WO2001037916A1

WO2001037916A1 - Irrigation of a hollow body

Info

Publication number: WO2001037916A1
Application number: PCT/GB2000/004490
Authority: WO
Inventors: Max Woolley; Ackerman; Vince Coveney
Original assignee: Ssl International Plc
Priority date: 1999-11-25
Filing date: 2000-11-24
Publication date: 2001-05-31
Also published as: HUP0203546A2; EP1231970A1; GB9927898D0; AU1536701A; CN1399569A; JP2003514632A; CA2392377A1

Abstract

The invention relates to 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 irrigant and debris (4) from the organ.

Description

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. Suprapubic 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 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 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 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. 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; 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 1 50 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 1 50 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 (ø). The flow rate was 1 50 ml/min.

Fig. 1 2 shows the percentage of debris removed (y) from model A after 4 min as a function of angle/misalignment θ. 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 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 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 10mm. In the embodiment, the length 'x', Fig. 1 , is 130mm.

Turning now to Figs. 7, 7(a) and 7(b), these show an experimental 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. 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 1 8 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 0.21 2 - 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 1 2 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. 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 1 2 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 (ø) at the debris (Fig.

9); (iv) tilting the bladder model and tube through angles (θ) 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 1 50 ml/min over a duration of 4 minutes]. 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 1 50 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%, 1 2%]. 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 1 2 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 extended upwards by ~ 8 mm - caused by interactions of the inflow 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 [ø, in test (iii] and combined angle and misalignment [θ, in test (iv] for values up to - 25 ° and 20 ° respectively (Figs. 1 1 and 12). It should be noted that an angle θ 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 θ > 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 1 50 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 1 50 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 1 80 ± 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 - 4) flows ~ 1 50 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 (σ) 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 σ < 0.5/3² (where p is the density of water and v the average velocity in the in-flow tube) gives a σ 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. 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.

Claims

1 . 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.

2. A catheter according to Claim 1 , one of the lumens having an orifice at a distal end of the catheter.

3. A catheter according to Claim 2, the orifice consisting of an open distal end of the one lumen at a distal end of the catheter.

4. A catheter according to Claim 2 or Claim 3, there being an orifice spaced from the distal end giving into the other lumen, the orifices of the respective lumens being closely adjacent one another.

5. A catheter according to Claim 4, the one lumen being a lumen adapted to provide entry of irrigant to or exit from the organ.

6. A catheter according to Claim 4, the other lumen being a lumen adapted to provide exit of irrigant from or entry thereof to the organ.

7. A catheter according to Claim 5 or Claim 6, the two lumens being substantially parallel with their respective orifices being defined by one open distal end of the catheter.

8. A catheter according to Claim 7, the two lumens being coaxial.

9. A catheter according to Claim 7, the two lumens being longitudinally axially offset.

10. A catheter according to either Claim 8 or Claim 9, the orifice spaced from the distal end comprising a plurality of orifices spaced longitudinally of the catheter and giving into one or the other lumen.

1 1 . A catheter according to Claim 10, the orifices being at substantially 90 ° to the length of the catheter.

1 2. A catheter according to Claim 10, the orifices being at about 60 ° to the length of the catheter.

13. A catheter according to Claim 12, the orifice being directed into the catheter at an angle towards the distal end thereof.

14. A catheter according to any preceding claim, comprising a spacer for spacing the distal end of the catheter from a wall of the internal organ in use.

1 5. A catheter according to Claim 14, the spacer comprising an extension of a boundary wall of the catheter.

16. A catheter according to Claim 14, the spacer comprising a separate spacer element adapted to be mounted on the distal end of the catheter.

17. A catheter according to any preceding claim, made integrally in one piece.

1 8. A method of irrigating a hollow internal body organ, comprising the steps of inserting a catheter according to any preceding claim 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.

1 9. A method according to Claim 1 8, the irrigant being passed under gravity into the organ.

20. A method according to Claim 1 9, the angle of entry of the irrigant towards debris in the organ is in the range 0 to 25 ° from the vertical.

21 . A method according to Claim 20, the distance of the orifice of the other lumen being 0 — 20 mm from the debris.

22. A method according to Claim 21 , the distance being about 10mm or less.

23. A method according to any of Claims 1 8 to 22, the entry flow rate of irrigant being up to about 650 ml/min.

24. A method according to Claim 23, the said flow rate being about 150 ml/min.

25. A system for irrigating a hollow internal body organ, comprising a catheter according to any of Claims 1 to 17, and a source of irrigant.

26. A system according to Claim 25, the source being connected to the entry lumen.