Gastrointestinal aspirator pump

Abstract

The gastrointestinal pump, preferably an aspirator, includes means for creating positive and negative pressures. A timer circuit, in conjunction with an arrangement of valves, activates the positive and negative pressure outputs of the pump in a selectable, alternately timed sequence. A double lumen tube transmits the pressures to the gastrointestinal tract. The negative pressure lumen withdraws the gastric fluids, while the positive pressure lumen exerts force at the opening of the negative pressure lumen to prevent blockage of the opening. A collecting vessel is connected in the negative pressure line. The lumens of the tube may be eccentrically or concentrically located. Openings may also be formed along the length of the double lumen tube.

Description

BACKGROUND OF THE INVENTION

This invention relates to a gastrointestinal pump and, more particularly, to an aspirator that avoids blockage of the negative pressure tube in the gastrointestinal tract.

Gastrointestinal aspirators are commonly used for withdrawing the fluid contents of the gastrointestinal tract.

One type of a known aspirator utilizes a single lumen tube for transmitting a negative pressure from the aspirator to the gastrointestinal tract. The negative pressure in the tube withdraws the contents.

One drawback with this type of aspirator resides in the tendency of the tube opening to become blocked by gastrointestinal membranes and debris. The blockage not only impedes effective aspiration but also may cause severe pain and discomfort to the patient. In cases where the intestinal wall becomes drawn to or into the suction opening, the tube cannot be moved within the digestion tract without release of the vacuum.

Known attempts to solve the problem have either not been successful or have been only partially effective and with the loss of other desirable features. In one conventional aspirator, the tube has a plurality of holes along its length so that if some openings are blocked, others may remain open. However, such an aspirator does not entirely prevent the undesirable blockage or attachment to the intestine. Additionally, it may be impossible with such a tube to reach certain parts of the gastrointestinal tract, or to identify the exact location in the tract from which a sample was taken.

Another known arrangement utilizes a hood at the end of the tube, the hood having a plurality of openings to permit gastrointestinal fluids to enter the hood, from which they are drawn into the tube. The hood also is provided with an air-tight compartment connected to another tube in such a way that air may be pumped into the compartment to extend the hood to keep the hood erect. Such an aspirator, however, does not entirely prevent blockage and is difficult to position in certain parts of the gastrointestinal tract.

Also known is an aspirator that sequentially supplies a positive and negative pressure to the tube, the gastrointestinal contents being withdrawn during the negative cycle, with the positive pressure intended to prevent blockage of the tube opening. With such a device, however, the blockage is removed only during the positive cycle with variable and irretrievable loss of fluids that are being forced back into the gastrointestinal tract, and blockage can occur before new fluid has been withdrawn. Therefore, the return of fluids to the gastrointestinal tract prevents accurate analysis. Important diagnostic information can be obtained from knowledge of the exact location in the tract from which a given sample is taken. However, if the tube contents are alternately pushed forward and backward in the tube, the identity of the location of a given portion of the sample can become confused or lost.

Thus, it is an object of the present invention to provide a gastrointestinal aspirator that prevents tube blockage, that operates efficiently and safely, that requires a minimum of time on the part of attendant personnel, and that accurately permits physicians to determine the location in the gastrointestinal tract from which samples are removed. Additional objects will appear as the description proceeds.

SUMMARY OF THE INVENTION

There is provided in accordance with the present invention, a gastrointestinal aspirator that accomplishes the above objects. In the aspirator of the present invention, means are provided for withdrawing gastrointestinal fluids through a suction tube and for preventing blockage of the opening of the suction tube in a manner independent of the passage of the contents through the suction tube. Thus, continuous operation and change of position are possible without attachment to the intestinal wall and the exact location in the gastrointestinal tract from which the fluids are withdrawn can be identified. Blockage of the tube inlet is prevented by injecting air into the intestine through a separate tube, having its opening positioned near to the opening of the suction tube. In this way, an air bubble is formed so as to lift blocking membranes or debris adjacent to the tube and thereby free the suction tube opening. Preferably, the positive and negative pressure cycles occur alternately.

In one form of the present invention, a single pump provides both the positive and negative pressures. The pump may be controlled by a timer that causes the pump to supply positive and negative pressures alternately. The duration of each pressure cycle is variable and may range from 10 to 0.1 seconds.

The two tubes are preferably joined to form a double lumen tube which permits the aspirator to operate more efficiently and facilitates insertion and positioning. The lumens may be either eccentrically or concentrically arranged, and may also be formed with openings along their lengths to provide a plurality of openings for withdrawing the fluids and for air injection.

Pressure, temperature, and/or pH sensing elements may be provided in the tube, for diagnostic purposes or to monitor and control the positive and negative pressures. Thus, if the pressure tends to exceed a safe limit, control elements can be activated to maintain the pressure within the safe range.

A vessel for collecting the gastric fluids may be inserted in the negative pressure line.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of the gastrointestinal aspirator according to the present invention;

FIG. 2 is a sectional view of the double lumen tube taken along the lines 2--2 of FIG. 1;

FIG. 3 is a view of an alternate form of a double lumen tube;

FIG. 4 is a sectional view of a triple lumen tube;

FIG. 5 is a schematic diagram of the aspirator.

DESCRIPTION OF PREFERRED EMBODIMENTS

In an exemplary embodiment of a gastrointestinal aspirator according to the present invention, as shown in FIG. 1, the aspirator includes a control mechanism indicated generally at 10, a positive pressure line 12, negative pressure lines 14 and 16, a vessel 18 for gastrointestinal fluids, and a double lumen tube 20. The control mechanism 10 operates to provide a negative pressure or suction to cause the gastrointestinal fluids to be withdrawn through line 16 and collected in the vessel 18. Positive pressure is provided in the line 12 for blockage prevention as will be described.

In the double lumen embodiment of FIG. 2, a tube 20 is provided with a lumen 22 for positive pressure and a lumen 24 for negative pressure. The tube 20 may be made of rubber, PVC, polyethylene, or other similar flexible materials. A wall 26 in the tube 20 forms a barrier between the two lumens 22 and 24. Openings 28 are provided in lumen 22 for supplying air under positive pressure to the gastrointestinal tract. Openings 32 are provided in the negative pressure lumen 24, to permit the fluids to be withdrawn through lumen 24 to the vessel 18. The emission of air under positive pressure adjacent to the negative lumen openings 32 prevents blockage by lifting the adjacent membranes. In this way a bubble of air is formed, and during the negative cycle, it will enter the negative lumen 24, but such air in the negative lumen does no harm and merely passes along to the vessel 18 and thence to exhaust. The openings 28 and 32 may be arranged in closely spaced pairs along a substantial length of the tube 20, or a single pair may be located at the end of the tube adjacent to a metallic slug to permit location identification by X-ray. The holes can be on opposite sides of the tube as shown in FIG. 2, but in that case, a solid object caught in the negative opening 32 may not be freed by the bubble. For this reason, placing the holes side-by-side as indicated by arrows 29 and 33 with the holes occupying the position shown in dotted lines, may be preferred. In FIG. 3 a form of multi-lumen tube is shown in cross-section, with a positive pressure tube 36 inside a negative pressure tube 38 and with webs 40 and 42 maintaining the concentric spacing, but in this case the positive pressure openings 28 are inside of and in alignment with the negative pressure openings 32. By this arrangement, when air is ejected, during the positive cycle, it passes outwardly through the negative opening 32 into the gastrointestinal tract so as to relieve blockage in the negative openings 32. Fluid back-pressure in the negative pressure lumen 24 prevents the air from following the negative lumen rather than passing out into the tract. In this way, blockage even by a loose particle is prevented. A fourth lumen 92 (see FIG. 4) can be provided to house filaments connected to pressure, pH, and temperature sensing instruments positioned appropriately in the tube.

The control mechanism 10 has indicators and controls for operation of the gastrointestinal aspirator. A positive pressure gauge 44 provides a visual indication of the positive pressure. Similarly, a pressure gauge 46 provides an indication of the negative pressure. These gauges are each provided with an adjustable maximum safe pressure switch controlling an alarm (not shown) which will be rung if the safe pressure is exceeded. A switch 48 activates power to the control mechanism. An "Activate-Standby" control 50 operates to control the supply of pressures to the lumens of tube 20. A pressure control 52 determines whether positive and negative pressures are applied alternately through the lumens of tube 20 or only negative pressure is applied through lumen 24. A switch 54, designated as "manual purge", permits a constant positive pressure to be provided through lumen 22 into the gastrointestinal tract. A positive pressure time duration switch 56 is provided to select the time duration of the positive pressure cycle. Similarly, a negative pressure time duration switch 58 is provided to control the duration of the negative pressure cycle.

FIG. 5 diagramatically illustrates the operation of the control mechanism 10. Power to operate the aspirator is provided through the power switch 48 from a source 59, which may be a standard outlet power of 120 volts, 60 hz. The power switch 48, when activated, provides electrical power to operate a pump 60, a timer control 62, solenoids for valve control, lights, warning buzzers, etc. The pump 60 is preferably a positive displacement pump of the piston or rotary types. A negative pressure line 62 and a positive pressure line 64 are provided for pump 60. When the pump 60 is of the piston type, both lines 62 and 64 may be provided on the same side of the piston with appropriate check valves. Lines 62 and 64 can also be arranged on either side of the piston with slight modification to the arrangement of FIG. 5. When the pump 60 is of the rotary type, the outputs are preferably arranged on either side of the rotating members.

The following description relates to the arrangement of the elements connected to lines 62 and 64. The negative pressure line 62 passes through a check valve 66 that only permits air to pass into the pump 60. Line 62 then leads to a valve 68, shown as a cylinder valve. Various forms of valves suitable for this purpose are available commercially. Similarly, the positive pressure line 64 leads to valve 68 through a check valve 76 that only permits air to pass out of the pump. The valve 68 includes portions for separately valving the positive and negative lines. Valve 68 is controlled by solenoid mechanism (not shown), energized by operation of the "Standby-Activate" switch 50 in the control mechanism 10. In operation, with the standby-activate switch on, both positive and negative pressures are permitted to pass through the valve 68. This is the position of the valve depicted in FIG. 5. When the "standby-activate" switch is off, or in the "standby" position, the valve 68 is positioned to connect the positive and negative outputs to the atmosphere and the pump will then operate without load.

The negative pressure line 62 then leads from the valve 68 to a pressure reducing valve 72 and also branches off to a pressure relief valve 74. Similarly, the positive pressure line 64 leads to a pressure reducing valve 76 and a pressure relief valve 78. The pressure relief valves are adjustable and provide a bleed-off to prevent the pressure from exceeding a selectable limit. The pressure reducing valves, also adjustable, may provide a means for setting the amount of positive and negative pressures. In the present context, I employ only 1 p.s.i. maximum pressure on each line.

The positive and negative lines next pass to a valve 80 that is controlled through a solenoid 82 by the timer 62. Valve 80 has two positions. In the position shown in FIG. 5, the negative pressure is being transmitted to lumen 24 of the tube 20, while the positive pressure is being transmitted to the atmosphere. When the valve 80 is in its alternate position, the negative pressure line is connected to the atmosphere and the positive pressure line to lumen 22 of the tube 20. The valve 80 is shown being controlled by solenoid 82 which in turn is controlled by either a signal from the timer 62 or by a signal from the manual purge switch 54.

The output from the timer 62 is provided to the solenoid 82 over a line 61. The purpose of the timer 62 is to provide a time duration for the generation of negative and positive pressure cycles. This is controlled by negative and positive duration switches 58 and 56 respectively. The details of the timers are standard and are not shown herein. Simple adjustable clock timers are available commercially to perform the functions described, and they form no part of the invention in themselves. In the present embodiment, the time durations are independently selectable on the positive line from 1 to 10 seconds, and on the negative line from 0.1 to 10 seconds. The switches 56 and 58 are provided with control points calibrated for these durations. For durations in the range of 1 to 10 seconds, the timer may comprise an electro-mechanical timer. For shorter durations, such as 0.1 seconds, it is preferable to provide a digital clock or an adjustable RC timer network. In operation, the timer provides an energizing signal for solenoid 82 corresponding to the selected duration of the positive pressure cycle and provides no signal to the solenoid 82 for the time interval of the negative pressure cycle, the valve 80 being moved to the negative pressure position by spring action.

The negative pressure line from valve 80 leads to negative pressure meter 46 and then to the vessel 18. The positive pressure line leads to a positive pressure control valve 86 and then to the positive pressure meter 44. The valve 86, when activated by the positive pressure control switch 52, exhausts the positive pressure air to atmosphere. Its primary purpose is to provide a quick method for interrupting positive pressure in the event of failure of the relief valve 78.

In operation, there is no operation of the aspirator when the switch 50 is in "standby". In this position, the valve 68 provides a bleed-off for both the negative and positive pressure lines and thereby prevents any pressure from being transmitted to the lumens of tube 20. The pump 60 is then operating under a no-load condition, and the check valves 66 and 76 permit air to enter and leave the pump 60.

During the normal operating cycle of the aspirator, an alternate positive and negative pressure is provided. Here the activate-standby switch 50 is in the "activate" position which controls the valve 68 to permit continuous positive and negative pressures to be supplied to the valve 80. During the positive pressure cycle determined by the timer 62, the solenoid 82 is energized and the valve 80 is placed in the position wherein positive output is provided to lumen 22 of the tube 20 and the negative line is open to the atmosphere. Air for the pump 60, which is required to generate the positive pressure, is supplied through the negative pressure line, which permits the air to pass the valve 80, the pressure reducing valve 72, the valve 68, and the check valve 66. During the duration of the negative pressure cycle, the timer 62 deactivates the solenoid 82 and, by spring return action, places the valve 80 in the position shown in FIG. 5. The pump 60 draws air from lumen 24 of the tube 20 through the vessel 18, the valve 80, the pressure reducing valve 72, the activate-standby valve 68 and the check valve 66.

The normal cycle is interrupted when the positive pressure control switch 52 is selected. Here, the valve 86 causes the positive pressure output to bleed off so that only negative pressure is transmitted to the gastrointestinal tract.

In another operational mode, a constant positive pressure may be provided. The manual purge switch 54 provides a signal to the solenoid 82 which holds the valve 80 constantly in the second position. The pressure relief valve 78, prevents positive output pressure from exceeding a given safe value. This prevents any undesirable pressures from building up in the gastrointestinal tract. During operation of this mode, a bubble of air builds up in the intestine creating positive pressure which forces fluids up through lumen 24. There is no suction on lumen 24 is this mode because the negative line is open to the atmosphere at valve 80, making it a pump not an aspirator.

The primary feature of the present invention is accomplished by preventing blockage of the openings of the negative pressure line independently of that line, and without reversing the direction of flow of fluids in the negative line.

In operation, a small bubble is injected into the digestive tract adjacent to the negative orifice, and by lifting the surrounding membranes, frees blockage. During the negative cycle, the bubble is sucked into the negative line, but with it also comes fluid. Thereafter, if the negative cycle is continued, intestinal membranes or debris may plug the openings, but the timing sequence can be selected to stop the negative cycle at that point, and reactivate the positive cycle for a short period. Part of the positive pressure bubble may escape from the area of the negative pressure opening and rise in the tract, but this causes no problem because any gas under pressure in the tract can readily be drawn off into the negative lumen 24 by moving the openings around to expose them to the gas. Of course, motion of the tube 20 is not impeded because of the constant "freeing" action of the positive cycle.

The embodiments of the present invention are intended to be merely exemplary and those skilled in the art will be able to make numerous variations of them without departing from the spirit of the present invention. All such variations and modifications are intended to be within the scope of the present invention as defined in the appended claims.

Claims

I claim:

1. An aspirator-pump and tube combination for evacuating liquid from an intestinal cavity wherein debris or tissue can block the evacuating means comprising:

a. air pump means with connections to supply both positive and negative pressure (relative to atmospheric) air;

b. a multi-lumen tube adapted to be inserted into said cavity having a positive air pressure lumen connected to the positive air connection of said pump and a negative pressure lumen connected to the negative pressure connection of said pump;

c. means including valves and a timer for supplying positive pressure air from said pump to said positive air pressure lumen for a measured period of time;

d. means for withdrawing liquids from said cavity comprising walls forming a negative pressure opening in said negative pressure lumen communicating with said cavity, and

e. means for moving debris or tissue away from said negative pressure opening comprising walls in said positive air pressure lumen forming a positive air pressure opening, and additional walls supporting said positive air pressure opening in position to project air against said debris or tissue blocking the negative pressure opening during said period.

2. The aspirator-pump and tube combination according to claim 1 including additional negative and positive pressure openings spaced along said tube.

3. The aspirator-pump and tube combination, according to claim 1 wherein said positive and negative pressure lumens are parallel tubes.

4. The aspirator-pump and tube combination of claim 1 wherein said positive pressure lumen is within said negative pressure lumen.