A MANUALLY OPERABLE ASPIRATOR
The present invention relates to a manually operable aspirator. The invention is motivated by the problem of regurgitation during unconsciousness and cardiac arrest. If this occurs in a hospital or in an ambulance, an aspirator is available to suck out regurgitated fluid to clear the patient's airway. Away from hospital and ambulance support no such device is available. An increasing number of members of the public are trained in CPR techniques. Such people are taught to clear the airway with their hand (perhaps with a handkerchief wrapped around the finger) . This is unpleasant for the first-aider and is useless when the patient is regurgitating fluid, particularly if this is recurrent. Unless the airway is clear, mouth-to-mouth breathing is of no value, and CPR techniques are useless. The present invention provides a manually operable aspirator comprising a compressible volume, an inlet into the compressible volume with a valve to prevent flow through the inlet as the compressible volume is compressed, an outlet from the compressible volume with a valve to prevent flow through the outlet as the compressible volume is expanded, .and manually operable means to compress and expand the' compressible volume to alternately expel fluid through the outlet and suck fluid in through the inlet; wherein the inlet and/or outlet have a bore of between 5 and 15mm. The invention provides a simple, manually operable device which can be cheap to manufacture allowing it to be made available in all manner of situations for which existing aspirators are prohibitively expensive. The aspirator could be available, for example, in schools, leisure centres, swimming pools,- theme parks, airlines, beaches or restaurants. It would also be available to the public for them to carry as part of a first-aid kit, or it could be used as a low cost replacement to conventional aspirators in hospitals and ambulances. By alternately sucking and expelling fluid, the conventional compressible volume can be made much smaller than the total volume of the liquid that needs to be pumped. Preferably, the total compressible volume is less than 150ml more preferably less than 100ml and most preferably less than 80ml. This allows the aspirator to be smaller and hence more portable.
The outlet may be connected to a reservoir to collect expelled fluid. Preferably, however, the outlet is open to its surroundings. This allows the aspirator to have an infinite capacity as all fluid is expelled to the surroundings, and also helps with the low cost and portability of the device.
The aspirator may be arranged to be gripped with one hand and operated with another hand. However, if the aspirator is arranged to be held in one hand and is also arranged to be operated by the same hand to compress and expand the compressible volume, the other hand of the first-aider operating the aspirator is kept free and can be used, for example, to ensure that the device remains correctly positioned.
The inlet may be connected to a rigid tube which is inserted into the mouth of the patient. However, for improved manipulation, the inlet is most preferably connected to a semi rigid tube which has sufficient flexibility to allow it to be manipulated into the correct position. The bore of the tube connected to the inlet is preferably between 5 and 15 mm, more preferably between 6 and 10 mm, and most preferably substantially 8 mm. Similarly, the outlet is preferably connected to a semi rigid tube of comparable cross-section.
If the inlet and outlet diverge from one another, for example if one of them has a bend and the other is straight, this helps the first-aider to direct fluid away from the patient.
The compressible volume may be provided by a bellows arrangement having collapsible walls which are biased into an expandable configuration either by their own resilience or by a separate resilient member, and which are compressed against this resilience by the hand of any user. However, the preferred arrangement is for the compressible volume to be provided in a cylinder in which a plunger is reciprocably movable. This arrangement can generate a level of suction force which is ideally suited to its use as an aspirator. The inlet and/or outlet valves are preferably permanently attached with respect to the compressible volume. This means that the aspirator does not require assembly before use and can hence be permanently ready for use. Also, preferably the inlet and/or outlet valves are non-adjustable. Again, the aspirator can be permanently ready for use and is incapable of being used incorrectly.
An example of an aspirator constructed in accordance with the present invention will now be described with reference to the accompanying drawing which is a cross-section through the aspirator. The aspirator comprises a cylinder 1 which typically has a length of 13 centimetres and a bore of
3 centimetres. A plunger 2 is reciprocably received within the cylinder 1 and typically has a stroke length of 11 centimetres.
The cylinder has an inlet 3 and an outlet 4. One way valves 5,6 are provided on the inlet 3 and outlet
4 respectively. In Fig.l the valves are represented as simple flap valves, but could be any one of a number of known valves and could even be combined as a single valve element. Protruding from the inlet 3 is a short rigid tube 7. Similarly, a short rigid tube 8 having a right angle bend leads from outlet 4. Each of the tubes is arranged to receive a length of semi-rigid tube typically 26 centimetres long and having an internal diameter of 0.8 centimetres. Preferably, the semirigid tubes for the inlet and outlet are identical so that it is not possible to accidentally attach the tubes the wrong way round. In use, when a patient is unconscious and a first-aider recognises that the patient is regurgitating fluid, the semi-rigid tube attached to the inlet is inserted into the mouth of the patient such that its end is within the fluid. The first-aider then holds the handle of plunger and withdraws it along the cylinder from the position shown in Fig.l. At this time the valve 5 opens and the valve 6 closes such that the cylinder 1 fills with fluid. Once an amount of fluid has been drawn into the cylinder the first-aider pushes the plunger 2 in the opposite direction. This time the valve 5 closes and the valve 6 opens so that the fluid within the cylinder 1 is expelled through the outlet 4. The right angle bend as shown in the outlet tube 8 ensures that this fluid can be directed away from the patient and will generally be expelled onto the ground to one side of the patient. The first-aider repeatedly operates the plunger 2 until all visible fluid has been expelled. The patient is then able to receive mouth-to-mouth breathing. If, at any time, the patient regurgitates further fluid, the inlet tube can be reinserted and the process of pumping out the fluid can be repeated.
The arrangement shown in Fig.l requires two handed operation. In order to provide one-handed operation, the plunger may be connected to a spring loaded trigger arrangement in which the squeezing of the trigger by the'first-aider moves the plunger in a first direction and, upon release of the trigger, the spring returns the plunger in the opposite direction.