 |
Description  |
|
|
This invention relates to an automated pressure relief mattress support
system, and, more particularly, a mattress system employing flexible,
pressurized air compartments, or cylinders, for patient support, with
automated control of the air pressure in the cylinders to maintain an
optimum air pressure which minimizes pressure between a patient and the
mattress surface, and to move the patient from center supine to right and
left side positions for selected periods of time.
BACKGROUND OF THE INVENTION
It is known in the medical field to provide mattress constructions having
flexible compartments for pressurized fluid to provide support for a bed
patient to reduce pressure and sheer forces on the body of the patient by
the mattress surface. It is also known to provide mattress constructions
incorporating variously arranged flexible air compartments which may be
inflated or deflated, as desired, to roll a patient from a center supine
to a right or left side position on the bed for selected periods of time.
Certain of such pressurized air support systems are known as "low air
loss" systems which are continuously connected to a pressurized air source
and have micropores in the flexible air compartments to continuously
release pressurized air therefrom for various effects, such as heating,
cooling, or drying of a patient's body.
U.S. Pat. Nos. which disclose and describe pressurized air mattress support
systems are exemplified, as follows:
______________________________________
5,103,519 5,020,176
4,949,412
5,092,007 5,003,654
4,803,744
5,073,999 4,995,124
4,797,962
5,070,560 4,989,283
4,694,520
5,062,167 4,949,414
4,617,690
4,279,044
______________________________________
Most of the listed patent constructions which utilize air compartment
arrangements for the support and positioning of a bed patient are of
relatively expensive and complex construction and design, and employ many
variously configured air compartments under various portions of the
patient's anatomy to move the patient, or to create a desired firmness or
softness of support of the patient, as controlled by the patient or a
patient attendant.
BRIEF OBJECTS OF THE INVENTION
It is an object of the present invention to provide an improved, relatively
inexpensive air support mattress of simplified construction having
associated control means for maintaining a desired uniform air pressure in
all air compartments of the construction to reduce patient/mattress
interface pressures, and for moving the patient from a center supine
position to right and left side positions, as desired.
It is a further object to provide an air mattress support system which may
be adjusted to maintain an optimum air pressure for minimum
patient/mattress interface pressure, depending upon the particular weight
of the patient, and wherein such optimum air pressure may be maintained
during use by the patient without continuous supply of pressurized air to
the mattress construction.
It is another object to provide a method of supporting a bed patient on a
mattress to minimize patient/mattress interface pressures.
It is further object to provide a method for supporting a bed patient on a
mattress to minimize patient/mattress interface pressures, and to move the
bed patient thereon from supine to right or left side positions.
It is a more specific object to provide a method for moving a bed patient
on a mattress construction from supine to right or left side positions
wherein a specific predetermined angle of roll of the patient in right or
left side positions can be accurately achieved automatically, based on the
particular body weight of the patient on the mattress.
BRIEF DESCRIPTION OF THE DRAWINGS
The above as well as other objects of the invention will become more
apparent and the invention will be better understood, from the following
detailed description of preferred embodiments, when taken together with
the accompanying drawings, in which:
FIG. 1 is a perspective view of a standard hospital bed frame supporting an
automated pressure relief mattress support system of the present
invention, with portions of the mattress construction of the system broken
away and removed to better show interior components of the mattress
construction;
FIG. 2 is an enlarged sectional plan view of the bottom portion of the
mattress construction of FIG. 1 taken generally looking in the direction
of arrows II--II, and with portions broken away and removed to show the
internal arrangement and connection of the flexible air compartments of
the mattress to a source of pressurized air;
FIG. 3 is an enlarged side elevation view of the left lower section of the
mattress construction of FIG. 1 showing the quick disconnect coupling
arrangement of the pressurized air supply conduit and pressure sensing
means communicating the air compartments with the pressurized air supply
and control unit of the system;
FIG. 4 is a sectional end elevation view of the bottom end of the mattress
construction as seen in FIG. 2;
FIG. 5 is a diagrammatic representation of the major component parts of the
mattress support system of the present invention, showing inner-connection
of the air supply and control units to the air compartments of the
mattress construction; and
FIG. 6 is a pneumatic representation diagram showing the operative
interconnection of the solenoid control valves with pressurized air supply
and air compartments of the mattress support system.
SUMMARY OF THE INVENTION
The present invention comprises an automated pressure relief air support
mattress construction having a plurality of longitudinally extending,
flexible air compartments, or cylindrical tubes, which are interconnected
and normally uniformly pressurized to an optimum air pressure to minimize
interface surface pressure between a patient and the mattress. The system
is of simplified, economical construction and can be operated both
passively and actively. In passive operation, the cylindrical air tubes of
the mattress are inflated to within a defined pressure range which
minimizes pressure at the patient/mattress interface and aids in
prevention and treatment of pressure sores on the patient.
The system also may be operated actively by connection to a pressurized air
supply, control, and monitoring system for roll, or rotation, of a patient
to right and left side positions, typically to selected angles of up to
about 30 degrees, for selected dwell times. Rotation of the patient is
accomplished by manual or automatic control of the air pressures in
selected pairs of air tubes to achieve pre-determined pressure values.
In one specific embodiment, the mattress construction includes an outer
cover of vapor-permeable material. Inside the cover are foam support
layers of selected densities to contour to the body of the patient and
reduce interface pressure. Flexible cylindrical air tubes extending in
parallel longitudinal relation throughout the length of the mattress are
maintained in supporting jackets to maintain proper position. The air
tubes may be framed on each end and on both sides with polyurethane foe
bolsters. Lateral slats may be positioned in the mattress to reduce
"hamhocking" of the patient and distribute weight forces of the patient's
body.
The control unit for the mattress system includes a source of pressurized
air, such as an air compressor, or blower, a valve and manifold
arrangement connecting the blower to the air tubes, air pressure sensors
associated with the tubes, and control means including a microprocessor
and a manual control panel for operating the valve and manifold
arrangement in an active mode, automatically or manually, to provide air
at a preselected pressure in the air tubes.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
As seen in the drawings, and more particularly FIG. 1, the pressurized air
mattress construction 10 of the present invention is of a generally
rectangular shape having an outer cover 12 of suitable material, such as a
vapor-permeable woven textile fabric, which encloses and contains a
plurality of flexible, essentially air-impervious compartments, or
cylindrical tubes 14a, 14b, extending longitudinally from head to foot of
the mattress in side-by-side relation. Extending transversely across the
mattress in parallel side-by-side relation may be a plurality of slats 16
of relatively resilient material which extend across the four air tubes
14a, 14b to permit more even body weight distribution across the mattress,
thereby reducing pressure on the tissue and skin of the patient. Overlying
and surrounding the air tubes 14a, 14b and slats 16 in the mattress cover
12 are one or more foam layers of material 17. Such a mattress
construction is disclosed in U.S. Pat. No. 5,070,560, the disclosure which
is incorporated herein by reference.
The mattress construction thus described may be placed on a conventional
hospital bed frame 18, head and foot portions of which may be articulated
to raise and lower upper and lower ends of the mattress. Due to the
arrangement of the air tubes 14a, 14b in longitudinal, side-by-side
position in the mattress construction, the mattress may be angularly
positioned without changing the air pressure in the compartments as a
result of articulation.
As shown in FIGS. 2, 4, and, 6, the longitudinal air tubes comprise
communicating left side and right side pairs, 14a and 14b, respectively.
Tube pair 14a and tube pair 14b communicate by separate supply conduits
20, 22 to a pressurized air source. As seen in FIGS. 5 and 6, pressurized
air, supplied from a suitable air source, such as an air compressor, or
pump P, is connected through a valve and manifold arrangement 28 to
provide air at a desired pressure in each of the air tube pairs 14a and
14b, as will be explained. The valves V1-V5 are solenoid-operated, either
manually or in response to microprocessor program information to maintain
a selected uniform optimum pressure in all air tubes to minimize
patient/mattress interface pressures, or to move the patient between
center supine and right and left side positions on the mattress, as will
be described. As shown in FIG. 1, a control box 29, located at a
convenient position on the foot of the bed frame 18, houses a manual
control panel 50, microprocessor 46 (FIG. 5), and valve and manifold
arrangement 28 (FIGS. 5 and 6).
The air tubes 14a, 14b of the mattress construction may be formed of a
suitable flexible, essentially air-impervious material, such as a woven
polymeric outer fabric sealed with a polymeric film, such as polyurethane.
The tube construction ensures that air can be maintained at a desired
pressure within the air tubes for an indefinite period of time, without
the need for continuous supply of additional pressurized air to maintain
such pressure, as in the case of the "low air loss" systems of the prior
art.
Through evaluation in test procedures, it has been found that the four air
tubes 14a, 14b of mattress construction 10 may be inflated to an air
pressure to minimize patient/mattress interface pressure and reduce
decubitus or pressure sores. Patient/mattress interface pressure may be
conveniently measured by use of an interface pressure tester, such as an
Ergo Check pressure measuring system manufactured by ABW, Gmbh of Germany.
An optimum air pressure for the particular mattress construction described
herein has been found, through interface pressure measurements, to reside
within a narrow range for most, if not all, patient weights and sizes, and
is established in the air tubes when the weight of a patient is on the
mattress. In the mattress construction described, this optimum range has
been found to be between about 0.250 and 0.350 psi.
To prepare the mattress for maintenance of a patient to minimize mattress
interface pressure on the body, the patient is placed in supine position
on the bed at a given geographic elevational location and the air tubes
pressurized or depressurized to the predetermined desired optimum value.
Thereafter, the pressurized air source and its related equipment may be
disconnected from the mattress and the mattress maintained at the optimum
air pressure for the particular patient for an indefinite period of time.
As best seen in FIGS. 5 and 6, the control valve and manifold arrangement
28 includes five direct-operated type, two-port solenoid valves V1-V5 with
manifold M, such as a Series VVX21/22/23, manufactured by SMC Pneumatics,
Inc. of Boston, Mass. As shown schematically, valves V1, V2 and V3 are
normally closed valves and valves V4 and V5 are normally open valves, such
that solenoid valves V1, V2, and V3 must be energized to open, while
valves V4 and V5 must be energized to close. The manifold M has two sides,
or compartments, one side or compartment M1 which communicates directly
with valves V1, V2 and V3 and the inlet side of air pump P, and the other
side or compartment M2 which communicates directly with valves V4 and V5
and the outlet side of air pump P. Under "no power" conditions, this
arrangement of the valves and manifold ensures that the 14a and 14b air
tube pairs of the mattress construction are cross-connected and pressure
is equalized, as will be explained.
As schematically illustrated in FIGS. 5 and 6, the solenoid-operated valve
and manifold arrangement 28 is electrically connected to and operated from
microprocessor 46 (which may be an INTEL microprocessor #8051) and control
panel 50. Valves V1-V5 and manifold compartments M1, M2 are interconnected
by air flow lines 31, 32 to the inlet and outlet sides of air pump P and
to the air tube pairs 14a and 14b by conduits 33-36. To inflate all the
air tubes to a desired air pressure, an air pressure sensor 40, such as a
Sylvania Pressure Transducer No. MPX106P/9310 (FIG. 5), is operatively
associated with each pair 14a and 14b of the air tubes to measure the
internal air pressure in each pair.
On the inlet side of pump P, in opened positions, valve V1 communicates
outside room air, as from air inlet 42, with manifold compartment M1,
valve V2 communicates air tube pair 14a and valve V4 with the manifold
compartment M1, and valve V3 communicates the 14b pair of air tubes and
Valve V5 with the manifold compartment M1.
On the outlet or pressure side of plump P, in opened positions, valve V4
communicates manifold compartment M2 with the air tube pair 14a and valve
V2, while valve V5 communicates the manifold compartment M2 with the 14b
pair of air tubes and valve V3.
The pressure sensor 40 located on the inside tube of each pair of tubes
14a, 14b is suitably operatively connected by electric leads 44 to the
microprocessor unit 46 which contains programmed air pressure set point
information to permit manual or automatic operation of the valves V1-V5 to
introduce or remove air from the tube pairs to obtain a desired or
preselected air pressure in the air tubes.
The operation of the air pressure regulation and control features of the
present invention may be described, as follows. FIG. 6 schematically
illustrates the air tubes 14a, 14b and manifold and valve control
arrangement 28, looking from the perspective of the foot of the bed,
patient, and the air mattress. To inflate the air tubes of the mattress to
a desired internal air pressure as set in the microprocessor program
information to minimize patient/mattress interface pressures, valve V1 is
opened and pump P energized to supply air to the 14a and 14b pairs of air
tubes via opened valves V4 and V5. When the pressure in the four air tubes
reaches the established uniform set point, e.g. 0.25 psi, valves V4 and V5
are closed to establish and maintain the desired set point uniform
pressure in all four of the air tubes. The pump P is de-energized and
valve V1 closed.
To deflate the air tubes of the mattress to a desired internal air pressure
set point to minimize patient/mattress interface pressures, valves V1, V2
and V3 are opened and valves V4 and V5 are closed. The pump reins
de-energized while air is bled from the air tube pairs via valves V2 and
V3, via the manifold compartment M1, and valve V1 to ambient air. When the
reduced set point is reached, valves V1, V2 and V3 are closed and valves
V4 and V5 are closed.
The mattress construction of the present invention may thereafter be
disconnected from the pressurized air source and control means through
quick-release coupling connectors 53, 54 (FIG. 3) and the mattress
utilized with a uniform optimum air pressure in the air tubes based on the
weight of the patient, at the particular geographic elevation of use.
The air mattress construction of the present invention may also be used in
an active mode to provide for orientation or adjustment of a patient from
left to right side positions on the mattress by means of the control
features and valving arrangement of the present invention. Air pressure
set points for air tube pairs 14a and 14b may be established for various
degrees of left or right side rotation of the patient from center supine
position, typically from about 5 degrees up to about 30 degrees from the
horizontal plane.
Referring to FIG. 6, to roll the patient (1) from a right side to a center
or a left side position, or (2) from a center to a left side position,
valves V3 and V4 are opened, the pump started, and valve V5 is closed to
transfer air from tube pair 14b to tube pair 14a. When a desired air
pressure set point is achieved in the 14b tube pair, valve V3 is closed.
If additional air is needed to achieve the desired set point in the 14a
pair tubes, valve V1 is opened and the pump operated to supply room or
outside air to the 14a pair tubes. When the set point is achieved in the
14a pair tubes, valve V1 is closed and V4 is closed. The plump is then
stopped.
To roll the patient (1) from a left side to a center or to a right side
position, or (2) from a center position to a right side position, valves
V2 and V5 are opened, the pump is started, and valve V4 is closed to
transfer air from the 14a pair tubes to the 14b pair tubes. When the
desired set point is achieved in the 14a pair, valve V2 is closed. If
additional air is needed to achieve the desired set point in the 14b pair,
valve V1 is opened and the pump operated to supply air until the set point
is reached on the 14b pair. At such time valve V1 is closed and valve V5
is closed. The pump is stopped.
To inflate the mattress construction to a firm or hard condition for
patient ingress and egress and for CPR administration, valve V1 is opened,
the pump started, valves V4 and V5 are opened and valves 2 and 3 are
closed to achieve preselected set points at 14a and 14b tubes. Valves V1,
V4 and V5 are then closed and the pump stopped.
In the event of power failure, with the valving arrangement shown, wherein
valves V1, V2 and V3 are normally closed and valves V4 and V5 are normally
open, power failure automatically cross-connects the 14a and 14b tube
pairs to equalize the pressure in the mattress construction. In situations
of loss of power to the control means and solenoid control valves, the
normally opened and normally closed valves, V1-V5 are connected to the air
tubes 14a, 14b to ensure their cross-connection and equalization of
pressure in all of the air tubes. As seen in FIG. 6 the communicating air
conduit lines connecting the valves to the air tubes, normally closed
valves V1, V2, and V3 and normally opened valves V4 and V5 (under no-power
conditions), communicate tubes 14a directly with tubes 14b by way of air
lines 33, 35, valve V4, manifold compartment M2, valve V5, and air line
36.
The operative relationship of the component parts of the automated pressure
relief mattress support system are shown diagrammatically in FIG. 5. As
seen, air tube pairs 14a and 14b of the mattress construction are
connected in pairs by conduits 20, 22 respectively to the valve and
manifold assembly 28, which is in turn operatively connected to the pump P
by the solenoid-operated valves V1, V2, and V3 connected to the inlet side
of the pump and solenoid valves V4 and V5 connected to the outlet side of
the pump. Pressure sensors 40 located in inside tubes of the two pairs of
tubes 14a and 14b are connected by suitable electrical leads to the
microprocessor unit 46 containing programmable means for automated
operation of the valve and manifold assembly and pump by way of electrical
lines 48. Internal air pressure set points in the air tube pairs 14a, 14b
are established in the control program, in known manner, to operate the
valves in establishing an optimum uniform air pressure in all the air
tubes of the mattress construction. Also operatively connected to the
microprocessor 46 for operation thereof in a manual mode is manual control
means shown, as control panel 50, on control box 29 of the bed 18.
Manually operated electrically connected buttons 52 are provided for use
by an operator to provide orientation of the patient from a center supine
position to right and left side positions and return, with dwell times of
selected periods and roll angles of selected angular position.
An important feature of the present invention provides that the mattress
construction and air control means may be used to move a bed patient from
supine to right or left side angular positions which are accurately
automatically established based on the body weight of a patient utilizing
the bed. It has been found that a particular roll angle of a patient's
body on the mattress construction of the present invention is directly
affected by the patient's body weight. For example, to rotate a person of
a given body weight to a given angular position, e.g., 30 degrees from the
horizontal, requires a different internal air tube pressure from that of a
person of a different bodyweight, due to the different air pressure
required to maintain the patient in the desired angular position.
Thus, it can be understood that it is necessary to establish an air
pressure differential, or variation, transversely cross the air mattress
construction by selectively increasing and/or decreasing the internal air
pressures in the right and left side pairs of air tubes 14a, 14b.
Typically, the air pressure in the lower pressure side pair of tubes may
be set at a preselected reduced pressure for the particular degree of
patient roll, such that only the air pressure in the higher pressure side
pair of air tubes need be varied, based on body weight, in accordance with
program information. This reduces the amount of program information which
must be employed to create the air pressure differential across the air
mattress to produce the roll angle desired. Alternatively, the air
pressure in the higher pressure side pair of air tubes may be set at a
preselected amount and the lower pressure side air tube pair pressure
varied, based on patient body weight. Additional data can be calculated,
in the manner hereinafter disclosed, to simultaneously adjust both air
tube pair air pressures, based on body weight, if desired.
The automated control mattress construction of the present invention may be
employed to measure body weight of a patient placed on the bed and to
utilize such information through program control of the microprocessor to
automatically adjust end-point internal air tube pressure settings
necessary to locate a particular weight patient at a desired angular
position, e.g., 5 degrees, 20 degrees, 30 degrees, relative to a
horizontal plane.
The following procedure was employed to establish the microprocessor
program data for automatically setting the air pressure end points based
on patient body weight. Patient subjects, two male and two female, were
used to obtain weight/air pressure information. Subject weights ranged
from 120 to 223.5 lbs. An internal air pressure was set for an unoccupied
inflated mattress construction having four 81/4 inch diameter air tubes. A
subject patient when lay down upon the mattress and the internal air tube
pressure for the loaded mattress was recorded. Four sets of measurements
for each subject were recorded and differential pressure increases were
calculated by subtracting the average increase or surge air pressure from
the average unoccupied air mattress pressure.
More specifically, all tubes of the mattress were inflated to 0.250 psi
from the air supply lines and the air supply lines disconnected from the
mattress | | |
