U.S. patent application number 11/241513 was filed with the patent office on 2007-05-10 for patient monitoring alarm escalation system and method.
Invention is credited to Li Li, Paul D. Mannheimer.
Application Number | 20070106126 11/241513 |
Document ID | / |
Family ID | 37560701 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070106126 |
Kind Code |
A1 |
Mannheimer; Paul D. ; et
al. |
May 10, 2007 |
Patient monitoring alarm escalation system and method
Abstract
Embodiments of the present invention relate to a patient
monitoring alarm escalation system and method. Specifically,
embodiments of the present invention include an alarm detection
device configured to measure physiological data received via a
patient monitor, the alarm detection device configured to initiate
an alarm in response to predefined measurements of the
physiological data, and an alarm device configured to emit a first
signal with a first property and a second signal with a second
property, the first signal being emitted when the alarm is
initiated, the second signal being emitted if an alarm
acknowledgement mechanism is not activated prior to a designated
event.
Inventors: |
Mannheimer; Paul D.;
(Danville, CA) ; Li; Li; (Petaluma, CA) |
Correspondence
Address: |
Michael G. Fletcher;FLETCHER YODER
P.O. Box 692289
Houston
TX
77269-2289
US
|
Family ID: |
37560701 |
Appl. No.: |
11/241513 |
Filed: |
September 30, 2005 |
Current U.S.
Class: |
600/300 ;
340/573.1; 600/323 |
Current CPC
Class: |
A61B 5/0002 20130101;
A61B 5/746 20130101; A61B 5/14551 20130101; A61B 2560/0276
20130101 |
Class at
Publication: |
600/300 ;
340/573.1; 600/323 |
International
Class: |
A61B 5/00 20060101
A61B005/00; G08B 23/00 20060101 G08B023/00 |
Claims
1. A monitoring system, comprising: a monitor having a plurality of
speakers and being configured to initiate a primary alarm through
one of the plurality of speakers in response to predefined
measurements of physiological data and, a secondary alarm through
another of the plurality of speakers.
2. The system of claim 1, comprising an alarm acknowledgement
mechanism.
3. The system of claim 2, comprising an alarm device configured to
emit the primary alarm at a first frequency and the secondary alarm
at a second frequency when an alarm condition is recognized, the
second frequency increasing if the alarm acknowledgement mechanism
is not activated prior to a designated event.
4. The system of claim 2, comprising an alarm device configured to
increase a magnitude of the secondary alarm if the alarm
acknowledgement mechanism is not activated prior to a designated
event.
5. The system of claim 2, comprising an alarm device configured to
increase magnitudes of the primary and secondary alarms if the
alarm acknowledgement mechanism is not activated prior to a
designated event.
6. The system of claim 5, comprising a timer configured to count
down a designated amount of time, wherein completion of the count
down is the designated event.
7. The system of claim 1, comprising a sensor configured to gather
actual physiological data from a patient.
8. The system of claim 1, wherein at least one of the plurality of
speakers is a component of a pager.
9. A patient monitor, comprising: an alarm detection device
configured to measure physiological data received via a patient
monitor, the alarm detection device configured to initiate an alarm
in response to predefined measurements of the physiological data;
and an alarm device configured to emit a first signal with a first
property and a second signal with a second property, the first
signal being emitted when the alarm is initiated, the second signal
being emitted if an alarm acknowledgement mechanism is not
activated prior to a designated event.
10. The system of claim 9, wherein the first and second signals are
different audible tones and the first and second properties are
different frequencies.
11. The system of claim 9, wherein the alarm device includes a
pager.
12. The system of claim 11, wherein at least one of the first and
second signals includes a vibration.
13. The system of claim 9, wherein the first property or the second
property is manipulated if the alarm acknowledgement mechanism is
not activated within a define amount of time.
14. The system of claim 9, wherein the alarm device includes a
plurality of speakers.
15. A method for facilitating clinical vigilance, comprising:
receiving physiological data from a patient; measuring the
physiological data and initiating an alarm in response to
predefined measurements of the physiological data; and emanating a
first signal with a first property and a second signal with a
second property when the alarm is initiated.
16. The method of claim 15, comprising changing the second property
if an alarm acknowledgement mechanism is not activated prior to a
designated event.
17. The method of claim 15, comprising emanating the first and
second signals from a speaker as different audible tones.
18. The method of claim 15, comprising emanating the first signal
from a first speaker and emanating the second signal from a second
speaker.
19. The method of claim 15, comprising emanating the first and
second signals from a pager as different vibrations.
20. The method of claim 15, wherein the first and second properties
are different frequencies.
21. The method of claim 15, wherein the first and second properties
are different volumes.
22. A monitor configured to receive physiological data from a
patient, the monitor comprising: an alarm detection device
configured to measure the physiological data and initiate an alarm
in response to predefined measurements of the physiological data;
and at least two speakers.
23. The monitor of claim 22, wherein the at least two speakers are
configured to emanate an escalating audible signal after initiation
of the alarm.
24. The monitor of claim 22, wherein a first speaker is configured
to emit a tone when an alarm condition is first detected and a
second speaker is configured to remain silent for a designated
amount of time after the alarm condition is detected.
25. The monitor of claim 22, wherein a first speaker is configured
to emit a first audible sound and a second speaker is configured to
emanate a second audible sound different from the first audible
sound
26. The monitor of claim 22, wherein a first speaker is configured
to emit and maintain a first audible sound while an alarm condition
is present and unacknowledged, and wherein a second speaker is
configured to emanate a second audible sound that escalates over
time while the alarm condition is present and unacknowledged.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Field of the Invention
[0002] The present invention relates generally to alarm systems for
patient physiological data monitoring instruments. In particular,
the present invention relates to an alarm escalation system
including mechanisms for indicating a level of criticality of
alarms corresponding to physiological measurements and equipment
status indicators of patient monitoring devices.
[0003] 2. Description of the Related Art
[0004] This section is intended to introduce the reader to various
aspects of art that may be related to various aspects of the
present invention, which are described and/or claimed below. This
discussion is believed to be helpful in providing the reader with
background information to facilitate a better understanding of the
various aspects of the present invention. Accordingly, it should be
understood that these statements are to be read in this light, and
not as admissions of prior art.
[0005] Patient monitors include medical devices that facilitate
observation of patient physiological data. For example, a typical
patient monitor detects and displays a patient's vital signs
continually. This improves patient care by facilitating continuous
supervision of a patient without continuous attendance by a human
observer (e.g., a nurse or physician). Typically, patient monitors
include alarm systems that provide audible and/or visual
indications of certain predefined conditions. For example, some
patient monitors include alarms that are triggered based on
physiological conditions (e.g., high and low patient heart rate
thresholds, arterial oxyhemoglobin saturation) or status indicators
for the monitor itself (e.g., power loss). These alarms further
facilitate supervision of patients and improve patient care by
providing caregivers with warnings concerning certain monitored
conditions. Generally, such alarms remain in an alarm state until
acknowledged by a user. For example, an audible alarm for a
patient's abnormal systolic condition may continue to sound until a
user presses an acknowledge button that silences the alarm and
indicates that the alarm has been recognized. Such audible alarms
for patient monitors generally incorporate unchanging alarm tones
or auditory effects. It is now recognized that such unchanging
alarms tend to cause patient monitor users/operators (e.g., nurses,
physicians, and caregivers) to become desensitized to ongoing and
unacknowledged audible alarms.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] Advantages of the invention may become apparent upon reading
the following detailed description and upon reference to the
drawings in which:
[0007] FIG. 1 is a perspective view of a patient monitor in
accordance with an exemplary embodiment of the present
invention;
[0008] FIG. 2 is a block diagram of a method for providing patient
monitor alarms in accordance with an exemplary embodiment of the
present invention;
[0009] FIG. 3 is a pressure-time plot of a primary alarm signal and
a secondary alarm signal in accordance with an exemplary embodiment
of the present invention; and
[0010] FIG. 4 is a block diagram of a monitoring system in
accordance with an exemplary embodiment of the present
invention.
DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS
[0011] One or more specific embodiments of the present invention
will be described below. In an effort to provide a concise
description of these embodiments, not all features of an actual
implementation are described in the specification. It should be
appreciated that in the development of any such actual
implementation, as in any engineering or design project, numerous
implementation-specific decisions must be made to achieve the
developers' specific goals, such as compliance with system-related
and business-related constraints, which may vary from one
implementation to another. Moreover, it should be appreciated that
such a development effort might be complex and time consuming, but
would nevertheless be a routine undertaking of design, fabrication,
and manufacture for those of ordinary skill having the benefit of
this disclosure.
[0012] FIG. 1 is a perspective view of a patient monitor in
accordance with an exemplary embodiment of the present invention.
Specifically, the patient monitor illustrated by FIG. 1 is a
multi-speaker pulse oximeter 10 having a first speaker 12 and a
second speaker 14.
[0013] The pulse oximeter 10 may be configured to provide an active
audible alarm with at least two distinctive tones. These
distinctive tones may be utilized to elevate annoyance when an
alarm condition remains unacknowledged for a certain period of
time, thus directing a user's attention to the unacknowledged alarm
condition. For example, in one embodiment, a first tone from the
first speaker 12 is sounded in response to an alarm condition, and
a second tone from the second speaker 14 is sounded as a reminder
tone. The reminder tone is sounded after the alarm condition has
remained unacknowledged for a designated amount of time. In another
embodiment, distinctive reminder tones are sounded alternatively
from the respective speakers 12 and 14, thus creating increasing
audio agitation (e.g., increasing volume, frequency, and/or
dissonance) after a designated amount of time has passed without
the alarm condition having been acknowledged by pressing an alarm
silence button 16. Additionally, the elevation of audio agitation
may be accelerated the longer an alarm remains unacknowledged. For
example, after the audio agitation has been increased a first time,
the amount of time until it is increased again may be reduced by
half and so forth.
[0014] In some embodiments, spatial separation of the first speaker
12 and the second speaker 14 may be used to increase alarm
awareness among caregivers and to ensure that all areas of a room
are accessible to an alarm. For example, stereo characteristics and
so forth may be utilized to get the attention of a caregiver that
is desensitized to typical alarms. In a specific example, the
spatial separation of the first speaker 12 and second speaker 14
may be used to create unique sounds and/or to improve sound
projection to all areas of a room. Further, embodiments of the
present invention may be engineered to ensure that the location of
the alarm device emitting the alarm is apparent to the caregiver.
For example, if multiple devices are in a room, certain sound
effects may be utilized to direct a caregiver's attention to the
specific device that is emitting an alarm.
[0015] Alarm conditions are designated on the pulse oximeter 10
using set points or by designating patterns of values (e.g.,
patterns in an SpO2 trend) that can be entered via adjustment
buttons 18. For example, a user can input a certain set point
(e.g., 103 degrees Fahrenheit, blood oxygen level of 97%) that
creates an alarm condition when crossed by actual patient data
(e.g., actual patient temperature, actual blood oxygen level), or
when processed values or patterns of values are detected. The pulse
oximeter 10 may detect alarm conditions using an alarm detection
device that compares designated set points with actual patient data
received from a sensor 20 via a cable connection port 22 that is
configured to communicatively couple with the sensor 20. For
example, in some embodiments, the alarm detection device employs
SatSeconds.TM. by Nellcor.TM. to detect alarms and manage nuisance
alarms. SatSeconds.TM. may include alarming based on an integral of
time and depth of a desaturation event. The sensor 20 may be
defined as an accessory used to collect and send patient data to
the pulse oximeter 10. One end of the sensor 20 is typically
coupled to a patient (e.g., to a patient's finger, toe, ear lobe,
or forehead) and the other end couples either directly or
indirectly (e.g., via a separate monitor cable) to the pulse
oximeter 10. Exemplary sensors may include sensors available from
Nellcor Puritan Bennett Incorporated. The sensor 20 in the
illustrated embodiment couples with a patient's finger and is
configured to collect patient physiological data by sensing a
patient's pulse rate and percentage of oxygen in the arterial
blood. Once collected, these measurements are sent to the pulse
oximeter 10.
[0016] As set forth above, the pulse oximeter 10 illustrated by
FIG. 1 includes dual speakers 12 and 14. The speakers 12 and 14 are
configured to provide audible alarms based on certain detected
conditions. For example, the speakers 12 and 14 may be utilized to
produce audible alarms for detected conditions including: low
battery, high or low oxygen saturation, high or low pulse rate,
sensor disconnect, high patient temperature, high or low blood
pressure, and so forth. While the embodiment illustrated by FIG. 1
includes a pair of speakers 12 and 14, other embodiments may
include a single speaker, more than two speakers, or options
relating to the provision of one or more speakers. Indeed, some
embodiments include a monitor having connection points adapted to
communicatively couple with a plurality of speakers. For example, a
monitor in accordance with present embodiments may include one or
more built-in speakers, expansion ports for coupling to one or more
speakers, or both. Further, in some embodiments, remote speakers
(e.g., pagers) may be utilized either with or without having
speakers directly coupled to the pulse oximeter 10. It should be
noted that in some embodiments, to utilize the connection points,
external speakers are communicatively linked with the connection
points and software on the oximeter 10 is updated to provide
additional related functions.
[0017] Incorporating a plurality of speakers (e.g., speaker 12 and
14) with the pulse oximeter 10 provides versatility, redundancy,
and reliability. For example, by emitting alarm tones and alarm
reminder tones from multiple speakers, embodiments of the present
invention can produce unique and recognizable alarm sounds that
attract the attention of users by elevating annoyance levels of the
alarm sounds. This versatility can increase the awareness of
caregivers that may not respond quickly to standard alarms,
resulting in improved response times and so forth. In a specific
example, an alarm may sound from speaker 12 based on a blood
pressure reading that passes a predefined alarm threshold. If this
alarm is not acknowledged by, for example, pressing the alarm
silence button 16, speaker 14 emits a secondary alarm having a
different tone than the first alarm to further alert the caregiver
of the alarm condition.
[0018] In addition to providing auditory versatility, having
multiple speakers creates redundancy that improves reliability in
the event of a speaker failure (e.g., a speaker being blocked and
muffled by an object or a speaker with a faulty connection). Not
all unacknowledged alarms will necessarily result from caregivers
failing to hear or recognize the initial alarm. Indeed, an initial
alarm may remain unacknowledged because a speaker assigned the task
of emitting the initial alarm either failed to produce or failed to
adequately emit the initial alarm tone. For example, if speaker 12
is configured to emit an initial alarm tone and speaker 14 is
configured to emit a reminder alarm tone after the initial alarm is
unacknowledged for a designated period, the reminder alarm tone
provided by speaker 14 will serve as a back up alarm to alert the
user of a pending alarm condition in the event speaker 12 fails to
provide the initial alarm tone.
[0019] In another embodiment, both speakers 12 and 14 are
essentially completely redundant. For example, in a completely
redundant embodiment, all speakers (e.g., 12 and 14) are configured
to emit the same alarm tones and alarm reminder tones based on the
same measured conditions and unacknowledged alarms. If one speaker
fails, at least one other speaker will have been redundantly
assigned the same alarming task.
[0020] It should be noted that, in some embodiments, alarms are
visually and/or haptically indicated in addition to being audibly
indicated. Indeed, alarms may be indicated to alert any of a
caregiver's senses (e.g., sight, touch, and hearing). These
alternative sensory indications (e.g., alarm lights and vibrating
pagers) are additional tools with which a user's attention can be
directed to an alarm condition. For example, the pulse oximeter 10
includes a display 24, such as a liquid crystal display (LCD), that
visibly displays alarm indications and other information. In one
embodiment, the display 24 is configured to visually communicate
patient physiological data (e.g., oxygen saturation percentage,
pulse amplitude, pulse rate) and alarms in the form of numeric
data, textual data, and/or graphical data (e.g., plethysmographic
waveforms and/or alarm icons). The display 24 may also be
configured to display equipment status indicators such as an on/off
indication depending on whether a power button 26 in latched or
unlatched, a power indication depending on whether a power cord 28
is receiving power, and/or other equipment status indicators. In
one embodiment, the display 24 is used to visually confirm values
entered while configuring aspects of the pulse oximeter 10 (e.g.,
providing set points for alarms via the adjustment buttons 18). It
should also be noted that these extra indications provide
supplemental redundancy.
[0021] FIG. 2 is a block diagram of a method 40 for providing
patient monitor alarms in accordance with an exemplary embodiment
of the present invention. The method 40 can be implemented with a
single alarm indicator or multiple alarm indicators. For example,
embodiments of the present invention may use speakers, pagers,
visual indicators, and/or haptic devices to provide the referenced
signals (e.g., audible tones). The method 40 begins at block 42 and
proceeds to block 44, which is a decision block regarding whether
an alarm condition has been detected. If an alarm condition has not
been detected, the method returns to the start (block 42). If an
alarm condition has been detected, an alarm signal is emitted by
one or multiple alarm indicators (e.g., speaker 12) in block 46 and
an alarm timer is initiated in block 48. The alarm signal may
include a tone emitted from a speaker, a vibration emitted from a
pager, a light emitted from a display and so forth.
[0022] After an alarm has been initiated (block 46), the method 40
begins determining whether the alarm condition still exists and/or
whether the alarm signal has been acknowledged, as illustrated by
blocks 50 and 52. Specifically, block 50 is a decision block
regarding whether a user has provided confirmation that the alarm
condition has been recognized or acknowledged. Such an indication
of acknowledgement may be provided by, for example, depressing the
alarm silence button 16. If the alarm condition has been
acknowledged, the unexpired alarm timer is reset or canceled (block
54) and an alarm silence timer may be initiated (block 56). In the
illustrated embodiment, the alarm silence timer is then monitored,
as illustrated by block 58. When the alarm silence timer expires,
block 58 directs the method 40 to start again at block 42. In some
embodiments, the alarm silence timer is not utilized. For example,
in some embodiments, once a specific alarm is acknowledged, the
same alarm condition will not initiate the primary alarm again,
thus eliminating potentially unnecessary alarms. In other words, in
such embodiments, the same alarm condition will not cause repeated
alarm signals to be periodically emitted after acknowledgement when
the alarm silence timer expires.
[0023] Block 52 is a decision block regarding whether the alarm
condition still exists after being initiated. If the alarm
condition is no longer present (e.g., the patient's blood pressure
returns to normal), the alarm signal is canceled in block 60, the
alarm timer is reset or canceled in block 62, and the method 40
begins again at block 42. For example, in one embodiment, if a
patient's temperature passes a set point and then returns to normal
the alarm will cease regardless of whether the alarm has been
acknowledged. If the alarm condition remains present and has not
been acknowledged, the alarm signal is continually emitted, the
alarm timer continues to run, and the method 40 proceeds to block
64. It should be noted that in some embodiments, the presence of
the alarm condition is not required to maintain the alarm. In other
words, the method 40 proceeds without determining whether the alarm
condition persists (block 52). For example, in some embodiments,
the alarm remains active until acknowledged regardless of whether
the alarm condition ceases to exist. This may be desirable in
situations that benefit from requiring a user to be made aware that
an alarm event occurred.
[0024] Block 64 is a decision block regarding whether the alarm
timer has expired. If the alarm timer has not expired, the method
40 loops back to block 50. If the alarm timer has expired, a
secondary alarm signal is emitted (block 66). As discussed above,
this secondary alarm not only serves to increase awareness but also
provides redundancy. In one embodiment, the secondary alarm signal
has properties different than the primary alarm. For example, where
the primary alarm is an audible tone, the secondary alarm may be an
audible tone that is emitted with a higher frequency and/or a
higher volume. Additionally, if the alarm timer has expired, the
alarm timer may be reset with different properties (block 68). For
example, the alarm timer may be reset with a reduced period (e.g.,
half of the initial alarm timer period). In some embodiments, this
procedure continues as each successive alarm timer expires, thus
gradually increasing communicated urgency, distinguishing features
(e.g., type of sound), and/or the annoyance level of the alarm.
Further, it should be noted that in some embodiments, acknowledging
the alarm by, for example, pushing the alarm silence button 16,
acknowledges and silences all alarms (e.g., both primary and
secondary alarms).
[0025] FIG. 3 is a pressure-time plot of a primary alarm signal and
a secondary alarm signal in accordance with an exemplary embodiment
of the present invention. While two signals are depicted in the
illustrated embodiment, in some embodiments a plurality of signals
may be utilized. Specifically, the plot 72 represents an audible
signal or alarm emitted from the first speaker 12 as a primary
alarm when an alarm condition is detected and unacknowledged. The
plot 74 represents an audible signal or alarm emitted from the
second speaker 14 as a secondary alarm when the primary alarm has
remained unacknowledged for a predetermined amount of time. In some
embodiments, a single speaker can be used to emit both alarms 72
and 74. It should be noted that while the illustrated alarms 72 and
74 have pulse waveforms, in other embodiments, the alarms 72 and 74
can have different waveforms (e.g., ramp wave, sine wave, triangle
wave). Further, in some embodiments, the alarm signals are not
audible but include other types of signals (e.g., vibrations from a
pager). For example, in one embodiment, alarm signals are provided
by a single or redundant set of vibratory transducers to provide
further safety, versatility, and reliability.
[0026] As shown in FIG. 3, the secondary alarm 74 is silent during
the initial alarm period and changes in frequency over time to
increase annoyance, thus drawing attention to the unacknowledged
alarm condition. In the illustrated embodiment, after the primary
alarm 72 remains unacknowledged for a first amount of time 76, the
secondary alarm 74 is initiated with a duty cycle that is
interleaved with that of the primary alarm 72. After a second
amount of time 78 (e.g., half of the primary time) beyond
initiation of the secondary alarm 74, properties of the secondary
alarm 74 are changed. Specifically, in the illustrated embodiment,
the frequency of the alarm is increased, thus increasing annoyance.
In other embodiments, different aspects of the primary and/or
secondary alarms 72 and 74 are changed. For example, amplitude,
duty cycle, frequency, and harmonic content can be manipulated over
time to increase annoyance levels of all or some signals being
emitted. In one embodiment, the alarms 72 and 74 begin sweeping
through frequencies as the alarm condition remains unacknowledged.
In the illustrated embodiment, the annoyance level is continually
increased until it reaches a peak level or the alarm is
acknowledged. For example, after a third amount of time 80 (e.g.,
half of the second time 78) beyond the second amount of time 78,
the frequency of the secondary alarm 74 is changed again.
[0027] FIG. 4 is a block diagram of a monitoring system in
accordance with an exemplary embodiment of the present invention.
Specifically, FIG. 4 illustrates a monitoring system 90 including a
plurality of patient monitors 92 networked to a central management
station 94 (e.g., a personal computer), which is coupled with an
audible alarm system 96 and an alarm paging system 98. The alarm
paging system 98 includes a set of wireless and mobile pagers 100.
This monitoring system 90 facilitates monitoring multiple patients
in, for example, a hospital or clinic. It should be noted that in
some embodiments, the audible alarm system 96 and the alarm paging
system 98 are included in the monitors 92. Further, it should be
noted that in the illustrated embodiment, the monitoring system 90
is networked with network cables. However, in some embodiments,
wireless communication is utilized.
[0028] Each of the patient monitors 92 includes a sensing device
102 (e.g., temperature sensor, pulse sensor) for measuring patient
physiological data. Additionally, each of the monitors 92 or the
central management station 94 is configured to alarm based on
predefined physiological data values or conditions relating to such
values. For example, an alarm may be activated when a patient's
temperature has been at a certain level for a predefined amount of
time.
[0029] When alarm conditions are detected, the system 90 emits
alarm signals from the audible alarm system 96 and/or the alarm
paging system 98. Further, as discussed above, if the alarm is not
acknowledged, the monitoring system 90 increases the alarm
annoyance level. For example, in the illustrated embodiment, a
primary alarm signal is sent to a first pager 100A. If this primary
alarm is not acknowledged within a predefined amount of time, a
second alarm is sent to a second pager 100B. If the second alarm
remains unacknowledged for a predefined amount of time (e.g., half
of the time allotted to acknowledge the primary alarm), a third
alarm is sent to a third pager 100C and so forth. Additionally, the
annoyance level of each pager alarm may be increased. For example,
the pagers may beep or vibrate with a higher amplitude and/or
frequency. Further, audible alarms from a speaker or speakers of
the audible alarm system 96 may substitute or supplement the pager
alarms. Indeed, the audible alarm system 96 may emit audible alarm
tones with increasingly annoying characteristics, as discussed
above with regard to FIG. 3.
[0030] While the invention may be susceptible to various
modifications and alternative forms, specific embodiments have been
shown by way of example in the drawings and will be described in
detail herein. However, it should be understood that the invention
is not intended to be limited to the particular forms disclosed.
Rather, the invention is to cover all modifications, equivalents
and alternatives falling within the spirit and scope of the
invention as defined by the following appended claims.
* * * * *