.2, for example.

A second 3-way valve200, proximate the patient, allows inspiratory air flow out of the port300labelled “patient” on the 3-way valve200when pressure on the distal side of the 3-way valve200exceeds pressure on the proximal side of the 3-way valve. The inspiratory air flows through a proximal flowmeter202, a section of pipe that represents the intubation tube, and into the lungs of the patient.

The expiratory path is the reverse of the inspiratory path in this example up until the point where the air flows into the 3-way valve200. Since the expiratory or proximal pressure now exceeds the inspiratory of distal pressure, air will flow out of the port302labelled “exhaust” on the 3-way valve200, through a check valve216, and out to ambient. The lower left quadrant ofFIG.3illustrates the devices that are used for feedback control, culminating in signals labeled actuator stroke and actuator stroke rate. These signals represent the amount of compression on the self-inflating bag102, which is controlled by the length of the stroke, and the rate at which the mechanical linear actuator102will compress the resuscitator bulb.

In order to perform the volume-based control utilized in the examples of this technology described and illustrated herein, the volume-time history of the air flow delivered to the patient during the inspiration phase of a breathing cycle is measured along with the flow rate expired by the patient during the expiration phase. To facilitate this measurement, a first flowmeter202is disposed upstream of the 3-way valve200on the inspiratory line from the self-inflating bag102and a second flowmeter204is disposed on the other leg of the 3-way valve200, which connects the flow branch for the expiratory flow.

The flowmeters202and204are a variation of a Venturi style flowmeter in some examples, a cross-section of which is illustrated inFIG.4. With flow from left to right inFIG.4, the exemplary flowmeter400, which can be used for one or both of the flowmeters202and204, has a smooth flow contraction from a larger inlet area402to a smaller throat area404. In this zone, the flow accelerates from the inlet velocity to a higher velocity at the throat. The contraction is designed with a fifth order polynomial contour to prevent flow separation and assure uniform velocity at the throat. The pressure will decrease from the inlet static pressure to the static pressure at the throat, in inverse proportion to the velocity at these respective locations. The inlet velocity and volumetric flow rate can be found by measuring the static pressure drop from inlet to throat.

To obtain pressure drops in measurable ranges for the expected flows, the flowmeter400in one particular example has an inlet diameter of 18 mm and a throat diameter of 5 mm, although other dimensions can also be used. Beyond the throat, the flowmeter has a diffuser section406that allows the flow to re-expand to the exit diameter. The flowmeter400ofFIG.4has a diffuser section406cone angle of 24° and the overall length of the flowmeter400is divided into equal lengths for the contraction section with the inlet area402and throat area404, and the diffuser section406, although other configurations can also be used in other examples.

As illustrated inFIG.4, static pressure taps408and410are located at the inlet and at the throat, respectively, of the exemplary flowmeter400. Threaded hose barbs or straight stainless-steel tubes, for example, are inserted into the taps408and410to connect tubing (e.g., plastic Tygon™) to the pressure transducers212and214in the control unit106. On the inspiratory flowmeter, the upstream pressure and the pressure drop are transmitted to two separate pressure transducers212and214in order to record both the upstream gage pressure and the pressure drop. In order to connect the flowmeters202and204to ventilator hoses and/or the 3-way valve200, adapters can be used (e.g., as machined from PVC).

Referring toFIG.5, a diagram of an exemplary bi-directional flowmeter a diagram of an exemplary bi-directional flowmeter500is illustrated. The converging section502and diverging section504of the flowmeter500in this particular example can be fabricated as one section, and the inlet section506and exit section508can be fabricated as separate sections, although other fabrication methods can also be used. The flowmeter500is bi-directional as it can be used to measure the flow from left to right or right to left, which is accomplished by replacing the conical diffuser section406with a reverse Venturi nozzle510so that the flowmeter500is substantially symmetrical around the throat. In order to be used in either flow direction, the flowmeter500has pressure taps at the inlet512, at the throat514, and at the exit516.

An external view and a cross-sectional diagram of the flowmeter500in this example are illustrated inFIGS.7A-7B, respectively. In this example, continuity is provided for outer pressure taps600,602, and604formed by the hose barbs606,608, and6010and the inner pressure taps512,514, and516through the inner flowmeter500wall. The overall length of the flowmeter500in this particular example is about 5 inches (127 mm), although other lengths can also be used in other examples.

Optionally, the flowmeter(s)202or204of the ventilator apparatus100can be fabricated using a variety of methods including machining (e.g., in PVT, aluminum) and/or 3D printing (e.g., using PLA, PC-ABS, and/or ONYX materials). In this example, the flowmeter500has a central converging/diverging Venturi section and separate inlet and exit connectors. The three sections are “stacked” together and inserted into an outer PVC or steel pipe section, for example. The internal sections have a set of O-rings612that isolate the three inner pressure taps512,514, and516so that the pressure in the zone between O-rings606equilibrates to the pressure in a corresponding one of the isolated inner pressure taps512,514, or516. The outer casing614has three threaded hose barbs606,608, and610that are inserted through the casing614and terminate in each of the respective pressure taps600,602, and604without regard to alignment with the internal static pressure taps512,514, and516.

The ventilator apparatus100in this example can be configured via the control unit106to operate in a CMV mode, wherein the principal variable to be controlled is TV. The following parameters can be set using a control panel of the control unit106: I/E ratios selectable: presets 1:1, 1:2, 1:3; respiratory rate: from 10 to 30 breaths per minute in steps of 2; TV: 250-800 (50 ml increments); error tolerance of 10%; and inspiratory pressure limit: 15-40 cmH2O in steps of 5. Although in this example the following variables are not directly set, the ventilator apparatus100can be configured to interface with clinical set-ups where it is possible to set one or more of the variables: PEEP: 5-20 in no more than 5 cm steps; FiO2over the range of 21% (ambient) to 90% of the source oxygen concentration input to the ventilator apparatus100in no more than 10% steps.

The ventilator apparatus100receives signal values from the flowmeters202and204that enable it to determine inspiratory and expiratory pressures and flow rates in this example. The control panel is connected to the microcontroller and sends the set values of I/E ratio, BPM, and required TV, which is used to determine inhalation and exhalation times. Based on this data, the actuator is given a control input using a proportional-integral-derivative (PID) control law with optimized gains, for example. The sensed flow velocity is integrated to determine the TV delivered, which is used as a control variable to retract the linear actuator104when the set point is reached.

In other examples, the ventilator apparatus100can be configured via the control unit106to operate in a Synchronized Intermittent Mandatory Ventilation (SIMV) mode in which the pressure sensor (e.g., pressure transducer212) is monitored for a sudden decrease in pressure that corresponds to the patient inhaling. At that point, a PID controller maintains a constant pressure to support the patient's own breath. In yet other examples, the ventilator apparatus100can be configured for other modes of operation.

Referring toFIG.7, a block diagram of an exemplary control unit106of the ventilator apparatus100is illustrated. In this particular example, the control unit106includes processor(s)700, a memory702, a sensor interface704, an actuator interface706, a control panel708, and a display device108, which are coupled together by a bus710or other communication link, although the control unit106can include other types and/or numbers of systems, devices, components and/or other elements in other configurations. Optionally, the components of the control unit106illustrated inFIG.7are housed within a control unit enclosure, such as the enclosure110illustrated inFIG.1, for example.

The processor(s)700of the control unit106may execute programmed instructions stored in the memory702of the control unit106for the any number of the functions and other operations illustrated and described herein. The processor(s)700may include one or more CPUs or general purpose processors with one or more processing cores, for example, although other types of processor(s) can also be used. In other examples, the processor(s)700can include a microcontroller, a reduced instruction set architecture (RISC) processor, configurable hardware logic (e.g., a field programmable gate array (FPGA), and/or any combination of such processing devices. Accordingly, while processor(s)700and separate memory702coupled via a bus710are included in the example illustrated inFIG.7and described herein, other architectures can also be used.

The memory702of the control unit106stores the programmed instructions for one or more aspects of the present technology as described and illustrated herein, although some or all of the programmed instructions could be stored elsewhere. A variety of different types of memory storage devices, such as random access memory (RAM), read only memory (ROM), flash memory, or other computer readable medium which is read from and written to by a magnetic, optical, or other reading and writing system that is coupled to the processor(s)700, can be used for the memory702. The memory702of the control unit106can store one or more applications that can include executable instructions that, when executed by the processor(s)700, cause the control unit106to perform actions, such as to communicate with the flowmeters202and204and/or control the linear actuator104, for example, and to perform other actions as described and illustrated by way of the examples herein.

Accordingly, the examples may also be embodied as one or more non-transitory computer readable media, such as the memory702of the control unit106, having instructions stored thereon for one or more aspects of the present technology as described and illustrated herein. The instructions in some examples include executable code that, when executed by one or more processing devices, such as the processor(s)700of the control unit, cause the processing devices to carry out steps necessary to implement the methods of the examples of this technology that are described and illustrated herein.

The memory702of the control unit106in these particular examples includes an actuator control module712and an output module714. The actuator control module712is configured to process input from the control panel708and sensors (e.g., flowmeters202and204and pressure transducers212and214) to selectively extend and retract the linear actuator104using control signals sent via the actuator interface706. The output module714is configured to communicate sensed or determined parameters to the display device108, as described and illustrated in more detail below. The display device108can be an LED display, for example, although other types of displays can also be used in other examples.

The sensor interface704of the control unit106operatively couples and communicates with the various sensors of the ventilator apparatus100, including the flowmeters202and204, pressure transducers212and214, and/or CO2/O2 sensors220. Accordingly, the sensor interface704obtains signals from the sensors that are communicated to the actuator control module712to facilitate determination of pressures and flow rates, for example. The actuator interface706of the control unit106couples and communicates with the linear actuator104by issuing control signals that selectively cause the linear actuator104to extend or retract, for example, as described and illustrated in more detail below. While a linear actuator104is described and illustrated herein, other types of actuation mechanisms and devices can also be used in other examples.

Referring toFIG.8, a flow diagram of an exemplary method of operation of the control unit106of the ventilator apparatus100is illustrated. In a first step in this example, the control unit106obtains ventilator parameter values via the control panel708. The ventilator parameter values in this example include at least an inspiratory pressure limit (referred to inFIG.8as setPmax), BPM, and required TV (referred to inFIG.8as setTV), although other parameter values can also be obtained in other examples.

In a second step, the control unit106sets or specifies the inhalation time and exhalation time based on the ventilator parameter values obtained in the first step. The inhalation time and exhalation time are used to facilitate control of the linear actuator104.

In a third step, the control unit106resets a timer. The timer is set to zero, for example, and is compared to the inhalation time in order to effectively define the respiratory cycle.

In a fourth step, the control unit106obtains a current inspiratory pressure and a current TV (referred to inFIG.8as tidal volume achieved) via signal values from the flowmeters202and204and/or pressure transducers212and214. The control unit106can optionally also obtain a current expiratory pressure and can calculate a current I/E ratio based on the current inspiratory and expiratory pressures. Also optionally, the control unit106can output one or more of the current inspiratory pressure, a current expiratory pressure, current I/E ratio, or flow rate on the display device108to facilitate monitoring by a clinician.

In a fifth step, the control unit106determines whether the timer value is less than the inhalation time set in the second step. In a first iteration, the timer value will always be less than the inhalation time. If the control unit106determines that the timer value is less than the inhalation time, then the control unit106proceeds to a sixth step.

In the sixth step, the control unit106determines whether the current inspiratory pressure is greater than or equal to the inspiratory pressure limit obtained in the first step. If the current inspiratory pressure is greater than or equal to the inspiratory pressure limit, then the control unit106in a seventh step sends a control signal to the linear actuator104to stop the linear actuator104. However, if the control unit106determines that the current inspiratory pressure is not greater than or equal to the inspiratory pressure limit, then the control unit106proceeds to an eighth step.

In the eighth step, the control unit106determines whether the current TV is equivalent to the TV obtained in the first step. If the current TV is equal to the TV obtained in the first step, then the control unit106in a ninth step maintains the current linear actuator104position by not sending any additional control signals to the linear actuator104. However, if the control unit106determines in the eighth step that the current TV is not equal to the TV obtained in the first step, then the control unit106proceeds to a tenth step.

In the tenth step, the control unit106generates and sends a control signal to the linear actuator104to cause the linear actuator104to extend, optionally according to a control algorithm established before initiation of the respiratory cycle. The control algorithm can define the rate and length/distance at which the linear actuator104is extended and/or retracted, for example. By extending the linear actuator104, the plate106compresses the self-inflating bag102of the ventilator apparatus100as part of an inspiratory phase of a respiratory cycle.

Subsequent to extending the linear actuator104according to the control algorithm, the control unit106proceeds back to the fifth step and again determines whether the timer value is less than the inhalation time. If in this iteration, the control unit106determines that the timer value is not less than the inhalation time, then the control unit106proceeds to an eleventh step.

In the eleventh step, the control unit sends a control signal to the linear actuator104to cause the linear actuator104to retract and thereby allow the self-inflating bag102to re-inflate during an expiratory phase of the respiratory cycle. The control unit106then determines whether the exhalation time has expired, such as based on a comparison of the exhalation time with the timer. If the exhalation time has expired, then the control unit106proceeds back to the first step in this example. In other examples, the first step can be skipped on second and subsequent iterations when a determination indicates that there are no changes in inputs.

Referring toFIG.9, a schematic of an exemplary microcontroller of the ventilator apparatus100is illustrated. The microcontroller can be used in combination with, or in place of, the control unit106and is configured to monitor the flow of air into the lungs and uses that signal to estimate the volume of air delivered, which allows for control of air volume on each cycle of the ventilator apparatus100. The microcontroller outputs a position command (e.g., the linear actuator stroke position command ofFIG.3) to the linear actuator104in order to control compression of the bulb of the self-inflating bag102for each cycle.

Referring toFIG.10, exemplary instructions for use of the ventilator apparatus100will now be described with reference to an exemplary control panel708. In a first step illustrated inFIG.10, a user of the ventilator apparatus100turns the ventilator apparatus100on and presses the bottom portion of the lock/unlock switch1000down to the ‘0’ setting, to unlock the controls. In this example, once controls are set, they can be locked to prevent accidental adjustment by pressing the lock/unlock switch1000to “I” to lock controls; In order to adjust the settings the lock/unlock switch1000must be turned down to “0” to unlock. The lock/unlock switch1000can be disposed on the control panel708of the control unit106, for example.

In a second step, a user of the ventilator apparatus100sets the tidal volume to a desired level by turning TV dial1002right to increase or left to decrease. The set tidal volume then optionally appears in mLs on a bottom row of the display device108of the control panel708.

In a third step, a user of the ventilator apparatus100sets a maximum pressure to a desired level, using the Px control knob1004. Optionally, the set maximum pressure in cmH2O is then displayed on the bottom row of the display device108of the control panel708in a second column.

In a fourth step, a user of the ventilator apparatus100sets a respiration rate to a desired level, using the RR control knob1006. In this example, the respiratory rate or “RR” can be set to the patient's breath rate per minute (BPM) by turning the RR control knob106right to increase or left to decrease. Optionally, the set RR in BPM is output to the bottom row of the of the display device108of the control panel708.

In a fifth step, a user of the ventilator apparatus100sets an inspiratory to expiratory ratio (I:E) to a desired level, using the I:E control knob1008. Optionally, the set I:E ratio appears on the bottom row of the display device108of the control panel708in a fourth column. Accordingly, subsequent to the fifth step, the patient variables are output in the top row of the display device108from left to right: tidal volume or TV (mL); pressure or P (cmH2O); and PEEP (cmH2O) (based on the PEEP valve216on expiratory limb).

In some examples, the display device708of the control unit106of the ventilator apparatus100can output current settings (inspiratory pressure, tidal volume, and/or frequency) and/or current delivery parameters (inspiratory pressure, tidal volume, and/or respiratory rate). PEEP and FiO2settings are not output by the display device708in some examples, but are available through inspection and can be output in other examples. Additionally, the control unit106can include an LED array (e.g., an 8×8 LED array) via which a flow rate vs. volume graph is output. Additionally, the display device708can be configured to display CO2 and/or O2 concentration communicated via the CO2/O2 sensors220.

In a sixth step illustrated inFIGS.11A-11B, the ventilator apparatus100is coupled to a patient at the patient's ETT connection. In particular, the patient end of the ventilator apparatus100is illustrated inFIG.11Aand the BVM compressor of the exemplary ventilator apparatus100is illustrated inFIG.11Bwith the following components: Mapleson bag1100represents patient lungs; HME filter/viral/bacterial filter1102; patient system1104—connects to BVM or self-inflating bag102; inspiratory flowmeter202; expiratory flowmeter204; PEEP valve216; BVM ventilation system1106; BVM compressor1108; and power cables1110.

In some examples, the ventilator apparatus100of this technology provides ventilation at a patient-connection port within alarm limits set by an operator, and/or informs the operator via an alarm condition that ventilation within the alarm limits is not occurring. Alarm notifications can be a combination of sounds and lights, for example. Such alarm conditions include the following in some examples: (1) ventilator not delivering because of gas or electricity supply failure or the ventilator is switched off, or there is a loose or broken connection; (2) inspiratory airway pressure exceeded (3) inspiratory pressure not achieved (equivalent to disconnection alarm condition); and/or (4) tidal volume not achieved or exceeded. Other alarm conditions and/or notifications can also be used in other examples.

Referring toFIG.12, exemplary alarm outputs of the ventilator apparatus100are illustrated via the control panel708. In this particular example, the buttons1200represent alarm reset buttons. The first button1202correlates with a tidal volume alarm reset. The first alarm light1204is illuminated when the tidal volume is less than 20% of the set tidal volume for more than five breaths. This alarm can be reset by pushing the first button1202. The second button1204in this example correlates with a pressure high alarm. The second alarm light1206is illuminated when the pressure is greater than the set max pressure. This alarm can be reset by pushing the second button1204. The third button1208represents an alarm silence button in this example. In other examples, other types of buttons, switches, and interface elements facilitating other functionality can also be used on the control panel708.

Referring toFIGS.13A-D, tables of exemplary failure scenarios and resulting actions, including particular triggered alarm(s), relating to the bag-mask-valve gas inlet, mechanical air-pump outlet, inspiration line outlet, and expiration line outlet, respectively, are illustrated. Failure of any of the components of the ventilator apparatus100in some examples is handled in a manner that puts the ventilator apparatus100out of operation and/or sounds an alarm to request manual intervention.

Referring toFIG.14, a table including exemplary components of the ventilator apparatus100is illustrated. In this example, component descriptions are identified along with the material, vendor, part number, and quantity, although different components, materials, vendors, and/or part numbers can be used in other examples.

Referring toFIG.15, a set of graphs1500,1502, and1504of exemplary testing results for the ventilator apparatus100is illustrated. The ventilator apparatus100of this technology was tested in a laboratory with a breathing lung simulator to determine control variables for the linear actuator104. The key variables in this example were pressures, flow rates, and volumes. Sample data for RR=18, I/E=1:2, and TV=500 is illustrated with respect to TV, flow, and pressure over time in graphs1500,1502, and1504, respectively.

FIGS.16A-C, graphs1600,1602, and1604of exemplary performance of the ventilator apparatus100with respect to respiratory rate and tidal volume is illustrated. In particular, the performance of the ventilator apparatus100for I:E ratio of 1:1, 1:2 and 1:3 is illustrated in graphs1600,1602, and1604, respectively. The rows in the graphs1600,1602, and1604in these examples represent the respiratory rates and the columns represent tidal volumes. The lighter shaded boxes illustrated all combinations that are possible with the ventilator apparatus100. The ‘x’ marks specific tests where detailed data was collected, and the darker shaded boxes indicate where the ventilator apparatus100was not able to deliver the set tidal volume. The numbers in the darker shaded squares record the actual volumes that were achieved. The pass condition was defined as being able to achieve the set tidal volume within plus or minus 25 cc, and all numbers were averaged over three cycles.

As described and illustrated by way of the example herein, this technology provides a relatively low-cost ventilator apparatus that can be manufactured relatively quickly with a reduced number of parts, while including alarms, safety shutoffs, and functional displays to enable effective and safe use in a clinical environments. The ventilator apparatus of this technology is advantageously capable of emergency use to improve outcomes for severely ill patients in underserved populations that are unable to breathe on their own due to a viral infection, for example.