U.S. patent application number 12/932128 was filed with the patent office on 2011-08-25 for iv infusion monitoring device.
Invention is credited to Jun Feng, Xueming Miao.
Application Number | 20110205074 12/932128 |
Document ID | / |
Family ID | 43882797 |
Filed Date | 2011-08-25 |
United States Patent
Application |
20110205074 |
Kind Code |
A1 |
Feng; Jun ; et al. |
August 25, 2011 |
IV infusion monitoring device
Abstract
An IV infusion monitoring device is provided to measure and to
display, during whole infusion process, the liquid level data
including the weight of remaining medical liquid in an IV bottle,
the liquid flow rate and the remaining time from the completion of
an IV infusion process. It also gives alarm as the medical liquid
in an IV bottle drops to a predetermined low level. The IV infusion
monitoring system comprises an electric load sensor, a signal
processor, a monitor terminal and a power provided preferably by a
battery. The load sensor measures the weight of the medical liquid
in the IV bottle. The measured signal is then transmitted to the
signal processor for processing and generating the liquid level
data, which are then sent to the monitor terminal for display. The
monitor terminal can also generate an alarm if the liquid level
drops to the predetermined value. Furthermore, the monitoring
device combines with a server and a plurality of PDA devices to
form a communication network so that a nurse can monitor the IV
infusion process from a remote location.
Inventors: |
Feng; Jun; (Lincoln, MA)
; Miao; Xueming; (Wuxi, CN) |
Family ID: |
43882797 |
Appl. No.: |
12/932128 |
Filed: |
February 17, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61338636 |
Feb 22, 2010 |
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Current U.S.
Class: |
340/613 |
Current CPC
Class: |
G06F 17/40 20130101;
G16H 40/67 20180101; A61M 2205/8206 20130101; G01F 23/20 20130101;
G16H 20/17 20180101; A61M 2205/18 20130101; A61M 2205/502 20130101;
A61M 5/16895 20130101; A61M 5/16845 20130101; G01F 1/00 20130101;
A61M 2205/6054 20130101; G01F 23/0076 20130101; A61M 2205/50
20130101; G06F 19/00 20130101; A61M 5/1414 20130101; A61M 2205/60
20130101 |
Class at
Publication: |
340/613 |
International
Class: |
G08B 21/00 20060101
G08B021/00 |
Claims
1. An IV infusion monitoring device, comprising: (a) a load sensor
including at least one strain gage for measuring weight of medical
liquid in an IV bottle and for sending a measured weight signal to
a signal processor, (b) said signal processor having signal
amplifier for amplifying said measured weight signal and outputting
an amplified weight signal, A/D converter for converting said
amplified weight signal from analog signal to a group of digital
data, microprocessor having software for statistically analyzing
said a group of digital data and obtaining liquid level data, said
liquid level data including weight of remaining medical liquid in
said IV bottle, liquid flow rate, and remaining time from
completion of IV process, data transmitter for transmitting said
liquid level data to a monitor terminal, (c) said monitor terminal
having display means for displaying said liquid level data, alarm
means for give alarm as said weight of remaining medical liquid
drops to a predetermined value, (d) power supplier comprising
selected one of battery, solar cell and external power source for
providing power to said monitoring device.
2. The monitoring device of claim 1, wherein said load sensor
including an electric bridge circuit consisting of 4 arms and 2
pair of ends, said at least one strain gage being installed in at
least one arm, two ends of said electric bridge receiving applied
electric voltage while other 2 ends of said electric bridge
outputting measured signal in proportional to applied weight load
on said at least one strain gage, said at least one strain gage
being made of at least one of resistor, capacitor and inductor.
3. The monitoring device of claim 1, wherein said monitor terminal
including said alarm means for give alarm as said liquid flow rate
drops to a predetermined rate value,
4. The monitoring device of claims, wherein selected one of
magnetic stripe, barcode label and RFID tag being disposed outside
said IV bottle for providing IV data.
5. The monitoring device of claim 1, wherein said monitoring device
connecting to a server and said server connecting to at least one
PDA devices by selected one of wire and wireless for forming a
communication network, said server including software for analyzing
and managing data flow within said communication network and
display means for displaying said liquid level data, said at least
one PDA devices including display means for displaying said liquid
level data and data reader means including selected one of magnetic
stripe reader, barcode scanner and RFID tag reader for reading said
IV data, said liquid level data being transmitted from said
monitoring device to said server, and being further transmitted to
said at least one PDA devices, said IV data being transmitted back
from said at least one PDA devices to said server and further to
said monitoring device.
6. A method of monitoring IV infusion comprising: (a) evaluating
initial weight Wo of medical liquid in an IV bottle by a
microprocessor, (b) measuring gross weight of said IV bottle
including said medical liquid and attachments by a load sensor, and
obtaining a measured weight signal, amplifying said measured weight
signal by a signal amplifier, and obtaining an amplified weight
signal, converting said amplified weight signal from an analog
signal to a group of digital data, analyzing statistically said a
group of digital data and obtaining said gross weight Wg as a
function of time, (c) calculating weight change .DELTA.W of said IV
bottle including said medical liquid and said attachments as a
function of time by said microprocessor, (d) calculating weight of
remaining medical liquid Wr=Wo-.DELTA.W in said IV bottle as a
function of time by said microprocessor, Wr Wo % , ##EQU00001## (e)
calculating percentage of said weight of remaining medical liquid
(f) calculating liquid flow rate W t ##EQU00002## as weight per
unit time, (g) calculating remaining time from completion of IV
process tr, (h) displaying liquid level data, said liquid level
data including said weight of remaining medical liquid, said liquid
flow rate, and said remaining time from completion of IV process,
(g) giving alarm as said weight of remaining medical liquid drops
to a predetermined value.
7. The method of claim 6, wherein said liquid level data being
transmitted to a server from a monitoring device by selected one of
wire and wireless through a communication network, said liquid
level data being further transmitted to a PDA device from said
server by selected one of wire and wireless through said
communication network.
8. The method of claim 6, wherein selected one of magnetic stripe,
barcode label and RFID tag being disposed outside said IV bottle
for containing IV data, said IV data including at least one of
patient name, IV identification, name and quantity of medicine, as
well as name and quantity of solution, said IV data being read by
selected one of magnetic stripe reader, barcode scanner and RFID
tag reader in said PDA device, being transmitted from said PDA
device to said sever, and being further transmitted to said
monitoring device by selected one of wire and wireless through said
communication network.
9. The method of claim 6, wherein said initial weight Wo being
inputted manually in a monitor terminal.
10. The method of claim 6, wherein said initial weight Wo being
inputted through said communication network from said server.
11. The method of claim 6, wherein said initial weight Wo being
inputted through said communication network from said PDA device by
selected one of magnetic stripe reader, barcode scanner and RFID
tag reader.
12. The method of claim 6, wherein said weight of medical liquid in
said IV bottle being converted from unit of weight to unit of
volume.
13. The method of claim 6, wherein said liquid flow rate being
converted into number of liquid drop per unit time based on
estimated weight per drop.
14. The method of claim 6, wherein said alarm being given as said
liquid flow rate drops to a predetermined rate value.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of provisional patent
application No. 61/338,636, filed on Feb. 22, 2010 by the present
inventors to US Patent and Trademark Office.
REFERENCES CITED
U.S. Patent Documents
TABLE-US-00001 [0002] 3,656,478 Apr. 18, 1972 Swersey 604/66
3,939,360 Feb. 17, 1976 Jackson 307/118 4,589,372 May 20, 1986
Smith 119/51.02 5,563,584 Oct. 8, 1996 Rader et al. 340/618
FEDERALLY SPONSORED RESEARCH
[0003] Not applicable
SEQUENCE LIST OF PROGRAM
[0004] Not applicable
FIELD OF INVENTION
[0005] The present invention relates to a monitoring system of a
liquid feeding line, and more particularly to an IV infusion
monitoring device.
BACKGROUND OF THE INVENTION
[0006] 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.
[0007] 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
an alarming system for IV infusion becomes a big demand from
hospitals and patients.
[0008] Furthermore, the hospitals also wish to monitor whole IV
infusion process for better care of the patients. For example, an
IV infusion process may go wrong if a patient or particularly a
baby moves violently during infusion. In this case, monitoring
whole infusion process, e.g., the liquid level and the infusion
speed at each time moment, becomes necessary. Unfortunately, there
is no any satisfied device existing in the current market for this
task. The present invention provides an IV infusion monitoring
device, which not only gives alarm when the IV bottle needs
replacement, but also provides all IV infusion data during whole
infusion process, e.g., the liquid level, the liquid flow rate and
the remaining time from the completion of the infusion process. The
present invention also includes a communication network, so that
the nurses or other hospital workers can monitor the whole IV
infusion process of each patient from either a close or a remote
location through the network.
[0009] U.S. Pat. No. 3,656,478 to Swersey, discloses an infusion
monitor which is able to supply a medical liquid to a patient at
either a high rate or low rate, depending upon the weight of the
patient. If the weight of the patient decreases below a preset
value, the infusion monitor is switched to the high speed. If the
weight of the patient returns to normal, the infusion monitor
switches back to the low speed. The present invention is apparently
different from the Swersey's. The present invention measures and
monitors the weight of the medical liquid in the IV bottle, and
calculates the liquid flow rate during infusion.
[0010] U.S. Pat. No. 3,939,360 to Jackson discloses a liquid level
sensor and electrode assembly therefore. Jackson's disclosure
applies three capacitance plates to measure the capacitance which
is related to the liquid level. The present invention applies
weight measurement of the medical liquid in the IV bottle by an
electric load sensor to monitor the infusion process.
[0011] U.S. Pat. No. 4,589,372 to Smith discloses a dispensing
system similar to the Swersey's. The Smith's system first
determines the weight of an animal subject, and then a delivery
unit supplies a predetermined amount of material to the animal
subject. The amount of supplied material is a function of the
weight of the subject. It is apparent that the present invention is
completely different from the Smith's. The present invention
monitors the weight of the remaining medical liquid in the IV
bottle and the liquid flow rate during infusion, not the control of
the infusion speed as a function of the weight of the animal
subject.
[0012] 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. A
pressure sensor is inserted into the outlet of a liquid container
and contacts the liquid for detecting the liquid level. The present
invention applies the load sensor for measuring the weight of the
medical liquid in the IV bottle during infusion.
[0013] The present invention provides an IV infusion monitoring
device, which is capable for measuring and monitoring the liquid
level and liquid flow rate of the medical liquid in the IV bottle
during whole infusion process, as well as for giving alarm when the
medical liquid in the IV bottle drops to a predetermined low level.
The present invention is different from and superior over all the
prior arts in function, structure, cost, accuracy and reliability,
as well as ease of use.
SUMMARY OF THE INVENTION
[0014] An IV infusion monitoring device is provided to measure and
to display the liquid level data including the weight of remaining
medical liquid in an IV bottle, the liquid flow rate as number of
drop per minute during infusion and the remaining time from the
completion of the IV infusion process etc. It also gives alarm as
the medical liquid in the IV bottle drops to a predetermined low
level. The monitoring devices further combines with a server and at
least one PDA devices (personal digital assistant) to form a
communication network for IV infusion monitoring (i.e., network of
things or interne of things for IV infusion monitoring). A PDA
device is a mobile device, e.g., a remote desk top computer in a
nurse station, a laptop computer, or a palmtop computer. The liquid
level data are transmitted from the monitoring device to the server
and then to the PDA devices through the communication network by
wire or wirelessly. Therefore the nurses and other hospital workers
can monitor the IV infusion process in a remote device, e.g. a
desktop computer in a nurse station or a palmtop computer carried
by a nurse or a hospital worker etc.
[0015] An IV infusion system is used for injecting a medical liquid
to a patient vein. It includes an IV bottle containing medical
liquid in bottom and air above the medical liquid. 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.
[0016] The preferred embodiment of the present invention comprises
a load sensor, a signal processor, a monitor terminal and a power.
The load sensor measures the gross weight of the IV bottle
including the medical liquid and the attachments e.g., the needles
and the tubes. The measured weight signal is then transmitted to
the signal processor, which is able to process the measured weight
signal and obtain the liquid level data including the weight of
remaining medical liquid in an IV bottle, the liquid flow rate
during infusion and the remaining time from the completion of the
IV infusion process. The signal processor also compares the
measured liquid level (e.g., the remaining weight of the medical
liquid or the percentage of the remaining liquid weight over the
initial liquid weight in the IV bottle) to a predetermined value,
and sends out an alarm signal to the monitor terminal as the
measured liquid level is equal or less than the predetermined
value. Meanwhile, all the liquid level data are sent from the
signal processor to the monitor terminal for display during
infusion process. The power is provided preferably by a battery or
a solar cell, alternatively by an external power source as an
option to user.
[0017] The load sensor includes at least one strain gage. As a
mechanical load (i.e., the gross weight of the IV bottle) is
applied, the load is sensed by the strain gage, which outputs an
electric signal, e.g., a voltage, in proportional to the applied
mechanical load. The strain gage can be bonded or un-bonded, can be
made of metal or semiconductor, can be made of resistor or
capacitor or inductor. To compensate the temperature change and
obtain the best resolution, typically, at least one strain gages
and other electric parts (e.g., resistor, capacitor and inductor)
form an electric bridge circuit consisting of 4 arms and 2 pair of
ends, in which two ends receive an applied voltage while another
two ends output the electric signal in proportional to the applied
load on the at least one strain gage.
[0018] The signal processor comprises (a) a signal amplifier, which
is able to amplify the measured weight signal (e.g., a voltage)
received from the load sensor, (b) an A/D converter, which converts
the amplified weight signal (e.g. an analog voltage) into a
plurality of digital data, (c) a microprocessor, which has software
to analyze the plurality of digital data statistically and obtain
the liquid level data. There is much interference electrically or
mechanically during infusion process, for example, as the patient
moves or IV bottle is touched, the measured signal values vary. The
microprocessor receives a plurality of digital data during infusion
process including interference and noise. The software in the
microprocessor is able to statistically analyze these data and
filter out the interference and noises in order to obtain accurate
weight measurement of the medical liquid as a function of time. The
liquid flow rate of the medical liquid in the IV bottle is
calculated as weight change per unit time, it can be converted into
number of drop per unit time by using the estimated weight of each
drop. The software is also capable for evaluating the initial
weight of the medical liquid in the IV bottle. In addition, the
software compares the measured weight of remaining medical liquid
in the IV bottle with the predetermined value, and sends out an
alarm signal as the measured weight is equal or less than the
predetermined value.
[0019] The monitor terminal comprises (a) a display mean which is
able to display all liquid level data including the weight of
remaining medical liquid in the IV bottle, liquid flow rate and the
time from the completion of the IV process, (b) an alarm means
which gives alarm as the monitor terminal receives an alarm signal
from the signal processor, and (c) a data input means which
receives data input and sends them to the signal processor. The
data input means includes manual input or the input from the
communication network. The display means includes a liquid-crystal
screen on the monitor terminal. The alarm means includes a sound
generator or a light generator.
[0020] There are two different monitoring modes, one is single
monitoring mode, and another is network monitoring mode. In single
monitoring mode, the monitoring is carried out in each monitoring
device. In network monitoring mode, each set of liquid level data
are transmitted through the communication network by wire or
wirelessly from each monitoring device to a remote device, e.g., a
desktop computer in a nurse station, a server or a palmtop computer
carried by a nurse or a hospital worker in a remote location.
[0021] The alternative embodiment is a method to monitor the IV
infusion process. The load sensor measures the gross weight Wg of
the IV bottle including the medical liquid and the attachments,
e.g., the needles and the tubes as a function of time. The measured
weight signal is transmitted to a signal amplifier for
amplification. An A/D converter receives the amplified signal from
the signal amplifier and converts the analog signal to a plurality
of digital data, which are then passed to a microprocessor for data
analysis statistically to filter out all interference and noise
etc. The microprocessor then calculates the weight change .DELTA.W
as a function of time during infusion. Since all parts have fixed
weight except the medical liquid during infusion, the weight change
must be the weight decrease of the medical liquid during infusion.
The initial weight Wo of the medical liquid is evaluated at the
beginning of the infusion process by one of 3 different methods:
(a) Evaluated by the software in microprocessor based the standard
weight category of the medical liquid in the IV bottle; (b) Manual
input from monitor terminal, this is not preferred option since it
increases the nurse's working load; (c) Input from the
communication network. All the IV data from a doctor is inputted
into the computer system including the patient name, IV
identification, the name and quantity of the medicine and solution
etc. These IV data are stored in the computer system, and will be
transmitted into the microprocessor through the communication
network. The weight of remaining medical liquid in the IV bottle is
calculated based on the difference between the initial weight of
the medical liquid in the IV bottle and the weight change during
infusion: Wr=Wo-.DELTA.W. The percentage of the remaining medical
liquid weight and the liquid flow rate are then respectively: Wr/Wo
% and dW/dt. The remaining time from completion of the infusion
process is obtained by dividing Wr by dW/dt. These liquid level
data are sent to the monitor terminal for display in single
monitoring mode, and are sent to the communication network in
network monitoring mode so that a nurse or a hospital worker can
monitor the infusion process from a remote location. The
microprocessor also compares the weight of the remaining medical
liquid to a predetermined value Wcritical, and sends an alarm
signal to the monitor terminal to generate an alarm if the weight
of the remaining medical liquid is equal or less than the
predetermined value: Wr. Meanwhile if the liquid flow rate is too
low in comparison to a predetermined rate vale due to some accident
during the infusion process, an alarm will also be generated to
alert the nurses.
BRIEF DESCRIPTION OF THE DR.DELTA.WINGS
[0022] FIG. 1 is a schematic drawing of the installation of an IV
infusion monitoring device for the present invention.
[0023] FIG. 1A is a block diagram of an exemplary data label for
the present invention.
[0024] FIG. 2 is the schematic drawing of an alternative
installation method of an IV infusion monitoring device for the
present invention.
[0025] FIG. 3 is a block diagram of an exemplary IV infusion
monitoring device for the present invention.
[0026] FIG. 4 is the schematic drawing of an exemplary electric
bridge circuit of the load sensor in the present invention.
[0027] FIG. 5 is a block diagram of an exemplary signal processor
for the present invention.
[0028] FIG. 5A is a block diagram of an exemplary microprocessor
including software for the present invention.
[0029] FIG. 6 is a block diagram of an exemplary monitor terminal
for the present invention.
[0030] FIG. 6A is a block diagram of an exemplary alarm means of
the monitor terminal in the present invention.
[0031] FIG. 6B is a block diagram of an alternative alarm means of
the monitor terminal in the present invention.
[0032] FIG. 7 is a flow chart of a monitoring method for the
present invention.
[0033] FIG. 8 is a block diagram of a communication network by
using the monitoring device.
[0034] FIG. 8A is a block diagram of an exemplary server in the
present invention.
[0035] FIG. 8B is a block diagram of an exemplary PDA device in the
present invention.
DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS
[0036] 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.
[0037] FIG. 1 is a schematic drawing of the installation of an IV
infusion monitoring device 10 for the present invention that is
capable of detecting the liquid level data including the weight of
the remaining medical liquid 11 in an IV bottle 12 or the ratio of
the weight of the remaining medical liquid 11 over the initial
weigh of the medical liquid 11, liquid flow rate, and the remaining
time from completion of IV process. It gives alarm when the weight
of the remaining medical liquid 11 in the IV bottle 12 drops to a
predetermined low level. It also gives alarm if the IV infusion
process encounters some trouble and results in a very slow liquid
flow rate below a predetermined rate value.
[0038] An IV infusion system comprises the IV bottle 12, a liquid
needle 14, an air needle 15, a liquid tube 16 and an air tube 17.
The IV bottle 12 contains the medical liquid 11 in its bottom and
the air 13 above the medical liquid 11. The IV bottle 12 functions
as a liquid supply source during infusion. The IV bottle 12 can be
made of stiff materials such as glass or harden plastics, or it can
be made of flexible plastic bags. The liquid needle 14 and an air
needle 15 are inserted into the IV bottle 12. The liquid tube 16 is
connected at the end of the liquid needle 14. The air tube 17 is
connected at the end of the air needle 15. A data label 18 (FIG.
1A) including either of a magnetic stripe 18A, barcode label 18B or
RFID tag 18C is disposed outside the IV bottle 12 for containing
all IV data including patient name, IV identification, the name and
quantity of medicine and solution etc. The weight of the medical
liquid 11 can be converted from weight unit (g) to volume unit
(ml). The liquid flow rate can be converted from weight per unit
time into the number of liquid drop per unit time based on
estimated weight per drop.
[0039] Preferably, the IV infusion monitoring device is installed
in an IV post 19, which is fixed in a patient bed or seat, or
stands alone next the patient bed or seat.
[0040] FIG. 2 is the schematic drawing of an alternative
installation method of the present invention. The IV infusion
monitoring device 10 is installed in an IV bar 19A, which is fixed
above the patient bed or seat horizontally. Alternatively, the IV
infusion monitoring device 10 can be installed or held in any other
position near the patient as long as the IV bottle 12 is relatively
stable during infusion as well as it is above the patient to
provide enough gravitational driving force for the medical liquid
flow.
[0041] FIG. 3 is a block diagram of an exemplary IV infusion
monitoring device for the present invention. The IV infusion
monitoring device 10 comprises a load sensor 20, a signal processor
21, a monitor terminal 22 and a power 23. The load sensor 20
measures the gross weight of the IV bottle 12 including the medical
liquid 11 and its attachments e.g., the needles 14, 15 and the
tubes 16, 17. The measured weight signal is then transmitted to the
signal processor 21, which is able to process the signal and obtain
the liquid level data including the weight of the remaining medical
liquid 11 in the IV bottle 12 or the ratio of the weight of the
remaining medical liquid 11 over the initial weigh of the medical
liquid 11, liquid flow rate, and the remaining time from completion
of IV process. The signal processor 21 also compares the measured
weight of remaining medical liquid 11 to a predetermined value, and
sends out an alarm signal to the monitor terminal 22 as the
measured weight of remaining medical liquid 11 is equal or less
than the predetermined value. All the liquid level data are sent
from the signal processor 21 to the monitor terminal 22 by wire 27A
for display during infusion process. The monitor terminal 22 gives
an alarm in response to the alarm signal from the signal processor
21. In addition, the monitor terminal 22 is capable of transmitting
an input data to the signal processor 21 by wire 27. The power 23
is provided preferably by a battery 24 or a solar cell 25,
alternatively by an external power source 26 as an option to user.
If the power is provided by a battery 24 or a solar cell 25, the
negative pole of the battery 24 or solar cell 25 will act as a
reference zero potential point, and therefore, all parts are
non-grounded and the monitoring device 10 becomes portable, i.e.,
it can move around with a patient while in working condition.
[0042] FIG. 4 is the schematic drawing of an exemplary electric
bridge circuit 30 of the load sensor 20 in present invention. The
load sensor 20 includes at least one strain gage 31. As a load
(i.e., the gross weight of the IV bottle) is applied, the load is
sensed by the strain gage 31, which outputs an electric signal
(i.e., measured weight signal), e.g., a voltage in proportional to
the applied load. The strain gage 31 can be bonded or un-bonded,
can be made of metal or semiconductor, and can be made of resistor
or capacitor or inductor. To compensate the temperature change and
obtain the best resolution, typically, at least one strain gages
(e.g, one gage, two gages or four gages) and other electric parts
(resistor, capacitor and inductor) 31, 31A, 31B and 31C form an
electric bridge circuit 30 consisting of 4 arms 32, 32A, 32B, 32C
and 2 pair of ends 33, 33A, 33B, 33C, in which two ends 33, 33B
receive an applied voltage while another two ends 33A, 33C output
the electric signal in proportional to the applied load on its at
least one strain gage 31.
[0043] FIG. 5 is a block diagram of an exemplary signal processor
21 for the present invention. The signal processor 21 comprises a
signal amplifier 41, an A/D converter 42, a microprocessor 43, a
data receiver 44 and a data transmitter 45. The signal amplifier 41
is able to amplify the measured weight signal (e.g., a voltage)
received from the load sensor 20. The A/D converter 42 converts the
amplified weight signal (e.g. an analog voltage) into a group of
digital data. The microprocessor 43 contains software 46 (FIG. 5A)
to analyze the digital data statistically and to obtain the liquid
level data. The data receiver 44 receives input data from monitor
terminal 22 by wire 27. The data transmitter 45 sends out liquid
level data to monitor terminal 22 by wire 27A. There is much
interference electrically or mechanically during infusion process,
for example, as the patient moves or IV bottle 12 is touched, the
measured weight signal values vary. The microprocessor 43 receives
a plurality of data during infusion process; these data also
include interference and noises. The software 46 in the
microprocessor 43 is able to statistically analyze these data to
filter out the interference and noises in order to obtain accurate
weight measurement of the medical liquid 11 in the IV bottle 12 as
a function of time. The software 46 is also capable for evaluating
the initial weigh of the medical liquid 11 in the IV bottle 12. The
initial weight of the medical liquid 11 can also be obtained
alternatively from manual input in the monitor terminal 22 or from
a communication network 70 (FIG. 8). The liquid weight can be
converted from weight unit (g) to volume unit (ml) by using the
liquid specific weight. The liquid flow rate is calculated as
weight change per unit time. However, the unit of the flow rate can
be converted from weight per unit time to number of drops per unit
time by using estimated weight per drop. The remaining time from
the completion of IV process is obtained based on the remaining
liquid weight and the liquid flow rate. In addition, the software
46 compares the measured weight of the medical liquid 11 or the
liquid flow rate to the predetermined values, and sends out an
alarm signal as the measured weight of the medical liquid 11 or
liquid flow rate are equal or less than the predetermined weight
value or rate value respectively.
[0044] FIG. 6 is a block diagram of an exemplary monitor terminal
22 for the present invention. The monitor terminal 22 comprises a
display mean 51, an alarm means 52 and a data input means 53. The
display means 51 is able to display the liquid level data. The
alarm means 52 gives alarm as the monitor terminal 22 receives an
alarm signal from the signal processor 21. The data input means 53
receives data input manually or from the communication network 70
(FIG. 8), and sends them to the signal processor 21. The monitor
terminal 22 communicates with the signal processor 21 by wire 27,
27A. The display means 51 includes a liquid-crystal screen on the
monitor terminal 22. The alarm means 52 includes either a sound
generator 56 (FIG. 6A) or a light generator 57 (FIG. 6B).
[0045] FIG. 7 is a flow chart of a monitoring method for the
present invention. Step 1 (61): The load sensor 20 measures the
gross weight of the IV bottle 12 including the medical liquid 11
and the attachments, i.e., the needles 14, 15 and the tubes 16, 17,
and obtains a measured weight signal. The measured weight signal is
amplified by the signal amplifier 41 to obtain an amplified weight
signal. The amplified weight signal is further converted from an
analog signal into a group of digital data, which are then analyzed
statistically by the microprocessor 43 to obtain the gross weight
Wg of the IV bottle 12 including the medical liquid 11 and the
attachments 14, 15, 16, 17 as a function of time. Step 2 (62): The
microprocessor 43 statistically analyzes the group of digital data
Wg to filter out interference and noise, and calculates the weight
change .DELTA.W of the IV bottle 12 including the medical liquid 11
and the attachments 14,15,16,17 as a function of time during
infusion. Since all parts of the IV infusion system have fixed
weight except the medical liquid 11 during infusion, the calculated
weight change must be the weight decrease .DELTA.W of the medical
liquid 11 during the infusion. Step 3 (63): The initial weight Wo
of the medical liquid 11 is evaluated at the beginning of the
infusion process by one of 3 different methods: (a) (63A) Evaluated
by the software 46 in the microprocessor 43. The initial weight of
the medical liquid 11 is not arbitrary, it is manufactured in
standardized categories (e.g., 50 g, 100 g, 250 g, and 500 g etc.,
which can be converted into volume unit ml by liquid specific
weight), and the weight of other parts are much smaller than the
medical liquid 11. Therefore, it is not difficult for software 46
to determine which initial weight category the medical liquid 11
belongs to. For example, if the initial gross weight of the IV
bottle 12 is measured to be between 260 g and 400 g, the initial
weight of the medical liquid 11 must be 250 g (or 250 ml in volume)
after deducting the weight of IV bottle 12, needles 14, 15 and
tubes 16, 17, it is the same for other weight categories of 50 g,
100 g, 500 g, 1000 g etc.; (b) (63B) Manual input from monitor
terminal 22, this is not a preferred option since it increases the
nurse's working load; (c) (63C) Input through communication network
70 from a remote device, e.g., a server 71 (FIG. 8A) or a PDA
device 72 (FIG. 8B). All the medical prescription data from a
doctor is inputted into the computer system including IV data,
e.g., the patient name, IV identification, the name and quantity of
the medicine and solution etc. These IV data are stored in the
computer system, and will be transmitted into the microprocessor 43
through communication network 70, for example, the PDA device 72
including a data reader means 74 (one of a magnetic stripe reader
74A, a barcode scanner 74B or a RFID tag reader 74C) to read in the
IV data from the data label 18 and then transmit all the IV data to
the server 71 and then to the microprocessor 43. Step 4 (64): The
weight of remaining medical liquid 11 Wr in the IV bottle 12 at a
given time is calculated by the difference between the initial
weight of the medical liquid 11 Wo and the weight change .DELTA.W
at the given time during infusion: Wr=W0-.DELTA.W. Step 5 (65): The
percentage of the remaining medical liquid weight and the liquid
flow rate (weight change per unit time) are then obtained
respectively: Wr/Wo % and dW/dt. Hereby, the liquid level is
defined as either Wr or Wr/Wo %. The remaining time from the
completion of the IV infusion process tr can also be calculated,
e.g., dividing the remaining liquid weight Wr by the liquid flow
rate dW/dt. The liquid level data including the liquid level Wr or
Wr/W0%, liquid flow rate dW/dt and the remaining time from IV
completion tr. The unit of the weight can be converted between g
and ml by liquid specific weight, and the unit of liquid flow rate
can be converted between g/s and drop/s by liquid weight per drop.
Step 6 (66): These liquid level data are sent to the monitor
terminal 22 for display, or are sent to the communication network
70 for display in a remove device, e.g., a server 71 (FIG. 8A) or a
PDA device 72 (FIG. 8B). Step 7 (67): The microprocessor 43 also
compares the weight of the remaining medical liquid 11 to a
predetermined value Wcritical (e.g., 10 g), and sends out an alarm
signal to the monitor terminal 22 or the communication network 70
to generate alarm if the weight of the remaining medical liquid 11
is equal or less than the predetermined value: Wr.ltoreq.Wcritical.
Meanwhile, if any trouble occurs during the IV infusion process,
the liquid flow rate may become very low, then an alarm will also
be generated to alert the nurses for treatment as the liquid flow
rate drops below a predetermined rate value. The above sequence of
steps is applied for sake of convenience. Any change of the
sequence also gives technical equivalent of the monitoring method,
for example, the step 3 could move to before step 1, and it still
gives the same method.
[0046] FIG. 8 is a block diagram of a communication network 70.
There are two different monitoring modes, one is single monitoring
mode, and another is network monitoring mode. In single monitoring
mode, the monitoring device 10 alone is applied for each patient,
and the IV infusion process is monitored by using the monitoring
device 10 only. In network mode, a communication network for IV
infusion monitoring 70 (i.e., internet of things or network of
things for IV infusion monitoring) comprises at least one
monitoring device 10, 10A, 10B, a server 71 and at least one PDA
device (personal digital assistant) 72, 72A, 72B, 72C. Each
monitoring device 10, 10A, 10B is located next to each patient
under IV infusion process for measuring the liquid level data
including the liquid level Wr or Wr/Wo %, the liquid flow rate
dW/dt and the remaining time tr from the completion of IV process.
The server 71, as shown in FIG. 8A, typically a PC, includes
display means 71A for displaying received liquid level data, as
well as software 71B to analyze and to manage data flow within the
communication network 70. Each PDA device (i.e., personal digital
assistant) 72, 72A, 72B, 72C, e.g., a remote desk top computer in a
nurse station, a laptop computer, a palmtop computer or other
mobile devices, as shown in FIG. 8B, is carried by a nurse or a
hospital worker. Each PDA includes display means 73 for displaying
received liquid level data and a data reader means 74, e.g., a
magnetic stripe reader 74A, a barcode scanner 74B or a RFID tag
reader 74C for scanning and reading in the IV data contained in the
data label 18 attached outside the IV bottle 12. The liquid level
data are transmitted from at least one monitoring device 10, 10A,
10B to the server 71 by wire or wireless. The server 71 further
sends all the liquid level data to each PDA device 72, 72A, 72B,
72C by wire or wireless. In reverse turn, the IV data including
patient name, IV identification, the name and quantity of medicine
and solution etc. are read by the PDA device 72, 72A, 72B, 72C and
they are then transmitted back to server 71 and further to each
monitoring device 10, 10A, 10B. The server 71 is also capable to
directly receive input data from the users.
* * * * *