Note: Descriptions are shown in the official language in which they were submitted.
CA 02354688 2001-08-03
MICROPROCESSOR BASED BED PATIENT MONITOR
BACKGROUND OF THE INVENTION
This invention relates generally to monitoring
systems and more particularly concerns devices and systems used
to monitor bed patients in hospital or other care giving
environments.
It is well documented that the elderly and post-
surgical patients are at a heightened risk of falling. There
are many reasons for this but, broadly speaking, these
individuals are often afflicted by gait and balance disorders,
weakness, dizziness, confusion, visual impairment, and postural
hypotension (i.e., a sudden drop in blood pressure that causes
dizziness and fainting), all of which are recognized as
potential contributors to a fall. Additionally, cognitive and
functional impairment, and sedating and psychoactive
medications are also well recognized risk factors.
A fall places the patient at risk of various injuries
including sprains, fractures, and broken bones - injuries which
in some cases can be severe enough to eventually lead to a
fatality. Of course, those most susceptible to falls are often
those in the poorest general health and least likely to recover
quickly from their injuries. In addition to the obvious
physiological consequences of fall-related injuries, there are
also a variety of adverse economic and legal consequences that
include the actual cost of treating the victim and, in some
cases, caretaker liability issues.
In the past, it has been commonplace to treat
patients that are prone to falling by limiting their mobility
through the use of restraints, the underlying theory being that
if the patient is not free to move about, he or she will not be
as likely to fall. However, research has shown that restraint-
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CA 02354688 2001-08-03
based patient treatment strategies are often more harmful than
beneficial and should generally be avoided - the emphasis today
being on the promotion of mobility rather than immobility.
Among the more successful mobility-based strategies for fall
prevention include interventions to improve patient strength
and functional status, reduction of environmental hazards, and
staff identification and monitoring of high-risk hospital
patients and nursing home residents.
Of course, monitoring high-risk patients, as
effective as that care strategy might appear to be in theory,
suffers from the obvious practical disadvantage of requiring
additional staff if the monitoring is to be in the form of
direct observation. Thus, the trend in patient monitoring has
been toward the use of electrical devices to signal changes in
a patient's circumstance to a caregiver who might be located
either nearby or remotely at a central monitoring facility,
such as a nurse's station. The obvious advantage of an
electronic monitoring arrangement is that it frees the
caregiver to pursue other tasks away from the patient.
Additionally, when the monitoring is done at a central facility
a single nurse can monitor multiple patients which can result
in decreased staffing requirements.
Generally speaking, electronic monitors work by first
sensing an initial status of a patient, and then generating a
signal when that status changes, e.g., he or she has sat up in
bed, left the bed, risen from a chair, etc., any of which
situations could pose a potential cause for concern in the case
of an at-risk patient. Electronic bed and chair monitors
typically use a pressure sensitive switch in combination with a
separate monitor/microprocessor. In a common arrangement, a
patient's weight resting on a pressure sensitive mat (i.e., a
"sensor" mat) completes an electrical circuit, thereby
signalling the presence of the patient to the microprocessor.
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CA 02354688 2001-08-03
when the weight is removed from the pressure sensitive switch,
the electrical circuit is interrupted, which fact is sensed by
the microprocessor. The software logic that drives the monitor
is typically programmed to respond to the now-opened circuit by
triggering some sort of alarm-either electronically (e.g., to
the nursing station via a conventional nurse call system) or
audibly (via a built-in siren). Some examples of devices that
operate in this general fashion may be found in U.S. Letters
Patent Nos. 4,484,043, 4,565,910, 5,554,835, and 5,634,760.
That being said, patient monitoring systems that rely
on sensor mats to detect the presence of a patient in a bed
suffer from a variety of drawbacks. For example, the bed
monitoring systems currently available in the marketplace
feature externally accessible configuration switches that allow
the caregiver to reconfigure the device at will and to adjust
parameters such as the duration of the alarm, and the time
lapse between the sensing of the "empty bed" condition and the
sounding of an alarm. External switching makes tampering with
the system extremely easy and makes it more difficult to
establish and maintain a hospital-wide policy with respect to
monitor settings.
A further problem with conventional bed monitoring
systems is that they use oscillating transducers in their alarm
audio circuits, resulting in single frequency audio alarms.
Since bed monitor alarms are frequently employed in
environments in which a multiplicity of other problems might
also trigger audio alarms, if the single alarm sound provided
by the bed monitor happens to be similar to one or more other
alarm sounds heard in response to different monitors, confusion
and consequential lengthened response times to patient monitor
alarms may result.
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Those skilled in the art know that there are many
nurse call station configurations and it is to the economic
advantage of a manufacturer to be able to accommodate all of
them. However, another problem with the present state-of-the-
art in bed monitoring systems is that they are typically pre-
configured internally at the factory for one particular type of
nurse call station. Thus, if the unit is misconfigured when it
arrives at an installation, it may be necessary
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' Br,.~CHK-88140
to summon a medical technician to reconfigure it, since internal modifications
to the unit are
required to adapt it to different call station types. This can result in
additional expense and
delay in getting the unit correctly configured and into operation. Further,
there are many
hospitals that use multiple incompatible nurse call system types, each having
been separately
added as a new building or wing was constructed. The inability to quickly and
reliable move
electronic monitors between these systems means that the hospital will
generally be required to
maintain excess inventory of each type of compatible monitor, a result that
ultimately adds to
the health care costs borne by the consumer / patient.
Still another failure in known bed monitoring systems is that they do not
provide a
method of accumulating statistical data relating to the operation of the unit
including, for
example, the response times of the caregiver to alarm conditions. This sort of
information
could be very helpful to the maintenance and proper operation of the monitor,
and for caregiver
quality control purposes.
It is, therefore, a primary object of this invention to provide a patient
monitor that is
microprocessor-based so as to be reconfigurable by the uploading of
configuration data to an
electronically erasable programmable read only memory accessible by the
microprocessor. A
further object of this invention is to provide a microprocessor based patient
monitor which
synthesizes multiple alarm sounds in software for selection by the caregiver.
It is also an object
of this invention to provide a microprocessor based patient monitor having a
nurse call interface
allowing interconnection with any nurse call station without modification of
the monitor. Yet
another object of this invention is to provide a microprocessor based patient
monitor having an >
electrically erasable programmable read only memory accessible by the
microprocessor for
logging statistical data with respect to the use of the monitor and the
response time of the
caregiver using the monitor. Another object of this invention is to provide a
microprocessor
based bed patient monitor which permits the downloading of the logged
statistical data to a host
microprocessor connected to the system. It is still another object of the
instant invention to
provide a system for configuration of monitor parameters and for recalling and
analyzing
statistical data accumulated therein.
Heretofore, as is well known in the bed monitor arts, there has been a need
for an
invention to address and solve the above-described problems. Accordingly, it
should now be
recognized, as was recognized by the present inventor, that there exists, and
has existed for
some time, a very real need for a electronic patient monitor that would
address and solve the
above-described problems.
Before proceeding to a description of the present invention, however, it
should be noted
and remembered that the description of the invention which follows, together
with the
accompanying drawings, should not be construed as limiting the invention to
the examples (or
preferred embodiments) shown and described. This is so because those skilled
in the art to
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Brl)CHK-88140
which the invention pertains will be able to devise other forms of this
invention within the
ambit of the appended claims. .
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SUI~IARY OF THE INVENTION
In accordance with the invention, a patient monitor
is provided in which a processor receiving electronic signals
from a sensor indicating the presence on the sensor and absence
from the sensor of a patient is combined with an alarm system
which includes a loudspeaker driven by a power amplifier which
responds to an input signal derived from a programmable volume
control to produce an aural alarm. The processor synthesizes
at least one and preferably multiple alarm sounds under
software control, operates the programmable volume control of
the alarm system to select the decibel level of the alarm and
activates and deactivates the alarm in response to the
electronic signals received from the sensor and a user
interface. Preferably, an electrically erasable programmable
read-only memory accessible by the processor stores a plurality
of alarm sounds for selection by the processor for synthesis of
the selected alarm sound. In addition, the electrically
erasable programmable read-only memory may store multiple
decibel levels for selection by the processor of the desired
decibel level of the alarm sound. In the preferred embodiment,
the patient monitor will be used to sense the presence of
patient who is lying in a bed, however, it should be noted and
remembered this monitor could also be used in other sorts of
applications, including with chair and toilet monitors.
Preferably, the electrically erasable programmable
read-only memory also permits storage of a plurality of options
for the delay time between initiation of the absence of a
patient from the sensor and the activation of the alarm by the
processor. Furthermore, the monitor is preferably provided
with an external switch connected to the processor for
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caregiver selection of the delay time from the plurality of
delay time options.
It is also preferred that the electrically erasable
programmable read-only memory log usage data with respect to
the monitor including the total hours of use of the monitor,
the total time of alarms sounded by the monitor, the total
number of alarms sounded by the monitor and the response time
between the most recent sounding of an alarm and a subsequent
operation of the monitor by the caregiver. The monitor will
include a port for downloading the log usage data to a host
computer.
The monitor also includes a nurse call interface
having a relay which is energized when the power amplifier is
de-energized and which has a normally opened contact, a
normally closed contact and a common contact for
interconnecting the monitor to a nurse call system to one of
the normally opened and normally closed contacts so that the
monitor requires no modification to accommodate the type of
nurse call station with which the monitor is used.
According to still another aspect of the instant
invention, there is provided a bed monitor/computer system
which allows easy on-site configuration of a monitor to work
with different nurses stations. In more particular, the
monitor of the instant invention is designed to be reconfigured
through the use of a host computer, which obviates the need for
internal modifications of monitor parameters through the use of
dip switches, rotary dials, etc., which
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Br:~CHK-88140
are commonly used in the industry. In the preferred embodiment, a standard
computer
interface, such as serial interface, is provided as a means for communication
between the
monitor and a separate host computer. This allows the unit to be readily
reprogrammed without
risking the exposure of the infernal electronic components to the environment.
According to still a further aspect of the instant invention, there is
provided a software
system for providing the monitor with new programming instructions or a new
"personality"
which will enable it to operate with potentially any plug-compatible nurse
call station. In the
preferred embodiment, the internal operating logic and various parameters
which change the
operation of the device to match a particular nurse call station are
preferably stored in
nonvolatile flash-type RAM which is RAM that can be modified on demand through
the use of
a host computer-to-patient monitor transfer. One obvious advantage of this
arrangement is that
it eliminates the many problems associated with mechanical configuration
switches, such as dip
switches and rotary dials, while providing an easy, inexpensive, and reliable
way of upgrading
or otherwise modifying the functionality of a monitor while it is in the
field.
The foregoing has outlined in broad terms the more important features of the
invention
disclosed herein so that the detailed description that follows may be more
clearly understood,
and so that the contribution of the instant inventor to the art may be better
appreciated. The
instant invention is not to be limited in its application to the details of
the construction and to the
arrangements of the components set forth in the following description or
illustrated in the
drawings. Rather, the invention is capable of other embodiments and of being
practiced and
carried out in various other ways not specifically enumerated herein.
Additionally, the
disclosure that follows is intended to cover all alternatives, modifications
and equivalents as
may be included within the spirit and scope of the invention as defined by the
appended claims.
Further, it should be understood that the phraseology and terminology employed
herein are for
the purpose of description and should not be regarded as limiting, unless the
specification
specifically so limits the invention.
While the instant invention will be described in connection with a preferred
embodiment, it will be understood that it is not intended to limit the
invention to that
embodiment. On the contrary, it is intended to cover all alternatives,
modifications and
equivalents as may be included within the spirit and scope of the invention as
defined by the
appended claims.
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BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the invention will become apparent upon
reading the
following detailed description and upon reference to the drawings in which:
Figure 1 is a block diagram illustrating a preferred embodiment of the
monitor;
Figure 2 is a schematic diagram illustrating a portion of a preferred
embodiment of the
processor of the monitor;
Figure 3 is a schematic diagram illustrating a portion of a preferred
embodiment of the
processor of the monitor;
Figure 4 is a schematic diagram illustrating a preferred embodiment of the
user interface
of the monitor;
Figure 5 is a schematic diagram illustrating a preferred embodiment of the
audio section
of the monitor;
Figure 6 is a schematic diagram illustrating a preferred embodiment of the
signal
condition circuit of the monitor;
Figure 7 is a schematic diagram illustrating a preferred embodiment of the non-
volatile
memory of the monitor;
Figure 8 is a schematic diagram illustrating a preferred embodiment of the
nurse call
interface of the monitor;
Figure 9 is a schematic diagram of a preferred embodiment of the power supply
of the
monitor;
Figure 10 is a flow diagram illustrating a preferred embodiment of a cold
start routine
of the monitor;
Figure 11 is a flow diagram illustrating a preferred embodiment of the
executive routine
of the monitor;
Figure 12 is a flow diagram illustrating a preferred embodiment of the hold
mode
routine of the monitor;
Figure 13 is a flow diagram illustrating a preferred embodiment of the monitor
routine
of the monitor;
Figure 14 is a flow diagram illustrating a preferred embodiment of a portion
of the
alarm mode of the monitor;
Figure 15 is a flow diagram of another portion of the alarm mode routine of
the
monitor;
Figure 16 is a flow diagram illustrating a portion of a preferred embodiment
of the
program mode of the monitor;
Figure 17 is a flow diagram illustrating a portion of a preferred embodiment
of the
program mode of the monitor;
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Figure 18 is a flow diagram illustratihg a portion of a preferred embodiment
of the
program mode of the monitor;
Figure 19 is a flow diagram illustrating a preferred embodiment of the data
logger
subroutine of the monitor; and
S Figure 20 is a flow diagram illustrating a preferred embodiment of the pull-
out
protection subroutine of the monitor.
Figure 21 contains an illustration of the general environment of the instant
invention,
wherein a host computer is connected to the monitor for purposes of data
transfer.
Figure 22 illustrates the main hardware elements of the reprogrammable monitor
embodiment.
Figure 23 contains a flow chart that illustrates the principle computer steps
in the
personality loading routine.
Figure 24 is a flow chart of the principle steps in the parameter recall
routine, wherein
data is passed from the monitor to the host CPU.
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B LOCH K-88140
DETAILED DESCRIPTION OF THE INVENTION
Microprocessor-Based Patient Monitor
According to a first aspect of the instant invention, there is provided a
microprocessor
based patient monitor that offers improved functionality in comparison with
known control
units by introducing added features and improvements in the intuitiveness of
the operation. As
is illustrated in Figure 1, a preferred embodiment of the instant monitor
hardware has seven
functional blocks including a processor 10, a user interface 4U, an audio
section 7U, a signal
conditioning circuit 100, a non-volatile memory 130, a nurse call interface
160 and a power
supply 190.
As is made clear in Figure 1, the microprocessor 10 is responsible for various
functions within the monitor including managing its user interface 40,
communicating with the
nurse call interface 160, and controlling the signal condition circuit lUU /
audio section 70.
Additionally, the processor 10 is able to retrieve from and store to non-
volatile memory 130 as
needed.
As shown in Figures 2 and 3, the processor 10 includes a microcontroller 11, a
latching display driver 13 and a latch 15. Since the microcontroller 11 is
synthesizing the
alarm sound in software, it is important to run the microcontroller 11 at its
maximum operating
speed. The microcontroller 11 preferably has fourteen general purpose I/O pins
grouped into a
port A and a port B and one interrupt request input IRQ. The pins of the
microcontroller 11 are
preferably utilized as follows:
Port A Bit 0: via a multifunction bus 17 to D1 of the latch 15, A1N of the
latching
display driver 13, INC of a volume control 71 in the audio section 70,
via a diode 25 to Ull 1 of the user interface 40 and via a resistor R1 to
VCC;
Port A Bit 1: via the multifunction bus 17 to D2 of the latch 15, B 1N of the
latching
display device 13 and U/D of the volume control 71, via a diode 27 to
UI12 of the user interface and via a resistor R2 to VCC;
Port A Bit 2: via the multifunction bus 17 to D3 of the latch 15 and CIN of
the
latching display driver 13;
Port A Bit : via the multifunction bus 17 to D4 of the latch 15 and DIN of the
latching display driver 13;
Port A Bit 4: to Key Input Enable of the user interface 40;
Port A Bit 5: via the multifunction bus 17 to D6 of the latch 15;
Port A Bit 6: to LE of the latching display driver 13;
Port A Bit 7: to CLK of the latch 15;
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Port B Bit 0: to SDA of the non-volatile memory 130 (EEPROM Data), via a
resistor
R3 to VCC and the power supply 190;
Port B Bit 1: to SCL of the non volatile memory 130 (EEPROM clock), via a
resistor
R6 to VCC and the power supply 190;
Port B Bit 2: to the nurse call interface 160 (pull out
detection);
Port B Bit 3: to CS of the volume control 71 (volume);
Port B Bit 4: to VH of the volume control 71 (audio out);
Port B Bit 5: to the signal condition circuit 100 (mat
detection);
IRQ: (Interrupt Request) to the signal condition
circuit 100 (mat input);
Reset: to VCC through the time delay R13/C13; and
OSCI & OSC2: to the master clock for the microcontroller 11.
Additionally, the remaining pins of the latching display driver 13 are
preferably used as
follows:
AoU.I.: Via a resistor R4 to UI1 of the user interface 40;
Boy: Via a resistor RS to UI2 of the user interface 40;
CoU.I.: Via a resistor R~ to UI3 of the user interface 40;
Dog: Via a resistor R8 to UI4 of the user interface 40;
EoU.I.: Via a resistor Rlo to UIS of the user interface 40;
FoU.I.: Via a resistor R~ 1 to UI6 of the user interface 40 ;
Got: Via a resistor R12 to UI7 of the user interface 40; and
LT and B 1: to VCC
The remaining pins of the latch 15 are preferably used as follows:
Q1: via a resistor R14 to UI8 of the user interface 40;
QZ: via a resistor Rls to UI9 of the user interface 40;
Q3: via a resistor R16 to UI10 of the user interface 40;
Q4: to the nurse call interface 160;
Q5: unused;
Q6: to the nurse call interface 160; and
DS and CLR: to V CC.
The multifunction bus 17 to D1, 2, 3, 4 and 6 of the latch 15 capitalizes on
the
bidirectional feature of the microcontroller 11 to create a local data bus.
This allows the
CA 02354688 2001-08-03
76907-18
associated pins PAO, 1, 2, 3 and 5 of the microcontroller 11 to
be used for several functions, reducing the total number of I/0
pins required and allowing for a smaller, less expensive
microcontroller 11 to be used. The multifunction bus 17
sources information for a numeric display 41 via the latching
display driver 13, selects annunciators 43 to be illuminated
via the latch 15, energizes the nurse call relay K1 via the
latch 15, provides up/down information for the programmable
volume control 71 and inputs the status of the keypad 45.
Operation of the multifunction bus 17 is purely under software
control. The microcontroller 11 contains internal RAM 19,
EPROM 21, and a Timer 23. One suitable hardware choice for the
microcontroller 11 is a Motorola* MC68HC705J2, the latching
display driver 13 is a Motorola 74HC4511 and the latch 15 is a
Motorola 74HC174.
A resistor R13 and capacitor C13 connected between
the power source VCC and the RESET port of the microcontroller
11 provide time delay at initialization and a typical clock
circuit is connected to the OSC1 and OSC2 ports of the
microcontroller 11.
Turning to Figure 4, the user interface 40 preferably
consists of the numeric display 41, an annunciator bank 43
including a HOLD annunciator 47, a MON annunciator 49 and an
ALARM annunciator 51 and the keypad 45 including a reset switch
53 and a delay adjust switch 55. Needless to say, many other
arrangements of the control switches and displays are possible
and are well within the capability of one of ordinary skill in
the art to devise.
The numeric display 41 is a seven segment display
driven by the latching display driver 13. The preferred
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takes Binary Coded Decimal (BCD) in and decodes it into the
appropriate segments to display the desired number. The BCD
input is provided by D1-D4 of the multifunction bus 17. The
information is latched into the latching display driver 13 by
Port A Bit 6. The latching operation frees up the
multifunction bus 17 for other purposes while maintaining a
stable display. The latching display driver 13 provides a
blanking function, a totally dark display, by writing a number
greater than nine to the BCD input. Four bits of data provide
16 possible combinations (0-15), while only ten combinations
are defined in BCD (0-9). The other six combinations (10-15)
result in turning off all of the display segments. The numeric
display 41 is used to display the seconds of delay which
precede an alarm in normal operation of the monitor. In
addition, the display 41 is used to show selected options
during the local programming mode, as is hereinafter further
described in relation to the monitor software. All three
annunciators, 43, 45 and 47, are LED's driven by the latching
display driver 13. The preferred latching display driver 13, a
Motorola 74HC4511, is capable of sourcing 20 milliamps per
output 50. No additional drive is necessary to each LED. The
driver 13 has a hex latch (six individual D flip/flops with a
common clock line). Only five latch outputs are implemented
and one of those is unused in the current software. Q1 through
Q3 are used for the annunciators 47, 49 and 51, respectively.
By using a latch 15 with sufficient drive capability, the
latching display driver 13 provides the source current to
illuminate each LED and also latches the data so that the
annunciators 43, 45 and 47 remain stable while the
multifunction bus 17 is used for other purposes. To turn on a
particular annunciator 47, 49 or 51, the processor 10 raises
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the appropriate bit of the multifunction bus 17, D1 for ALARM
47, D2 for MON 49 or D3 for HOLD 51, and then toggles Port A
Bit 7 to latch the data. Operating characteristics for each
mode are hereinafter described in relation to the monitor
software. The reset switch 53 and delay adjust switch 55 are
inputted to the processor 10 on bits D1 and D2 of the
multifunction bus 17. The two switches 53 and 55 share a
common select line so a read of either switch 53 or 55 always
reads both switches 53 and 55. To accomplish a read, the
processor 10 must make Port A Bit 0 and Port A Bit 1 inputs.
The switches 53 and 55 are then read by taking Port A Bit 4
low. The two inputs are pulled up by resistors R1 and R2 and
these two bits may be pulled low through diodes D1 and D2
respectively. This can only happen if the appropriate switch
53 or 55 is closed and the key enable line is low.
Looking now at Figure 5, the audio section 70
consists of a programmable volume control 71, a power amplifier
73 and a loudspeaker 75. The audio is a single bit square wave
generated by the processor 10 under software control. The
audio signal is divided to the requested volume by the
programmable volume control 71, the power amplified to a
sufficient level to drive the loudspeaker 75, and converted to
audio by the loudspeaker 75.
The volume control 71 is preferably a Xicor
Corporation* X9314 digital potentiometer. This integrated
circuit performs the same function as a potentiometer except
the wiper position VW is digitally positioned to any one of 32,
(i.e., 0-31) possible steps. The circuit is designed such that
position zero corresponds to a minimum volume (no sound) and
position 31 is maximum volume. To control the volume chip
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select CS, which is connected to VCC via a pull-up resistor
R32, is set low (Port B Bit 3), the up-down pin U/D (mfb D1) is
set low to reduce volume or high to increase volume, and the
increment-decrement INC pin (mfb DO) is toggled the appropriate
number of times to reach the new wiper position.
The multifunction bus 17 is used for the U/D control
and for the INC control since these signals have no effect on
the chip in the absence of a valid chip select signal.
Therefore, using mfb D1 and mfb D2 will not effect the volume
when used for other purposes and the chip select signal (active
low) is high. The output of the programmable volume control 71
is AC coupled by a resistor R33 and capacitor C5 and directed
to the input of the audio power amplifier 73.
The power amplifier is preferably a National
Semiconductor* LM388 audio amplifier which has adequate drive
for the required volume levels and requires relatively few
discrete components to produce a viable audio amplifier. It is
used in its simplest configuration and
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directly drives the unit's loudspeaker 75. It preferably has a fixed gain of
20 and a resistor R.,6
scales the audio appropriately for the desired maximum output level.
The loudspeaker 75 is preferably a simple two inch polycone speaker. However,
it
should be noted that other an:angements are certainly possible and it is
within the ordinary skill
of in the art to devise. By way of example only, the loudspeaker element might
be a
piezoelectric device capable of generating an audible alarm signal. Thus, when
the term
"loudspeaker" is used hereinafter, that term should be construed in the
broadest possible sense
to include any device capable of emitting an audible alarm signal under the
control of the
microprocessor 10. Additionally, when loudspeaker is used herein that term
should also be
taken to include an associated power amplifier, if one is necessary from the
context of its use
(as it usually will be). Finally, it should also be noted that it is not an
essential element of the
instant invention that the loudspeaker 75 be found within the body of the
monitor. The
speaker 75 could also be mounted externally thereto, and, as an extreme
example; might by
located in an adjacent hallway or at the nurses station.
The signal conditioning circuit 100, shown in detail in Figure 6, filters
noise from the
mat inputs JR1-1 and 2 and provides a reasonable degree of protection to the
monitor from
static discharge. Filtering at one input JRl-2 is accomplished by a single RC
circuit including
resistors R2~ and RZ~ and a capacitor C6 and at the other input JR1-1 by a
simple RC circuit
including resistors R~9 and R31 and a capacitor C3. This eliminates some noise
and assists in
increasing the immunity from static discharge. A static discharge to the
monitor passes through
the RC filters and is then clamped by surge limiting devices, RV 1 and RVZ of
Figure 6. The
combination of the first input components R2o, R21, C6 and RVZ and the second
input
components R ~ 9, R3 ~ , C 3 and RV 1 should provide static protection far in
excess of known
monitors.
The non-volatile memory 130 illustrated in Figure 7 includes a 1 Kbit (128x8)
electrically erasable programmable read only memory EEPROM 101. It is
connected via
resistors R25 and R2~ to the power supply interface connections J3-4 and J3-5.
The actual IC
chip is preferably a Microchip X24LC01 which uses a two wire serial interface
to communicate
with the processor 10. The interface is based on the I2C bus which has become
the
predominant standard for low cost inter-chip communications (i.e., "Inter-IC"
bus, which is a
standard means of providing a two-wire communication link between integrated
circuits) .
Detailed information on the chip and the I2C bus may be found in the Microchip
Nonvolatile
Memory Products databook. The EEPROM 101 is used to store operating
characteristics,
usage information and device specific information such as a repair log and
unit serial number.
The operating characteristics are defined, in part, by a collection of user-
modifiable parameters
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that control various aspects of the monitor's operations, including, for
example, the type of
alarm tone (e.g., Figure 15, item 329), the relay action, the hold time delay,
and the volume of
the alarms. These memory locations may be modified either through use of the
front panel
control switches or, as hereinafter described, via a computer program that is
executing on a
S remote host connected to the monitor via an electronic interface, such as a
serial port. Usage
information might consist, by way of example only, of an hour meter which logs
total hours of
use of the monitor, the total time alarming, the total number of alarms, the
response time to the
last alarm, and / or the date and time of past alarms (the calendar date and
time being provided
by, for example, a date / time chip 595 of the sort illustrated in Figure 22).
Downloading usage information to a host computer allows a number of diagnostic
statistics to be calculated, including the "average time to respond". This
information is
preferably only be written by the monitor, and read only to an inquiring host
computer. Read
only status is purely a software function of the host. Device specific
information would
typically not be used by the monitor and is never written to or read by the
monitor. It is
preferably written only at the time of manufacture or time of repair by an
external host
computer. The information is intended for use by the factory, a repair
station, or a facilities
biomedical staff and might include, for example, the date of the last ten
repairs and
corresponding work order numbers and the unit's serial number.
Turning now to Figure 8, the nurse call interface 160 uses a relay K1 to
provide
isolation between the monitor circuitry and the nurse call system. A normally
open contact
161, a normally closed contact 163 and a common contact 165 of the relay Kl
are connected
to a connector J2. The nurse call cord (not shown) plugs into this connector
J2 and would
typically be an ~RJ-45 or similar connector. Since there is always a potential
for inadvertent
disconnection of a connector J2, two additional pins J2-4 and 5 are used in
the connector J2 to
provide a continuity loop. By monitoring this loop, the processor 10 can
detect a pulled-out
nurse call cord. If this condition is detected, a distinct in-room alarm is
sounded. Pull-out
protection may be disabled via the profile stored in the nonvolatile memory
130 when the
system is used in a facility without a nurse call system or in a home. The
relay K1 is energized
in the non-alarming state. This effectively reverses the contacts 161 and 163
so that the
normally open contact 161 appears to be normally closed and vice versa. Thus,
a nurse call is
issued whenever power is interrupted to the monitor. This provides a fail safe
on the power
supply 190 and its interconnects. A single RC filter consisting of a resistor
R18 and a
capacitor C4 Provides static protection for the Processor 10. The relay Kt it
turned on by the
transistor Q1 via a current limiting resistor R23 and a diode D3 which absorbs
the inductive kick
which occurs when the relay Kl is de-energized.
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As shown in Figure 9, the power supply 190 includes an external connector J3.
The
connector J3 includes a transformer (not shown) connected between two pins J3-
1 and J3-2 of
the connector. Power VCC is brought into the monitor through a voltage
regulator 191
connected to the first connector pin J3-1. Two additional pins J3-4 and 5 of
this connector J3
are used for the read/write interface of the external EEPROM 101. Filter
capacitors C 11 and
C12 are preferably connected on either side of the voltage regulator 191.
Monitor Front Panel Control Functions
The internal software allows the monitor to perform a variety of functions. As
illustrated in Figure 4, the user interface 40 includes inputs allowing a user
to modify control
unit actions via the reset button 53 and to adjust the delay via the delay
adjust button 55 and
outputs for controlling operation of the 0 through 9 numeric display 41, the
status annunciators
43 and various aural signals.
An idle mode (HOLD), which is active when the monitor is not monitoring,
enables
automatic advancement to the monitor mode, manual override for immediate
advancement to the
monitor mode, adjustment of the delay time, aural indications of any unsafe
conditions and
logging of hours in use. The monitor mode (MON) enables monitoring of the
patient for
activity within the bed which could be a precursor for a bed evacuation,
adjustment of the delay
time, manual return to the idle mode (HOLD), automatic advancement to the
alarm mode
(ALARM), aural indications of any unsafe hardware conditions and logging of
hours in use.
The alarm mode (ALARM) enables generation of a nurse call through the nurse
call system
160, aural in-room alarm, manual return to the idle mode (HOLD) and logging of
response
time and total alarm time. A program mode enables the user to customize the
features of the
monitor and to update the non-volatile memory 130 with user selected
parameters.
All functions which utilize the user interface 40 are consistent with the
nomenclature
which the user sees on the labels of the buttons 53 and 55 and on the numeric
display 41. For
example, any features which use the reset button 53 have an intuitive
connection to the word
"reset". Likewise, the delay adjust button 55, which preferably features a
triangle pointing up,
causes an upward adjustment in the numeric display 41 with appropriate roll
over at a
maximum value.
Internal Software / Logic Functions
Figure 10 illustrates the main steps that are executed within the monitor as
part of a
power-up (i.e., cold start) sequence. In the preferred embodiment, a cold
start 201 will cause
the processor 10 to automatically enter into the HOLD mode as part of step
201. Then, the
system initialize hardware 203 and variables 205, after which it will then set
the I2C interface
to inputs 207 to determine whether the interface is already being used, for
example to change
CA 02354688 2001-08-03
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the programs in the EEPROM 101. An inquiry is then made as to whether the I2C
is busy
209. If the response to this inquiry is "YES," then the inquiry is repeated
until the response is
"NO." If a "NO" response is received, the system proceeds to recall parameters
stored
previously within EEPROM 213. The system will next inquire as to whether the
delay time
equals nine (step 215). If the response to this inquiry is "YES," the system
will next inquire
as to whether the reset is pressed 217. If the response to either the inquiry
as to whether the
delay time equals nine 215 or whether the reset is pressed 217 is "NO," then
the system
proceeds to go to executive routine 219. If the response to the inquiry as to
whether the reset
is pressed 217 is "YES," the system proceeds to go to local configuration 221.
As is illustrated in Figure 11, if the system has gone into executive 223
mode, the
system will again inquire as to whether the I2C is busy 225. If the response
to this inquiry is
"YES," the system will continue to inquire as to whether the I2C bus is still
busy 227. As
long as the response to this inquiry is "YES," the inquiry continues. If the
response to the
inquiry as to whether the I2C bus is still busy 227 is "NO," then the system
will go to cold
229 and resume from the cold start 201 as shown in Figure 10. If, however, on
inquiry as to
whether I2C is busy 225 the response is "NO," the system proceeds to display
delay time 231
on the display 41 and will turn on hold annunciator light 233 which is an
indication to the
caregiver that there is no weight on the mat used to monitor the patient's
presence. The system
then inquires as to whether it is time to log (step 235). In the preferred
embodiment, every six
minutes or 1/lOth of an hour the system will log the lapse of an increment so
as to maintain a
record of total hours of use of the monitor. If six minutes have not elapsed,
the response to the
inquiry is "NO" and the system proceeds to inquire as to whether the delay
adjust switch is
pressed 237. If six minutes have elapsed, the response to the inquiry as to
whether it is time to
log 235 is "YES" and the system will proceed to call data logger 239 so as to
register this
increment. The system then continues to the delay adjust switch pressed
inquiry 237 until
another six minute interval has elapsed and the call data logger 239 is again
cycled. If the
response to the inquiry as to whether the delay adjust switch is pressed 237
is "NO," the
system proceeds to inquire as to whether the mat is pressed 241. If the
response to the inquiry
as to whether the delay adjust switch is pressed 237 is "YES," the system
proceeds to
increment delay 243 by stepping to the next of the nine increments available
for delay as
hereinbefore discussed and then inquires as to whether the mat is pressed 241.
If the response
to the mat pressed inquiry 241 is "NO," the system will recycle to the time to
log inquiry 235
and continue the process until the response to the mat pressed inquiry 241 is
"YES," indicating
that a patient is on the sensor mat. If the response to this inquiry is "YES,"
the system then
proceeds to go to hold delay 245.
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Turning now to Figure 12, representing the transient condition between the
hold mode
201 and the monitor mode 273, when the monitor is at hold delay 247, the
system will
initialize hold timer to program value 249. Generally, the hold timer will
permit selection by
the caregiver of from 1 to 20 seconds as the interval that the patient's
weight must be on the
sensor mat before monitoring of the patient's presence is initiated. In the
preferred embodiment
described herein, this available time interval is in a range of 1 to 9
seconds. The system then
proceeds to initialize flasher timer 251. The flasher timer establishes the
flash interval for the
attenuator indicating that a patient's weight is on the sensor mat. With the
timers initialized, the
system proceeds to get keys 253 by examining the switches 53 and 55 of the
keypad 45.
Inquiry is first made as to whether the caregiver has operated the delay
adjust 255. A "YES"
response indicating that the delay adjust switch 55 is depressed will result
in an increment
change 257. If the response to the delay adjust inquiry 255 is "NO" or the
increment change
257 is made, the system continues on to inquire as to whether the reset is
pressed 259. If the
response to this inquiry is "NO," the system proceeds to inquire as to whether
the hold time is
expired 261. If the response to this inquiry is "NO," the system inquires as
to whether the
flash time has expired 263. If the flash time has expired, providing a YES
response, the
system will toggle the hold light and reset the timer 265. If the flash time
has not expired or
has been reset, the system will proceed to inquire as to whether there is a
weight on the mat
267. If the response to this inquiry is "NO," the system will go to executive
219, rehirning to
the loop illustrated in Figure 11. If the response to the weight on mat
inquiry 267 is "YES,"
the system will perform a pullout check 269 to determine if there is an
improper connection in
the system. After performing the pullout check 269, the system will return to
the get keys step
253 of the hold delay loop 247. If, in the operation of the hold delay loop
247, the response
to the reset pressed inquiry 259 or the hold time expired inquiry 261 is
"YES," then the
system will go to monitor 271, as will hereinafter be described.
The HOLD mode 235 is characterized by a continuous hold indicator 47 and the
number of seconds of delay time is displayed on the numeric display 41. The
nurse call relay
Kl is energized (non-alarming state). There is no testing of the sensor
validation input, there is
no pull-out detection, and the keypad 45 is monitored at least 20 times per
second except
~ during tone generation. Upon pressing the delay adjust button 55, the delay
is bumped by one
second and the display 41 is updated with the new delay time. After nine
seconds, the delay
time resets to one second. If the reset button 53 is pressed, a 1/2 second
tone at lkHz is
generated. Software exits this loop and enters the pre-monitor phase of the
monitor mode
MON when weight is detected on the mat (1RQ goes low). During the hold mode
HOLD,
logging of hours in use occurs every 1/lOth of an hour (six minutes).
The main monitor routine is illustrated in Figure 13. When the system goes to
monitor
273, it will change the annunciator condition by turning on MON and turning
off HOLD 275.
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Thus, the HOLD annunciator 47 will be de-energized and the monitor annunciator
4 9
energized. The system will then inquire as to whether it is time to log 277,
as has been
hereinbefore explained. If the response to this inquiry is "YES," then the
system will call data
logger 279 to log the expiration of the six minute increment. If the answer to
the inquiry as to
time to log 277 is "NO," or if an increment has been logged, the system will
proceed to a get
keys status 281. The system will inquire as to whether the delay adjust switch
is pressed 283.
If the response to this inquiry is "YES," an increment change 285 will be made
in the time
delay. If the response to the delay adjust inquiry 283 is "NO" or the
increment change 285
has been made, the system will proceed to inquire as to whether the reset is
pressed 287. If
IO the response to this inquiry is "YES," the system will go to executive 289
and perform the
loop illustrated in Figure 11. If the response to the reset pressed inquiry
287 is "NO," the
system will proceed to call pull-out 291 to determine whether there is an
electrical connection
failure in the system. The system then inquires as to whether there is a
weight on the mat 293.
If the response to this inquiry is "YES," the system will return to the time
to log step 277 of
the monitor loop 273. If the response to the inquiry as to weight on the mat
293 is "NO," the
system will proceed to go to alarm 295. The monitor mode 273 has a transient
pre-
monitor phase shown in Figure 12 and a steady-state monitor phase shown in
Figure 13. The
. pre-monitor state is characterized by a flashing hold indicator 47. The LED
flash period is .2
seconds on and .2 seconds off. During the pre-monitor phase, the nurse call
relay K1 is
energized (non-alarming state), nurse call pull-out protection is active, the
sensor input is
validated, the numeric display 41 continues to display delay time, and the
keypad 45 is polled
at least 20 times per second. If the software detects an improperly inserted
nurse call
connector, a tone will be generated, preferably sixteen cycles of 400Hz
followed by 42 msec of
silence, repeated four times, followed by a minimum of 320 msec of silence
before repeating
the entire process. Pressing the delay adjust button 55 will increment the
delay time one
second up to a maximum of nine seconds. The delay time then resets to one
second. The
numeric display 41 is updated with each change in the delay time. Pressing the
reset button 5 3
will cause the monitor to immediately proceed to the monitor phase 273. This
mode expires
after a programmable hold time. The hold time defaults to ten seconds but may
be programmed
by the user for any time from 1 to 10 seconds. Upon expiration of the hold
time or upon
pressing the reset button 53, the software advances to the monitor phase 273.
The software
will return to the hold mode 247 if weight is removed from the mat prior to
entering the
monitor phase 273.
The monitor phase of the monitor mode 273 is characterized by a solid monitor
status
indicator 49. During this phase, the sensor is monitored for weight on mat,
the nurse call relay
K1 is energized (non-alarming state), nurse call pull-out protection is
active, the numeric
display 41 continues to display the delay time, and the keypad 45 is polled at
least 20 times per
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second. If an improperly inserted nurse call cord is detected, the unit will
sound an alarm as
described in the pre-monitor phase. Pressing the delay adjust button 55 will
advance the delay
time one second up to a maximum of nine seconds. The delay time then resets to
one second.
The numeric display 41 is updated with each change in the delay time. Pressing
the reset
button 53 will return the software to the hold mode 247, allowing removal of
the patient from
the bed. Since there must be weight on the mat to be in this mode 247, the
hold mode 247
will automatically advance to the pre-monitor phase of the monitor mode 273.
To improve
functionality, the hold time will temporarily be set to 25 seconds when this
path is taken to
allow sufficient time to remove the patient from bed. If weight is removed
from the mat, the
software advances to the pre-alarm phase of the alarm mode 302. That parameter
"hours in
use" is logged / incremented every 1/lOth of an hour.
The alarm mode 301 illustrated in Figure 14 consists of a transient re-alarm
phase and
a steady state alarm phase. The pre-alarm phase is characterized by a flashing
alarm indicator
51. The flash period is .2 seconds on and .2 seconds off. During the pre-alarm
phase the
nurse call relay K1 is energized (non-alarming state), the mat input is
monitored, and the
keypad 41 is polled at least 20 times per second. Returning weight to the mat
will cause the
software to return to the monitor mode 273. Pressing the delay adjust button
55 has no effect.
. Pressing the reset button 53 will return the software to the hold mode 247.
Since this mode
247 is only active with weight off the mat, the monitor will remain in hold
upon returning to
the hold mode 247. This mode 247 expires after the number of seconds displayed
in the
numeric display 41 and then enters the alarm phase.
The alarm phase of the alarm mode 301 is characterized by a solid ALARM
indicator
51 and an audible alarm. During this mode the nurse call relay K1 is operated
in accordance
with a pre-programmed protocol and the keypad 41 is polled at least 20 times
per second.
Pressing the delay adjust button 55 has no effect. The audible alarm will
continue to sound
until the reset button 53 is pressed, returning the unit to the hold mode 247.
The alarm
preferably provides one of six possible user selectable alarms (see, for
example, 329)
including a lkHz beep in intervals of .5 seconds on and .5 seconds off, a lkHz
beep in
intervals of .25 seconds on and .25 seconds off, a lkHz beep in intervals of 1
second on and 1
second off, 15 cycles at 400Hz followed by 18 cycles at 440Hz repeated 12
times followed by
one second of silence, a rising whoop or a stepped alarm providing four alarms
at 320 Hz in
intervals of 28 cycles and 28 cycles off, four alarms at 392 Hz in intervals
of 32 cycles on and
32 cycles off, four alarms at 277 Hz intervals of 24 cycles on and 24 cycles
off with 1/2 second
of silence. It is also possible to have no audible alarm. The nurse call relay
Kl has three
possible operating modes to accommodate various nurse call systems including
continuous
closure, one-shot and asynchronous 331. At the termination of the ALARM mode
301, the
response time is written to the EEPROM 101, the stored number of alarms is
bumped by one
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and rewritten to the EEPROM 101 and the current response time is added to the
total alarm
time and the EEPROM 101 is updated with the new value.
In the alarm mode 301 the system will initialize flash timer 303 and change
the
annunciator status to turn on alarm and turn off HOLD 305. The system then
inquires as to
whether reset is pressed 307 and, if the response to this inquiry is "YES,"
the system will go
to executive 309 and repeat the executive loop 223 illustrated in Figure 11.
If the response to
this inquiry is "NO," the system will proceed to inquire as to whether the
flash timer has
expired 311. If the response to this inquiry is "YES," the system will toggle
the alarm light
313 and reset the timer 315. If the response to the flash timer expired
inquiry 311 is "NO" or
the timer is reset 315, the system will proceed to inquire as to whether there
is weight on mat
317. If the response to this inquiry is "YES," the system will go to monitor
319 and repeat
the monitor loop 273 illustrated in Figure 13. If the response to the weight
on mat inquiry
317 is "NO," the system will inquire as to whether the delay timer expired
321. In this step,
the system determines whether the time selected by the caretaker to elapse
after weight has left
. the mat and before weight has returned to the mat has expired. If the
response to this delay
time expired inquiry 321 is "NO," the system will return to the reset pressed
inquiry 307 of
the alarm loop 301. If the response to the delay timer expired inquiry 321 is
"YES," the
system proceeds to loop A 323 of the alarm mode illustrated in Figure I5 to
provide the audio
alarm. In this phase of the alarm mode 301, the system will set the volume 325
and initialize
the alarm variables 327 established by the caregiver for the system. The
system then
dispatches for selected tone 329, causing the monitor to give the audio tone
selected from the
six audio tones available to the caregiver. The system will also exercise
relay per selected
option 331, causing the nurse call station relay KI to function according to
one of the four
alternatives selected by the caregiver for the system. The system will next
inquire as to whether
the reset is pressed 333. If the reset button 53 has not been operated by the
caregiver, the
response to the inquiry is "NO" and the system will return to the dispatch for
selected tone 3 2 9
step of the alarm loop 301 and continue to provide the selected audio alarm.
If the response to
the reset press inquiry 333 is "YES," the system will bump event counter, save
response time
and total response 335 in which the system makes a record of the responses and
response
times of the caregiver. When this has been completed, the system will go to
executive 337 and
return to the executive loop 223 illustrated in Figure 11.
The local configuration or program mode 341 provides the user with a means to
select
various user options and save these selections in the non-volatile memory 131.
To enter this
mode 341, the delay time is set to nine seconds. The monitor is then powered
down. The
monitor then is re-powered up with the reset button 53 pressed. The software
will then
illuminate multiple annunciators to indicate the particular phase of the
programming mode 341
which has been entered. There are four phases of the program mode 341
including tone select,
CA 02354688 2001-08-03
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relay action & pull-out detection enable, hold time select and volume adjust.
The tone select
phase will display the last tone selected in the numeric display 41. A new
tone may be chosen
by cycling through the available options with the delay adjust button 55.
Preferably, the
default for the first time to apply power is the lkHz beep at .5 second
intervals mentioned
above. The relay action phase will display the current relay action in the
numeric display 41.
A different action may be chosen by cycling through the available options with
the delay adjust
button 55. The default for the first time to apply power is continuous
operation. The available
relay options are discussed above in relation to the alarm mode 301.
Programming to a three
will disable the pull-out detection. This allows the unit to be used in
facilities which do not
have a nurse call system or choose not to connect to the nurse call system.
Programming this
to a zero, one, or two enables the pull-out detection. The hold time phase
allows the user to
adjust the time delay between a patient placing weight on the mat and the
beginning of
monitoring. The default is preferably 10 seconds. The user may select 1 to 10
seconds. A
zero in the numeric display 41 represents 10 seconds. The volume adjust allows
the user to
select one of ten possible volume levels. The alarm is silent when set to zero
and at full volume
when set to nine. The software translates 1 through 9 into actual steps (0-31
) of the wiper
control VW of the programmable volume control 71. When programmed from the
external
interface, all 32 steps are available. The default volume is seven (numeric
displayed value)
which translates to a wiper position of 25. For all of the above, a value is
accepted and the next
phase is entered by pressing the reset button 53. After the programming of the
volume control
71, the monitor enters the hold mode 247. If power is removed during the
programming
process, the new values up to the last time reset 53 was pressed will be
saved.
In the local configuration loop 341, the system will first turn on hold,
monitor and
alarm lights, load tone selection and output to numeric display 343. The
system then proceeds
to get keys 345 as earlier discussed with respect to other system loops,
inquiring as to whether
the delay adjust is pressed 347. If the response to this inquiry is "YES," the
system will
increment the toning selection 349 and then inquire as to whether the tone is
greater than five
351. This relates to the sequence of six tones earlier referenced in relation
to the alarm mode
301. If the response to this inquiry 351 is "YES," the system will reset the
alarm mode to
zero 353. If, after incrementing tone selection 349 the tone is not greater
than five 351 or is
set to zero 353, the system returns to the turn-on hold, monitor and alarm
lights, load current
tone selection and output numeric display step 343. If the response to the
delay adjust pressed
inquiry 347 is "NO," the system next inquires as to whether the reset is
pressed 355. If the
answer to this inquiry 349 is "NO," the system returns to the get keys step
345. If the
response to this inquiry 349 is "YES," the system will save tone to EEPROM
357. When the
tone has been saved in EEPROM 101, the system will beep 359 to indicate this
status. The
system will then turn off alarm light, load current relay action and output to
numeric display
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361 and again proceed to get keys 363. The system again inquires as to whether
the delay
adjust is pressed 365. If the response to this inquiry 365 is "YES," the
system will increment
relay action 367 according to the sequence discussed in relation to the alarm
mode 301. The
system will inquire as to whether the relay is greater than three 369,
determining which
increment of the relay options the system will select. If the response to this
inquiry 369 is
"YES," indicating that the option will be greater than three, the system sets
to zero 371 to
begin a recycle of available selections. If the answer to the inquiry 369 is
"NO" or if the
selection is set to zero 371, the system returns to the turn off alarm light,
load current relay
action and output to numeric display step 361. If the response to the delay
adjust pressed
inquiry 365 is "NO" the system proceeds to inquire as to whether the reset is
pressed 373. If
the answer to this inquiry is "NO," the system returns to the get keys step
363. If the answer
to this inquiry is "YES," the system proceeds to point B 375 of Figures 16 and
17. Looking
at Figure 17, if the reset pressed inquiry 373 response is "YES," the system
will save relay to
EEPROM 377, storing the selected relay position in the EEPROM 101. The system
then
proceeds to beep 379 to advise the caregiver of the status. The system then
turns on the alarm
annunciator, turns off the monitor annunciator, loads the current hold time
and outputs to
numeric display 381. The system then again proceeds to get keys 383, first
inquiring as to
whether the delay adjust is pressed 385. If the response to this inquiry is
"YES," the system
will increment hold time 387. Inquiry is made as to whether the hold is
greater than nine 3 8 9
and if the response to this inquiry is "YES," the system will set to zero 391.
If the response to
the inquiry 389 is "NO," or the system has been set to zero 391, the system
will return to the
turn-on alarm enunciator, turn-off monitor enunciator, load current hold time
and output
numeric display 381. If the response to the delay adjust pressed inquiry 385
is "NO," the
system will then inquire as to whether the reset is pressed 393. If the
response to this inquiry
is "NO," the system returns to the delay adjust pressed inquiry 385. If the
response to the
inquiry 393 is "YES," the system will save hold time to EEPROM 395, storing
the selected
delay time in the EEPROM 101. The system will then provide a beep 397 to
indicate the
status and will then turn off the HOLD annunciator, turn on monitor
annunciator, load, e.g., 7
as the volume and output to the numeric display 399. That is, of the ten
volume increments
selectable, the system will automatically proceed to the seventh increment
level. The system
then proceeds through point C 401 as illustrated in Figure 18 to get keys 403
and inquire as to
whether the delay adjust is pressed 405. If the response to this inquiry 405
is "YES," the
system will increment volume 407 and inquire whether the volume is greater
than nine 409. If
the response to this inquiry 409 is "YES," the system will reset volume to
zero 411. If the
response to the volume greater than nine 409 is "NO," or the system has set
the volume to
zero 4I1, the system then returns through point D 413 to turn-off HOLD
annunciator, turn-on
monitor annunciator, load 7 as volume and output to numeric display 399 as
shown in Figure
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CA 02354688 2001-08-03
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17. Returning to Figure 18, if the response to the delay adjust pressed
inquiry 405 is "NO,"
the system proceeds to inquire as to whether the reset is pressed 415. If the
response to this
inquiry 415 is "NO," the system returns to the get key step 403. If the
response to the inquiry
415 is "YES," the system proceeds to look up actual volume 417. The system
then writes the
volume to EEPROM 419, storing the selected volume in the EEPROM 101, and then
goes to
cold 421, returning to the cold start 201 illustrated in Figure 10.
The data logger subroutine 431 illustrated in Figure 19 is used by the system
at the call
data logger steps 239 and 279 of the executive loop 223 illustrated in Figure
11 and the
monitor mode 273 illustrated in Figure 13, respectively. In the data logger
sub routine 431,
the system will read hours from RAM 433 and write hours to EEPROM 435, storing
the
number of hours that the system has operated in EEPROM 101. The system will
then read
minutes from RAM 437 and write minutes to EEPROM 439 to store any portion of
an hour
not already stored in EEPROM 101. The system will then reset 0.1 hour timer
441 and return
443 to the routine making the data logger demand.
The pull-out protection sub routine 451 illustrated in Figure 20 is used by
the system at
the call pull-out steps 269 and 291 of the hold delay mode 247 illustrated in
Figure 12 and
the monitor mode 273 illustrated in Figure 13, respectively. In the pull-out
protection
subroutine 451, the system will read the output Q6 of the latch and read the
status of Bit 2 of
Port B 455. The system will then inquire as to whether PB2 is high 457. If the
response to
this inquiry is "NO," the system will sound alarm 459 and return 461 to the
pull-out
protection step 451. If the response to this inquiry is "YES," the system will
proceed to return
461 to the routine making the pullout protection demand without sounding the
alarm.
In summary, the monitor will preferably conform to the following
specifications:
Specification Min: Max: Units Tolerance
Delay Time 1 10 seconds +/-5%
Hold Time 1 10 seconds +/-5%
Relay One-shot Duration 0.5 5 seconds n/a
Relay Asynchronous On 0.25 2 seconds n/a
Relay Asynchronous Off 0.25 2 seconds nla
Tone Programming 0 7 n/a n/a
Relay Programming 0 2 n/a n/~
Pull-out Programming 0 1 n/a n/a
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EDCHK-88140
Specification Min: Max: Units Tolerance
Hold Time Programming 0 9 n/a n/a
Warning Frequencies n/a n/a Hertz +/-10%
Tone Durations n/a n/a seconds +/-10%
Microprocessor-Based Monitor with a Modiriable Personality
According to a second aspect of the instant invention, there is provided a
microprocessor based monitor substantially as described above, but wherein the
software that
controls the actions of the monitor is stored within modifiable nonvolatile
memory (e.g., flash-
y RAM) within the device, so as to be modifiable to create a patient monitor
that has different
personalities, depending on the needs of a particular application. More
specifically, it is
contemplated that much, if not all, of the software illustrated in Figures 10
to 20 - the
software that controls the personality / functionality of the unit - will be
stored within the
monitor in a form that can be modified to suit the requirements of any site or
individual patient
(per doctor's orders) and, more particularly, the needs of the particular
nurse call station to
which the monitor is connected.
Turning first to Figure 21 wherein the general environment of the instant
invention is
broadly illustrated, in the preferred embodiment the reprogrammable monitor
550 is connected
to sensor mat 500 by way of an RJ-11 connector 525. As has been discussed
previously, the
IS RJ-11 connector 525 provides the internal microprocessor 10 access to the
state of the patient
detector circuit within the mat 500. During normal operations, power line 565
would be
plugged into monitor 550 to provide a source of external power to the unit.
However, Figure
21 illustrates the preferred configuration of the monitor 500 and a
interconnected computer
host 570 during exchange of information. Interface unit 560 is designed to act
as a data
conduit and pass serial information along line 580 from the host computer 570
to the monitor
550 and back again on demand from the host 570 or monitor 550. Additionally,
the instant
interconnection incorporates a power line into the serial line 590 for use by
the monitor 550
during programming. It is not essential that the power be incorporated into
the interconnecting
line 590, but it is part of the presently preferred embodiment that it be so
designed. In the
event that a source of power is not needed via line 590, that line could take
the form of a
simple parallel serial, USB, etc. cable and interface unit 560 could then be a
standard
computer port (serial, parallel, etc.). Additionally, it should be noted that,
although the
interface unit 560 is pictured as being a separate device that is external to
hoth the monitor 550
and the host 570, it might easily be incorporated into one unit, or the other,
or both.
In the preferred embodiment, the lines 580 and 590 that interconnect the host
computer
570 and electronic monitor 550 are serial lines, and the data communications
protocol used is
24
CA 02354688 2001-08-03
' BDCHK-88140
the I2C standard. However, those skilled in the art will recognize that there
are many other
standard and non-standard communications protocols that could be used in the
alternative. For
example, the instant inventors specifically contemplate that the
interconnecting communications
lines ( 580 and 590) could be parallel cables. Further, it might prove to be
desirable in some
S cases to put a separate data port on the monitor 550 which might be, for
example, a serial or
parallel connector and which is dedicated for use in communications with a
host computer 570,
i.e., it does not share the responsibility of conveying power to the unit
during data transfer.
Finally, it specifically contemplated by the inventors that it would even be
possible to
communicate with a remotely positioned monitor 550 through nurse call
interface 130 (Figure
1), thereby eliminating the need to physically bring together the host
computer 570 and
monitor 550, it being well within the capability of one of ordinary skill in
the art to modify the
invention-as-disclosed to implement this variation.
Within the monitor 550 and as is illustrated in Figure 22, data sent from the
host
computer 570 are received by the CPU 620 of the microprocessor 10 and then
subsequently
stored, preferably within a local flash RAM 610. As is well known to those
skilled in the art,
many other similar arrangements might be used instead that would be
functionally equivalent to
using flash RAM, including using conventional RAM with battery backup, EEPROM,
a local
disk drive, etc, the key feature being that - what ever type of storage is
used - it should be at
least relatively nonvolatile for purposes of the instant embodiment and, most
importantly,
modifiable under local program control. Thus, in the text that follows the
phase "modifiable
nonvolatile RAM" will be used in the broadest sense to refer to the type of
storage just
described. Additionally, it is anticipated that CPU 620 will be provided with
some amount of
ROM 130 or other storage type for permanently storing information and which
could contain,
for example, the serial number of the unit, date of manufacture, and the code
that would control
the basic operations of the CPU 10 during cold starts, resets, personality
uploads, etc.
During operation, the monitor 550 could use the flash RAM 620 as storage for
various
data parameter values including accumulated performance statistics, data /
time stamps of alarm
events, patient identification numbers, hold delay, delay time, speaker
volume, type of alarm
tone (i.e., what sort of alarm will be sounded - e.g., fast beep, slow beep,
whoop, etc.),
relay action type (e.g., continuous, one-shot, asynchronous, etc.), total time
in service, date of
last bio-med check,total number of alarms sounded, response time to last
alarm, average
response to last four alarms, alarm history (e.g., response times for the last
fifteen or so alarms
and time / date of alarm occurrence), repair history, hospital equipment
identification number
(e.g., asset number), or a current time / date stamp. Additionally, this same
connection could
be used to read parameters from the monitor 550 such as total time in service,
date of last bio-
medical check, the unit serial number, etc.
CA 02354688 2001-08-03
cDCHK-88140
However, the main anticipated use for the flash RAM 620 is for storage of the
operating personality of the unit. In particular, Figures 10 to 20 discussed
previously are
implemented within the monitor in the form of assembly language computer
instructions which
are stored in and read from ROM memory 130, thereby making those program steps
immutable, unless the memory chip containing them is replaced. In the instant
embodiment, it
is anticipated that much of the functionality of the software illustrated in
those figures would be
stored in a form that can be modified to suit the requirements of a particular
nurse call station,
or hospital environment, e.g., within flash RAM 620.
As is broadly illustrated in Figure 23, the personality loading program 700
within the
monitor 550 is preferably initiated through the use of a non-maskable
interrupt 705 (defined as
a "master mode" interrupt) as is provided for by the I2C communications
standards. In more
particular, when the CPU 610 senses an interrupt on the pins associated with
port 593, it
preferably enters a slave mode, wherein the host computer 570 completely
controls its
operations. The host computer 570 then directs the monitor CPU 610 to begin
receiving
"data" 715 and storing that data 725 at predetermined locations within the
flash RAM 620,
which data may be parameter values as discussed previously or, preferably,
binary computer
instructions that define the personality / operations of the unit.
At the conclusion of the loading process, the host computer will preferably
require the
monitor to execute a cold start 735, after which the monitor will continue
execution as before,
only this time using the various aspects of the new personality stored 740 in
flash-RAM. Of
course, the obvious advantage of an arrangement such as this is that it
permits the functionality
of the monitor to be modified to suit specific applications and, indeed, makes
it possible for a
single monitor to function with multiple nurse call station formats with only
minimal effort.
System for Programming a Reprogrammable Monitor
According to still a further aspect of the instant invention, there is
provided a monitor /
host software combination that allows the end-user to make personality changes
in the software
that controls the monitor. Additionally; this same system provides a means for
the user to read
and / or modify data values that are maintained in the nonvolatile memory of
the patient
monitor. In the preferred embodiment, the software that manages the user
interface would run
on a host computer 570 such as a lap top computer. As is well known to those
skilled in the
art, the software embodying the instant invention might be conveyed into the
computer that is to
execute it by way of any number of devices 571 including, for example, a
floppy disk, a
magnetic disk, a magnetic tape, a magneto-optical disk, an optical disk, a CD-
ROM, flash
RAM, a ROM card, a DVD disk, or loaded over a network.
As is broadly illustrated in Figures 21 through 23 and as has been discussed
previously, a preferred embodiment of the instant invention uses a host
computer 570 to load
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CA 02354688 2001-08-03
yEDCHK-88140
operating parameters and executable instructions into the monitor.
Additionally, this same
connection is used to retrieve statistical and other information from the
monitor. Further,
cumulative statistical values such as total time spent in an alarm condition,
alarm history, etc.,
can be reset (e.g., made equal to zero) by this same process.
As is illustrated in Figure 24, the host control program for parameter and
operating
statistics recall 800 preferably begins by generating a non-maskable interrupt
805 which
results in monitor 550 passing operating control to the host computer 570. The
host computer
570 then instructs the monitor CPU 610 to pass the contents of specific memory
locations
(steps 815 to 830) back to itself. The data returned from the monitor 550 are
then presented
to the user for review. Needless to say, once the data have been collected
additional analysis of
the resulting information would certainly be useful in some situations and
that additional step
has been specifically contemplated by the instant inventors.
Conclusions
Although the preceding text has occasionally referred to the electronic
monitor of the
instant invention as a "bed" monitor, that was for purposes of specificity
only and not out of
any intention to limit the instant invention to that one application. In fact,
the potential range of
uses of this invention is much broader than bed-monitoring alone and might
include, for
example, use with a chair monitor, a toilet monitor, or other patient monitor,
each of which is
configurable as a binary switch, a binary switch being one that is capable of
sensing at least
two conditions and responding to same via distinct electronic signals. In the
preferred
embodiment, those two conditions would be the presence of patient and the
absence of a patient
from a monitored area. Although a pressure sensitive switch is the binary
switch of choice for
use in the preferred embodiment, other types of switches could work as well
for some
applications. Additionally, it should be noted that the use of the term
"binary" is not intended
to limit the instant invention to use only with sensors that can send only two
signal types.
Instead, binary switch will be used herein in its broadest sense to refer to
any sort sensor that
can be utilized to discern whether a patient is present or not, even if that
sensor can generate a
multitude of different of signals.
Thus, it is apparent that there has been provided, in accordance with the
invention, a
monitor and method of operation of the monitor that fully satisfies the
objects, aims and
advantages set forth above. While the invention has been described in
conjunction with
specific embodiments thereof, it is evident that many alternatives,
modifications and variations
will be apparent to those skilled in the art and in light of the foregoing
description.
Accordingly, it is intended to embrace all such alternatives, modifications
and variations as fall
within the spirit of the appended claims.
27
