WO2008029109A1

WO2008029109A1 - Pneumothorax treatment apparatus and methods

Info

Publication number: WO2008029109A1
Application number: PCT/GB2007/003321
Authority: WO
Inventors: Jonathan Peter Hughes
Original assignee: Smiths Group Plc
Priority date: 2006-09-05
Filing date: 2007-09-05
Publication date: 2008-03-13
Also published as: GB0617505D0

Abstract

Apparatus for treating pneumothorax comprises a catheter (1, 101, 201) and a needle (12, 212) with a pointed tip (15, 215) removably received in the catheter. The catheter has a planar mount (3, 8) with an adhesive surface (9) or suture holes (8', 108') by which the catheter can be secured to the patient. A thumb pad 14 at the upper end of the needle (12, 212) enables pressure to be applied during insertion. The apparatus may include a visual or audible indicator (232, 237, 30, 35, 38, 39, 49', 50, 54, 57, 62, 66, 70, 73, 77, 80, 86) to indicate correct placement of the apparatus. A one-way valve (121) may be attached with the catheter (1, 101, 201) after removal of the needle (12, 212) to allow air to escape from the pleural cavity without allowing air to flow into the cavity via the apparatus.

Description

PNEUMOTHORAX TREATMENT APPARATUS AND METHODS

This invention relates to pneumothorax apparatus of the kind including a catheter and a needle removably received in the catheter and having a pointed tip projecting at the forward, patient end of the catheter.

Tension pneumothorax is a condition where air is trapped in the pleural space between the inside of the chest wall and the outside of the lungs. It is usually caused when damage to lung tissue forms a passage through the tissue into the pleural cavity that acts as a one-way valve. This allows air to move into the pleural space but prevents the air returning to the lungs. With each breath the lungs collapse progressively and the free air in the pleural cavity increases in pressure causing the heart and mediastinal structures to be pushed to one side. This restricts venous flow to the heart, the airway becomes compromised and, if untreated, can lead to rapid death.

The conventional way of treating pneumothorax in an emergency is by needle thoracentesis. In this technique a 14-gauge over-the-needle intravenous catheter is pushed through the chest wall into the intercostal space to allow the trapped air to be released. Correct insertion is determined by listening for the escape of air through the needle. The needle is then removed and some form of one-way valve is attached to the catheter to permit air to escape but to prevent air flowing back into the pleural space via the catheter. This provides temporary relief until a chest tube can be inserted.

Because the needle-catheter used to perform the pneumothorax is not specifically intended for this purpose it can be difficult to use reliably and to retain and seal after insertion. The cannula is too short and, because it is not designed for the forces involved, it tends to kink. The cannula is also prone to becoming occluded by blood or tissue. The needle used may lacerate lung tissue. The device often becomes dislodged and falls out of place. The device is difficult and inconvenient to use especially with a diagnostic syringe. The device does not sit flush on the patients body and often is bent over itself, blocking flow and rendering it useless. Furthermore, it is difficult to know when the device is working, or how much air is coming out because the user is meant to listen for a hiss of air, which is often impossible in a noisy environment.

It is an object of the present invention to provide alternative apparatus and methods for the treatment of pneumothorax.

According to one aspect of the present invention there is provided pneumothorax apparatus of the above-specified kind, characterised in that the apparatus includes a mount arrangement attached with the catheter towards its rear end, that the mount arrangement extends substantially radially of the catheter and is arranged to be secured with the skin around the insertion site of the catheter, and that the apparatus includes a removable insertion member fitted on the rear end of the apparatus, the insertion member providing a generally laterally- extending surface by which the apparatus can be pushed through the chest wall.

Preferably the apparatus includes an indicator mounted with the rear end of the apparatus and responsive to flow of gas along the needle on penetration of the pleural space. The indicator may be selected from a group comprising a carbon dioxide indicator, an inflatable device, a transparent container of liquid through which bubbles can flow, a displaceable flag member, an acoustic device, an electrical indicator, a flow meter and a container of a powder that is released by gas flow through the container. The indicator may be removable after determination of correct location. The apparatus preferably includes a one-way valve securable with the apparatus after removal of the needle to permit gas to flow outwardly from the rear end of the catheter but substantially to prevent gas flow in the opposite direction. The mount arrangement is preferably has an adhesive surface arranged to be secured to the skin and or alternatively suture formations by which the mount arrangement can be sutured to the skin.

According to another aspect of the present invention there is provided pneumothorax apparatus, characterised in that the apparatus includes an elongate member and a resilient member arranged to urge the elongate member along the bore of the needle such that the forward end of the elongate member projects from the tip of the needle in its natural state, is displaced rearwardly during insertion through tissue and is displaced forwardly on penetration of the pleural space such as to protrude beyond the tip of the needle and protect lung tissue from damage by the needle.

The rear end of the elongate member is preferably visible at the rear end of the apparatus to provide an indication of penetration of the pleural space.

According to another aspect of the present invention there is provided a method of treating pneumothorax including the steps of: inserting the forward end of a catheter and needle assembly through the chest wall into the pleural cavity, monitoring an indicator at the rear end of the assembly, removing the needle from the catheter when the indicator indicates that the pleural cavity has been penetrated, securing a mount attached with the catheter to the skin around the insertion site and attaching a one-way valve to the rear end of the catheter to allow gas to flow outwardly from the rear end of the catheter but substantially to prevent gas flow in the opposite direction. Pneumothorax apparatus and its method of use, according to the present invention, will described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a first form of the apparatus;

Figure 2 is an exploded view of the apparatus in Figure 1;

Figure 3 is a perspective view of the apparatus of Figure 1 with the needle and thumb pad removed;

Figure 4 is a perspective view of a modified apparatus after removal of the needle and attachment of a valve;

Figure 5 is an exploded view of the apparatus shown in Figure 4;

Figure 6 is a perspective view of an alternative form of the apparatus;

Figure 7 is an exploded view of the apparatus of Figure 6;

Figures 8A and 8B show an alternative, inflatable indicator;

Figure 9A and 9B show another inflatable indicator;

Figure 10 shows an indicator where gas bubbles through a liquid;

Figure 11 shows another indicator where gas bubbles through a liquid;

Figures 12A and 12B show an indicator with a rotating flag;

Figures 13 A and 13B show another indicator with a rotating flag;

Figures 14 A and 14B show an indicator with a sprung flap; Figures 15A and 15B show an indicator with an external flag;

Figures 16 and 17 show two different forms of acoustic indicator;

Figure 18 shows an electronic audible indicator;

Figure 19 shows an electronic visual indicator;

Figures 2OA and 2OB show a moving-ball flowmeter indicator; and

Figure 21 shows an indicator arranged to release a powder.

Figures 1 and 2 show a first, simplest form of the apparatus assembled ready for insertion. The apparatus comprises a flexible catheter or cannula 1 of PVC reinforced with a steel spring helix. The reinforced construction of the cannula makes it less likely to kink and occlude even if compressed or bend to a very acute angle. The catheter 1 is attached at its upper, rear end 2 to a mount arrangement including a hub 3 moulded of a translucent polypropylene. The translucent nature of the hub 3 enables the clinician to view the site after insertion to check for bleeding, air leek, infection or the like. The hub 3 is circular in shape comprising a radially- extending disc 4, about 24mm in diameter at its lower end, and an externally-threaded cylindrical sleeve 5 extending axially from the upper surface of the disc. An axial bore 6 extends through the sleeve 5 and disc 4. The upper end of the sleeve 5 is molded with castellations 7 or some other form of anti-occlusion formation. Attached to the lower surface of the disc 4 is a circular mounting pad 8 of a polyurethane foam. The pad 8 is about 50mm in diameter, so it projects radially outwardly of the disc 4. The pad 8 has four suture slots 8' or similar formations to enable it to be sutured to the user's skin if desired. The lower surface 9 of the pad is adhesive and is protected before use by two peel-off release sheets 10 and 11 made of a polymer-coated paper. The release sheets 10 and 11 each have a tab 10' and 11' projecting outwardly beyond the mounting pad so that they can be gripped when the pad is located against the skin surface. The apparatus also includes a needle assembly 12 comprising a stainless steel needle 13 and an insertion member in the form of a thumb pad 14 bonded to the rear end of the needle. The needle 13 has a sharp, pointed forward end or tip 15 and its length is such that this tip projects slightly beyond the forward end of the catheter. The thumb pad 14 is moulded from polypropylene and comprises a rigid circular disc 16 slightly smaller than the disc 4 on the hub. The upper surface 17 of the disc is moulded with ribs, ridges or other surface formations to improve grip by the user's thumb. From the lower side the disc 16 depends a short axially- extending stem 18 having a recess in which the upper end of the needle 13 is received and secured. The bore through the needle opens through the thumb pad 14, where gases can escape. There is, however, a risk that the bore through the needle may be occluded by tissue or blood during insertion. Removing the needle ensures gases from the pleural cavity escape through the bore of the cannula. The external diameter of the stem 18 is such that it is a push fit within the bore 6 through the sleeve 5. Castellations on the top of the sleeve 5 prevent the lower surface of the thumb pad 14 blocking free passage of the gas to atmosphere.

The apparatus described above is inserted in the assembled state shown in Figure 1. The tip 15 of the needle 13 and catheter is aligned with the 2^nd intercostal space mid clavicular line and is pushed inwardly at right angles to the skin surface by the user pushing his thumb on the disc 16 of the thumb pad 14 such that an axially-directed force is applied to the assembly. The length of the needle 13 and catheter 1 projecting forwardly beyond the lower surface of the mounting pad 8 is about 83mm, which is selected to allow safe full insertion without damage. As soon as the tip 15 enters the pleural space, the air trapped in that space escapes initially via the needle bore. Blockage in the needle may prevent or restrict air escaping but the user can confirm correct placement by removing the needle. Passage of air is apparent to the user from the hissing sound it makes when it emerges from the upper end of the sleeve 5, thereby confirming that the apparatus has been correctly inserted. The clinician then removes the needle assembly 12 by pulling the thumb pad 14 up to draw the needle 13 axially, rearwardly out of the catheter 1. The catheter 1 is pushed fully in, after removal of the needle, so that the pad 8 contacts the skin surface. The user then grips the two tabs 10' and 11' on the release sheets 10 and 11 and pulls them outwardly away from one another parallel to the skin surface so as to peel the release sheets onto the patient's skin. The user then presses the mounting pad 8 downwardly to press the adhesive surface of the pad into contact with the skin to secure the apparatus in place. Instead of, or as well as, using the adhesive surface on the pad 8 to secure the apparatus to the patient's skin, the apparatus could be secured in place by suturing through the suture holes 8'. The apparatus shown in Figure 3 is thereby secured in place and provides a temporary ventilation channel from the pleural cavity to atmosphere. The reinforced construction of the catheter 1 makes it less prone to kinking and occlusion than previous catheters used in thoracentesis procedures. This can be an advantage because the catheter can be subjected to quite high compressive forces as the patient is manipulated.

The-apparatus described-above-is-simply -left open-a-fter-insertion. This allows free air trapped in the pleural cavity to escape so significantly improves the pneumothorax. It does not, however, prevent atmospheric air flowing back into the pleural space via the catheter. This can be easily prevented by attaching a one-way valve to the apparatus in the manner shown in Figures 4 and 5. Features of the apparatus shown in these figures that are equivalent to those in Figures 1 to 3 are given the same reference numerals with the addition of 100. The apparatus is substantially the same as that shown in Figure 3 except that the disc 104 of the hub 103 has four extensions 120 that overlay the suture holes 108' in the mounting pad 108, for greater suturing security. The valve 121 comprises a moulded resilient elastomeric duck-bill valve element 122 of a conventional kind enclosed between a lower support 123 and an upper cap 124. The lower support 123 has a stem 125 with a bore 126 through it that opens into the centre of a radially- extending support plate 127 and into the centre of the valve element 122. The stem 125 is a gas- tight push fit into the bore 106 of the sleeve 105 on the hub 103. The cap 124 is cylindrical in shape and is bonded around its lower end to the edge of the support plate 127. The upper end of the cap 124 has a central opening 128 through which gas can escape. The duck-bill valve element 122 is oriented so that gas can flow from the catheter 101 to atmosphere but gas flow in the opposite direction is substantially prevented. It will be appreciated that there are many alternative one-way valves, such as involving spring-loaded valve elements, that could be used instead of a duck-bill valve

The apparatus described above relies on the user listening for the hiss of escaping air to confirm correct placement. In some cases it may be preferred to have some form of indicator means to provide a visual, audible or tactile indication to confirm correct placement or to warn of incorrect placement.

Figures 6 and 7 show one example of apparatus including two different forms of indicator means. Features of this apparatus that are equivalent to those in the apparatus shown in Figures 1 to 3 are given the same reference numerals with the addition of 200. The apparatus includes a hollow, blunt-ended guard rod 230 or similar elongate member extending slidably along the bore of the needle 212. The upper end of the rod 230 engages a helical spring 233 or similar resilient means is located between a disc 232 on the rod and the upper end of the housing 231. This urges the rod 230 down so that its lower end projects a short distance out beyond the tip 215 of the needle 212.

The upper end of the indicator housing 231 is formed by a channel member 234 projecting to one side of the housing and having a transparent thumb plate closure 235 secured in it. The upper surface of the plate 235, at its inner end, is formed with shallow ribs 236 or other formations to improve grip during insertion and this part of the plate is aligned axially of the needle 212 and catheter 101. The outer end of the plate 235 supports a colorimetric, carbon dioxide indicator strip 237 on its underside, that is, between the lower surface of the plate and the upper surface of the channel 234. Because the plate 235 is transparent, the strip 237 is visible through it. The dimensions of the channel 234 and the plate 235 are such that there is a gas flow path between them from the inside of the indicator housing 231 radially outwardly and over the underside of the indicator strip 237. Before use, the indicator strip 237 is protected from the atmosphere by a folded aluminium foil tab 238 adhered to the strip in a releasable manner. The tab 238 projects outwardly beyond the plate 235 a short distance so that it can be gripped and pulled outwardly to peel it from the indicator strip 237 when required.

In use, when the needle 212 and catheter 101 are inserted through chest tissue, the guard rod 230 is pushed rearwardly along the needle, against the resilience of the spring 233, by contact with the tissue. When the tip 215 of the needle 212 enters the pleural cavity, therefore, three events occur. First, as mentioned previously, air escapes through the apparatus making an audible hissing sound. Second, gas flows over the exposed surface of the carbon dioxide indicator strip 237 causing it to change colour, because the carbon dioxide content of the air in the pleural cavity is higher than that of atmospheric air. This arrangement, therefore, provides plural, independent indications of correct insertion. The third event is that the rod 230 is moved forwardly by the spring 233 so that its forward end projects beyond the tip 215 of the needle 212. The force of the spring 233 is selected to exceed the resistance provided by lung tissue so that if the needle with its extended rod should contact the lung tissue, its effect would be to push the lung tissue forwardly rather than push the rod rearwardly relative to the needle. This, therefore, ensures that the rod remains extended and has the effect of reducing the risk of damage to lung tissue. The disc 232 at the rear end of the rod could be coloured or made conspicuous in some other way and be visible through a window in the indicator housing 231 to provide a further indication of correct insertion. After correct insertion has been confirmed, the indicator 231 and needle 212 are removed to leave the cannula 201 in position. There are many other ways in which insertion can be indicated as alternatives or additional arrangements to those mentioned above. The indicators may be of the kind that provide a visual, audible or tactile indication of insertion.

Figures 8 A and 8B show a visual indicator 30 having an inflatable member mounted at the rear end of a needle. The inflatable member is in the form of a resilient membrane 31 joined around the edge of a plate 32 so that it normally lies flat against the plate, as shown in Figure 8 A. When gas flows along the needle 33, it inflates the membrane 31 to the domed shape shown in Figure 8B.

Figures 9A and 9B show an alternative inflatable indicator 35 in the form of a tube 36, closed at one end and which is naturally of a curled shape, as shown in Figure 9 A, but is straightened, in the manner of a Bourdon tube, by the flow of gas into it to the shape shown in Figure 9B. Other forms of inflatable indicator are possible. These need not be resilient but could, for example, have a pleated or concertina construction.

Figure 10 shows an indicator 38 having a transparent chamber 39 mounted at the upper end of a needle 40 and containing a liquid 41 such as saline. Gas flow out of the needle 40 is indicated by a flow of bubbles 42 through the chamber 39. A hydrophobic membrane or valve may be mounted at the top of the needle 40 to prevent the liquid 41 flowing down the needle.

Figure 11 also shows a bubble indicator. In this arrangement, the needle 44 opens above the level of the liquid 45 into an enclosed space 46 defined by a downwardly-extending annular wall 47 the lower edge 48 of which is spaced a short distance above the floor 49 of a transparent chamber 49'. When gas flows through the needle 44 it enters the enclosed space 46 and forces gas downwardly through the liquid 45 and under the lower edge 48 of the wall 47, thereby producing visible bubbles.

Figures 12A and 12B show an indicator 50 with an indicator disc 51 mounted in a housing 52 for rotation about a horizontal axis through the diameter of the disc. The disc 51 has differently-coloured segments above and below its rotational axis on its two sides so that, when there is no gas flow, the disc is stationary and two different colours are visible, as shown in Figure 12 A. The disc 51 is exposed towards one edge to gas pressure from the housing 52 such that, when gas does flow, this causes the disc to spin about its axis and gives the appearance of being coloured the same across its face. This thereby gives a readily- visible indication of gas flow.

Figures 13 A and 13B show another rotating indicator 54. This one having a centrally mounted paddle blade 55, which is stationary when there is no gas flow, as shown in Figure 13A, and rotates when gas starts to flow, in the manner shown in Figure 13B.

Figures 14A and 14B show an indicator 57 having a lightweight flap 58 resiliently hinged at one end 59 at the top of an indicator housing 60. Gas flowing out of the top of the housing blows the flap 58 up and to one side as shown in Figure 14B. The flap 58 springs back and forth depending on the gas flow.

Figure 15 A and 15B show an indicator 62 having a housing 63 on the outside of which a flag 64 is pivotally mounted. The flag 64 is coupled to a vane (not shown) within the housing 63 exposed to any gas flow through it. In its normal position, as shown in Figure 15 A, the flag 64 hangs down indicating no gas flow. When gas does flow it displaces the vane and causes the flag 64 to rotate up to the position shown in Figure 15B to give a clear indication of gas flow.

Figure 16 shows an indicator 66 arranged to provide an audible indication, the indicator being a whistle chamber 67 with an acoustic gas outlet slot 68 so that flow of gas through the chamber produces a clearly audible sound.

Figure 17 similarly shows an audible indicator 70 provided by a duck-bill valve 71, which opens and closes to produce a sound. Other similar, reed-like devices could be used.

Figure 18 shows an electronic gas flow detector 73 mounted at the upper end of a needle 74 and arranged to produce an audible indication of gas flow from a sounder device 75.

Figure 19 shows another electronic gas flow detector 77 but this one includes a visual indicator, such as an LED 78, which is energised to produce visible light when gas flow is detected.

Figures 2OA and 2OB show an indicator 80 in the form of a flowmeter and, in particular, a floating-ball flowmeter having a lightweight ball 81 movable along a transparent vertical tube 82. The lower end of the tube 82 connects to a needle 83 and its upper end is open. When no gas flows, the ball 81 sits at the lower end of the tube 82, as shown in Figure 2OA. When the pleural space is penetrated, gas flows and the ball 81 is displaced upwardly by the flow of gas along the tube 82. The tube 82 can have graduations 84 to give an indication of the rate of gas flow.

Figure 21 shows another alternative indicator 86 having an indicator housing 87 with an open upper end 88 and containing a quantity of a coloured powder 89. When gas flows into the lower end of the housing 87 it blows at least some of the coloured powder 89 out of the open upper end 88 of the housing. By viewing the release of the coloured powder 89, the clinician knows that the pleural space has been penetrated.

A tactile indicator could be provided by extending the rod 230 of the arrangement shown in Figures 6 and 7 so that is exposed through an opening in the thumb plate 235 during insertion and is no longer exposed after penetration. The user could readily detect the presence or absence of the rod by feeling with his thumb.

It will be appreciated that other forms of indicator could be used or that different forms of indicator could be used in combination with each other.

Claims

1. Pneumothorax apparatus including a catheter (1, 101, 201) and a needle (12, 212) removably received in the catheter and having a pointed tip (15, 215) projecting at the forward, patient end of the catheter, characterised in that the apparatus includes a mount arrangement (3, 8) attached with the catheter (1, 101, 201) towards its rear end (2), that the mount arrangement (3, 8) extends substantially radially of the catheter (1, 101, 201) and is arranged to be secured with the skin around the insertion site of the catheter, and that the apparatus includes a removable insertion member (14) fitted on the rear end of the apparatus, the insertion member (14) providing a generally laterally-extending surface (17) by which the apparatus can be pushed through the chest wall.

2. Pneumothorax apparatus according to Claim 1, characterised in that the apparatus includes an indicator (232, 237, 30, 35, 38, 39, 49', 50, 54, 57, 62, 66, 70, 73, 77, 80, 86) mounted with the rear end of the apparatus and responsive to flow of gas along the needle (12) on penetration of the pleural space.

3. Pneumothorax apparatus according to Claim 2, characterised in that the indicator is selected from a group comprising a carbon dioxide indicator (237), an inflatable device (30, 35), a transparent container (39, 49') of liquid (41, 45) through which bubbles can flow, a displaceable flag member (50, 54, 57, 62), an acoustic device (66, 70, 73), an electrical indicator (73, 77), a flow meter (80) and a container (86) of a powder that is released by gas flow through the container.

1- Pneumothorax apparatus according to Claim 2 or 3, characterised in that the indicator (232, 237, 30, 35, 38, 39, 49', 50, 54, 57, 62, 66, 70, 73, 77, 80, 86) is removable after determination of correct insertion.

5. Pneumothorax apparatus according to any one of the preceding claims, characterised in that the apparatus includes a one-way valve (121) securable with the apparatus after removal of the needle (12) to permit gas to flow outwardly from the rear end of the catheter (1) but substantially to prevent gas flow in the opposite direction.

6. Pneumothorax apparatus according to any one of the preceding claims, characterised in that the mount arrangement (3, 8) has an adhesive surface (9) arranged to be secured to the skin.

7. Pneumothorax apparatus according to any one of the preceding claims, characterised in that the mount arrangement (3, 8) has suture formations (8', 108') by which the mount arrangement can be sutured to the skin.

8. Pneumothorax apparatus, characterised in that the apparatus includes an elongate member (230) and a resilient member (233) arranged to urge the elongate member along the bore of the needle (212) such that the forward end of the elongate member (230) projects from the tip (215) of the needle (212) in its natural state, is displaced rearwardly during insertion through tissue and is displaced forwardly on penetration of the pleural space such as to protrude beyond the tip (215) of the needle (212) and protect lung tissue from damage by the needle.

9. Pneumothorax apparatus according to Claim 8, characterised in that the rear end (232) of the elongate member (230) is visible at the rear end of the apparatus to provide an indication of penetration of the pleural space.

10. A method of treating pneumothorax including the steps of: inserting the forward end of a catheter and needle assembly (1, 101, 201 and 12, 212) through the chest wall into the pleural cavity, monitoring an indicator (232, 237, 30, 35, 38, 39, 49', 50, 54, 57, 62, 66, 70, 73, 77, 80, 86) at the rear end of the assembly, removing the needle (12, 212) from the catheter (2, 202) when the indicator (232, 237, 30, 35, 38, 39, 49', 50, 54, 57, 62, 66, 70, 73, 77, 80, 86) indicates that the pleural cavity has been penetrated, securing a mount (4, 8, 108) attached with the catheter (1, 101, 201) to the skin around the insertion site and attaching a one-way valve (121) to the rear end of the catheter (101) to allow gas to flow outwardly from the rear end of the catheter but substantially to prevent gas flow in the opposite direction.