This invention relates to closed-system suction catheter assemblies of the kind having a suction catheter, a patient end fitting with a seal through which the forward, patient end of the catheter can be advanced and retracted, a machine end fitting attached to the rear end of the catheter, and a flexible envelope enclosing the catheter from the patient end fitting to the machine end fitting.

Suction catheter assemblies may be used to remove secretions from within a tracheal tube or the respiratory passages of a patient. They are also used in other applications. Suction catheter assemblies may be of the closed-system kind in which the catheter is enclosed within a flexible envelope. Such assemblies have a patient end fitting with a sliding seal through which a suction catheter can be advanced and withdrawn. The flexible envelope is joined at one end to the patient end fitting and encloses the catheter along its length. The other end of the envelope and the catheter are joined with a rear, machine end housing including a suction control valve and a connector. The connector connects the catheter to a suction source and the valve enables the clinician to control the suction applied by the catheter.

Examples of closed-system suction catheter assemblies are described in US5269768, US5300043, US4569344, US4638539, US4872579, US5167622, US5779687, US5325850, US5490503, US5419769, US5460613, US5349950, GB2394761, GB2400160, US6109259, US6227197, EP801577B, W096/09082, EP1239907B, EP1478424B, US6588427, EP1620148B, US2004/0221852, EP1911482A, EP1795217A, US2007/0282250, W02007/143502, US2008/0188833, US6227200, US6543451, EP1239909B, US6602219, EP 1347798, W002/49680, US6609520, WO/055143, US6805125, US6923184, US7021313, US7191782, W02004/101045, US7263997, W02004/103448, WOOO/15276, EP637257B, EP1113835B, EP1210957A, EP1237612B, US7152603, EP1267957B, US6978783, US2004/0007236, US2005/0211253, US2005/0211245, US2005/0235987, US7059322, W02004/032817, US2008/0135051, US4836199, US4850350, US4967743, US5025806, US5083561, US5220916, US5215522, US5255676, US5277177, US5309902, US5333606, US5343857, US5487381, US5513628, US5791337, EP1343552A, WO02/49699, US6612304, EP1322371A, WO02/28463, US6629530, W002/051485, US6769430, EP1330284, WO02/36191, US6886561, W02004/034946, US7188623, W02006/014431, US7341059, W02005/094925, W02006/ 103233, W02007/030388, W02009/003135, US4838255, US5107829, US5133345, US5642726, US6702789, US7458955, US7273473, US5139018, US4327723, US4515592, US6099519, EP695556B, US5065754, US5730123, US5207220, US5309903, US7086402, US7597686, US7726315, WO 11020985 and GB2468946. Closed system suction catheters are available from various manufacturers including Smiths Medical, Kimberley Clark, Covidien and Viasys.

One problem with conventional closed-system suction catheter assemblies arises from the sliding seal in the patient end fitting. The length of the suction catheter and the outer envelope are chosen so that, when the suction catheter is pulled rearwardly to its full extent, the tip of the catheter projects a short distance through the sliding seal into the patient end fitting. This has the advantage that the ensuring that the tip of the catheter is aligned with the opening in the seal and also prevents the envelope being inflated by gas pressure in the patient end fitting. Previous closed system catheter assemblies may, therefore, be manufactured and stored in this state, with the catheter extending through the sliding seal. The problem with this is that the relatively soft nature of the plastics material from which the catheter is extruded and the relatively tight interference fit exerted by the seal (needed to resist the positive pressure from the ventilator) means that the catheter is deformed by contact with the seal and takes on a permanent set in the form of a shallow indented annular groove or channel. This is unsightly and gives a poor feel as the catheter is advanced and retracted through the seal and during passage through the airway. Another disadvantage is that the indented groove weakens the tip of the catheter, which can be so severe, especially after repeated use and in small diameter catheters, that the tip of the catheter on the patient side of the groove detaches from the main part of the catheter and can enter the patient’s airway. This problem is exacerbated when the catheter is exposed to elevated temperatures such as during sterilization or storage. It is an object of the present invention to provide an alternative closed-system suction catheter assembly.

According to one aspect of the present invention there is provided a closed-system suction catheter assembly of the above-specified kind, characterised in that the seal includes a compressible member having a bore extending therethrough within which the catheter extends, that the length of the bore is greater than the external diameter of the catheter, and that the seal includes means for manually and adjustably applying force to the compressible member to compress it about the outside of the catheter in sealing engagement.

The compressible member preferably has a taper externally along a part at least of its length, the seal including a component having a recess that is tapered along a part at least of its length, a part at least of the taper along the compressible member extending along a part at least of the taper in the recess, and the means for applying force to the compressible member being arranged to apply a longitudinal force between the compressible member and the component to displace the compressible member further into the taper in the recess and thereby apply a radially inwardly directed compressive force to the compressible member to force the bore through the member closer into contact with the outside of catheter.

The means for applying force to the compressible member may include a manually rotatable screw-threaded member that engages with one end of the compressible member such that rotation of the screw-threaded member moves it longitudinally and applies a longitudinal force to the compressible member. The assembly may include a washer between the screw-threaded member and the compressible member to reduce twisting of the compressible member caused by rotation of the screw-threaded member. The means for applying force to the compressible member may include angular markings to indicate the relative angle of rotation of the screw-threaded member. The assembly may include a detent formation between the screw-threaded member and the component on which it is threaded to resist displacement of the screw-threaded member from a position where a force is applied to the compressible member. The assembly could include a substance in or on the compressible member that changes colour when the desired compression is achieved. According to another aspect of the present invention there is provided a method of providing a tracheostomy closed system suction catheter assembly having a suction catheter, a patient end fitting with a seal through which the forward, patient end of the catheter can be advanced and retracted, a machine end fitting attached with the rear end of the catheter, a flexible envelope enclosing the catheter from the patient end fitting to the machine end fitting, wherein the seal includes a compressible member having a bore extending therethrough within which the catheter extends, wherein the length of the bore is greater than the external diameter of the catheter, the seal including means for manually and adjustably applying force to the compressible member to compress it about the outside of the catheter in sealing engagement, wherein the assembly is packaged with the means for applying force in a first position where it does not apply any significant force to the compressible member and where the compressible member does not apply any significant force to the catheter, and wherein the assembly is subsequently removed from the packaging and before use the means for applying force is moved to a second position where the compressible member is compressed sufficiently for its bore to make a sliding, sealing contact with the outside of the catheter.

A closed-system suction catheter assembly according to the present invention will now be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a side elevation view of the assembly;

Figure 2 is an enlarged sectional perspective view of the patient end of the assembly with the wiper seal open; and

Figure 3 is an enlarged sectional side elevation view of the patient end of the assembly with the wiper seal compressed.

With reference first to Figures 1 and 2, the assembly has a rear, machine end fitting 1 with a ribbed, tapered male coupling 2 at its rear end adapted to receive one end of suction tubing 3 fitted on the coupling. Other forms of suction coupling are also available. The machine end fitting 1 includes some form of valve 4 that the user can actuate to control suction applied to the machine end of a flexible, plastics suction catheter 5, which is fixed with the forward end of the machine end fitting. The catheter 5 extends forwardly to a patient end fitting 10. The catheter 5 is enclosed along its length between the machine end fitting 1 and the patient end fitting 10 within a flexible plastics envelope or sleeve 11 fixed at opposite ends to the forward end of the machine end fitting and to the rear end of the patient end fitting respectively.

In use, the patient end fitting 10 assembly is connected to the machine end of a tracheal tube 12 or other airway and the catheter 5 is manipulated through the envelope 11 to advance it forwardly through the patient end fitting and down the bore of the tracheal tube. The patient end fitting 10 is usually connected to the tracheal tube 12 via a manifold 13 of cruciform shape with four arms 14 to 17. Two arms 14 and 15 are axially aligned with one another and are formed with female-tapered openings 14’ and 15’ adapted to receive a male- tapered coupling 18 on the machine end of the tracheal tube 12 and the patient end of the fitting 10, which is provided with a male-tapered surface 19. Other forms of conventional coupling between the tracheal tube and the manifold could be used. The other two arms 16 and 17 of the manifold 13 project in opposite directions at right angles to the arms 14 and 15. These two arms 16 and 17 may be connected to opposite limbs of a dual-limb breathing circuit (not shown) or one may be capped and the other arm connected to a single-limb breathing circuit. Where the patient is breathing spontaneously one arm would be capped and the other open to atmosphere, such as via an HME or filter.

As so far described the assembly is conventional.

The suction catheter assembly of the present invention differs from previous assemblies in the manner by which a seal is made with the outside of the suction catheter 5. Instead of the conventional narrow wiper seal that makes a relatively tight sliding fit with the outside of the catheter in the present arrangement the seal is made in an adjustable manner and along an extended length along the catheter 5. More particularly, the patient end fitting 10 includes a forward, patient end component 100 and a rear, machine-end unit or screw-threaded member 101. The patient end component 100 is moulded from relatively rigid, transparent plastics materials. Its patient end 102 is tubular and tapers slightly externally to provide the male tapered surface 19 that is received in the opening 15’ of the manifold 13. At its tip, the patient end 102 tapers more steeply to form a reduced diameter opening 103 that makes a close sliding fit with the outside of the catheter 5 when this is extended through the opening. Approximately midway along the patient end fitting 10 an irrigation port 105 projects radially outwardly by which irrigation fluid can be introduced to a forward cavity 6 in the fitting to wash the tip of the catheter 5. The port 105 is coupled to a short irrigation line 106 terminated by a valved or capped connector 107 arranged to receive the nose of a syringe or other source of irrigation liquid (not shown). The rear, machine end 108 of the patient end fitting 10 has a screw formation 109 on its outer surface and a tapered recess 110 on its inner surface.

The machine end unit 101 of the patient end fitting 10 comprises an outer component in the form of a sleeve 112 and an inner washer 113, both being moulded of relatively hard plastics materials and being of generally tubular form. The outer sleeve 112 is of a clear, hard transparent material and has, at its forward end, an internal screw thread 114 threadingly engaged with the external thread 109 on the rear of the patient end component 100. The outer surface of the sleeve 112 may be moulded with formations such as ribs or knurls or other projections (not shown) to assist manual gripping and rotation of the sleeve. The sleeve 112 also includes a wall 116 at its rear end having a central opening 117 that allows free, loose passage of the catheter 5. A disc-shape washer 113 of a hard, low-friction plastics material is housed in the rear end of the sleeve 112 and is trapped between the inside surface of the wall 116 and a rear end face 131 of a compressible member 130. The washer 113 is free to rotate relative to the sleeve 113.

The sleeve 112 and the patient end component 100 may have angular markings to indicate the relative angle of rotation between the two components and thereby indicate when the compression member 130 is in an open state or in a compressed state. The sleeve 112 and patient end component 100 may be provided with detent or stop formations that engage when the sleeve is tightened to a compressing position. These formations could be arranged such that the sleeve could not be twisted back to its original position after being tightened to the compressing position. Alternatively, or additionally, some means could be provided for indicating the extent of compression of the compression member, such as by including a piezochromic or other substance in or on the compression member that changes colour when the desired compression is achieved.

The compressible member 130 of an elastomeric material and is preferably transparent. The compressible member 130 has an axial bore 132 extending along its entire length, the diameter of the bore, in the natural, uncompressed state of the member, being sufficient to receive the catheter 5 therethrough as a loose sliding fit. The length of the bore 132 is greater than the external diameter of the catheter 5 and is typically about three times its diameter. The outer surface 134 of the compression member 130 is tapered from its patient end along most of its length. The forward and rear end surfaces 133 and 131 of the compressible member 130 are flat and smooth.

After manufacture the assembly is set in an initial state with the patient end tip of the catheter 5 is located forwardly of the compressible member 130 in the cavity 6, such as shown in Figure 2 with the sleeve 112 is in a rearward location along the patient end component 100 so that no significant pressure is applied to the compressible member 130 and the catheter 5 is free to be manipulated along the patient end fitting 10. In this state the outer surface of the catheter 5 is not subjected to any pressure from the compressible member 130. The assembly is packaged and stored in this state. When the assembly is to be used it is removed from packaging (not shown) and the clinician rotates the sleeve 112 of the patient end fitting 10 so that its screw-thread 114 and the thread 109 on the patient end component 100 cause it to be displaced forwardly relative to the patient end component. Engagement of the rear end wall 116 with the rear face 113’ of the washer 113 causes this to be moved forwardly but without rotation. The nature of the materials used for the washer 113 and the sleeve 112 are selected to reduce friction between the two components. In this way, when the sleeve 112 is manually and adjustably tightened there is little risk that the compression member 130 will be twisted. The forward end face of the washer 113 thereby applies pressure to the rear end face 131 of the compressible member 130 and causes it to be pushed further into the taper 110 at the rear end of the patient end component 100. This causes the compression member 130 to be compressed radially inwardly and its bore 132 thereby to reduce in diameter as shown in Figure 3. The result of this is that the compression member 130 is squeezed about the outside of the catheter 5 along the length of the bore 132 forming an elongated wiper seal along the bore and along a length about three times the diameter of the catheter 5. The seal is sufficient to prevent air leaking past the seal into the envelope 11 but still allows the catheter 5 to be advanced and retracted by sliding through the seal.

Although the catheter 5 is engaged by the compression member 130 during use it need not be engaged during storage, which can be for months or years. Also, the seal contact with the catheter 5 is spread out along the catheter and is not localised as in conventional wiper seals, thereby distributing the loading and reducing the risk of damage to the catheter.

Instead of using a screw sleeve and taper to compress the compression member about the catheter other arrangements could be used such as an outer sleeve slidable longitudinally along an inner sleeve and engaged by a ratchet mechanism. Alternatively, a band embracing the compression member and a cam lever could be used to tighten the band. The present invention can be applied to various different forms of suction catheter assembly, such as those having a dual-lumen catheter and those having provision for irrigation in the patient end fitting. The invention is not limited to suction catheter assemblies for use with tracheal tubes but could be used with other tubes requiring suction.