U.S. patent number 3,712,298 [Application Number 05/066,767] was granted by the patent office on 1973-01-23 for medical treatment apparatus.
Invention is credited to Robert Gonne Redhead, Charles Snowdon.
United States Patent |
3,712,298 |
Snowdon , et al. |
January 23, 1973 |
MEDICAL TREATMENT APPARATUS
Abstract
Apparatus and method for treating a human limb. The apparatus
comprises a container connected to a source of gas under pressure.
The limb intrudes into the container through a seal which allows
gas to leak out over the surface of the limb at a controlled rate,
so ventilating the limb. The leaking seal is so constructed that it
applies no tourniquet effect to the distal end of the limb within
the container. The seal may register with a substantial length of
the limb, which may thus be subjected to a beneficial pressure
gradient.
Inventors: |
Snowdon; Charles (Esher,
EN), Redhead; Robert Gonne (Richmond, EN) |
Family
ID: |
22071564 |
Appl.
No.: |
05/066,767 |
Filed: |
August 25, 1970 |
Current U.S.
Class: |
601/11;
604/23 |
Current CPC
Class: |
A61H
9/0071 (20130101) |
Current International
Class: |
A61H
9/00 (20060101); A61h 001/00 () |
Field of
Search: |
;128/1A,1B,38-40,184,256,298,299,82.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Trapp; Lawrence W.
Claims
We claim:
1. Limb treatment apparatus comprising a container, means for
supplying gas under pressure to the interior of said container,
said container having a resilient wall section defining an aperture
adapted to receive a limb to be treated, said wall section having a
circumference normally less than that of said limb and being
stretchable so as to yield to extend the aperture when a limb
intrudes and, when thus stretched, forming a leaking seal between
itself and said limb, the part of the stretchable wall section
defining the aperture being in the form of a gaiter that surrounds
an intruding limb snugly over a length of said limb, whereby the
leaking seal may expose the surrounded length of limb to a pressure
gradient when gas is supplied under pressure to the interior of the
container.
2. Limb treatment apparatus according to claim 1, in which the
gaiter is positioned so that its free end registers with the
proximal end of the limb.
3. Limb treatment apparatus comprising a container, means for
supplying gas under pressure to the interior of said container,
said container having a wall section defining an aperture adapted
to receive a limb to be treated, said wall section being
deflectable so as to yield to extend the aperture when a limb
intrudes and, when thus deflected, forming a leaking seal between
itself and said limb, the part of the deflectable wall section
defining the aperture being in the form of a gaiter that surrounds
an intruding limb snugly over a length of said limb, whereby the
leaking seal may expose the surrounded length of limb to a pressure
gradient when gas is supplied under pressure to the interior of the
container, a jacket enclosing the gaiter section of the wall, and a
source of fluid under variable pressure is connected to the jacket,
whereby to vary the clearance of the leaking seal and so modify the
pressure gradient to which the gripped length of limb is
exposed.
4. Limb treatment apparatus according to claim 3, in which the
source of fluid is adapted to apply a vacuum to the jacket to lift
the gaiter clear of the limb whereby to reduce the gradient to
zero.
5. Limb treatment apparatus according to claim 1, having control
means to regulate the supply of gas to the interior of the
container, said means being operable to supply alternate pulses of
atmospheric pressure and a higher than atmospheric pressure and
thereby subject the limb to a vascular pumping action.
6. Limb treatment apparatus comprising a container, means for
supplying gas under pressure to the interior of said container,
said container having a wall section defining an aperture adapted
to receive a limb to be treated, said wall section being
deflectable so as to yield to extend the aperture when a limb
intrudes and, when thus deflected, forming a leaking seal between
itself and said limb, said seal being adapted to exert no greater
pressure upon the part of the limb that lies within it than is
exerted upon the rest of the limb lying within the container, a
substantial part of the wall of the container being lightweight and
flexible, and a harness connected to the container by which it can
be attached to the owner of the limb being treated, whereby to
allow that owner some mobility while treatment proceeds.
Description
This invention relates to medical treatment of limbs of the body,
and to apparatus for carrying out the treatment. It applies
particularly to the treatment of limbs that have been badly burned,
or of a limb such as the stump that remains after an amputation.
During conventional post-operative treatment, such stump is encased
in a fixed volume dressing such as a plaster cast. This treatment
is beneficial because it opposes the tendency for fluids to
accumulate and cause swelling. However, the treatment also has some
disadvantages. For instance, slight movement of the stump within
the cast may create a slight clearance between the distal end of
the cast and the stump within it. This causes the maintained
pressure between the rest of the cast and the stump to produce an
undesirable tourniquet effect. The stump can also suffer from lack
of ventilation and from other factors leading to sepsis, and the
presence of the cast hinders any normal and regular examination
whereby such a condition might otherwise be detected at an early
stage. An object of the present invention is to facilitate medical
treatment whereby these disadvantages may be diminished while many
benefits are retained.
The scope of my invention is defined by the claims at the end of
this specification, and certain apparatus according to the
invention will now be described, with reference to the accompanying
drawings, in which:
FIG. 1 is a part schematic drawing of one apparatus;
FIGS. 2, 3 and 4 are perspective drawings of a detail of FIG.
1;
FIG. 5 is an axial section through another apparatus;
FIG. 6 is a similar section through a further apparatus;
FIG. 7 is a diagrammatic drawing illustrating the form of the sock
shown in FIG. 6;
FIG. 8 is an axial section through yet a further apparatus;
FIG. 9 is an axial section through the sock of FIG. 7, when not
under pressure; and
FIGS. 10, 11 and 12 are graphs illustrating modes of treatment
possible with apparatus according to the invention.
In FIG. 1 treatment apparatus includes a container comprising a
rigid transparent cylinder 1 of "Perspex" or similar material. At
one end of the cylinder a rigid end plate 2 is fixed by bolts 3,
making a joint with the aid of a gasket 4. End plate 2 contains an
inlet 5 for air under pressure, and provides a mounting for a
temperature sensor 6 and a humidity sensor 7. A pressure sensor 8
is mounted in the wall of cylinder 1. A pump 9 draws in fresh air
or other suitable gas through an inlet 10 and pumps it first
through a pressure regulating device 11 responsive to sensor 8,
then through a temperature regulator 12 responsive to sensor 6,
then through a humidity regulator 13 responsive to sensor 7, and
finally through a bacterial filter 14 before the air supply, now
purified and carefully controlled as to temperature, pressure and
humidity, enters the cylinder via inlet 5. Regulating devices 11,
12 and 13 may be pre-set. Alternatively, by means of a programming
device, they may be programmed to maintain a desired relationship
between the parameters concerned although the values of each of
these may change. As indicated by the dotted extensions 6a and 7a
of 6 and 7, these sensors and others not shown could respond to
conditions -- e.g., surface temperature, weight, surface moisture,
color, body temperature, etc. -- on or in the limb itself, not just
within the container.
At the other end of cylinder 1 a gasket 15 and bolts 16 make an
air-tight joint with an end plate 17 containing a central aperture
18. A hollow cylindrical member 19 carries a flange 20 which is
fastened to the outer face of end plate 17, around the aperture 18,
by bolts 21. A human limb 22, for treatment within chamber 1, is
inserted through cylindrical member 19, at the righthand end of
which is a seal 23, described in more detail with reference to
FIGS. 2, 3 and 4.
Inside chamber 1, the limb may be subjected to sterile air under
variable pressure, as will be described. It is essential, however,
that the atmosphere should be capable of exerting a pressure upon
the limb that exceeds atmospheric pressure, typically by 0.3 to 1.5
psi. It is also desirable that the seal 23 shall exert no greater
pressure upon the part of the limb that lies within it than is
exerted upon the rest of the limb lying within the chamber. Any
"tourniquet" effect of the seal would be most undesirable. An
element of a suitable seal, as used in the apparatus of FIGS. 1 and
5, is shown in FIG. 2 and comprises a piece of flexible material,
inelastic and preferably fluid-tight, folded at 24 to form a
sling-shaped member with triangular sides 25 and U-shaped edges 26,
27. As FIG. 3 shows most plainly, the members are mounted in a ring
around the inner surface of the free end of cylindrical member 19,
with sides 25 of adjacent members in contact and with edges 26
bonded to member 19 and lying parallel to the axis of it. The
convex faces of the U-bends 24 face axially outwards, and the
radial depth of the members is such that they leave a circular
clearance 28 around the axis of member 19. The girth of this
clearance is smaller than that of any limb that may require
treatment within the apparatus. When no limb is inserted through
the seal, air at high pressure within cylinder 1 will cause each of
the members of the seal to take up the shape shown in FIG. 3, and
throughput of air will be great because it can escape with ease
through clearance 28. However, when a limb is inserted, as shown in
FIG. 4, the radially inner end 29 of each U-bend 24 will conform to
the surface of the limb, and air will escape through the seal by
forcing itself through the gaps between the sides 25 of adjacent
seal members, or by leaking through the similar clearance between
the inner ends 29 of the seal members and the intruding limb. Thus
the folds 24 of the seal members constitute a deflectable end wall
of the container. When deflected by an intruding limb, the seal
members take up a funnel shape in which the spout of the funnel is
defined by the radially inner ends 29 of all the members, and the
stem of the funnel is formed by the parts of the members that
conform to the surface of the limb.
The flexibility of the material ensures that the pressure it exerts
upon that part of the limb passing through the seal is dictated
only by the pressure difference between the inside and outside of
chamber 1, and is nominally the same as that exerted upon all parts
of the limb that lie completely within the chamber. Furthermore,
the seal allows air to escape from within the chamber at a
reasonable rate when a limb is inserted, and this facilitates
continuous changing of the pressurized atmosphere within the
chamber, and thus ventilation of the limb being treated, and
prevents the ingress of undesirable bacteria.
Apparatus according to the invention enables pressure to be applied
to the limb under treatment. The application of pressure is of
benefit in counteracting oedema or swelling which endangers limbs
so often after serious tissue damage such as amputation. Unlike the
plaster cast, the apparatus shown in FIG. 1 allows the limb to be
surrounded by an atmosphere of sterile air, to be ventilated by
constant changing of that atmosphere, and to be continuously
visible. The nature of the seal 23 is such that even if the girth
of the part of the limb lying within it changes, the flexible
material of the members of the seal will allow the dimensions of
the seal to change with it without introducing extraneous
pressures.
The apparatus so far described with reference to FIG. 1 has a rigid
chamber and considerably limits the mobility of the patient.
However, with the modified apparatus of FIG. 5 the patient can be a
little more mobile. Here the wall 30 of the container is of
lightweight, flexible, inelastic air-tight transparent plastics
material, for example that sold under the trade mark "Melinex." The
air inlet 5, at the left-hand end in the figure, comprises a hollow
conical boss 31 containing a threaded portion 32 to receive a hose
carrying the pressure air supply. The flexible wall 30 is attached
to boss 31 by a rubber ring 33 which registers with a groove 34. At
the other end, the wall 30 is bonded to a flexible sleeve 35 on
which is mounted the seal 23. A strap-type harness 37 is anchored
to sleeve 35 at opposite ends of a diameter. This is necessary to
attach the apparatus to the patient, since the higher pressure
inside the chamber than outside tends to blow the apparatus off the
patient. The same applies to the apparatus of FIG. 1, but in that
case the patient is almost bound to be a lying case and it will be
simple to mount supports on the bed to prevent patient and
apparatus blowing apart. With the apparatus of FIG. 5, the harness
37 will pass round some part of the patient's body; for instance,
if the limb being treated is the stump of an amputated leg, harness
37 may pass round the back of the patient's waist, or may be a form
of shoulder harness.
The apparatus hitherto described enables the limb to be subjected
to a uniform pressure, but not to a pressure gradient along the
length of the limb. It may be desirable to subject a stump or other
limb to such a pressure gradient, the maximum pressure being at the
distal end of the stump, thus assisting the driving of fluid away
from it towards the body. Apparatus according to the invention,
which achieves this effect, is shown in FIGS. 6 to 8. In FIG. 6 the
container is a resilient, gas-tight sock 38 with a gas inlet 39
connected at 40 to a hose 41 coming from a pump, which may be
associated with sensing and controlling devices as described with
relation to FIG. 1. 42 represents the stump of a human limb lying
within the sock.
FIG. 7 compares the shape of a typical stump 42 with the shape of
the sock 38 when unstretched. It will be seen that the sock is
nearly as wide as the stump at the body end, then becomes
progressively less than the stump in circumference until it
approaches the area of the wound 43 at the tip of the stump, when
it widens out again. If such a sock is fitted over such a stump, it
will clearly fit loosely over the wound, will then tighten so as to
become a "gaiter" around the limb. This gaiter grips most tightly
shortly behind the wound, and grips progressively less tightly
between that point and the proximal end of the sock. If the inlet
39 is now connected, as in FIG. 6, to a source of gas under
pressure, the end 44 of the sock that surrounds the wound will
distend so that it lies clear of the wound, so that the wound
receives the full pressure of the sterile air. Immediately behind
the wound the pressure exerted by sock upon a stump is greatest,
because, as FIG. 7 shows, the difference in diameter between the
stump and the unstretched sock is greatest in the region. However,
this region like the wound is subject to the full delivery pressure
of the sterile air, which is set high enough to just separate sock
and stump, creating the beginning of an annular-section passage for
the flow of sterile gas between stump and sock. As the gas travels
towards the remote end of the stump, the pressure of sock on stump
progressively decreases but so does the pressure head behind the
flow of air, due to the resistance that has already been overcome.
In consequence, a clearance between stump and sock is maintained
and the air flowing through this clearance subjects the stump to a
pressure gradient. In effect, `A` and `B` in FIG. 6 mark the limits
of the region in which the sock acts as a gaiter on the intruding
limb, subjecting it to a pressure gradient. The leaking seal
between sock and stump over this distance is comparable to that
which existed between the intruding limb and the "stem" of the
funnel shape formed by the members of the seal 23 in FIGS. 1, 4 and
5. This region of sock 38, and the remaining part 36 of the sock to
the left-hand side of line `A,` together constitute the part of the
wall of the container that deflects so as to yield to the intrusion
of a limb.
FIGS. 8 and 9 illustrate a different construction of sock. This
modification is shown in the unstretched state in FIG. 9 and is of
resilient gas-tight material thicker at the distal end 44 than at
the proximal end 45, and having a bore 46 appropriate to stump
circumference. As with the previous form of the invention, there is
an inlet 39 at the distal end. When stump 42 is inserted, as in
FIG. 8, the greater thickness of the walls at the inner end give
rise to a clearance between stump and sock between the limits C and
D, just as the shape of the alternative sock did in FIG. 6 and
7.
In FIG. 6, 8 and 9 the containers constituted by socks 38 and 47
are surrounded by non-collapsible jackets 48 which have two inlets
49, 50 in their end walls 51. Inlet 49 is to receive pressure hose
41 for connection to inlet 39 of the sock. Inlet 50 is for
connection to a vacuum source, not shown. When this source is
energized, the parts of resilient socks 38 or 47 that act as
gaiters to the limbs within are lifted quite clear of stump 42 so
that the pressure at the surface of the stump is reduced to
atmospheric level.
By cyclically applying a vacuum and atmospheric pressure at inlet
50 the stump 42 within socks 38 or 47 is subjected alternatively to
atmospheric pressure and to a higher pressure. This cyclic
variation in pressure has a desirable vascular pumping action; the
intermittent higher pressure can tend to expel undesirable tissue
fluids.
The pulsations just described with relation to the forms of the
apparatus shown in FIGS. 6 to 9 can of course be applied to other
forms of the invention. It can be effected in the forms shown in
FIGS. 1 and 5 by simply using the pressure controller 12,
responsive to the sensor 6, to produce a desired pattern of
pressure changes within the container. FIG. 10 is a graph of
pressure P against time T and illustrates a simple regular program
of alternate pulses of equal length of uniform pressure and zero.
FIG. 11 illustrates a more complicated pattern of pulses in which a
succession of pulses of low pressure gives way gradually to a
period in which the pulses are of higher pressure but are less
frequent, and then proceeds in reverse sequence to conclude one
cycle of a pressure pattern. FIG. 12 is a graph of pressure P
against distance D and illustrates the pressure gradients that may
be created by the gaiter parts of socks 38, 47 in FIGS. 6, 8 and 9.
P.sub.o equals atmospheric pressure, and P.sub.1 equals the full
supply pressure at 39. AC represents the distal end of the gaiter,
i.e., the location of line A in FIG. 6 and line C in FIG. 8; BD
represents the proximal end of the gaiter, i.e., the location of
line B in FIG. 6 and line D in FIG. 8. Function 52 represents the
pressure distribution over the length AC or BD when vacuum is
applied at 50. Functions 53 represent four alternative pressure
distributions when atmospheric pressure is applied at 50; which of
them actually applies in a particular case will depend upon many
factors including the construction of the stock, the shape of the
limb within it, and the relative values of P.sub.o and P.sub.1. The
important thing is that all these functions maintain a positive or
zero gradient between AC and BD. If the gradient becomes negative
anywhere within this region there is danger of creating a
tourniquet effect, since fluid in some distal part of the limb
cannot travel to the main body of the patient without passing
through a region subjected to a higher pressure.
* * * * *