Patent Application
20110166510
Not Applicable
Not Applicable
The present invention relates to a portable monitoring system of the liquid level in a medical liquid feeding line, and more particularly to a portable IV infusion monitoring system.
Assume a patient lies on bed to receive IV infusion. There are two types of infusion systems. One is by pump, another is by gravity. The pump infusion system is very costly and often encounters maintenance trouble. Therefore, many hospital workers prefer to use the traditional gravity infusion system. The gravity IV infusion line consists of three parts: a) An IV bottle contains medical liquid and air above the medical liquid; (b) Infusion line includes a liquid needle inserted inside the IV bottle to receive medical liquid, a plastic tube (liquid tube) with one end connected to the liquid needle as liquid inlet and another end connected to the IV injection needle for injecting the medical liquid into the patient vein. A flow rate switch is located in the middle of the plastic tube to control the flow rate manually; (c) Air line includes an air needle inserted into the IV bottle to apply air pressure for driving the liquid flow, and a plastic tube (air tube) with one end connected to the air tube as air outlet and another end opened to the environment as air inlet. As the medical liquid in the IV bottle drops to a predetermined low level, i.e., nearly finished, the bottle must be replaced by a new one, otherwise air may enter the infusion line and causes serious medical problems.
So far, the job of bottle replacement needs frequent supervision from patient and nurses by eyeball. This task becomes a heavy burden of medical workers, particularly at night. To develop a monitoring system for IV infusion becomes a big demand from hospitals and patients. Many efforts have been done in this field.
U.S. Pat. No. 3,375,716 to Hersch discloses a fluid quantity measuring device including a sensing capacitor to measure the prevailing quantity of fluid in a container. Hersch's disclosure uses a time-constant circuit, and therefore the measurement accuracy is very poor as well the poor reliability, both of which are very critical in medical application. The present invention applies a microprocessor including an interference filtering means, which acts as a mini computer to process all received electric parameters from the electrodes in digital format, and therefore warrant a very high accuracy and high reliability. Further more, the present invention uses sound alarm, terminal display and signal network to further ease the hospital works.
U.S. Pat. No. 3,390,577 to Phelps et al. discloses a monitoring system for fluid flow in drop form. Phelps' disclosure only applies for measuring the liquid drop. Such system is poor in accuracy and reliability. The present invention can measure the liquid level data at any time moment. Further more, the present invention applies a microprocessor, which acts as a mini computer to process all received electric parameters from the electrodes in digital format, and therefore warrant a very high accuracy and high reliability. In addition, the present invention uses sound alarm, terminal display and signal network to further ease the hospital works.
U.S. Pat. No. 3,641,543 to Rigby discloses a low-level detector and drop rate monitor that can only detect the low solution level and drop rate. Rigby's first embodiment is for detecting a low solution level, where the conductor means needs to be mounted on opposite one another in juxtaposition, one of the conductors and a multivibrator means are required to be grounded. His second embodiment is for monitoring drop rate, where the two electrode means must be placed diametrically opposite one another in juxtaposition, a stabilizing means and a tachometer means are required. The present invention can detect all liquid infusion information including the liquid level at any time moment and liquid moving rate including the low liquid level. Furthermore the present invention does not require two electrodes being placed on opposite one another, does not require any element to be grounded and therefore is portable. In addition, the present invention does not need stabilizing means and tachometer means for operation.
U.S. Pat. No. 3,939,360 to Jackson discloses a liquid level sensor and electrode assembly therefore. Jackson's disclosure requires three capacitance plates to measure the capacitance. Furthermore, the circuit means uses analog signal for measurement, and therefore results in a poor accuracy and poor reliability. The present invention needs only minimum two electrodes for measurement, and the signal process is accomplished by a microprocessor, therefore, warrant a high accuracy and high reliability.
U.S. Pat. No. 4,002,996 to Klebanoff et al. discloses a level detector using oscillator circuit with two capacitive probes. Klebanoff's disclosure detects the low liquid level by emitting an oscillation using a feed-back network. The present invention applies the received signal to microprocessor and send out an alarm signal when the microprocessor analyzes the digital data and finds that the liquid level has dropped to a predetermined low level.
U.S. Pat. No. 4,470,008 to R. Kato et al. discloses a capacitance sensor for detecting liquid level. Kato's disclosure requires three electrodes to measure the capacitance. Furthermore, it applies an analog circuit for measurement, and therefore results in a poor accuracy and poor reliability. The present invention needs only minimum two electrodes for measurement, and the signal process is accomplished by a microprocessor, therefore, warrant a high accuracy and high reliability.
U.S. Pat. No. 4,671,110 to de Kock discloses a level sensing device. De Kock's disclosure is for sensing the liquid level in a boiler or vessel, and therefore need to have tubular glass and a conduit for communication with the liquid inside the vessel. One of the conductors needs to contact the liquid inside the vessel. The present invention is for detecting the liquid level in an IV bottle, and does not need any contact with the liquid inside the liquid container.
U.S. Pat. No. 4,749,988 to Berman et al. discloses a non-invasive liquid level sensor. Berman's disclosure requires the outer shield conductor of a shielded cable to be grounded in order to avoid external interference to the electrode, and therefore such a sensor is not portable. Furthermore, his disclosure does not include any signal process element and signal terminal equipment. The present patent does not need any part to be grounded and therefore is portable. The present invention includes a microprocessor acting as a mini computer, and all the interferences from environment are processed in the microprocessor to be filtered out. Furthermore, the present invention includes the monitor terminal for alarm and display.
U.S. Pat. No. 5,563,584 to Rader et al. discloses a liquid level sensing and monitoring system for medical fluid infusion systems. Rader's disclosure applies pressure sensor technology. In his second embodiment, a sensor is inserted into the outlet of a liquid container and contacts the liquid for detecting the liquid level. The present invention applied the impedance sensor, and none of elements in the present invention needs to be inserted into the outlet of a liquid container.
U.S. Pat. No. 6,964,278 to Tschanz discloses a non-invasive gauge glass liquid level sensor apparatus. Tschanz's disclosure is for sensing liquid level in a boiler or other vessel. Therefore his apparatus requires a tubular gauge glass. In addition, the boiler or vessel must be metallic material. The present invention is for monitoring IV infusion liquid level, and does not requires a gauge glass as well as a metallic material for the liquid container.
U.S. patent application Ser. No. 11/140,087 to Cassidy discloses 3 different embodiments: detecting air bubbles trapped inside liquid, an active gas removal system and an IV flow control system, none of any Cassidy's disclosures is related to an IV monitoring system of the present invention. Furthermore, Cassidy's system needs 3 or 4 electrodes for sensing, but the present invention only needs 2 electrodes.
The present invention provides a portable IV infusion monitoring system, which only needs minimum 2 electrodes for a liquid level sensor and is capable for detecting and displaying both the liquid level and liquid flow rate, as well as giving alarm when the medical liquid in the bottle drops to a predetermined low level. The present invention is different from and superior over all the prior arts in structure, cost, accuracy and reliability, as well as in ease of use.
A portable IV infusion monitoring system is provided to monitor the liquid level and to give alarm as the medical liquid in the IV bottle drops to a predetermined low level. The IV infusion is used for injecting a medical liquid to a patient vein. It includes an IV bottle containing medical liquid in lower part and air above the medical liquid. The IV bottle, as the supplier of the IV infusion medical liquid, comprises at least one of a glass bottle, a plastic bottle, and a plastic bag. The liquid level is defined as the interface between the medical liquid and the air above the medical liquid in the IV bottle. Both a liquid needle for liquid flow and an air needle for air flow are inserted into the IV bottle. A plastic liquid tube for liquid flow is connected at the end of the liquid needle. A plastic air tube for air flow is connected at the end of the air needle.
The preferred embodiment of the present invention comprises a set of liquid level sensor including at least two electrodes, a microprocessor, and a monitor terminal. The power is provided preferably by a battery or an external power source as an option to user. The at least two electrodes are located at either two sides of the IV bottle in opposite direction or one side of the IV bottle in parallel location. They are capable of conducting an electric current between them, e.g., an alternating current. The microprocessor acting as a mini computer is capable of detecting the electric parameters of the alternating current, converting the detected electric parameters into a group of digital data points, analyzing the group of digital data points by statistics to obtain the liquid level data inside the IV bottle, and sending all the liquid level data to the monitor terminal. The electric parameters related to the liquid level include at least one of voltage, current, impedance, phase and frequency etc. The liquid level data include the liquid level inside the IV bottle at any time moment, the liquid flow rate during infusion process, and the comparison with the predetermined low level. The monitor terminal includes an alarm means for sending an alarm, and a display means to display the liquid level data in a terminal screen. Alternatively, the liquid level sensor uses an electric bridge to detect the electric signal for better accuracy.
The microprocessor acting as a mini computer includes a control means for applying the alternating current to the at least two electrodes, receiver means for receiving the electric signal of the alternating current, detector means for detecting the electric parameters of the electric signal, converter means for converting the detected analog electric parameters into a group of digital data, process means for analyzing the group of digital data by statistics, which results in the liquid level data inside the IV bottle, as well as transmission means for sending out the liquid level data. Each of above elements may be built together in one chip, or they can stand alone as individual circuit or chip. The control means includes at least one of an oscillator, an oscillator circuit, a logic circuit etc. The receiver means includes at least one of an input pot, an amplifier, a filter etc. The detector means includes at least one of a CN converter (capacitance to voltage converter), a differential circuit, or a voltage meter etc. The converter means includes at least one A/D converter. The process means includes at least one of signal interface, digital register, processor, or logic circuit etc. The transmission means includes at least one of output pot, conductive wire or antenna etc.
Alternatively the microprocessor includes receiver for receiving the electric signal of the alternating current, detector for detecting the voltage signal from the electric signal, signal interface for storing the voltage signal, A/D converter for converting the voltage signal into a group of digital data points, digital register for storing the digital data, processor for analyzing the group of digital data points by statistics and obtaining the liquid level data simultaneously, output port for transmitting the liquid level data. All the functions of each element are controlled by program controller, which is programmed with unique software code for administrating the operation of all above elements. Each of above elements may be built together in one chip, or they can stand alone as individual circuit or chip. The microprocessor further includes an interference filtering means for removing all interference from the environment.
The electric interference from environment often degrades or sometime disables the normal operation of such a monitoring system. Therefore, to move the signal interference becomes very critical in order to obtain high accuracy and high reliability of the monitoring work. In a typical electric environment, at least one shielding plate made of conductive materials is placed on the outer surface of each electrode. The shielding plate is insulated to the electrodes. The at least one shielding plate is connected to a reference point with zero potential, e.g., the negative pole of a battery. Alternatively, the interference noise in the at least one shielding plate is passed over to the microprocessor, and it is then filtered out in signal processing. Meanwhile, at least two coaxial cables consist of a center conductor surrounded by a concentric outer shielding layer made of conductive materials. The center conductor is insulated from the outer shielding layer. The center conductors of the at least two coaxial cables connect the at least two electrodes to the microprocessor for transmitting the signal. The outer shielding layers of the at least two coaxial cables are connected to the reference point with zero potential, e.g., the negative pole of a battery. Alternatively, the outer shielding layers are connected to the microprocessor for interference filtering process. The microprocessor, part of the monitor terminal and the battery are contained in an assembly box. To shielding the microprocessor and other parts inside the assembly box from the environmental interference, either the assembly box is made of metal or the assembly box is coated with conductive materials. The coated methods include chemical coating, physical coating, mechanical coating, or a simple metal lining. Similar to the shielding plate, the conductive part of the assembly box is connected to a reference point with zero potential, e.g., the negative pole of the battery. Alternatively, the environmental noise in the assembly box is passed over to the microprocessor for interference filtering.
However, if the electric environment is very noisy, and the interference becomes too strong to perform a normal operation of this monitoring system, the signal interference from the environment can be removed by special signal processing methods. The control means in the microprocessor generates the alternating current in various forms such as narrow band signal, multi-frequency signal, and encoded signal (containing continuous wave, pulse and digital signal etc.). If a narrow band signal is applied, the interference filtering means in the microprocessor has a narrow band filter, which can filter out the signal within this narrow band, and remove all random interference outside the narrow band. If a multi-frequency signal is applied, the interference filtering means has a Fourier analyzer, which can perform Fourier analysis to pick up the right signal, and remove the noise interference. If an encode signal is applied, the interference filtering means has a decoder, which can perform decoding to pick up the right signal, and remove the noise interference. The way of encoding includes frequency modulation, angle modulation, phase modulation, pulse modulation, pulse code modulation, FDMA and CDMA modulations etc. All above filtering methods are more effective in digital format
Further alternatively, two pairs of electrodes can be positioned in parallel outside the IV bottle 11. By differentiation of the signal or electric parameters, the environmental interference will be removed too. Hereby there is no need of grounding in order to avoid the environmental interference since this monitoring system is designed as a portable device.
In addition to the environmental interference, the signal deformation may also reduce the reliability of the monitoring system, e.g., in the case of flexible IV bag (i.e., a soft IV bottle), the bag may deform during infusion process and therefore lead to the deformation of the electrical signal and related electrical parameters. However, such signal deformation can be analyzed by the microprocessor, and the corrected electric parameters can be picked up by the analysis. Therefore, it would be impossible to obtain high accuracy and high reliability without the microprocessor.
The monitor terminal includes alarm means for providing an alarm, and display means for displaying the liquid level data in a terminal screen. The alarm means includes a sound generator for giving a loud sound when the medical liquid level inside the IV bottle drops below the predetermined low level. Alternatively the alarm means includes a switch means for cutting off the feeding of medical liquid when the medical liquid level inside the IV bottle drops below the predetermined low level. Further alternatively, the alarm means includes a signal network for sending the liquid level data by the network to a nurse station through wire or wirelessly.
The monitor terminal further includes a rate controller for controlling the infusion rate according to a predetermined rate value. The rate controller comprises an input port for inputting the desired infusion rate of the medical liquid inside the IV bottle, a comparator for comparing the desired infusion rate and the detected infusion rate, and an electric switch means for adjusting the infusion rate according to the results from the comparator.
The preferred embodiment can be further simplified as the followings: A portable IV infusion monitoring system comprises
(a) A liquid level sensor consists of two electrodes. An IV bottle comprises at least one of a glass bottle, a plastic bottle, and a plastic bag, the IV bottle contains medical liquid in lower part and air above the medical liquid. The two electrodes are positioned outside the IV bottle for conducting an electric current between the two electrodes, and for detecting liquid level of the medical liquid. The liquid level is defined as the interface between the medical liquid and the air above the medical liquid in the IV bottle. Therefore, the statement of “detecting liquid level of the medical liquid” is equivalent to say “measuring the interface between the medical liquid and the air above the medical liquid in the IV bottle.” Each of the electrodes is made of only one piece of metal or other conductive material, and therefore the Kato's reference includes 3 electrodes to make up the transducers;
(b) A microprocessor includes control means for controlling the electric current between the two electrodes, receiver means for receiving an electric signal of the electric current, detector means for detecting electric parameters of the electric signal, the electric parameters comprising voltage or impedance, A/D converter means for converting the electric parameters into a group of digital data points, process means having a program or software for statistically analyzing the group of digital data points and obtaining both liquid level and liquid flow rate simultaneously by the statistical analysis, as well as transmission means for sending out the liquid level and liquid flow rate to a monitor terminal. The statistical analysis includes at least one of data filtering, curve fitting and statistical modeling to a group of numerous data points as a function of time, and statistical method to remove electronic noise due to environment. It must be indicated that the applied statistical analysis of the present invention comprises 2 key factors: (1) measuring a group of data points as a function of time; (2) using statistical technique, e.g. curve fitting and modeling etc. The results are obtained from the modeled curve. Hereby, the statistical analysis excludes any algebra method, e.g., comparing one point to another point in Cassidy's reference;
(c) The monitor terminal has alarm means responsive to the liquid level data for giving alarm;
(d) a battery for providing an electric power to the monitoring system, the battery has a negative pole for providing a zero potential reference point to the monitoring system, all parts in the monitoring system are non-grounded, the “portable” is defined as a function such that the IV infusion monitoring system can operate while moving around with a patient.
In describing preferred embodiment of the present invention illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the invention is not intended to be limited to the specific terminology so selected, and it is to be understood that each specific element includes all technical equivalents which operate in a similar manner to accomplish a similar purpose.
The IV infusion system comprises the IV bottle 11 containing the medical liquid 10 in the lower part and air 12 above the medical liquid 10. The IV bottle 11 being the supplier of the IV infusion medical liquid 10 comprises at least one of a glass bottle, a plastic bottle, and a plastic bag. The liquid level is defined as the interface between the medical liquid 10 and the air 12 above the medical liquid 10 in the IV bottle 11. Therefore, the statement of “detecting liquid level of the medical liquid 10” is equivalent to say “measuring the interface between the medical liquid 10 and the air 12 above the medical liquid 10 in the IV bottle 11.” A liquid needle 13 and an air needle 14 are inserted into the IV bottle 11. A liquid tube 15 is connected at the end of the liquid needle 13. An air tube 16 is connected at the end of the air needle 14. The IV bottle 11 can be made of stiff materials such as glass or harden plastics, or it can be made of flexible plastic bags.
The IV infusion monitoring system comprises a liquid level sensor 20 including at least two electrodes 20A, 20B, a microprocessor 30, and a monitor terminal 40. The power is provided preferably by a battery 50 or by an external power source as an option to user. The at least two electrodes 20A, 20B are located at two sides of the IV bottle 11 in opposite direction with each other, and are capable of conducting an alternating current between them. Each electrode 20A, 20B is made of one piece of metal or other conductive material, and it must be insulated with other conductive material in a sensing system. The microprocessor 30 acting as a mini computer is capable of detecting the electric parameters of the alternating current, converting the detected electric parameters into a group of digital data points, analyzing the group of digital data points statistically to obtain the liquid level data inside the IV bottle 11, and sending all the liquid level data to the monitor terminal 40. The electric parameters related to the liquid level include at least one of voltage, current, impedance, phase and frequency etc. The liquid level data includes the liquid level inside the IV bottle 11 at any time moment, the liquid flow rate during infusion process, and the comparison with the predetermined low level. The monitor terminal 40 includes an alarm means for sending out an alarm signal to activate an alarm to patient and nurses if the medical liquid 10 has dropped to the predetermined low level.
In a typical electric environment, at least one shielding plate 20C, 20D made of conductive materials is placed on the outer surface of each electrode 20A, 20B, and is insulated from the electrodes 20A, 20B. The at least one shielding plate 20C, 20D is connected to a reference point with zero potential, e.g., the negative pole of a battery 50. Alternatively, the interference noise in the at least one shielding plate is passed over to the microprocessor 30, and it is then filtered out in signal processing. Meanwhile, at least two coaxial cables 20E, 20F consist of a center conductor surrounded by a concentric outer shielding layer made of conductive materials. The center conductor is insulated with the outer shielding layer. The center conductors of the at least two coaxial cables 20E, 20F connect the at least two electrodes 20A, 20B to the microprocessor 30 for transmitting the signal. The outer shielding layers of the at least two coaxial cables 20E, 20F are connected to the reference point with zero potential, e.g., the negative pole of a battery 50. Alternatively, the outer shielding layers are connected to the microprocessor 30 for interference filtering process. However, if the electric environment is very noisy, and the interference becomes too strong to perform a normal operation of this monitoring system, the signal interference from the environment can be removed by special signal processing methods described in
Again, for removing the interference from the environment, at least one shielding plate 20I made of conductive materials is placed on the outer surface of each electrode 20G, 20H. The at least one shielding plate 20I is connected to a reference point with zero potential, e.g., the negative pole of a battery 50. Alternatively, the interference noise in the at least one shielding plate 20I is passed over to the microprocessor 30, and it is then filtered out in signal processing. Meanwhile, at least two coaxial cables 20J, 20K consist of a center conductor surrounded by a concentric outer shielding layer made of conductive materials. The center conductors of the at least two coaxial cables 20J, 20K connect the at least two electrodes 20G, 20H to the microprocessor 30 for transmitting the signal. The outer shielding layers of the at least two coaxial cables 20J, 20K are connected to the reference point with zero potential, e.g., the negative pole of a battery 50. Alternatively, the outer shielding layers are connected to the microprocessor 30 for interference filtering process. However, if the electric environment is too noisy to perform the normal operation of this monitoring system, the signal processing methods described in
In addition to the environmental interference, the signal deformation may also reduce the reliability of the monitoring system, e.g., in the case of flexible IV bag, the bag may deform during infusion process and therefore lead to the deformation of the electrical signal and related electrical parameters. However, such signal deformation can be analyzed by the microprocessor 30, and the corrected electric parameters can be picked up by the analysis. Therefore, it would be impossible to obtain high accuracy and high reliability without the microprocessor 30.
This application is a CIP of Ser. No. 11/811,466 filed on Jun. 10, 2007 and RCE filed on Feb. 16, 2010, by the present inventors to US Patent and Trademark Office. It is also noted that the above mentioned non-provisional applications claim the benefit of PPA Ser. No. 60/814,238, filed on Jun. 16, 2006, and Ser. No. 60/815,204 filed on Jun. 20, 2006, by the present inventors to US Patent and Trademark Office.
| Number | Date | Country | |
|---|---|---|---|
| 60814238 | Jun 2006 | US | |
| 60815204 | Jun 2006 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 11811466 | Jun 2007 | US |
| Child | 12932990 | US |
