Note: Descriptions are shown in the official language in which they were submitted.
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IRRIGATION OF A HOLLOW BODY
The invention relates to irrigation of a body, say wound/surgical
irrigation or irrigation of a hollow internal body organ, particularly a
bladder of a patient, and includes a catheter, method and system
for such irrigation, which term it is to be understood includes
washout of debris from the bladder being irrigated.
Bladder washout and irrigation is often used for the removal of
debris from a bladder, in order to ameliorate the effects of build up
of such debris, stone formation and encrustation, which can lead
to blockage.
Catheterisation is used in the management of urinary dysfunction
in a large number of patients. About 4% of the community nursing
caseload is attributed to patients undergoing long-term
catheterisation (LTC) and about 10% of patients admitted to
hospitals will have a urinary catheter inserted. Applications of
urinary catheterisation are varied with reasons for short-term
catheterisation (STC) including post-operative urinary drainage,
monitoring of urinary output during acute illness and relief of
urinary retention. LTC is considered in the management of long
term urinary dysfunction such as intractable urinary incontinence,
neurological disorders or bladder outlet obstruction.
Complications associated with LTC are common and include
discomfort, infection, leakage of urine, trauma and catheter
blockage, encrustation and blockage and stone formation.
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Supra pubic catheterisation appears to ameliorate some of the
complications associated with urethral catheterisation including
infection. The problems of build up of debris, formation of stones
and of (catheter) encrustation leading to blockage however remain.
The most common cause of catheter blockage is the development
of encrustations within the catheter lumen. Encrustation and
stones are composed of a range of materials including struvite; the
densest major constituent of stones is brushite (density 2500
kg/m3) .
Bladder washout and irrigation has been practised, particularly via
a urethral catheter. A bladder washout usually involves delivering a
given volume of washout solution into the bladder via a catheter,
often by means of a solution bag or syringe connected to a
catheter, with the bladder subsequently having the liquid drawn
out or allowing the solution and debris to drain out into a bag.
Bladder irrigation consists of simultaneous delivery and drainage
into and out from the bladder. Within these two definitions,
(irrigation and washout) there can be a wide range of flow rates.
Irrigation is currently used in the belief that it clears blood and light
debris from the bladder following surgical procedures.
Existing practice in the management of encrustation and blockage
relies to a certain extent on bladder washout or changing of the
catheter, though diet, fluid intake etc. are also relevant. Despite
regular bladder washouts being used with 40% of LTC patients, it
has been found that such washouts do not remove debris
efficiently from the bladder. Surgical irrigation at higher flow rates
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are also used to remove debris, including small stones, from the
bladder although stones often grow to a size which necessitates
removal by endoscopic or surgical procedures. Potential risks
associated with the use of bladder washouts include trauma to the
bladder mucosa.
It is accordingly an object of the invention to seek to mitigate the
aforementioned disadvantages of prior irrigation and washout
procedures.
According to a first aspect of the invention, there is provided a
catheter for irrigating an internal hollow body organ with an
irrigant, comprising a lumen for entry of an irrigant, and a lumen
for exit of irrigant and debris from the organ.
According to a second aspect of the invention, there is provided a
method of irrigating a hollow internal body organ, comprising the
steps of inserting a catheter into the organ, positioning the distal
end of the catheter a desired distance from the interior boundary
wall of the organ, passing irrigant from a source thereof along one
lumen of the catheter for entry into the organ, and exiting irrigant
and debris from the bladder along the other lumen.
The irrigant may be passed under gravity into the organ.
Alternatively, the irrigant may be passed into the organ by a
suitable device such as a pump.
According to a third aspect of the invention, there is provided a
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system for irrigating a hollow internal body organ, comprising a
catheter and a source of irrigant.
The lumens may have an orifice at a distal end of the catheter.
This provides for ease and efficiency of use.
The orifice may consist of an open distal end of the one lumen at a
distal end of the catheter. This provides a relatively simple
construction.
There may be an orifice spaced from the distal end giving into the
other lumen, and the orifices of the respective lumens may be
closely adjacent one another. This provides for efficiency of entry
and exit of irrigant.
The one lumen may be a lumen adapted to provide entry of irrigant
to or exit from the organ.
This provides for a relatively simple construction which is
nevertheless flexible in providing for entry or exit as desired.
The other lumen may be a lumen adapted to provide exit of irrigant
from or entry thereof to the organ. This again provides for
flexibility in use.
The two lumens may be substantially parallel with their respective
orifices being defined by an open distal end of the catheter. This is
a relatively simple construction, particularly if the two lumens may
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be coaxial.
The two lumens may alternatively be longitudinally axially offset.
The orifice spaced from the distal end may comprise a plurality of
orifices spaced longitudinally of the catheter and giving into one or
the other lumen.
This provides for a relative unobstructed flow of fluid irrigant.
The orifices may be at substantially 90 ° to the length of the
catheter, or alternatively the orifices may be at about 60 ° to the
length of the catheter.
When inclined, the orifice may be directed into the catheter at an
angle towards the distal end thereof.
There may be a space for spacing the distal end of the catheter
from a wall of the internal organ in use. This provides for efficient
removal of irrigant and debris, and prevents the bladder mucosa
from being sucked into the drainage orifices.
The spacer may comprise an extension of a boundary wall of the
catheter. This is a relatively simple construction, as is an
alternative where the spacer may comprise a separate spacer
element adapted to be mounted on the distal end of the catheter.
The catheter may be made integrally in one piece.
In the method, the angle of entry of the irrigant towards debris in
the organ may be in the range 0 ° to 25 ° from the vertical.
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The distance of the orifice of the other lumen may be 0 --- 20mm
from the debris. This provides for efficient washout.
The distance may be about 8mm.
The entry flow rate of irrigant may be up to about 650 ml/min,
suitably about 150 ml/min. This again provides for an efficient
method.
In the system, the source of irrigant may be connected to the
entry lumen.
A catheter, method and system for irrigation of a hollow internal
body organ are hereinafter described, by way of example, with
reference to the accompanying drawings.
Fig. 1 is a perspective view of a catheter according to the
invention;
Fig. 1 A is an enlarged view of the distal end of the catheter of Fig.
1;
Fig. 2 is a yet further enlarged end elevational view of the distal
end of the catheter of Figs. 1 and 1 A;
Figs. 3(a) and 3(b), 4(a) and 4(b), 5(a) and 5(b) and 6(a) and 6(b)
respectively show schematically to a smaller scale four different
embodiments of catheter according to the invention, the (a) Figs,
showing one system of flow through a particular embodiment and
the (b) Figs, showing a second system of flow through a particular
embodiment of catheter;
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Fig. 7 shows a model of a bladder irrigation system according to
the invention;
Figs. 7(a) and 7(b) show variations in use of the system;
Fig. 8 shows the percentage of debris removed (y) (averaged over
2 tests) as a function of time (t) for irrigation tubes 3(a)-6(b) - held
vertically 5mm from the floor of bladder system A. The flow rate
was 150 ml/min;
Fig. 9 shows the percentage of debris removed (y) as a function of
time (t) for tubes 3(a) - 6(b) - held vertically 5mm from the floor of
bladder system B. The flow rate was 150 ml/min;
Fig. 10 shows the percentage of debris removed (y) from model A
after 4 min as a function distance of the tip of tube 1 (a) from the
floor of bladder system X. The flow rate was 150 ml/min;
Fig. 1 1 shows the percentage of the debris removed (y) from
model A after 4 min as a function of angle of attack (~). The flow
rate was 150 ml/min.
Fig. 12 shows the percentage of debris removed (y) from model A
after 4 min as a function of angle/misalignment O. The flow rate
was 150 ml/min;
Fig. 13 shows the percentage of debris removed (y) from model A
with tube 1 (a) after 4 min as a function of the flow rate (x); and
Fig. 14 shows a photograph of irrigation/washout in progress,
showing region of fluidised particles close to the distal end of the
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catheter.
Referring to the drawings, there is shown a catheter 1 for irrigating
an internal hollow body organ with an irrigant, comprising a lumen
2 for entry of an irrigant, and a lumen 3 for exit of an irrigant and
debris 4 (Fig. 14) from the organ. The catheter 1 shown in the
drawings is a dual lumen catheter, in other words there are only
two lumens, one of the lumens having an orifice 5 at a distal end 6
of the catheter which consists of an open distal end of the one
lumen at the distal end of the catheter. The other lumen 3 also has
an orifice giving into it, the orifices 5, 7 of the respective lumens
2, 3 being closely adjacent one another.
It is important to note that in all embodiments the one lumen 2 can
be used for entry of irrigant into the hollow body organ, in the
embodiments a bladder, or for exit therefrom of irrigant and debris,
and that the other lumen 3 can be used vice versa, depending on
the role of the one lumen.
Stated in another way, the one lumen can be used for entry of
irrigant or exit of irrigant and debris from the bladder, and the
other lumen can be used for exit of irrigant and debris from the
bladder or entry of irrigant thereto for irrigation and washout. The
respective flows are indicated by I, for entry and R for exit and
washout in the Figs.
Fig. 1 and 1 A and 2 show a typical embodiment, formed integrally
of polymeric or other suitable material such as stainless steel by a
suitable forming process such as moulding and/or extrusion or the
like. The catheter 1 is a dual or bi-lumen catheter having a large
diameter lumen 3 for exit of irrigant and debris for washout and a
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smaller one lumen 2 for entry of irrigant. The catheter 1 has a
handle or finger grip 8 with inlet 9 and outlet 10 ports at a position
remote from the distal end, for connection with a bladder
management system. The exit from the lumen 2 is a cut-off part or
open orifice at the distal end, as is the entry to the lumen 3 for
exit of irrigation and debris, passage into the lumen being
enhanced by the provision of through bores or eyelets 1 1. In a
preferred embodiment the area of the lumen 2 IS 2.85mm2 and
that of the lumen 3 8.095mm2.
Figs. 3(a) - 6(b) show embodiments either of bi- or dual-lumen
catheters, 30, 40, 50, 60 for use in, and according to, the
invention. In Figs. 3(a) and 3(b), the two lumens 2, 3 are coaxial,
with the entry and exit being formed by a cut-off open end of the
catheter.
In Figs. 4(a) and 4(b), the lumen 2 is open to the bladder at the
distal end, to provide an entry (Fig. 4(a)) or exit (Fig. 4(b)), while
passage into or out of the lumen is by spaced through orifices 41
the axis of which are substantially at right angles to the
longitudinal axis of the catheter.
In Figs. 5(a), 5(b), 6(a) and 6(b), the respective passage into or out
of the lumen 3 is by through orifices 51, 61 which are inclined at
an angle to the longitudinal axis of the catheter 50. The angle of
inclination is at about 60 ° to the longitudinal axis of the catheter.
The distance 'S' between the centres of the orifices in Figs. 4(a)
and 4(b) is 1 Omm. In the embodiment, the length 'x', Fig. 1, is
130mm.
Turning now to Figs. 7, 7(a) and 7(b), these show an experimental
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apparatus 70 simulating a bladder irrigation and washout system
embodying the invention. A spherical transparent flask 71
represents the bladder, to enable visual observation of the
disturbance of the debris 4, shown in Fig 14. Only one apparatus
is shown, but in experiments, two sizes of flask 71 were used,
one, model A, being 80mm in diameter (about 270 ml in volume)
and in model B the flask being 60mm in diameter, (about 1 10 ml in
volume). In model A, (shown in Figs. 7, 7(a) and 7(b)), the flask
71 had one central 72 and two oblique ports 73, 74 the central
port 72 being used for a tube 75, simulating the catheter in having
two lumens, one of the oblique ports 74 being blanked off. In
model B (not shown) the flask had only one oblique port in
addition to the central port.
For both models, the oblique port 73 was used to house a
calibrated pressure transducer 76 (0 - 0.35 bar gauge), in order to
monitor internal bladder pressure during experiments. Thus the
general arrangement is shown in Fig. 7. For both flasks 71, tap
water was used as the fluid medium or irrigant since its density
(993 kg/m 3 at 37 ° C) does not differ significantly from that of
urine (1016 to 1022 kg/m3). Flow rate through the irrigation tube
75 and into the flask, or bladder model 71, was controlled by
pressure head and a choke (adjustable constriction) and was
monitored by a suitable flow meter. A standard irrigation bag was
used as the reservoir for the irrigant. A pressure head of
approximately 1.6m of water was used to obtain the volume flow
rates required, the change in the pressure head during tests
(approximately 60mm of water) was therefore small in proportion;
this ensured that flow rate remained essentially constant, to within
3%, during each test.
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The irrigant fluid, and any suspended particles, on the out-flow
side of the irrigation tube, was directed onto a piece of filter paper
in one of 3 vacuum assisted filter funnels 77 (Fig. 7). All tests
were performed at room temperature (between 18 and 24°C). In
some tests the flask was immersed in a rectangular perspex tank
containing water to eliminate optical distortion.
The irrigation tube embodiments of Figs. 3(a) - 6(b) were tested.
All consist of a stainless steel outer tube with an internal diameter
(i.d.) of 5.84mm, and a coaxial stainless steel inner tube with an
i.d. of 3.2 mm, with both tubes having wall thicknesses of 0.5
mm. The inner and outer tubes were brazed together at the "T"
configuration end. For each embodiment, the inner tube was used
(a) for in-flow 'I' and (b) for out-flow 'R'. A test as a control, was
a proprietary 3-way continuous irrigation 20 Ch catheter (Rusch
Simplastic) made from PVC. Glass beads 0.212 - 0.300 mm in
diameter and density of 2500 kg/m3 were used to simulate hard
dense debris in the bladder. The collection system comprised 3
vacuum assisted filter funnels (one is shown in Fig. 7), used
sequentially with Whatman grade 1 filter paper (qualitative,
medium fast).
For each test the model bladder 71 was filled with water, 5 gm of
dry glass beads were then added. The irrigation/washout tube and
model bladder were then positioned and oriented as required. Flow
of the irrigation fluid under gravity was started by opening a valve
(not shown) and continued for a maximum of 12 minutes. The
outflow 'R' from the model bladder 71 was redirected to a
different filter funnel at 4 minute intervals so that all 3 receptacles
were used over the 12 minute (maximum) duration of a run.
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After each test the model bladder 71 was emptied and thoroughly
rinsed to remove all glass beads. The three filter papers were
removed from the funnels to be oven dried at 150 ° C for 30
minutes with the mass of irrigated, dried, glass beads
subsequently determined. (Preliminary tests indicated that constant
weight was achieved within a drying period of 30 minutes).
The following experiments were carried out.
(i) Tests of 12 minutes' duration performed to determine which
tube designs were effective in debris removal from bladder
model A and B. Each of the 5 irrigation/washout tubes or
catheters were held vertically with the distal end or tip 5 mm
from the floor of the bladder model.
Subsequent tests were performed to investigate the effect
of:
(ii) altering the proximity of the tube tip to the floor of the
bladder. Distances in the range 5 - 10 mm were studied;
(iii) directing the tube at an angle of attack (~) at the debris (Fig.
9):
(iv) tilting the bladder model and tube through angles (O) from
the vertical to give a combined angle of attack and offset
(Fig. 7(b)); and
(v) different flow rates.
[Unless otherwise stated the tube of Fig. 3(a) was used held
vertically and directed at the debris at a distance of 5 mm from the
flow of bladder model A and 150 ml/min over a duration of 4
minutes].
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The pressure within the bladder model was found to be within --
0.01 bar (1 kPa) of atmospheric pressure during initial tests on the
tubes of Figs. 3(a) - 6(b) (performed at flow rates of 150 ml/min);
these pressures were judged to be too small to justify recording in
subsequent tests. Flow rates were found not to vary by more than
-~-3% during the course of the initial tests; these variations were
judged to be acceptably low.
In test (i) the performances of different tube designs were
compared (Figs. 8, 9, 10 and 1 1 ). Two runs were performed for
each tube for model A; significant debris removal was achieved for
the tubes 3(a) [87%, 91 %], 3(b) [45%, 59%], and 4(b) [13%,
12%]. In all cases the major part of debris removal occurred in the
first 4 minutes; other tubes removed less than 5% of debris over
the 12 minute test duration (Fig. 8). Comparison of the removal
rates for model A and B indicated that, within the range tested,
bladder size exerted little or no effect.
The removal rates achieved for the tube of Fig. 3(a) were much
higher and more reproducible than those achieved for other
designs; the tube of Fig. 3(a) was hence used exclusively for
subsequent tests.
The results of test (ii) indicated high removal rates (about 80%
after 4 min) provided that the tube was within 8 mm of the floor of
the bladder model (Fig. 8). For distances larger than 8 mm there
was a sharp diminution of effectiveness with the removal falling to
less than 20% for a distance of 10mm. Visual observation and
photography strongly suggested that the dependence of debris
removal with distance occurred because there was a local volume
of high debris-particle velocity ("fluidised" region) - which
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extended upwards by - 8 mm - caused by interactions of the in-
flow jet, the bladder model wall and the glass beads (Fig. 14). The
fluidised particle region was observed for tubes of Figs. 3(a), 4(a),
5(a) and 6(a) and for tubes 3(b) and 4(b) but did not occur with
other tubes. That tubes 1 and 2 gave high removal rates and that
tube 4(b) performed better than 4(a) support the view that
presence of the outflow tube in the fluidised particle region was a
key factor in effective debris removal. It was also found that debris
removal rates were relatively insensitive to angle [~, in test (iii]
and combined angle and misalignment [O, in test (iv] for values up
to ~ 25 ° and 20 ° respectively (Figs. 1 1 and 12). It should be
noted that an angle O of 20 ° corresponded to a misalignment of
14 mm and an additional vertical distance of 2mm from the debris,
the reduction in effectiveness of debris removal for O > 20 ° may
therefore have been due in part to inclination and change in
vertical distance from the debris misalignment and not simply
inclination.
Finally, the results of test (v) indicated that debris removal
increased rapidly with increasing flow rate up to 150 ml/min;
thereafter removal was essentially unaffected by flow rate up to a
rate of 650 ml/min (the maximum rate used, Fig. 13).
Although the flow rates (typically 150 ml/min) used in the
experiments are relatively large in comparison with those currently
used in irrigation procedures, preliminary studies have indicated
that they are much lower than the maximum and average flow
rates typically occurring during bladder washouts (1 180 ~250
ml/min and 540 ~ 200 ml/min respectively, average ~ SD)
measured and recorded on an ural flowmeter for 8 subjects. It is
also notable that for the designs of irrigation tube studied (tubes 1
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- 4) flows --- 150 ml/min were delivered without any appreciable
hydrostatic overpressure occurring in the bladder model.
Furthermore, an upper limit can be set, for tube 1 (a) to the normal
stress (Q) occurring, due to the in-flow jet of irrigation fluid, on the
bladder model's floor; for a flow rate of 150 ml/min the inequality
a < 0.5p2 (where p is the density of water and v the average
velocity in the in-flow tube) gives a o of 50 Pa or less.
The experiments show that a region of fluidised debris is close to
where a jet of incoming irrigant strikes the floor of the bladder
model, and when the outflow area of the irrigation tube was within
the fluidised region, high rates of debris removal occurred /Fig.
14). In contrast, debris removal was poor when the outflow tube
was not within the fluidised region. Thus for steady flow debris
washout catheters, the exit of the inlet lumen into the catheter and
the entrance of the outlet lumen should be in close proximity to
one another. Moreover, provided the jet of incoming irrigant fluid is
directed towards the settled debris, angles of up to ---25° from the
vertical should give acceptably high removal rates.
In all embodiments, to ensure that the distal end of the catheter 1
is spaced from the wall of the bladder the optimum distance for
irrigation and washout, so that the outlet lumen is in the
"fluidised" debris 4 caused by the impingement thereon of the
incoming irrigant jet, the distal end of the catheter may have a
spacer device or means, which can be an extension of the catheter
per se, by being for example a curved part of the end formed by
cutting say a semi-circular part away, or there may be a separate
spacer which can be removably mounted on the distal end before
an irrigation and washout procedure commences.
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In all embodiments, the procedure described is conducted under
gravity. However, it will be understood that a suitable device such
as a pump may be used instead of relying on gravity alone. It is
intended that existing washout/irrigation solutions can be used in
conjunction with the catheters and/or systems described herein.
Also, in all embodiments, it will be understood that the ratio of the
diameter of the lumens is such as to optimise removal of debris
from the bladder.
It will be understood that the invention hereinafter described with
reference to the drawings can find other applications, for example
the cleaning out of bodies such as storage tanks, swimming pools,
vats or bodies which contain a fluid and the interiors of which are
relatively inaccessible for cleaning.
