U.S. patent number 3,814,105 [Application Number 05/230,618] was granted by the patent office on 1974-06-04 for portable defibrillators including rotary solenoid relays for energy transfer and dumping.
This patent grant is currently assigned to Physio-Control Corporation. Invention is credited to Jack D. Howard, Stanley V. Seiffert, Christopher R. Wartes.
United States Patent |
3,814,105 |
Howard , et al. |
June 4, 1974 |
PORTABLE DEFIBRILLATORS INCLUDING ROTARY SOLENOID RELAYS FOR ENERGY
TRANSFER AND DUMPING
Abstract
A portable defibrillator including at least one open-frame relay
is disclosed. The relay combines the functions of previously-used
transfer, dump, and ECG protection relays required in portable
defibrillator-ECG monitor units. The relay includes at least one
rotary solenoid for providing reliable operation while yet
resisting accidental operation due to physical shock or the
like.
Inventors: |
Howard; Jack D. (Seattle,
WA), Seiffert; Stanley V. (Snohomish, WA), Wartes;
Christopher R. (Lynnwood, WA) |
Assignee: |
Physio-Control Corporation
(Seattle, WA)
|
Family
ID: |
22865920 |
Appl.
No.: |
05/230,618 |
Filed: |
March 1, 1972 |
Current U.S.
Class: |
607/5;
335/122 |
Current CPC
Class: |
A61N
1/3904 (20170801); A61N 1/39046 (20170801); A61N
1/3912 (20130101) |
Current International
Class: |
A61N
1/39 (20060101); A61n 001/36 () |
Field of
Search: |
;128/419D,419R,421,423
;335/114,122,193,26B |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Kamm; William E.
Attorney, Agent or Firm: Christensen, O'Connor, Garrison
& Havelka
Claims
What is claimed is:
1. A portable defibrillator for operation from a source of power,
said defibrillator comprising:
1. a source of defibrillation energy;
2. an electrical network means for storing said defibrillation
energy;
3. a pair of electrodes engagable with a patient; and,
4. circuit means for controlling the selective application of said
defibrillation energy to said patient via said electrodes, said
circuit means including:
a. a first switch;
b. a first relay including a first set of contacts normally
connecting said defibrillation energy source to said electrical
network means, and a second set of contacts for connecting said
electrical network means to said electrodes to selectively apply
said stored defibrillation energy to said electrodes, said first
relay further including a first rotary solenoid having a shaft
rotatable upon energization thereof and means responsive to the
rotation of said shaft for sequentially opening said first set of
contacts and closing said second set of contacts; and,
c. means interconnecting the source of power, said first switch and
said first rotary solenoid to energize said first rotary solenoid
upon actuation of said first switch; and,
5. means for automatically shunting said electrical network means
whenever power is removed from said portable defibrillator, said
shunting means including:
a. a second relay including a set of contacts, a second rotary
solenoid having a shaft rotatable upon energization thereof and
means responsive to the rotation of said shaft for opening said set
of contacts;
b. a resistance means;
c. means connecting said set of contacts and said resistance means
in series across said electrical network means;
d. means for connecting said second rotary solenoid to the source
of power; and,
e. a set of contacts forming part of said first switch and
connected to said second rotary solenoid for removing power from
said second rotary solenoid when said first switch is actuated.
2. A portable defibrillator for operation from a source of power in
combination with a heart signal monitoring means for displaying the
heart signals of a patient, said combination comprising:
1. a source of defibrillation energy;
2. an electrical network means for storing said defibrillation
energy;
3. a pair of electrodes engagable with a patient; and,
4. circuit means for controlling the selective application of said
defibrillation energy to said patient via said electrodes, said
circuit means including:
a. a first switch;
b. a first relay including a first set of contacts normally
connecting said defibrillation energy source to said electrical
network means, and a second set of contacts for connecting said
electrical network means to said electrodes to selectively apply
said stored defibrillation energy to said electrodes, said first
relay further including a first rotary solenoid having a shaft
rotatable upon energization thereof and means responsive to the
rotation of said shaft for sequentially opening said first set of
contacts and closing said second set of contacts; and,
c. means interconnecting the source of power, said first switch and
said first rotary solenoid to energize said first rotary solenoid
upon actuation of said first switch;
5. means for automatically shunting said electrical network means
whenever power is removed from said portable defibrillator, said
shunting means including:
a. a second relay including a set of contacts, a second rotary
solenoid having a shaft rotatable upon energization thereof and
means responsive to the rotation of said shaft for opening said set
of contacts;
b. a resistance means;
c. means connecting said set of contacts and said resistance means
in series across said electrical network means; and,
d. means for connecting said second rotary solenoid to the source
of power; and,
6. means for protecting said heart signal monitoring means from
receiving any of said defibrillation energy, said protection means
comprising:
a. a third set of contacts connected between said heart signal
monitoring means and said patient; and,
b. means responsive to the rotation of the shaft of said first
rotary solenoid for opening said third set of contacts prior to the
closure of said second set of contacts.
3. The combination recited in claim 2 wherein said third set of
contacts normally connects said heart signal monitor means to said
electrodes, and wherein said means responsive to the rotation of
the shaft of said first rotary solenoid opens said third set of
contacts so as to disconnect said heart signal monitoring means
from said electrodes prior to closure of the second set of contacts
and the application of defibrillation energy to said
electrodes.
4. A portable defibrillator for operation from a source of power in
combination with a heart signal monitoring means for displaying the
heart signals of a patient, said combination comprising:
1. a source of defibrillation energy;
2. an electrical network means for storing said defibrillation
energy;
3. a pair of electrodes engagable with a patient; and,
4. circuit means for controlling the selective application of said
defibrillation energy to said patient via said electrodes, said
circuit means including:
a. a first switch;
b. a first relay including a first set of contacts normally
connecting said defibrillation energy source to said electrical
network means, and a second set of contacts for connecting said
electrical network means to said electrodes to selectively apply
said stored defibrillation energy to said electrodes, said first
relay further including a first rotary solenoid having a shaft
rotatable upon energization thereof and means responsive to the
rotation of said shaft for sequentially opening said first set of
contacts and closing said second set of contacts; and,
c. means interconnecting the source of power, said first switch and
said first rotary solenoid to energize said first rotary solenoid
upon actuation of said first switch; and,
5. means for protecting said heart signal monitoring means from
receiving any of said defibrillation energy, said protection means
comprising:
a. a third set of contacts connected between said heart signal
monitoring means and said patient; and,
b. means responsive to the rotation of the shaft of said first
rotary solenoid for opening said third set of contacts prior to the
closure of said second set of contacts.
Description
FIELD OF THE INVENTION
This invention generally relates to apparatus for monitoring the
electrical activity of the heart of a person and selectively
applying an electric impulse to the person to stop heart
fibrillation, and, more particularly, to an improved relay
combining the transfer, dump, and ECG protection relay functions
normally required in such devices.
BACKGROUND OF THE INVENTION
By monitoring the heartbeat of a patient, it can be recognized, by
a skilled operator, when the heart is fibrillating and hence is in
immediate need of a defibrillation signal to terminate
fibrillation. Devices such as ECG monitors have long been used in
the art to visually display to an operator all information
regarding the heartbeat that is necessary to recognize
fibrillation. Once the need for a defibrillation signal has been
established, a high voltage pulse obtained from a defibrillator may
be applied to the patient via appropriate electrodes to momentarily
stop the heart and terminate fibrillation.
ECG monitors and defibrillators are now used customarily in
intensive care sections of most hospitals and generally comprise
stationary units for which considerations of cost, size and weight
are not critical. However, portable defibrillators have been used
with increasing frequency in ambulances and coronary care vehicles.
Considerations of cost, size and ruggedness and reliability under
adverse environmental conditions are very important in the
construction of portable units. One type of portable unit is that
combining a defibrillator and an ECG monitor with a single set of
paddle electrodes which are used for both heart monitoring and for
the application of a defibrillation pulse, as more completely
described and claimed in U.S. Pat. No. 3,547,108, by Stanley V.
Seiffert, Dec. 15, 1970, which is also assigned to the assignee of
the present invention. Portable combination defibrillator and ECG
monitors have typically included two relays for controlling the
transfer of a defibrillation pulse to the patient. The first of
these relays is commonly known as the transfer relay and operates
to transfer a charge from a storage capacitor in the defibrillator
to a set of electrodes connected to the patient upon the actuation
of a switch by the operator. The second of these relays is commonly
known as the dump relay and operates to discharge the
defibrillator's storage capacitor whenever the defibrillator is
turned off or whenever power supply voltage is lost. In cases where
the unit is of the type described and claimed in the aforementioned
patent, a third relay is also provided, known as the protection
relay, for protecting the ECG monitor from the defibrillation pulse
which is applied via the same set of electrodes that are used for
the monitor.
In normal cases, the electrodes are continuously attached to the
patient. Therefore, it is imperative that a defibrillation signal
not be applied unless absolutely needed. The vibrations and shocks
to which a portable unit is normally subjected, particularly when
placed in a vehicle, are such so as to prohibit the use of
ordinary, open-frame relays. Accordingly, the prior art has almost
exclusively used, in portable units, vacuum relays to effect the
functions of the transfer and dump relays. Although vacuum relays
perform satisfactorily in portable units, they are bulky and their
expense is a significant portion of the total cost of a portable
defibrillator.
Accordingly, it is an object of this invention to provide an
improved portable unit including a defibrillator which does not
require separate vacuum relays for the transfer and dump functions
thereof.
It is another object of this invention to provide, in a portable
unit including a combination defibrillator and ECG monitor with a
single set of electrodes, a combination relay for transferring a
charge stored in a capacitor to a patient through a set of
electrodes upon receipt of a defibrillation signal, for protecting
the input an ECG monitor using that set of electrodes when the
defibrillation pulse is being applied, and for discharging the
capacitor when the defibrillator unit is turned off or when power
is removed in any fashion from the portable unit.
It is yet another object of this invention to provide, in a
portable unit including a defibrillator, such a combination relay
which is inexpensive, simple in construction, and yet resistant to
actuation by external shocks and other vibrations.
SUMMARY OF THE INVENTION
These objects and others are achieved, briefly, by using at least
one rotary solenoid to actuate a plurality of contacts providing
the transfer, dump and ECG protection functions previously
requiring separate relays and relay coils in the prior art. In a
preferred embodiment, a first rotary solenoid is normally
deenergized and actuates the transfer and ECG protection contacts
upon actuation of an appropriate first switch, and a second rotary
solenoid is normally energized and actuates the dump contacts to
discharge the defibrillator's storage capacitor when power to the
unit is lost or when the first switch is actuated.
BRIEF DESCRIPTION OF THE DRAWINGS
The invention can perhaps best be understood by reference to the
following portion of the specification, taken in conjunction with
the accompanying drawings, in which:
FIG. 1 is a combined block/schematic diagram of a portable unit
including a defibrillator and the combination relay of this
invention; and
FIG. 2 is a pictorial diagram illustrating a preferred embodiment
of the combination relay.
DESCRIPTION OF A PREFERRED EMBODIMENT
While the invention will be hereinafter described with reference to
its use in combination with a portable defibrillator and ECG
monitoring unit using a single set of paddle electrodes, it is to
be clearly understood that the invention has broad applicability to
practically any portable unit including a defibrillator.
Now turning to the drawing, a defibrillator DC supply and control
circuit 10 is energized from a DC battery 12 when both an on-off
switch 14 for the portable unit and an on-off switch 16 for the
defibrillator have been closed. The DC signal supplied on line 17
is converted by the circuit 10 into a high voltage signal appearing
across leads 18 and 20 which are connected in turn to first
stationary contacts 23a, 24a of a transfer relay 22. Second
stationary contacts 23b, 24b of transfer relay 22 have connected
thereto leads 27 and 28 which are connected to a set of paddle
electrodes 30, 32 and to movable contact arms 25, 26 of transfer
relay 22. Stationary contacts 25a, 26a associated with movable
contacts 25, 26 have connected thereto leads 50, 51 which are
coupled to the input of an amplifier 52 whose single output 53
drives an ECG monitor scope 54.
As will be described hereinafter, relay 22 is normally de-energized
and accordingly movable contacts 23, 24, 25 and 26 thereof appear
in the positions illustrated in the drawing. As such, if the paddle
electrodes 30, 32 have been placed in appropriate positions on the
patient's chest, the ECG monitor space 54 is normally connected
thereto and displays information regarding the patient's
heartbeat.
During this time, the high voltage appearing on output leads 18 and
20 from circuit 10 is coupled through contacts 23a, 23 and 24a, 24
across the series connection of a pulse-shaping inductor 36 and
storage capacitor 37. Accordingly, storage capacitor 37 is charged
and provides a defibrillation pulse, when relay 22 is energized to
switch movable contacts 23, 24, into engagement with stationary
contacts 23b, 24b.
Relay 22 is energized in the following manner. DC power is supplied
to its coil via lead 21 from lead 17. The other side of the coil is
connected by a lead 35 to a first push-button switch 31 placed on
the handle of paddle electrode 30, which is in turn connected by a
lead 34 to a second push-button switch 33 placed on the handle of
paddle electrode 32. Switches 31 and 33 are normally open, and the
other side of switch 33 is connected to ground.
When the operator detects fibrillation by observation of the ECG
monitor scope 54, he then simultaneously depresses switches 31 and
33 to complete a path to ground for the coil of relay 22.
Accordingly, relay 22 is energized to discharge the capacitor 37.
Relay 22 is designed so that shortly before movable contacts 23 and
24 engage stationary contacts 23b and 24b, movable contacts 25 and
26 are moved out of engagement with stationary contacts 25a, 26a so
that the defibrillation pulse applied on common leads 27, 28 will
not harm the ECG monitor scope 54.
To discharge the storage capacitor 37 if the portable unit or the
defibrillator is turned off without being used, a dump relay 40 is
provided whose coil is connected from the lead 17 to ground.
Therefore, dump relay 40 is normally energized when power is being
supplied to the defibrillator circuit 10. Leads 46 and 47 connect
one end of discharge resistors 43, 44 to series network of inductor
36 and capacitor 37. The other ends of resistors 43 and 44 are
connected to stationary contacts 41a, 42a associated with movable
contacts 41, 42 of dump relay 40. Movable contacts 41 and 42 are
interconnected by a lead 45, and are shown in the drawings in their
normal position when relay 40 is energized.
It will be readily appreciated that when power is removed from the
coil of relay 40, contacts 41 and 42 move to engage stationary
contacts 41a, 42a to provide a discharge shunt path for capacitor
37 through resistors 43 and 44.
In some cases, it may be desirable to de-energize the dump relay 40
when the defibrillation pulse is to be applied by actuation of
relay 22. Accordingly, a set of contacts 31a, which are actuated by
push-button switch 31, may be interposed in lead 17 to the coil of
relay 40. Contacts 31a are open when push-button switch 31 is
depressed. Therefore, relay 40 is de-energized to provide a shunt
path for discharge of capacitor 37 through resistors 43 and 44.
If the resistance of resistors 43 and 45 is chosen to be
sufficiently high with respect to the resistance offered by the
body of the patient (typically on the order of 70 ohms) then the
shunt connection provided thereby will have little or no effect
upon the defibrillation pulse if in fact the paddle electrodes 30
and 32 are connected to the patient. If they are not, however, this
shunt connection provides an additional safety feature in allowing
discharge of capacitor 37 without the possibility of the paddles
electrodes 30, 32 later being accidentally touched by the operator
or another person.
With reference now to FIG. 2, the relays 22 and 40 are supported on
and secured to a base 60 which may be formed from a sheet of
transparent plastic stock material. The relays 22 and 40 both
comprise rotary solenoids having a pair of terminals for making
connections to the coils of the solenoids and additionally having
output shafts 82, 64, respectively. In the embodiment shown, shafts
82 and 64 rotate in a clockwise direction when the solenoids are
energized. In a working model, the solenoids comprised 24-volt
relays obtainable from Ledex, Inc.
The movable contact arm of dump relay 40 is formed by a first
machined steel member 62 which is keyed onto shaft 64. The ends of
member 62 are recessed at 62a, 62b to receive, respectively,
insulating members 66, 68, which may be secured thereto by
appropriate fastening means. Movable contacts 41, 42 comprise
standard metallic contact discs which are respectively secured to
upper portions of insulating members 66 and 68. As also shown in
FIG. 1, contacts 41 and 42 are interconnected by a lead 45.
Support members 70, 72 of insulating material are secured to base
60 adjacent the extremities of members 66, 68 and have attached to
their upper ends stationary contacts 41a, 42a, also of metallic
material. The relative positioning of support members 70, 72 is
such so that contact pairs 41, 41a and 42, 42a are in alignment and
in engagement when relay 40 is de-energized. With the arrangement
of FIG. 2, the shunt resistors 43, 44 may be conveniently
positioned adjacent support members 70, 72.
The contact structure of relay 22 is similar to that of relay 40. A
second machined steel member 80 is keyed to shaft 82 and supports
for rotation first and second insulating members 84, 86. Member 84
in turn has attached thereto movable contacts 23 and 25, and
insulating member 86 has attached thereto movable contacts 24 and
26. As best seen with respect to movable contact 24, each of
movable contacts 23 and 24 includes a metallic contact disc on
opposite sides of its insulating member.
A first insulating support member 90 is secured to base 60 and
positions stationary contacts 24a, 26a so that they are aligned
with and in contact with movable contacts 24, 26 when relay 22 is
de-energized. A second insulating support member 96 is identical
and supports contacts 23a, 25a for engagement with movable contacts
23 and 25. Third and fourth insulating support members 92, 94 are
also secured to base 60 and support stationary contacts 24b, 23b
for engagement with movable contacts 24, 23 when relay 22 is
energized.
Although interconnection between the components illustrated in FIG.
2 is made by wire leads, it is also contemplated that a portion of
base 60 comprise a printed circuit board substrate with a printed
circuit placed thereon for providing the necessary
interconnections. In a working model, the entire assembly
illustrated in FIG. 2 was provided with a dust-proof, transparent
casing, not illustrated, of a plastic material similar to that used
for base 60.
As a matter of design, the stationary contacts illustrated in FIG.
2 may be supported from their respective support members by leaf
springs so as to provide resilient contact engagement and dampening
of contact "bounce," or the stationary members themselves may be
made of a resilient material.
The design illustrated in FIG. 2 accordingly combines, into one
combination relay, the transfer, dump and ECG protection functions
previously provided by three separate relays in the prior art.
Since the stationary ECG protection contacts 25a, 26a are placed on
support members 90, 96, the circuit path from the electrodes to the
ECG monitor scope 54 will be broken before the defibrillation pulse
is applied via contacts 23, 23a, 24, 24a. In addition, the relay
contacts are actuated by rotary solenoids which are virtually
impervious to actuation by external shocks or vibrations.
Although the invention has been described with respect to a
preferred embodiment thereof, it is to be clearly understood by
those skilled in the art that the invention is not limited thereto,
but rather is to be bounded only by the limits of the appended
claims.
* * * * *