Patent Description:
The present disclosure relates generally to a flow sensor system. More particularly, the present disclosure relates to a flow sensor system for providing intravenous bolus injections of medication to a patient which provides healthcare professionals with an automated record of medication, concentration, volume, dose, and time of each injection. Preferably, the system has an ultrasonic flow sensor.

There is a need to reduce medication error at bedside during bolus delivery. It would be advantageous to provide a record of, and electronically measure, bolus delivery which allows monitoring bolus delivery and automatic documentation of bolus delivery as part of a patient's health record. Additionally, it would be advantageous to provide alerts when bolus delivery inconsistent with a patient's medical record is about to occur.

<CIT> discloses an ultrasonic flow meter with a butyl rubber ultrasonic wave absorber which allows only for directly transgressing waves to be measured but dampens waves which are reflected within the flow tube.

The present disclosure provides a system for sensing flow of a fluidic medicament. The system includes an intelligent injection port which may attach to an injection site (such as a "Y Site" or a stop cock) for manually administered IV injections. The system includes two main sub-assemblies: a single-use flow sensor and a reusable base unit, which fit together prior to use.

According to the invention, there is disclosed a flow sensor sub-assembly for sensing flow of a fluidic medicament comprising: a flow tube assembly through which said medicament flows having: a flow tube having a lumen, an outside diameter, a first end, and a second end; an inlet fitting having a conical orifice with an abutting shoulder, wherein said conical orifice is sized for insertion of either end of said flow tube; and an outlet fitting having a conical orifice with an abutting shoulder, wherein said conical orifice is sized for insertion of either end of said flow tube; a first transducer arranged at the inlet fitting; and a second transducer arranged at the outlet fitting, wherein said conical orifices of said inlet fitting and said outlet fitting are two-part tapers having an intermediate shoulder approximately halfway along the length of said taper wherein a transducer adhesive bonds said first transducer to the inlet fitting and said second transducer to the outlet fitting, the transducer adhesive bonds the first transducer to the inlet fitting and the second transducer to the outlet fitting such that energy from the transducers is transmitted optimally across a transducer-fitting transmission zone while also dampening at least one of out of phase vibrations and rogue vibrations induced in the inlet and outlet fittings by transmission of sound energy between the first and second transducers and the inlet and outlet fittings. The flow sensor sub-assembly further includes a first piezo element arranged at an upstream position of the flow tube assembly and a second piezo element arranged at a downstream position of the flow tube assembly. The first piezo element is integrated to the inlet fitting and the second piezo element is integrated to the outlet fitting and each piezo element is spaced apart a pre-selected distance from each other. Each of the conical orifices has an inner diameter and a taper to engage the outer diameter of said flow tube thereby allowing capillary insertion of an adhesive during assembly.

In flow sensor sub-assembly may include an absorber sheath encircling said flow tube, wherein said absorber sheath is comprised of a material different than said flow tube. The absorber sheath may be heat shrunk onto the outside diameter of the flow tube. Alternatively, the absorber sheath may be adhered to the flow tube. Alternatively, the absorber sheath can be insert molded around the flow tube.

The first piezo element and the second piezo element may be annular in shape and encircle each respective fitting at each respective mounting point. The internal passage of either the inlet fitting or the outlet fitting is tapered and terminates at an end opposite the shoulder to engage a lumen of a flexible tubing.

In certain configurations, the flow tube assembly is contained within a flow sensor housing having a circuit engaged to the piezo elements, wherein the flow sensor housing is coupled to a flow sensor base which contains a microprocessor and the circuit includes connecting pins for providing the electrical signal from the flow sensor sub-assembly to the microprocessor within the flow sensor base. The flow sensor sub-assembly may be disposed of after the flow sensor sub-assembly is used to sense the flow of at least one fluidic medicament. In certain configurations, the flow sensor base may be used with a different flow sensor sub-assembly.

The internal passage of the inlet fitting is tapered and may terminate at an end opposite the shoulder to engage a Luer type fitting. The internal passage of the inlet fitting is tapered and may terminate with an obconic section at an end opposite the shoulder. The conical orifices taper and the inlet fitting and the outlet fitting are two-part tapers having an intermediate shoulder approximately half-way along the length of the taper.

In accordance with an embodiment of the present invention, a method of assembly of a flow sensor sub-assembly for sensing flow of a fluidic medicament includes the steps of providing a flow tube having a lumen, an outside diameter, a first end, and a second end, and providing an inlet fitting having a conical orifice with a shoulder, the shoulder having a matching size and orientation to match an end of the flow tube. The method also includes the steps of inserting the flow tube into the inlet fitting conical orifice until an end of the flow tube abuts the shoulder of the inlet fitting, and providing an outlet fitting having a conical orifice with a shoulder, the shoulder having a matching size and orientation to match an end of the flow tube. The method further includes the step of inserting an opposite end of the flow tube into the outlet fitting conical orifice until the opposite end of the flow tube abuts the shoulder of the outlet fitting. Additional steps of the method include bonding a first piezo element onto the inlet fitting, bonding a second piezo element onto the outlet fitting, applying an adhesive to a gap between the outer diameter of the flow tube and an inner diameter of the conical orifice on the inlet fitting thereby allowing capillary wicking of the adhesive, and applying an adhesive to a gap between the outer diameter of the flow tube and an inner diameter of the conical orifice on the outlet fitting thereby allowing capillary wicking of the adhesive.

Optionally, the method may also include inserting the flow tube into an absorber sheath encircling the flow tube, wherein the absorber sheath is comprised of a material different than the flow tube. Additional steps of the method may include inserting the flow tube into an absorber sheath encircling the flow tube, and heating the absorber sheath to shrink the absorber sheath onto the outside diameter of the flow tube. The absorber sheath may be adhered to the flow tube. Optionally, the method may include insert molding the absorber sheath around the flow tube.

The material of the absorber may be one of any polymers or elastomers, such as polyvinylchlorider, silicone rubber, and the like. In one embodiment, the material of the absorber may be flexible in nature and have a lower durometer than that of the flow tube. By providing an absorber having a different and lower durometer than that of the flow tube, the vibrations are maintained within the absorber, rather than passed into the flow tube.

In additional configurations, the method may also include the steps of inserting the inlet fitting into an opening in the first piezo element, and inserting the outlet fitting into an opening in the second piezo element. The method may also include the step of bonding a flexible tubing to an opposite end of the internal passage of either the inlet fitting or the outlet fitting.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate exemplary embodiments of the disclosure, and such exemplifications are not to be construed as limiting the scope of the disclosure in any manner.

The following description is provided to enable those skilled in the art to make and use the described embodiments contemplated for carrying out the invention.

As used herein, proximal shall refer to a part or direction located away or furthest from a patient (upstream), while distal shall refer to a part or direction towards or located nearest to a patient (downstream). Also, a drug substance is used herein in an illustrative, nonlimiting manner to refer to any substance injectable into the body of a patient for any purpose. Reference to a patient may be to any being, human or animal. Reference to a clinician may be to any person or thing giving treatment, e.g., a nurse, doctor, machine intelligence, caregiver, or even self-treatment.

<FIG> illustrate an exemplary embodiment of a flow sensor system <NUM> of the present disclosure. Referring to <FIG>, a flow sensor system <NUM> of the present disclosure includes two main assemblies which fit together prior to use: a flow sensor <NUM> and a base <NUM>. In one embodiment, the flow sensor <NUM> can be a single-use flow sensor which is engageable with reusable base <NUM>. The flow sensor system <NUM> is an intelligent injection port. The flow sensor system <NUM> is attachable to an injection site ("Y Site" or stop cock, for example) for manually administered IV injections.

The flow sensor system <NUM> of the present disclosure can reduce medication error at bedside during bolus delivery. The flow sensor system <NUM> of the present disclosure can also provide a record of and electronically measure bolus delivery, which allows monitoring bolus delivery and automatic documentation of bolus delivery as part of a patient's health record. The flow sensor system <NUM> of the present disclosure can also provide alerts when bolus delivery inconsistent with a patient's medical record is about to occur.

Referring to <FIG>, in one embodiment, the base <NUM> is a non-sterile, reusable device that houses a battery, a scanner (either optical, mechanical, inductive, capacitive, proximity, or RFID), electronics, and wireless transmitter. In some embodiments, the base <NUM> is battery powered, and rechargeable. In some embodiments, each base <NUM> has a unique serial number imprinted on a surface of the base <NUM> or embedded therein that may be transmitted to a data system before use. The data system can be a local computer or tablet "Computer", a cellular phone, another medical device, or a Hospital Data System.

In one embodiment, the base <NUM> is removably connectable to the flow sensor <NUM>. Referring to <FIG> and <FIG>, the base member <NUM> and the mechanical connection of the flow sensor <NUM> to the base member <NUM> is described. The base member <NUM> includes at least one deflectable wing tab <NUM> defining an opening for receiving at least a portion of the flow sensor <NUM> therein and for securing the flow sensor <NUM> within a portion of the base <NUM> prior to use. In one embodiment, a pair of wing tabs <NUM> secure the flow sensor <NUM> within the base <NUM>. Optional gripping ribs <NUM> may be provided on an exterior profile for enabling a user to grasp the base portion <NUM>.

An interior profile of the wing tab <NUM> may be provided with a catch <NUM> for corresponding engagement with a tab <NUM> provided on the flow sensor <NUM>, as shown in <FIG>, to restrain the flow sensor <NUM> within the base <NUM>, as will be discussed further herein. The wing tabs <NUM> may be flexible to the extent that they may be outwardly deflected to allow for passage of the flow sensor <NUM> thereover. The interior of the wing tab <NUM> may be provided with a pin cam <NUM> which allows a pin <NUM> of the flow sensor <NUM>, as shown in <FIG>, to ride along such that the flow sensor <NUM> is moved proximally during assembly onto the base <NUM>, to precisely align various optical and electrical components of the flow sensor <NUM> and the base member <NUM>, as will be discussed further herein.

Referring to <FIG> and <FIG>, the base member <NUM> and the electrical connection of flow sensor <NUM> to the base member <NUM> is described. The base <NUM> includes an activation/engagement button <NUM> which allows for an indication that the flow sensor <NUM> has been engaged with the base <NUM>. In one embodiment, the activation/engagement button <NUM> signals to a microprocessor within the base <NUM> that a syringe has been properly engaged with the sensor <NUM> and its injection port <NUM>.

The base <NUM> further includes a plurality of contacts <NUM> (<FIG>) for electrically engaging corresponding electrically active portions of the plurality of contact pins <NUM> (<FIG>). A contour protrusion <NUM> surrounds at least a portion of the tongue <NUM>. As shown in <FIG>, a bottom surface of the sensor <NUM> includes a pin seal <NUM> surrounding a plurality of contact pins <NUM> to prevent contamination, thus minimizing electrical disruptions. In some embodiments the plurality of pins <NUM> comprise a four pin connector with two pins electrically connected to each piezo element <NUM>, <NUM>, as will be discussed further. In other embodiments, the plurality of pins <NUM> comprise a six pin connector with two pins electrically connected to each piezo element <NUM>, <NUM> and two pins electrically connected to a battery (not shown) in the flow sensor <NUM>.

The base member <NUM> further includes a tongue <NUM> surrounded by a shoulder <NUM> having a plurality of contacts <NUM> for electrically engaging corresponding electrically active portions of sensor <NUM> and a charger <NUM> (<FIG>), as will be discussed herein.

Referring to <FIG>, <FIG>, and <FIG>, in one embodiment, the flow sensor <NUM> is a pre-sterilized disposable having an injection port <NUM> and a distal tubing connection, such as a Luer tip <NUM>.

The flow sensor <NUM> may include a flow tube sub-assembly <NUM> consisting of a flow tube <NUM> having an outlet end <NUM> and an inlet end <NUM>. The outlet end <NUM> may be provided in fluid communication with an outlet tubing <NUM> having an outlet connection <NUM> including a Luer tip <NUM> which may be optionally covered by a Luer cap <NUM>. In a preferred embodiment, the outlet connection <NUM> is a plastic connector with a Luer tip <NUM>, however, any suitable method to inject the medicament into a patient is envisaged to be within an aspect of an embodiment of the invention. For example, it may be desirable to replace the outlet connection <NUM> and tubing <NUM> with a needle for direct injection/infusion into a patient. Furthermore, it may be desirable to integrate the base <NUM> into a medication pen or infusion device for the delivery of insulin.

The inlet end <NUM> may be coupled to the reservoir of a medication pen or infusion reservoir. The inlet end <NUM> of the flow tube <NUM> may be provided in fluid communication with an injection port <NUM>, and may optionally include a connection such as a threaded Luer lock <NUM> which is engageable with a source of a fluid to be injected. A pierceable septum <NUM> may be provided with the injection port <NUM> for maintaining sterility prior to use.

In a preferred embodiment, the injection port <NUM> is a plastic container with a split septum <NUM>, however, any suitable method to inject the medicament through a flow sensor inlet <NUM> to a patient is envisaged to be within an embodiment of the present invention. For example, it may be desirable to replace the injection port <NUM> for direct connection to a medicament delivery device. In addition, it may be desirable to integrate the flow sensor inlet <NUM> to accept a direct fluidic connection to a medication delivery device.

In one embodiment, the flow tube <NUM> is comprised of a medical grade stainless steel and is approximately <NUM> long with a <NUM> inner diameter and a <NUM> outer diameter.

The flow sensor <NUM> also includes a first piezo element or upstream transducer <NUM> and a second piezo element or downstream transducer <NUM>. The first piezo element <NUM> may be provided with an inlet fitting <NUM>, as shown in <FIG>, for coupling with the injection port <NUM>. Similarly, the second piezo element <NUM> may be provided with an outlet fitting <NUM>, for coupling with the outlet tubing <NUM>.

The flow sensor <NUM> can be supplied in a sterile package for a single patient use. In one embodiment, labeling is printed on the individual sterile package. In one embodiment, each flow sensor <NUM> has a unique serial number imprinted on a portion of its surface. In some embodiments, there are electronics in the flow sensor <NUM> which retain a unique identifier. These identifiers are transmitted either automatically or manually to a data system during use and data collection. In one embodiment, at the inlet end <NUM> of a flow sensor <NUM> the injection port <NUM> is a common needleless, Luer-Lok type. Typically, the inlet port or the injection port <NUM> is cleaned prior to giving an injection according to hospital policy. Additionally, flushing the flow sensor <NUM> with an IV fluid (e.g., normal saline syringe) is desirable before use. The injection port <NUM> on the flow sensor <NUM> typically supports up to <NUM> injections. In one embodiment, the flow sensor <NUM> has a male Luer-Lok connection, e.g., an outlet connection <NUM> having a luer tip <NUM>, on a one-inch IV tubing pigtail at the outlet end <NUM>. This male Luer-Lok connection may be attached to an IV line at a Y-site or IV manifold. Each flow sensor <NUM> has a unique serial number, however it may be desirable to only display a portion of the serial number on a portion of the exterior of the flow sensor <NUM>. For example, the last <NUM> digits of the serial number may be imprinted on the surface next to its bar code. This human readable number is used to visually identify a flow sensor <NUM> within wireless range of communication of a computer. In some embodiments, the flow sensor <NUM> measures with an accuracy of ± <NUM>% for bolus volumes > <NUM> to <NUM> and ± <NUM>% for bolus volumes of <NUM> to <NUM> and has a dead-space volume of less than <NUM>.

Referring to <FIG>, in one embodiment, an optional separate charger <NUM> is compatible with the flow sensor system <NUM> and recharges a battery in the reusable base <NUM>, if required, for reuse of the base <NUM>. Referring to <FIG>, in one embodiment, the charger <NUM> includes a charger base <NUM> having an opening <NUM> for receiving the base <NUM>, the opening <NUM> having charging pins <NUM> which engage corresponding contacts <NUM> in the reusable base <NUM>. The charger <NUM> may include a sloped floor <NUM> for allowing disinfection liquid to drain therefrom. The device may also include elevated feet <NUM> to assist in drainage.

Reusable bases are typically supplied non-sterile and require disinfection and charging before use. It is preferred to disinfect each base <NUM> before first use. Typical commercial hospital disinfectants include alcohol-based quaternary ammonium, e.g., Metrex Research Cavi Wipes. In some embodiments, the base <NUM> can be used up to <NUM> times. Preferably, a rechargeable lithium ion battery is used within the base <NUM> and is not removable from the base <NUM>. It is envisaged that a fully-charged base <NUM> will accommodate an entire patient case. In some embodiments, each base <NUM> is identified by labeling on the bottom of the device. Optionally, bases <NUM> are provided in individual boxes and each box is in a case package. The charger <NUM> may also include a power indicator <NUM>. In one embodiment, when the base <NUM> is connected to a charger <NUM>, up to four green light bars will illuminate on the top. The number of solid green light bars indicates the level of charge. A green blinking light on the base <NUM> will indicate it is recharging. In some embodiments, a useful life indicator is employed when the base <NUM> is connected to a charger <NUM> by use of a red light that indicates that the base <NUM> has exceeded its useful life. Optionally, on the Computer, an error message will display when a flow sensor system <NUM> whose useful life is completed is wirelessly connected to a tablet during patient setup. It would then be desirable to replace the base <NUM> with another and repeat the wireless connection to the Computer. Optionally, the flow sensor system <NUM> is provided in a mount which is an appliance that fits a standard Clarke socket to keep the flow sensor system <NUM> in place at the patient's bedside. Additionally, it may be desirable to clean and disinfect the charger <NUM> by using the procedure used for cleaning and disinfecting the base <NUM>.

In one embodiment, the flow sensor system <NUM> supports injections using any Luer-lock type syringe. For example, referring to <FIG>, the flow sensor system <NUM> is compatible with a syringe <NUM> that is labeled. In one embodiment, the syringe <NUM> includes scale markings <NUM>, a distal tip <NUM>, a luer tip <NUM>, a proximal end <NUM>, a flange <NUM>, a tip label <NUM> having human readable indicia <NUM> and machine readable indicia <NUM>, a barrel label <NUM> having human readable indicia <NUM>, and a plunger <NUM>.

The base <NUM> of the flow sensor system <NUM> includes optics and a digital camera disposed within or behind a first window <NUM>, as shown in <FIG>, capable of reading the machine readable indicia <NUM> provided on a label <NUM> of an encoded syringe. The first window <NUM> may be precisely aligned with Luer lock threads <NUM> present on the flow sensor <NUM> when the flow sensor <NUM> is assembled with the base <NUM>, thus aligning the machine readable indicia <NUM> present on the label <NUM> on the syringe <NUM> during an injection cycle and/or medication determination cycle. The base <NUM> may further include a second window <NUM>, as shown in <FIG>, having a light source for providing adequate lighting to the camera disposed within or behind window <NUM>.

Additionally, the flow sensor system <NUM> is designed to work with encoded syringes that have a special barcode identifier on the Luer collar of the syringe, called "encoding". Preferably, encoded syringes include commercially-available drugs in prefilled syringes with a special barcode that stores information about the medication contained within the syringe. Encoded syringes are ready-to-use, passive, and disposable. The flow sensor system <NUM> also accommodates syringes not having encoding. The encoding syringes store the drug name and concentration contained within the syringe. Additional characteristics such as drug source, container size, drug manufacturer source, drug category color, among others, may also be included. When an encoded syringe is attached to the injection port <NUM> of the flow sensor <NUM>, this barcode information is read by a scanner in the base <NUM> wirelessly transmitted by the flow sensor system <NUM> to the data system. Preferably, the <NUM>-D barcodes will be added to syringes during the filling process.

In one embodiment, the flow sensor system <NUM> contains a device to capture and transmit an image of a <NUM>-D barcode on the Luer collar of the syringe, and wirelessly transmit this image to a "Computer". Typically the Computer is a tablet computer communicating with multiple flow sensor systems <NUM>. The <NUM>-D barcode contains data, typically including the name and concentration of the drug in the syringe among other data. The Computer decodes this image, and displays and announces the drug attached. The barcode can contain the drug name and concentration. As the drug is injected, the flow sensor <NUM> in conjunction with the base <NUM> ultrasonically measures the volume of the injected drug and the time the drug was administered. This information may be stored in the flow sensor system <NUM> for later transmission to the Computer. The Computer uses this information to provide clinicians with an automated record of the drug name, concentration, volume, dose, and time of injection. The medication administration information is time stamped and displayed for clinical reference. Not all syringes used by the healthcare professional will contain a <NUM>-D barcode. If a syringe without a <NUM>-D barcode is inserted into the flow sensor system, the injection port <NUM>, the flow sensor system <NUM> will prompt the user to manually enter the drug name and concentration into the computer. Information that is manually entered into the flow sensor system <NUM> is included in the patient medication record.

In one embodiment, the Computer can use a radio to wirelessly communicate with the flow sensor system <NUM> using an RF signal at <NUM> to form a local medical device network. A number of flow sensor systems <NUM> and Computers may be used in the same vicinity such as a pre-operative care area or a post anesthesia care unit (PACU). Alert messages are communicated between the flow sensor system <NUM> and the Computer to advise the clinician of various operational characteristics of the flow sensor system <NUM>. Some of these alerts inform the clinician of potential hazardous situations to allow user action to prevent harm to the patient or loss of medical data. Preferably, a lost wireless communication message will display when communication is lost between the flow sensor system <NUM> and the Computer. Preferably, all medication administration data from the flow sensor system <NUM> is transferred to the specific patient's medical record. In the event of a communication loss, medication administration data will be stored locally at the flow sensor system <NUM> and transferred to the Computer when communications are resumed.

The Computer may operate in a variety of modes. Typically the Computer has specialized flow sensor system <NUM> software for operations, a touch screen, and a wireless communications (Radio). It is typically mounted near an anesthetist or nursing work envelope and it may be removed for hand-held use. When the Computer is used in a hospital having a paper anesthesia record, the Computer supports features that assist with documenting the flow sheet portion and may help clinicians make the right decisions. In this configuration, the Computer complements the paper recordkeeping activities by tracking and displaying injections given through the flow sensor system <NUM>. The Computer also enables clinicians to manually document other pertinent IV drug injection and infusion information.

In one embodiment, the software screens follow a three-step approach consisting of: (<NUM>) connecting the flow sensor system <NUM> to the Computer; (<NUM>) setting up a patient's flow sensor system <NUM> for use; and (<NUM>) viewing medication administration in multiple views.

In some embodiments, a view on the computer displays anesthesia based information in an anesthesia view, as shown in <FIG>. Preferably, this view provides information about the patient and displays drug name/concentration and dose for a current injection as well as a historical list of medications that have been delivered to the patient since the current case was opened. It may also include a listing of infusions given to the patient, if the clinician recorded them on the Computer. In this view, up to three injection bars display across the top of the screen, one corresponding to each wirelessly connected flow sensor system <NUM>. Each injection bar is a real time representation of the medication being administered through an individual flow sensor system <NUM>. When an encoded syringe is attached to a single flow sensor system <NUM>, the injection bar displays the drug name and concentration. When a non-encoded syringe is attached, the injection bar will prompt the clinician to identify the medication and concentration being delivered. As the medication is being delivered, the volume pushed (in mL) and the corresponding dose displays in real time in the injection bar on the Computer display.

A flow sensor system <NUM> of the present disclosure may also provide optional medication history. For example, an anesthesia view can include a historical list of medications delivered to the patient organized by the surgical care area (medications given in the transition time between care areas, will post to the next care area) arranged in a flow sheet format. Preferably, this view includes all medications that were administered to the patient since the flow sensor system <NUM> was activated with the more recent medication administrations preferably at the bottom of the list. A scroll bar is enabled when the list exceeds the visible space on the screen of the Computer. Preferably, when a new medication is added, the medication list scrolls automatically so the new medication name is visible. In the view, preferably a color tile corresponding to American Society for Testing and Materials International (ASTM) standards and endorsed by the American Society of Anesthesiologists displays to the left of the drug name. Optionally, a clinician may also specify that an admixture (mixed medication), or a diluted or reconstituted medication was delivered. Optionally, the Computer displays a case header which lists the patient name, date of birth, age in years, medical record number, and patient identification number. Optionally, the Computer will indicate that the patient has "no known allergies". Preferably, if the patient has allergies that text is replaced by a button, more preferably, the button has a number on the button that indicates the number of allergies.

A flow sensor system <NUM> of the present disclosure may also provide an optional tabular view, as shown in <FIG>. For example, the tabular view is an alternate view for the clinician to interact with the flow sensor system <NUM>. Similar to the anesthesia view described above, this view provides information about the patient and displays drug name/concentration and dose for a current injection as well as a historical list of medications that have been delivered to the patient. It may also include a listing of infusions given to the patient, if recorded by the clinician. The tabular view has many of the features of the anesthesia view; however, it is arranged in a tabular format. Preferably, the column headings in this view include time administered, medication with concentration, dose, and unit total. Optimally, the medications are displayed in reverse chronological order with most recent medication administered at the top of the list.

In one embodiment, the Computer provides two types of messages: (<NUM>) "Clinical" and (<NUM>) "System". Clinical messages are alerts and reminders that relate directly to an aspect of patient care delivery (e.g. contraindication or a reminder that it may be time to re-dose antibiotics). System messages provide status on relevant system operating parameters.

Messages provide instructions and a button for acknowledging or resolving. Messages display on the Computer until they are acknowledged or are no longer clinically relevant. Messages can be answered any time during a case. Prior to pausing or closing a case, the clinician is prompted to respond/answer unresolved medication messages generated during the case. An allergy alert illuminates the flow sensor system <NUM> and displays on the Computer when a clinician attaches an encoded syringe or selects a medication for a non-encoded syringe to which the patient has a known allergy. Optionally, this message may be overridden.

When dosing antibiotics, preferably the Computer tracks elapsed time since an antibiotic was last administered and displays and announces an antibiotic redosing message if the configured redosing interval has elapsed. The redosing interval is individual to each antibiotic, and it is configured in the drug library of the Computer or Gateway, as further described below. In one embodiment, the flow sensor system <NUM> does not prevent or block the injection of a medication. In other embodiments, the flow sensor system <NUM> is able to block the injection of a medication.

In one embodiment, the Computer posts a message when the volume injected through the flow sensor system <NUM> was not measured. This may occur when the volume measured is outside of a range of sensing of the flow sensor system <NUM>.

Optionally, the Computer wirelessly communicates bi-directionally with a software application that acts as a central hub to which all Computers (and thus multiple upon multiples of flow sensor systems <NUM>) are connected, the "Gateway". Preferably, the Gateway is also connected to the hospital's other networked information systems. The Gateway allows all Computers to share patient case information such as drug name, dose, and time delivered with each other, and with the hospital's networked information systems. The Gateway also allows Computers to receive patient information such as patient drug allergies and patient drug orders from other networked hospital information systems.

Utilizing the flow sensor system <NUM> of the present disclosure encompasses the steps of connecting the flow sensor <NUM> to the patient's catheter or injection port (Y-site). Preferably, the flow sensor <NUM> and line is flushed. The flow sensor <NUM> is keyed to an individual patient using a unique serial number and the base <NUM> records medication administration through the port at the inlet end <NUM> of the flow sensor <NUM>.

When a syringe <NUM> is attached to the injection port <NUM>, the flow sensor system <NUM> identifies the medication and concentration for an encoded syringe by optically imaging and decoding a barcode on the Luer-Lok collar of the syringe <NUM>. This information is wirelessly transmitted to the Computer. Preferably, the Computer displays and audibly announces the drug attached. The Computer also may perform allergy safety checks based on the patient's medical record.

In one embodiment, as the drug is injected, the flow sensor system <NUM> measures the volume dosed ultrasonically. The flow sensor system <NUM> wirelessly sends volume measurement information to the Computer. The Computer uses this information to provide clinicians with a medication administration record which is time stamped and displays for clinical reference during surgical procedures. Manually entered infusions and other information pertaining to non-encoded drug injections may be included in the patient medication record in the Computer and the Gateway. The Computer wirelessly communicates with the Gateway on the hospital network, and it may send medication administration to Hospital Information Systems, when configured, for reporting and electronic recordkeeping purposes. Preferably, the Computer wirelessly communicates with the existing Hospital Network using a standards based IEEE <NUM>. 11a/b/g/n enterprise WLAN network. The Gateway software and accompanied database will be a part of the hospital's enterprise information system. A number of Computers may be connected to the healthcare enterprise wireless network and to the intended Gateway software and database. Preferably, the Gateway and accompanied database provides a list of patients for the user to select and a formulary library of medications and fluids for injection or infusion. In one embodiment, actual medication and fluid administration data are sent to the Gateway and accompanied database for recordkeeping. Once recorded on the Gateway and accompanied database these data are preferably available in other care areas when the patient is transferred and the flow sensor system <NUM> is wirelessly connected to a Computer. Preferably, in the event of a communication loss, medication administration data will not be sent to the Gateway and therefore not available in the next care area.

Referring to <FIG>, use of a flow sensor system <NUM> of the present disclosure will now be described. First, preparing the flow sensor system <NUM> for an injection will be discussed.

In one embodiment, the flow sensor system <NUM> is prepared, attached to an IV line, and assembled for use. Preferably, there are pre-printed instructions located on the flow sensor <NUM> sterility pouch. First, a user obtains a flow sensor <NUM> in its sterile packaging and a fully-charged and disinfected reusable base <NUM>. In one embodiment, a fully-charged base <NUM> has sufficient power for at least <NUM> hours of use under typical conditions. Optionally, the base <NUM> provides a visual indication of charge level via a display.

Next, the flow sensor <NUM> is flushed with sterile IV fluid before attaching to the Y-site. In one embodiment, the flow sensor <NUM> is flushed with more than <NUM> of sterile IV fluid. After flushing, a user can visually inspect the IV line for leaks, air, or blockage.

Next, a user attaches the flow sensor <NUM> to the base <NUM> by joining the flow sensor <NUM> (tubing side) and base <NUM> front sections first, and then snapping the two together. Preferably, an audible snapping sound is heard to indicate a secure connection between the flow sensor <NUM> and the base <NUM>. In one embodiment, connecting the flow sensor <NUM> to the base <NUM> automatically powers on the flow sensor system <NUM>. In one embodiment, the connection of the flow sensor <NUM> to the base <NUM> is verified by a blinking light on the base <NUM>. In other embodiments, other indicators may be used. Catch <NUM> of the base <NUM>, shown in <FIG>, engages tab <NUM> of the flow sensor <NUM>, shown in <FIG>, to restrain the flow sensor <NUM> with the base <NUM> prior to initiation of an injection. In one embodiment, deflection of the wing tab or wing tabs <NUM> moves tab <NUM> with respect to catch <NUM> to initiate engagement or disengagement therewith. When the flow sensor <NUM> is assembled to the base <NUM>, a cantilever <NUM> provided on the base <NUM>, such as a lower housing <NUM> as will be discussed herein, is aligned with button <NUM> provided on the base <NUM>. The interior of the wing tab <NUM> may also be provided with a pin cam <NUM> which allows pin <NUM> of the flow sensor <NUM>, as shown in <FIG>, to ride along such that the flow sensor <NUM> is moved proximally during assembly onto the base <NUM>. During engagement, tongue <NUM> shown in <FIG>, is engaged within an opening <NUM> shown in <FIG>. With continued reference to <FIG> and <FIG>, a vault <NUM> having ribs <NUM> on the flow sensor <NUM> as shown in <FIG>, has a corresponding exterior profile taken with the shoulder <NUM> of the base <NUM>, as shown in <FIG>, to engage for alignment of the first window <NUM> to precisely align with Luer lock threads <NUM> when the flow sensor <NUM> is assembled to the base <NUM>.

In some embodiments, where appropriate, the flow sensor system <NUM> is secured to a surface in preparation for giving injections. For example, in some embodiments, referring to <FIG>, a mount <NUM> is used to secure the flow sensor system <NUM> to a surface. During this step, it is important to avoid kinks in the line between the flow sensor system <NUM> and IV line.

The flow sensor system <NUM> is now ready for delivery of IV medications. Preferably, any medications given through the flow sensor system <NUM> will be recorded in the electronic base <NUM> memory. In one embodiment, in the event of a flow sensor system <NUM> failure (excluding the IV fluid pathway), the flow sensor system <NUM> will still allow standard medication or fluid delivery through the port.

Next, giving an injection using the flow sensor system <NUM> will be discussed. First, the injection port <NUM> is cleaned by swabbing the hub according to normal hospital procedure. Next, a syringe <NUM> can be attached to the injection port <NUM> of the flow sensor <NUM> by completely turning the syringe <NUM> until the syringe <NUM> stops, i.e., a secure connection between the syringe <NUM> and the injection port <NUM> is made. Ideally, the caregiver double checks each medication name and concentration on the syringe <NUM> prior to attachment to the injection port <NUM> to assure the correct medication is given. During the injection cycle and/or medicament determination cycle, when syringe tip <NUM> contacts a syringe protrusion <NUM>, as shown in <FIG>, the cantilever <NUM> is deflected radially from the longitudinal axis of the syringe <NUM>. A pad protrusion <NUM> depresses button <NUM> on the base <NUM> and the button <NUM> signals the microprocessor to act.

Next, the drug and concentration displayed and announced by the Computer is verified as the intended drug and concentration. In one embodiment, the base <NUM> will alert the caregiver that an allergy is detected by an alert, for example, by flashing red, green, and yellow lights if a medication allergy is detected. Optionally, the Computer calculates a potential allergy reaction and provides an alert when any of these conditions is true: (<NUM>) an encoded syringe is inserted into the flow sensor <NUM> and the drug matches the patient's allergy profile; or (<NUM>) a non-encoded syringe is inserted into a flow sensor <NUM> and you select a drug from the select medication screen that matches the patient's allergy profile. If one of these conditions is true, the allergy alert flag on the Computer configuration is turned on.

In one embodiment, there is no check valve in the flow sensor <NUM>, nor is one needed to use the flow sensor <NUM> safely and effectively. Typically, the flow sensor system <NUM> measures <NUM> to <NUM> per injection. If the injection flow rate is slow or a small volume is delivered (<<NUM>) preferably an alert will display on the Computer. Optionally, an alarm is configured to detect rapid delivery from a large volume, e.g., <NUM> syringe. In this case, an alert is provided to check the dose.

In one embodiment an indicator <NUM>, such as a series of four LED indicators, turn on in sequence to indicate to the user that fluid is moving through the flow sensor <NUM>. When base <NUM> is mounted in the charger <NUM>, the indicator <NUM> can indicate a level of battery charge of the base <NUM>.

In one embodiment, it is preferred to follow all medication injections through the flow sensor system <NUM> with an encoded normal saline flush syringe to ensure the full dose of medications reaches the patient, especially when successively delivering two incompatible medications. Optionally, the flow sensor system <NUM> records such saline flush activity.

In one embodiment, injections are recorded whether or not the flow sensor system <NUM> is wirelessly connected to the Computer. The base <NUM> stores injection information in its memory and transmits this information upon wireless connection to the Computer.

In one embodiment, the Computer can accommodate multiple flow sensor systems <NUM> connected to one patient at a time. An additional flow sensor system <NUM> may be added at any time during a patient's treatment. When a flow sensor system <NUM> is connected to a Computer and there is no syringe attached to the flow sensor <NUM>, the active injection bar reads "Sensor Connected, No syringe". On the Computer display, a battery status icon in the upper right corner of the injection bar indicates the battery charge level of the base <NUM> to which the flow sensor <NUM> is connected. For each injection a caregiver may enter a comment on the Computer.

The present disclosure provides a flow sensor sub-assembly for sensing flow of a fluidic medicament. The flow sensor sub-assembly includes a first spring contact and a second spring contact. In one embodiment, the spring contacts are secured to a base that has a circuit for conducting an electrical signal to and from the spring contacts to a microprocessor. The first spring contact is in electrical communication with a first piezo element and the second spring contact is in electrical communication with a second piezo element. The first spring contact has a first contact force against the first piezo element and the second spring contact has a second contact force against the second piezo element, and the first contact force is equivalent to the second contact force. The present disclosure also provides a circuit board for interfacing to a flow sensor having a plurality of piezo elements for transmitting a flow signal indicative of flow of a fluidic medicament.

A spring contact of the present disclosure provides electrical contact to a piezo element. For example, a spring contact of the present disclosure provides electrical contact to a silvered surface of a piezoelectric crystal. Furthermore this contact provides a spring force selected to accommodate assembly tolerances, temperature variation, electrical requirements, material selection for a long life to silver, and assembly features for a single-sided printed circuit board assembly (PCBA) attachment. The flow sensor sub-assembly of the present disclosure provides for four contacts used in a sensor to have the same force on both surfaces of each of two piezo elements, such as crystals, in a single transducer.

A circuit board of the present disclosure provides a single-sided PCBA. The single-sided PCBA of the present disclosure provides a lower cost design than conventional double-sided PCBA designs. The circuit board of the present disclosure also provides a means to maintain mechanical loading of the crystal contacts when the transducer is inserted to the PCBA.

Electrical contacts to the ultrasound crystal have previously been accomplished by soldering wires to a silver coating. A spring contact of the present disclosure provides a cost reduction method by using the spring contacts to connect to the crystal. In particular, a single-sided printed circuit board (PCB) of the present disclosure provides for a lower cost design and a through hole contact design. The design of the present disclosure includes the force exertion by the spring constant, dimension of separation between contacts, material type of the springs, the range of forces necessary, and tolerance control of forces exerted by the spring contact, which are all important to eliminate soldering. If soldering is too hot it often takes silver off the surface of the crystal. Another problem with soldering is leaving too much solder behind, which may also cause loading of the ultrasonic physical characteristics. Consistent electrical and physical contact (repeatability) for both crystals is important as well as sensor to sensor calibration. The forces cannot be too high (potential for a slurry to develop) or too low (variable impedance).

The flow sensor sub-assembly of the present disclosure provides a high volume, disposable design with benefits for its cost, reliability, and repeatability. The flow sensor sub-assembly of the present disclosure allows for future automation features. The flow sensor sub-assembly of the present disclosure provides for maximal tolerance designed in conditions. The flow sensor sub-assembly of the present disclosure is able to fit inside the housing of a flow sensor <NUM>.

Referring to <FIG> and <FIG>, a flow tube sub-assembly <NUM> for a flow sensor <NUM> for sensing flow of a fluidic medicament generally includes a flow tube <NUM> having a flow tube inlet <NUM> and a flow tube outlet <NUM>, through which a medicament flows, a first piezo element <NUM> arranged at an upstream position of the flow tube <NUM> and a second piezo element <NUM> arranged at a downstream position of the flow tube <NUM>, a first spring contact <NUM>, and a second spring contact <NUM>. The flow tube inlet <NUM> may be coupled to the reservoir of a medication pen or infusion reservoir. As described herein, in some embodiments, the inlet end <NUM> of the flow tube <NUM> may be provided in fluid communication with the injection port <NUM>.

In one configuration, the sub-assembly <NUM> for a flow sensor <NUM> may be utilized as a flow sensor <NUM> and inserted into the base <NUM>, where contacts <NUM> are integrated into the base <NUM> rather than as a component of the housing <NUM>, <NUM> of the flow sensor <NUM>. Preferably, the upstream transducer <NUM> and downstream transducer <NUM> are interchangeable, however, it is envisaged that they may be purposefully constructed for their respective positions on the flow sensor sub-assembly <NUM>.

In one embodiment, the first piezo element <NUM> and the second piezo element <NUM> are mounted apart a pre-selected distance from each other. In one embodiment, each of the spring contacts <NUM> are secured to a base, e.g., a circuit board <NUM>. The circuit board <NUM> includes a circuit for conducting an electrical signal to and from the spring contacts <NUM> to a microprocessor. The first spring contact <NUM> is in electrical communication with the first piezo element <NUM> and the second spring contact <NUM> is in electrical communication with the second piezo element <NUM>. The first spring contact <NUM> has a first contact force against the first piezo element <NUM> and the second spring contact <NUM> has a second contact force against the second piezo element <NUM>. In one embodiment, the first contact force is equivalent to the second contact force. In another embodiment, circuit board <NUM> can contain a non-volatile memory containing the serial number of the sensor <NUM>, calibration data and/or flow calculation constants for communication to the electronic microprocessor of the base <NUM>.

Referring to <FIG> and <FIG>, in one embodiment, the flow sensor <NUM> includes an inner flow tube <NUM> and end fittings, e.g., an inlet fitting <NUM> at an inlet end <NUM> and an outlet fitting <NUM> at an outlet end <NUM>, for securing the inner flow tube to the respective end fittings <NUM>, <NUM>. In one configuration, a transducer <NUM> is coupled to at least one of the inlet fitting <NUM> and the outlet fitting <NUM>. In a further configuration, a transducer <NUM> is coupled to each of the inlet fitting <NUM> and the outlet fitting <NUM>. In still a further configuration, a first piezo element <NUM> is coupled to the inlet fitting <NUM> and a second piezo element <NUM> is coupled to the outlet fitting <NUM>.

A transducer adhesive <NUM> is used to bond a transducer <NUM>, such as first piezo element <NUM> and second piezo element <NUM> to a fitting <NUM>, such as the inlet fitting <NUM> and the outlet fitting <NUM>. Transducer adhesive <NUM> bonds the transducer <NUM> to the fitting such that energy from the transducer <NUM> is transmitted optimally across the Transducer-Fitting Transmission Zone <NUM>, as shown by arrow T, while minimizing the losses at the Fitting-Tube Transmission Zone <NUM>, as shown by arrow T1. The fitting adhesive <NUM> dampens out of phase and/or rogue vibrations induced in the end fittings <NUM>, <NUM> by the transmission of sound energy between the first and second piezo elements <NUM>, <NUM> and the end fittings <NUM>, <NUM>.

The first piezo element <NUM> is arranged at an upstream position of the flow tube <NUM> and the second piezo element <NUM> is arranged at a downstream position of the flow tube <NUM>. The first and second piezo elements <NUM> and <NUM> are configured to transmit a flow signal indicative of a flow of the fluidic medicament in the flow tube <NUM>. In an embodiment, the first piezo element <NUM> and the second piezo element <NUM> are annular in shape and encircle the flow tube <NUM> at each respective mounting point. In an embodiment, the first piezo element <NUM> and the second piezo element <NUM> are mounted apart a pre-selected distance from each other. Each of the first and second piezo elements <NUM>, <NUM> are mounted to the end fittings <NUM>, <NUM>, respectively. Each of the first and second piezo elements <NUM>, <NUM> are bonded to the end fittings <NUM>, <NUM> by transducer adhesive <NUM> such that energy from the transducers <NUM>, <NUM> is transmitted optimally across the Transducer-Fitting Transmission Zone <NUM> of each end fitting <NUM>, <NUM>. The adhesive can increase or maximize the energy transfer across the Transducer-Fitting Transmission Zone <NUM>, while reducing or minimizing the losses. Preferably, the transducer adhesive <NUM> facilitates the transmission of sound energy between the first and second piezo elements <NUM>, <NUM> and the end fittings <NUM>, <NUM>. The transducer adhesive <NUM> can be a moderately viscous, medical grade adhesive. Air gaps between the first and second piezo elements <NUM>, <NUM> and the end fittings <NUM>, <NUM> can be eliminated to enable more efficient sound energy transmission. Preferably, the transducer adhesive <NUM> maintains its properties after sterilization.

Referring again to <FIG> and <FIG>, an absorber sheath <NUM> may encircles the flow tube <NUM>. In some embodiments, there may be a gap between the absorber sheath <NUM> and the inlet fitting <NUM> exposing a portion of the flow tube <NUM> at the inlet end <NUM> and/or a gap between the absorber sheath <NUM> and the outlet fitting <NUM> exposing a portion of the flow tube <NUM> at the outlet end <NUM>. For example, the absorber sheath <NUM> may be positioned about <NUM> away from the inlet fitting <NUM> and about <NUM> away from the outlet fitting <NUM>. The absorber sheath may comprise a material with an acoustical transmission rate different than an acoustical transmission rate of a material of the flow tube <NUM>. For example, the flow tube <NUM> can comprise a stainless steel material, and the absorber sheath <NUM> can comprise a plastic material, a PVC material, an elastomer material, a 70A Shore hardness medical grade silicone rubber material, or a heat shrink tubing material.

In one embodiment, the absorber sheath <NUM> may be heat shrunk onto an outside diameter of the flow tube <NUM>. In another embodiment, as shown in <FIG>, the absorber sheath <NUM> is adhered to the flow tube <NUM> with an absorber adhesive <NUM>. In another embodiment, as shown in <FIG>, the absorber sheath <NUM> is adhered to the flow tube <NUM> by insert molding the absorber sheath around the flow tube <NUM>. The absorber adhesive <NUM> can be acoustically transparent. In some embodiments, it is preferable that the absorber adhesive <NUM> forms a flexible bond with the flow tube <NUM>. In other embodiments, it is preferable that the absorber adhesive <NUM> forms a rigid bond with the flow tube <NUM>. In some examples, the absorber adhesive <NUM> can be a similar or the same adhesive as the transducer adhesive <NUM>.

The material of the absorber may be one of any polymers or elastomers, such as polyvinylchloride, silicone rubber, and the like. In one embodiment, the material of the absorber may be flexible in nature and have a lower durometer than that of the flow tube. By providing an absorber having a different and lower durometer than that of the flow tube, the vibrations are maintained within the absorber, rather than passed into the flow tube. At the interface of the absorber and the flow tube is a boundary, and the behavior of energy at the boundary has essentially two useable factors: reflection and transmission/refraction. The reflected and transmitted waves will obey Snell's Law.

With continued reference to <FIG>, a fitting adhesive <NUM> is preferably used to bond the flow tube <NUM> to the end fittings <NUM>, such as inlet fitting <NUM> and outlet fitting <NUM>. Fitting adhesive <NUM> is provided such that energy from the transducers <NUM>, such as piezo elements <NUM>, <NUM> is minimized across the Fitting-Tube Transmission Zone <NUM>, as shown by arrow T1. In certain configurations, energy from the transducers <NUM> is not transmitted across the Fitting-Tube Transmission Zone <NUM>. The fitting adhesive <NUM> dampens the energy transfer across the Fitting-Tube Interface Zone <NUM> and maximizes losses at the Fitting-Tube Transmission Zone <NUM>. Preferably, the fitting adhesive <NUM> dampens out of phase and/or rogue vibrations induced in the end fittings <NUM>, <NUM> by the transmission of sound energy between the first and second piezo elements <NUM>, <NUM> and the end fittings <NUM>, <NUM>. Preferably, the fitting adhesive <NUM> is a low viscous, medical grade adhesive, able to flow via capillary action into fill gaps, although other adhesives are also envisaged. In the Fitting-Tube Transmission Zone <NUM>, an air gap between the outside diameter and the flow tube <NUM> and the end fittings <NUM>,<NUM> may be desirable as this may reduce or prevent out of phase and/or rogue energy transmission which interferes with the main signal to be detected by the microprocessor.

However, regardless of the configuration of the Fitting-Tube Transmission Zone <NUM>, it may be desirable that the sidewall <NUM> of the flow tube <NUM> is in minimal contact with the end fittings <NUM>, <NUM>. Rather, it is desired that the end faces <NUM> of the flow tube <NUM> are provided in contact with the end receiving face <NUM> of each of the end fittings <NUM>, <NUM> as maximum transmission of energy is to occur from end face <NUM> to end receiving face <NUM> across End-Face Transmission Zone T2. During assembly this is accomplished by application of a longitudinal biasing force on flow tube <NUM> in a direction toward the end fittings <NUM>, <NUM> as fitting adhesive <NUM> permanently bonds the flow tube <NUM> and the end fittings <NUM>, <NUM>. Preferably, the fitting adhesive <NUM> maintains its desirable properties after sterilization.

In one embodiment, it is desired that fitting adhesive <NUM> fills the cavity between the flow tube <NUM> and the end fittings <NUM> via capillary action providing a low flex modulus to attenuate acoustic coupling. Previous attempts to minimize energy transmission have involved the use of conventional O-rings, however, the use of O-rings is not possible in gaps which are less than <NUM>", such as the present gap between the flow tube <NUM> and the end fitting <NUM>.

In order to optimize the capillary transmission of the fitting adhesive <NUM>, the fitting <NUM>, such as either or both of the inlet fitting <NUM> or the outlet fitting <NUM>, may define an orifice having a conical interior profile and an adjacent shoulder having a matching size and orientation to match a received end of the flow tube <NUM> therein.

With specific reference to <FIG>, <FIG>, and <FIG>, inlet fitting <NUM> has a distal orifice <NUM> adapted to receive a proximal portion of the flow tube <NUM> therein. The distal orifice <NUM> defines an obconic or conical orifice <NUM> having an abutting shoulder <NUM>. Both the distal orifice <NUM> and the abutting shoulder <NUM> have a matching size and orientation to match an end of the flow tube <NUM> which is receivable therein. The conical orifice <NUM> is sized for insertion of either end of the flow tube therein, such that the distal orifice <NUM> of the inlet fitting <NUM> is coaxial and concentric with the lumen of the flow tube <NUM>, and such that the end of the flow tube <NUM> abuts the abutting shoulder <NUM>. The obconic or conical orifice <NUM> has a distal taper section <NUM> designed to allow capillary action to draw fitting adhesive <NUM> into the void between the exterior of the flow tube <NUM> and the interior surface of the conical orifice <NUM> during assembly. In one embodiment, the conical orifice <NUM> includes a proximal taper section <NUM> which creates a gap between the exterior surface of the flow tube <NUM> proximal to the distal end which does not fill with fitting adhesive <NUM> and provides an air gap, as shown in <FIG>. The distal orifice <NUM> may be tapered and terminate at an end which is opposite the abutting shoulder <NUM> to engage the lumen of the flow tube <NUM>. The distal orifice <NUM> of the inlet fitting <NUM> may be tapered and terminate at an end which is opposite the abutting shoulder <NUM> to engage a Luer type fitting. In certain embodiments the distal orifice <NUM> is conical. In other embodiments the distal orifice is obconic. In certain embodiments, the distal orifice <NUM> includes a two-part taper having an intermediate shoulder <NUM> between the proximal taper section <NUM> and the distal taper section <NUM>. In other embodiments, the intermediate shoulder <NUM> is disposed approximately half-way along the length of the distal orifice <NUM>. In another embodiment, the taper between the intermediate shoulder <NUM> and the abutting shoulder <NUM> is such that tube <NUM> press fits with minimal to no air in this cavity and is not in contact with surface <NUM>.

With specific reference to <FIG>, <FIG>, and <FIG>, outlet fitting <NUM> has a proximal orifice <NUM> adapted to receive a distal portion of the flow tube <NUM> therein. The proximal orifice <NUM> defines an obconic or conical orifice <NUM> having an abutting shoulder <NUM>. Both the proximal orifice <NUM> and the abutting shoulder <NUM> have a matching size and orientation to match an end of the flow tube <NUM> which is receivable therein. The conical orifice <NUM> is sized for insertion of either end of the flow tube therein, such that the proximal orifice <NUM> of the outlet fitting <NUM> is coaxial and concentric with the lumen of the flow tube <NUM>, and such that the end of the flow tube <NUM> abuts the abutting shoulder <NUM>. The obconic or conical orifice <NUM> has a proximal taper section <NUM> designed to allow capillary action to draw fitting adhesive <NUM> into the void between the exterior of the flow tube <NUM> and the interior surface of the conical orifice <NUM> during assembly. In one embodiment, the conical orifice <NUM> includes a distal taper section <NUM> which creates a gap between the exterior surface of the flow tube <NUM> distal to the proximal end which does not fill with fitting adhesive <NUM> and provides an air gap, as shown in <FIG>. The proximal orifice <NUM> may be tapered and terminate at an end which is opposite the abutting shoulder <NUM> to engage the lumen of the flow tube <NUM>. In certain embodiments the proximal orifice <NUM> is conical. In other embodiments the proximal orifice <NUM> is obconic. In certain embodiments, the proximal orifice <NUM> includes a two-part taper having an intermediate shoulder <NUM> between the proximal taper section <NUM> and the distal taper section <NUM>. In other embodiments, the intermediate shoulder <NUM> is disposed approximately half-way along the length of the proximal orifice <NUM>. In another embodiment, the taper between intermediate shoulder <NUM> and abutting shoulder <NUM> is such that tube <NUM> press fits with minimal to no air in this cavity and is not in contact with surface <NUM>.

As shown by the progression of <FIG>, the end fittings <NUM>, <NUM> may be adhered to the flow tube <NUM> with a fitting adhesive <NUM>. In the case of the inlet fitting <NUM>, the fitting adhesive is draw into the distal taper section <NUM> by capillary action. In the case of the outlet fitting <NUM>, the fitting adhesive is drawn into the proximal taper section <NUM> by capillary action. In one embodiment, the end fittings <NUM>, <NUM> may be adhered to the flow tube <NUM> prior to the adhesion or other attachment of the absorber sheath <NUM> to the flow tube <NUM>.

In another embodiment, as shown in <FIG>, the absorber sheath <NUM> can be adhered to the flow tube <NUM> with an absorber adhesive <NUM>. The absorber adhesive <NUM> can be acoustically transparent. In some embodiments, it is preferable that the absorber adhesive <NUM> forms a flexible bond with the flow tube <NUM>. In other embodiments, it is preferable that the absorber adhesive <NUM> forms a rigid bond with the flow tube <NUM>. In some examples, the absorber adhesive <NUM> can be a similar to or the same adhesive as the fitting adhesive <NUM> or the transducer adhesive <NUM>. As shown by the progression of <FIG>, the absorber sheath <NUM> can be adhered to the flow tube <NUM> with the absorber adhesive <NUM> before the end fittings <NUM>, <NUM> are adhered to the flow tube <NUM>.

Claim 1:
A flow sensor sub-assembly (<NUM>) for sensing flow of a fluidic medicament comprising:
a flow tube assembly (<NUM>) through which said medicament flows having:
a flow tube (<NUM>) having a lumen, an outside diameter, a first end, and a second end;
an inlet fitting( <NUM>) having a conical orifice (<NUM>) with an abutting shoulder (<NUM>), wherein said conical orifice (<NUM>) is sized for insertion of either end of said flow tube (<NUM>); and
an outlet fitting (<NUM>) having a conical orifice (<NUM>) with an abutting shoulder (<NUM>), wherein said conical orifice (<NUM>) is sized for insertion of either end of said flow tube (<NUM>);
a first transducer (<NUM>) arranged at the inlet fitting (<NUM>); and
a second transducer (<NUM>) arranged at the outlet fitting (<NUM>),
wherein said conical orifices (<NUM>, <NUM>) of said inlet fitting (<NUM>) and said outlet fitting (<NUM>) are two-part tapers having an intermediate shoulder (<NUM>, <NUM>) approximately half-way along the length of said taper,
wherein a transducer adhesive (<NUM>) bonds said first transducer (<NUM>) to the inlet fitting (<NUM>) and said second transducer (<NUM>) to the outlet fitting (<NUM>),
the transducer adhesive (<NUM>) bonds the first transducer (<NUM>) to the inlet fitting (<NUM>) and the second transducer (<NUM>) to the outlet fitting (<NUM>) such that energy from the transducers is transmitted optimally across a transducer-fitting transmission zone (<NUM>) while also dampening at least one of out of phase vibrations and rogue vibrations induced in the inlet and outlet fittings (<NUM>, <NUM>) by transmission of sound energy between the first and second transducers (<NUM>, <NUM>) and the inlet and outlet fittings (<NUM>, <NUM>).