TITLE : Pneumothorax Needle And Indicator DeviceDESCRIPTIONSpontaneous pnuemothorax (collapsed lung) is a relatively common medical emergency requiring treatment in hospital.
A pneumothorax occurs when the potential space between the lung and the inside of the chest wall (the pleural space) is breached and becomes an actual space and the lung collapses as the closed space fills with air. This causes chest pain and difficulty in breathing.
Assessment of the degree of lung collapse is made by inspection of a plain chest radiograph (X-Ray) and can be re-assessed by repeating such at intervals.
If the collapse is small and the amount of air in the space is judged to be of low volume, no immediate treatment is necessary and the lung will often re-inflate with. time. However if the degree of collapse is significant or causing distress then the air in the closed pleural space (between collapsed lung and chest wall) must be evacuated allowing full lung expansion.
In the past this was done by cutting a hole through the chest wall under local anaesthetic and placing a large bore (1cm) flexible rubber tube through the hole and into the pleural space. The tube would then be sutured into place and attached to an underwater seal allowing air to pass out of the chest but not in, thus allowing the lung to reinflate. Typically the tube would remain in-situ for several days.
The procedure can be painful and the inconvenience of having a tube sited in the side of the chest with a water bottle attached, can be considerable. The hospital stay is costly and may be inconvenient for the patient. After removal of the tube from the chest there is often left an unsightly scar.
This unsatisfactory situation was addressed by the British Thoracic Society who compiled and published guidelines which have now become established practice.
The main change was to institute the less invasive practice of percutaneous intercostal needle aspiration of the air in the pleural space (passing a hollow needle through the skin and between the ribs and into the space between collapsed lung and the chest wall). This is now performed as a first procedure only progressing to full chest intubation if unsuccessful.
Needle aspiration is a relatively painless and simple procedure that is often highly effective and allows full lung expansion to be achieved quickly and easily.
In its simplest form the equipment required is a simple metal hypodermic needle and a plain syringe. The needle is passed through the chest wall after first numbing the site and once the tip is positioned in the pleural space air can be aspirated (sucked out) with the syringe allowing the lung to reinflate.
The potential problems of a rigid needle puncturing the re-expanding lung have been overcome by using a plastic cannula (tube) such as is used for intravenous cannulation. This is a small bore flexible plastic tube sheathing a rigid hollow needle. The rigid needle is used to introduce the flexible plastic cannula through the chest wall and is removed once the cannula is adequately sited. The cannula is left in place. A syringe can then be attached to remove the air. The whole assembly can be easily withdrawn once the lung is inflated leaving a tiny puncture wound which can be dre$sed with a simple sticking plaster and leaves no noticeable scar.
Though some efforts have been made to design a dedicated aspiration needle for this purpose thy are not widely available and as yet there is no means of signalling when the pleural space has been reached and the cannula is correctly sited.
The purpose of the present invention is to provide a dedicated, single-use, disposable pneumothorax aspiration needle designed with ease of use in mind and incorporating a novel mechanism for indicating correct positioning of the flexible cannula part in the pleural space.
It is envisaged that the new device will make the procedure of chest aspiration simpler for the doctor, more acceptable to the patient and will reduce the potential complications of the procedure making it quicker, simper and safer.
It is an object of the present invention to provide a means for piercing the chest wall allowing access to the pleural space for the sitting of a plastic cannula for the purposes of aspiration of air from that space.
It is a further object of the present invention to provide a means of indicating successful entry of the needle tip into the pleural space ie. correct placement of the needle/cannula assembly prior to aspiration.
According to one aspect of the present invention there is provided a rigid hollow needle, pointed at one end for piercing the chest wall and open at the other end for attachment of the new device for signalling correct positioning of the needle.
Sheathing the rigid needle is a flexible plastic cannula with one or more openings at its far end which will be within the chest cavity and closed at its near end by a seal that will allow passage of the needle through it but self seal in an air-tight fashion once the needle is withdrawn. In one embodiment of the present invention this might be in the form of a bung made of rubber or similar materials.
It is envisaged that the flexible plastic cannula will have a flange or stop along its length that allows only its far end to lie in the chest cavity and its near end, stoppered in one instance by the rubber bung to remain outside the chest wall and therefore accessible.
The part of the cannula between flange and stopper is envisaged to be at least semi if not fully rigid.
Between the flange and the end stopper there is envisaged to be a rigid access port that will allow passage into or out of the chest cavity. This access port will have standard means for attachment of various accessories already in existence in the clinical setting eg. syringe, tubing etc. and will have an open and close mechanism which in one embodiment might be in the form of a simple tap mechanism.
Attached at the near end. of the hollow needle is the signalling device for showing correct placement of the far end of the needle in the pleural space. The signalling device according to one aspect comprises a housing open at two spaced apart locations with a member In the housing responsive to air flow through the housing between said spaced locations. The member responsive to air flow can be a lightweight float free to move over a predetermined length of the housing preferably to the extent that its movement is readily detectable by eye.
The housing may consist of any shaped conduit or vessel for containing a float having a bore there through for free flow of air. Preferably the housing is in the form of a transparent cylindrical tube having a retaining lip at each end thereof. The housing is preferably made of a durable lightweight plastics material. The float should be made of a lightweight material such as polystyrene so that it is sensitive to even slight alterations in flow of air. The float which might preferably be a ball is dimensioned to be retained within the housing but freely movable therein and is preferably brightly coloured.
The whole assembly would be made of materials that would withstand sterilisation procedures and be packaged in sterile packaging for hygiene reasons. It is envisaged that the assembly would be used once only and discarded after use.
The various embodiments of the present invention may be used to access the pleural space and allow passage of air or fluids to and from it in a controlled manner.
Access to the pleural space may be indicated by the signalling device attached to the needle.
The pressure changes generated within the pleural space by breathing are transmitted through the hollow needle to the signalling device and are represented by the to and fro movement of the float within the housing which can be easily recognised by the clinician undertaking the procedure.
Only when the needle tip is correctly positioned in the pleural space will there be movement of the ball thus indicating safe and correct positioning of the needle tip.
The needle and signalling device can then be withdrawn en-masse through the sheathing plastic cannula and seal at its near end leaving the far end of the flexible plastic cannula in the pleural space within the chest cavity, its near end remaining accessilble outside the chest cavity and sealed in an air-tight fashion. The whole being secured to the chest wall with sutures or adhesive tape applied to the flange which is sited at a suitable fixed point on the cannula between its near and far ends.
The tapped port allowing entry to and from the plastic cannula and therefore the pleural space, is then easily accessible between the near end of the cannula and the flange.
For a better understanding of the present invention and to show more clearly how it can be carried into effect reference will now be made by way of example only to the accompanying drawings in which :Fig 1. is a side-on view of a section through the needle assembly and signalling device.
Fig 2. is and end-on view of the whole assembly.
Fig 3. shows a simplified schematic representation of the essential features of a pneumothorax (collapsed lung).
Fig 4. shows the correct placement of the needle assembly through the chest wall and into the pleural space within the chest cavity with the outlet tap in the closed position and the signalling device indicating correct placement.
Fig 5. shows the plastic cannula remaining in the pleural'space and air from that space being evacuated through the open outlet port allowing lung re-inflation. The rigid needle and signalling device have been removed and discarded.
Referring to Fig 1. of the accompanying drawing a signalling device comprising a housing 1 with end stops 3 and an opening 4 containing a light weight float 2 is attached in continuity with a rigid hollow needle 5. This needle and signalling assembly are sited through a rubber (or similar materials) end-stop or bung 6 which fills the near end of a barre. l 7 that has a port 8 along its length that has in one instance a tap mechanism 9 to allow the port 8 to be open or closed. The barrel 7 is attached or integral with a flange 10 used for securing the assembly to the chest wall 14. The interior of the. barrel 7 is in continuity through the flange 10 with a flexible plastic cannula part 11 which has one or more openings at its far end 18.
Fig 2. shows an end-on view of the same with openings 12 in the flange 10 for fixing the flange 10 to the chest wall 14 by means of sutures.
Fig 3. shows a simplified schematic representation of a trachea (wind-pipe) 13 in communication on one side with a fully inflated lung 16 within the chest wall 14 and on the other in communication with a collapsed lung 15. The space between the collapsed lung 15 and the chest wall 14 represents the air filled pleural space 17 which develops as the lung collapses.
Fig 4. shows the correct positioning of the assembly through the chest wall 14 with the far end correctly placed in the pleural space 17 and the light weight float 2 within the signalling housing 1 moving to and fro as the subjects breathes in and out. The tap 9 in the barrel port 8 is in the closed position.
Fig 5. shows the barrel 7 and cannula11 assembly correctly sited within the pleural space 17 with the needle 5 and signalling assembly 1 removed and the tap 9 on the barrel part 8 in the open position allowing air in the pleural space 17 to be evacuated through it allowing the collapsed lung 15 to re-inflate. The flange 10 is closely approximated to the chest wall 14 and may be fixed to it by sutures or adhesive materials.
The device of the present invention operates in the following manner.
When a pneumothorax (collapsed lung) requiring needle aspiration in accordance with current guidelines has been diagnosed, the patient can be prepared for the procedure of needle aspiration of air in the pleural space 17 allowing lung 15 reinflation. The site on the chest wall for needle puncture is identified and anaesthetised with local anaesthetic. The devise of the present invention can be removed from its sterile packaging and holding the assembly in one hand the whole can be advanced such that the rigid hollow needle 5 pierces the skin of the chest wall14 at a perpendicular angle. It is then pushed further through the chest wall 14 until the pleural space 17 is breached and the tip of the needle 5 lies between the chest wall 14 and the collapsed lung 15 ie. In the pleural space 17. Correct positioning in this space 17 will be demonstrated by the to and fro movement of the light weight float 2 within the transparent housing 1 of the signalling device, the light weight float 2 having been hitherto stationary.
If the pleural space 17 is not breached the incorrect positioning of the needle 5 tip is shown by lack of linear movement of the light weight float 2 within the transparent housing 1.
Once the operator is confident that the needle 5 tip has breached the pleural space 17 and that the tip of the flexible plastic cannula 11 with its one or more openings 18 at its far end has been delivered to the pleural space 17 then the rigid hollow needle 5 assembly and signalling device 1 and 2 with which it is connected and in communication, can be withdrawn as one through the end stopper 6. The stopper 6 being made of rubber or similar materials will self-seal as the needle 5 is withdrawn through it thus closing the near end of the rigid barrel section 7 of the device in an air-tight fashion. The rigid barrel section 7 remains in connection and communication across the flange 10 with the flexible cannula part 11 of the device.
The needle 5 and the signalling assembly 1 and 2 thus removed can be discarded.
The remainder of the assembly comprising the stoppered 6 and sealed rigid barrel 7 with side-port 8 and the flange 10 between this and the flexible plastic cannula 11 can then be safely further advanced toward the collapsed lung 15 without fear of piercing it (the plastic cannula 11 being blunt and flexible) until the flange 10 abuts the chest wall 14 to which it can then be fixed by sutures or adhesives.
The operator then has fixed access to the pleural space 17 via the port 8 in the rigid barrel section 7 which can be opened and closed with a tap 9 or such-like mechanism. Passage is then possible to and from the pleural space 17 in a controlled fashion for gas or fluid media.
Once the operator has no further need of such access the remaining assembly described above can be withdrawn en-masse and the tiny puncture wound dressed with a simple proprietary dressing such as a sticking plaster.
Thus the whole procedure of the treatment of pneumothorax is greatly improved by simplifying the clinicians role and improving patient comfort, safety and outcome.