Abstract:
The present invention provides an apparatus for instilling fluid into a patient having an intestinal stoma so as to administer an antegrade colonic enema. The portable instillation apparatus comprising in combination: a fluid reservoir, a pump assembly, a control module, a fluid delivery tube and an intestinal stoma catheter wherein the control module is operable to automatically deliver a predetermined volume of instillation fluid at a specific flow rate and pressure range suitable for a particular patient. The portable instillation apparatus utilities a gear pump manifold and a robust empty reservoir detection mechanism, facilitating the portability, durability and reliability of the apparatus over-coming the disadvantages of traditional peristaltic pump mechanisms. The portable instillation apparatus maximizes the ease of transport and use of the device while also enabling a method for a patient to self-administer an antegrade colonic enema within a short time period and without intervention.

Description:
[0001]    The present invention relates to a human large intestine flushing apparatus such as required for patients with large intestinal disorders including fecal incontinency or intractable constipation. More particularly, to an apparatus for automatic instillation of flushing fluids to the large intestine for managing bowel movements in patients exhibiting fecal incontinency, intractable constipation or related disorders who have undergone a Malone type, Monti plasty or similar surgical procedure wherein a catheterizable stoma is constructed into the large intestine allowing insertion of the instillation apparatus for the purpose of administering an Antegrade Colonic or Continent Enema (ACE). 
       BACKGROUND OF THE INVENTION 
       [0002]    Medical disorders of the large intestine can result in symptoms which prevent the patient from adequately evacuating fecal material from the large intestine. Fecally incontinent and intractably constipated patients have difficulties managing their bowel movement. Bowel movement management is typically accomplished by a daily flushing of the large intestine by enema wherein fluids are introduced into the large intestine to flush materials retained in the intestine. Fluids can be introduced from the rectum into the large intestine to flush and allowed to drain out. There are disadvantages with the application of a rectal enema flush including the lack of penetration of fluid throughout the entire interior of the large intestine, thereby leaving fecal matter lodged in the intestine, cleanliness issues, general difficulty of self application, lack of privacy, discomfort, and bulky enema equipment. 
         [0003]    Surgical techniques have been developed to permit the application of an enema into the large intestine from the top of the intestine as opposed to the rectum. The enema from above or Antegrade Colonic Enema requires that a patient undergo a surgical procedure to create a stoma or entry through the skin into the intestine proximal to the top of the large intestine, principally to the cecum. Fluids are introduced and permitted to flush and drain to and out the rectum. Several surgical procedures have been developed to construct an entry point intestinal stoma proximal to the cecum. The Malone or Continent Appendicostomy surgical procedure constructs a connection conduit made between the appendix and the navel (belly-button) wherein a “button” or piercing is created at the navel. Using the “button” the patient can insert a needle or catheter and deliver fluid, a process known as instillation, into the large intestine as an alternative to performing a rectal enema. The procedure permits use of the appendix or neoappendix to be used as a way to administer an antegrade colonic enema or an antegrade continent enema without a rectal maneuver. 
         [0004]    Another similar procedure known as a Monti plasty procedure surgically fashions a conduit between the large intestine and an insertion stoma in the skin also for purposes of instillation of an antegrade colonic enema. 
         [0005]    Regardless of the technique elected to create a stoma entry into the large intestine, the instillation of fluids requires an external mechanism to introduce the fluids into the stoma and therefore into the intestine. Fluid is typically introduced to sweep the large intestine of fecal matter at least once a day. 
         [0006]    The typical method for irrigating patients who have undergone a Malone, Monti or similar surgical procedure have been required to introduce fluids into the large intestine by means of a drip consisting typically of a saline filled bag elevated above the patient with a drain tube attached at one end to the bag and terminated by a needle or catheter at the other end which, in turn, is inserted into the button or piercing at the navel. Fluid is permitted to drip into the large intestine which migrates to the rectum and the flushing is accomplished. The drip procedure requires the patient to remain immobile and sitting on a commode as the fluid passes through the intestine and out the rectum for a period of several hours. The procedure typically requires on standard drip bag to be used. 
         [0007]    More recently, flushing of the intestine through the entry stoma piercing has been accomplished by introducing fluids into the large intestine by utilizing a series of fluid-filled syringes. A large syringe filled with the flushing fluid is attached to a needle or catheter and inserted into the piercing or button. The fluid contents of the syringe is dispensed and then refilled periodically until the required amount of fluid is delivered. The syringe technique requires two competent people to administer. One caretaker is required to fill the syringe. At the same time the patient is responsible for pinching the catheter shut when the syringe is removed from the catheter as introduction of flushing fluid into the intestine produces back pressure. The catheter must be pinched shut to prevent fecal matter and intestinal fluid from flowing back through the catheter and out the now open catheter end when the syringe is removed for filling. The procedure using the syringe technique requires the syringe to be refilled 10 to 20 times. If the client is not competent or able enough to assist, a second caretaker is needed. Many individuals requiring this type of treatment often have other handicaps that prevent them from assisting themselves. The use of multiple syringes also increases the risk of introducing air into the installation fluid. The introduction of quantities of air into the soma necessarily induces significant discomfort or pain in the patient. 
         [0008]    Automated instillation devices directed to address the disadvantages of the drip bag and syringe techniques exhibit the principle disadvantage associated with the difficulty to manipulate the various elements of the device as required during self-administration, usually requiring the use of both hands for manipulation. Devices with separate fluid reservoir bags must be separated from the apparatus in preparation to fill the reservoir bag a maneuver that requires dexterity not always present in patients requiring the apparatus. Further, separation of the fluid reservoir can introduce volumes of air into the pump potentially causing discomfort to the patient during the administering the procedure. 
         [0009]    In order to determine when a predetermined volume of instillation flushing fluid has been delivered, a pump control system may monitor the pump motor current and stop the pump motor with the pump motor current draw increase as a sealed collapsible fluid reservoir is depleted of fluid. The disadvantage of this technique is that current draw from the pump varies between pumps, the viscosity of flushing fluid, and the varying fluid resistance resulting from using differing sizes of catheters, thereby resulting in difficulties starting the apparatus and causing the pump to run dry. Alternatively the delivery volume may be determined when using an open reservoir by incorporating a level sensor to stop the flow at a predetermined volume. Such level sensors often prone to triggering falsely due to obstructions, other external effects or corrosion. In the case of open reservoir systems, level sensors located within the reservoir typically indicate an empty reservoir before the fluid is fully depleted resulting in inaccurate fluid volume delivery and residual fluid at the bottom of the reservoir complicating use of a portable device. 
         [0010]    There is a need for an improved instillation apparatus and method to administer an antegrade colonic that avoids these disadvantages. The present invention fulfills this need, and further provides related advantages. 
       SUMMARY OF THE INVENTION 
       [0011]    Accordingly, the present invention is directed to colonic instillation pumps and, more specifically, to such an automated apparatus with improved portability, reliability and user convenience. 
         [0012]    The present invention further improves the portability, reliability and ease of use of prior art devices by integrating all pump components into a single unit and incorporating high reliability fluid delivery shutoff and improved volumetric delivery. The present invention therefore generally comprises a fluid reservoir having an open top and a bottom suitable for holding instillation fluid, an internal component chamber having a top and a bottom wherein the chamber top is formed from the fluid reservoir bottom being a bulkhead plate, a pump assembly having a motor, drive transfer, and manifold with the manifold mounted in the bottom of the fluid reservoir and inside the internal component chamber having an inlet and an outlet with the inlet in direct fluid communication with the fluid reservoir and the outlet protruding upwardly through the bulkhead into the fluid reservoir but not in fluid communication with the reservoir, a delivery tube being flexible and having proximate and distal ends with the proximate end in direct fluid communication with the pump manifold outlet, a catheter suitable for insertion into a patient with an intestinal stoma constructed for purposes of instilling fluid into a patient&#39;s intestines in direct fluid communication and removably attached to the distal end of the delivery tube, a pump control module communicatively attached to the pump assembly for purposes of activation and mounted in the internal component chamber, a fluid recess chamber formed in the inlet of the pump manifold and in direct fluid communication with the fluid reservoir, the fluid recess chamber being a cylindrical expansion of the pump manifold inlet has a fine sieve filter positioned level with or below the fluid reservoir, an optical level sensor mounted in the fluid recess chamber wall operable to communicate the presence of fluid in the fluid recess chamber to the pump control module to which it is communicatively attached, and a vertical draw tube forming an extension of the pump manifold inlet with the top positioned near and below the filter having a drain hole tangent with the bottom of the recess chamber, the pump control module further being in direct electrical communication with a power supply, and a user interface panel mounted proximate to the internal component chamber being in direct electrical communication with the pump control module. 
         [0013]    The method of using the present invention to self-administer an antegrade colonic enema comprises the steps of; filling the reservoir with a flushing fluid, priming the device, inserting the catheter suitable for insertion into a patient with an intestinal stoma, activating the apparatus, waiting for the apparatus to automatically deactivate, and then removing the catheter from the patient&#39;s intestinal stoma. The operation is therefore simple and within the capabilities of most patients, including those with disabilities. 
         [0014]    Reduced manufacturing costs are accomplished by eliminating the need for molds to be produced as the pump body may be fabricated from stock sizes of polymer tubing cut to form a cylinder. The bulkhead plate, preferably also constructed of a polymer, is pressed into place inside the polymer tube and secured in place by an o-ring circumferentially mounted to the bulkhead plate. The region above the bulkhead plate is the fluid reservoir. The region below the bulkhead plate is a component chamber wherein the bottom of the chamber comprises a circular base element also with a circumferentially mounted o-ring pressed into the bottom of the polymer cylinder. 
         [0015]    As the apparatus is intended to be portable, in normal use the pump is periodically subjected to inspection such as at airports and other such security points, another objective of the invention is therefore to minimize the burden of security inspection procedures. Use of a transparent polymer cylinder to form the body of the apparatus enables convenient visual inspection of the device&#39;s internal components thereby improving ease of transit. Further a flexible delivery tube, being connected within the bottom of the fluid reservoir permits easy storage of the tube within the fluid reservoir for transport. Most powered instillation devices require mains power. In the present apparatus, power is supplied by batteries therefore eliminating the need for mains power to be available improving convenience, safety and regulatory acceptance. 
         [0016]    Of noteworthy import, the present invention utilizes a unique integrated pump manifold assembly. Cleanliness of the fluid flow paths in devices that deliver fluid to the body is important. Keys to maintaining the cleanliness of the pathway include reducing the overall path length, minimizing back flow, and to reduce the number of crevices or surface imperfections where debris may collect. Peristaltic pumps, well know to those in the field, are typically used in the prior art because the peristaltic pumps do not require a back flow restriction device and the activating surfaces of the pump are comprised of a flexible tube, known as a tube set, which is squeezed. The tube set has a smooth interior and requires replacement. Unfortunately peristaltic pumps are large and bulky compared to gear pumps with similar volume capabilities. And, repeated squeezing of the tube set eventually results in sloughing of material from the tube into the delivered fluid as the tube wears. Consequently, the tube set must be replaced frequently. Peristaltic pumps also consume more power than gear pumps. The characteristics of peristaltic pumps are therefore not suitable for small and portable instillation pumps. The pump manifold assembly of the present invention overcomes these disadvantages by incorporating a gear pump in combination with a back flow restrictor that permits the use of a gear pump. The back flow restrictor is located in the fluid path of the manifold and prevents back flow into the delivery tube and the reservoir through the gear pump. Further the restrictor requires a small fluid pressure in order to allow a forward flow thereby assuring firm seating of a valve ball on the valve seat in the restrictor and hence a secure seal. Still further by integrating the fluid flow direction restrictor in-line and in close proximity to the gear pump, the fluid path can be constructed in such a fashion that it is short and having a smooth interior while gaining the advantages of the reliability of gear pumps. 
         [0017]    Typical back flow restrictors utilize a diaphragm construction that tend to allow back flow at low pressures and also provide surface areas where deposits can collect. The smooth surface of the valve ball and small valve seat surface area mitigate the buildup problem and prolong the life of the mechanism. A smooth surfaced glass material is used form the valve ball in the present invention. 
         [0018]    Water and flushing fluid intrusion into the interior of mechanized instillation devices manifests undesirable corrosion and deterioration of internal components thereby reducing the mean time to failure of the pump and the various electronic control components. The construction of the present invention utilizing a sealed interior component chamber increases reliability and availability of the apparatus by attaining improved water resistance over prior devices. Hence, a further objective of the invention is to provide an instillation pump that is water resistant for protection of the internal components and for more convenient cleaning. 
         [0019]    Ideally, the instillation fluid draw from the fluid reservoir should be complete such that no or minimal draining by the user is required. To accomplish this objective, the present invention incorporates a fluid recess chamber in the inlet of the pump manifold presenting a fine sieve filter at a low point within the bottom of the fluid reservoir through which the instillation flows into the chamber having a vertical draw tube in direct contact with inlet portion of the pump at the bottom of the chamber, with the top end open near the sieve filter and a small opening on the side of the tube near the bottom of the recess chamber. An optical fluid level sensor is positioned to face into the fluid recess chamber and is used to detect low fluid level and, in turn, is in direct electrical connection with the pump control module for purposes of shutting off the pump motor when the fluid level is low. The fluid recess chamber mechanism facilitates the use of a fine sieve filter which, due to the surface tension of the instillation fluid may retain a small air bubble or bubbles below the filter in normal use. This condition also occurs during initial filling of the reservoir as air is trapped below the filter. A vertical draw tube top opening is positioned such that when the pump is started, any small air bubble is drawn away from the filter thereby preventing trapped air which can prevent fluid from entering the fluid recess chamber or falsely indicate an empty reservoir condition. The small opening in the side of the vertical draw tube then also permits instillation fluid to drain from the recess chamber and below the optical fluid level sensor. The pump control module further orchestrates a sequence of steps when the apparatus is first activated to manage the air removal from the recess chamber. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0020]    The accompanying drawings, which are incorporated in and constitute a part of this specification illustrate embodiments of the invention and, together with the description, serve to explain the features, advantages, and principles of the invention. 
           [0021]    In the drawings: 
           [0022]      FIG. 1  is a perspective view of an embodiment of the portable instillation apparatus constructed in accordance with this invention when arranged so as to illustrate the major components of the pump assembly of the invention. 
           [0023]      FIG. 2  is a top plan view of the invention shown in  FIG. 1  showing the inlet and outlet of the pump manifold in the bottom of the fluid reservoir. 
           [0024]      FIG. 3  is a bottom plan view according to the present invention showing the removable battery compartment cover. 
           [0025]      FIG. 4  is an elevation sectional view taken on Line  4 - 4  of  FIG. 2  showing details of the pump manifold according to the present invention. 
           [0026]      FIG. 5  is an enlarged elevation sectional view of the portion at  5  of  FIG. 2  showing details of the fluid recess chamber with instillation fluid present in the fluid reservoir. 
           [0027]      FIG. 6  is similar to  FIG. 5  showing details of the fluid recess chamber with an empty fluid reservoir. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0028]    Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications may be made without departing from the spirit and scope of the invention. Accordingly, the invention is not to be limited except as by the appended claims. Referring now in greater detail to the various figures of the drawing wherein like reference characters refer to like parts, there is shown at  10  in  FIG. 1 , portable instillation apparatus constructed in accordance with the subject invention. It will be appreciated that while the apparatus is particularly suited for affecting an antegrade colonic enema procedure, device may also be used of other similar irrigations of the intestines as well. Moreover, the subject invention can further be used for non-enema applications wherein instillation of a fluid is indicated. 
         [0029]    A preferred embodiment of the instant invention is illustrated in  FIGS. 1-6 .  FIGS. 5-6  are directed to details of the fluid recess chamber, an essential element of the present invention. 
         [0030]    In the preferred embodiment, the present invention comprises a cylindrically shaped tube forming the housing for a fluid reservoir having a top and a bottom, a circular bulkhead plate having a top and a bottom, forming the bottom of the fluid reservoir and the top of a component chamber, pressed and sealed, by means of an o-ring, into the inside circumference of the cylinder housing, the component chamber having a top and a bottom with bottom being a circular base inserted into the inside circumference of the bottom of the cylinder housing, sealed by means of an o-ring, thereby enclosing and protecting the component chamber from fluid intrusion, the circular base further comprising a battery cavity accessible from the bottom of the base by removing a battery cover threaded to the circular base suitable for retaining a battery, a pump manifold mounted through the bottom of the bulkhead pate having an inlet and an outlet with the inlet in direct fluid communication with the fluid reservoir and the outlet protruding upwardly from the pump manifold into the fluid reservoir but not in fluid communication with the reservoir, the pump manifold further comprising a gear pump having a pump motor, the gear pump being in direct fluid communication with the manifold inlet and a back flow restrictor, the restrictor being operable to permit flow only in a direction from the manifold inlet, the restrictor being in further direct fluid communication with the manifold outlet, a delivery tube being flexible and having a proximate and distal end with the proximate end in direct fluid communication with the pump manifold outlet, a catheter suitable for insertion into a patient with an intestinal stoma constructed for purposes of instilling fluid into a patient&#39;s intestines in direct fluid communication and removably attached to the distal end of the delivery tube, a pump control module communicatively attached to said gear pump motor suitable for activating the pump motor, the manifold inlet further comprising a fluid recess chamber being a cylindrical expansion of the inlet comprising a fine sieve filter fitted to the top of the recess chamber and in direct fluid communication with the reservoir, a vertical draw tube with a top near and below the filter being removably inserted into the pump manifold inlet and secured with a seal, and an optical fluid level sensor mounted in wall of the recess chamber operable to communicate the presence of fluid to the pump control module, the pump control module further being in direct electrical communication with the battery, a user control panel mounted to the cylinder proximate to the component chamber with a switch and indicators being in direct electrical communication with the pump control module, and a lid assembly being generally circular is detachably inserted into the circumference of the top of the fluid reservoir. 
         [0031]    Referring to  FIG. 1  at  10 , an overall perspective view and the preferred embodiment of the apparatus according to the present invention, the portable instillation apparatus is of a unibody cylindrical construction comprising a transparent polymer cylinder  12  forming the housing wherein a fluid holding portion forms the reservoir  14  and a component portion forms the component chamber  16 . The fluid reservoir portion is defined by the inside of the polymer cylinder  12  and the bulkhead  18  forming the bottom of the reservoir  14  which is pressed into the inside circumference of the polymer cylinder  12 . The pump manifold assembly  20  has a circularly shaped top pressed into the bulkhead  18  from below into a circularly shaped receiving opening in the bulkhead  18 . An pump manifold  20  further has outlet adapter  22  directed upwardly into the fluid reservoir  14  for adapting the outlet of the pump manifold  20  to a delivery tube  26  and providing direct fluid communication from the outlet of the pump manifold  20  to the deliver tube  26  without providing for fluid communication with the fluid reservoir  14 . A fine sieve filter  24  is removably pressed into the inlet of the pump manifold  20  through which fluid is drawn being secured by a resilient draw tube seal  104  and being in direct fluid communication with the fluid reservoir  14 , thereby prohibiting particulate matter from entering the pump manifold  20 . 
         [0032]    Still referring to  FIG. 1 , a flexible delivery tube  26  is removably pressed onto the pump manifold outlet adapter  22  at the proximate end of the tube while the distal end is removably pressed into a catheter adapter  28  having an inlet sized to receive the flexible delivery tube  26  and an outlet to receive a stoma catheter  30 . A stoma catheter  30  is removably pressed into the outlet of the catheter adapter  28  wherein the assembled components provide for direct fluid communication from the pump manifold outlet to and through the stoma catheter delivery openings  43  and into a stoma on the patient. 
         [0033]    Also in  FIG. 1 , the component compartment  14 , having a top formed from the bulkhead plate  18  and the bottom from the circular base  32  pressed into the bottom of the polymer cylinder  12 . The component chamber  14  houses the pumping elements, pump control module and user control panel  34 . The user control panel  34  is mounted in an opening in the circumference of the polymer cylinder  12 . The user control panel  34  provides a user activation switch  36  which is the sole user activating and deactivating means for the device. Also provided in the user control panel  34  is power connector  38  for providing electrical power to the device for purposes of charging internal rechargeable batteries. Visual illuminating devices are also provided on the user control panel  34  for indicating the internal battery charge levels and conditions at  40 ,  42 ,  44 , and  46 ; and also provided is the activation status at  48 . 
         [0034]    The operation of the apparatus is easy and simple to understand as patients requiring the device are often significantly disabled. The user fills the fluid reservoir  14  with fluid to be instilled, primes the pump, if necessary, by momentarily pressing the user activation switch  36 , momentarily pressing the user activation switch  36  again to deactivate the device when fluid appears at the delivery openings  43  of the stoma catheter  30 , inserting the stoma catheter  30  into the patient&#39;s stoma, and momentarily pressing the user activation switch  36  once again to begin the delivery of fluid into the patient&#39;s stoma. The operation of the apparatus is thereon directed by the pump control module which maintains a safe pressure and flow rate into the patient until the instillation fluid is depleted from the fluid reservoir or directed to stop by the user momentarily pressing the user activation switch  36 . The total volume of instillation fluid to be delivered into the patient is user selected by filling the fluid reservoir  14  to a preselected or prescribed graduation mark. The graduation marks  60  are etched into the transparent polymer cylinder  12  corresponding to various fluid volumes. 
         [0035]    Referring to  FIG. 2 , a top plan view according to the present invention, the polymer cylinder  12  surrounds the fully revealed top of the bulkhead plate  18  with the top of the pump manifold  20  protruding through and the opening in the bulkhead plate  18 . Preferably, the top of the pump manifold  20  is positioned recessed slightly below the surface of the bulkhead plate  18  so as to provide a low point drain area at the bottom of the fluid reservoir. The fine sieve filter  24  is removably inserted into the top of the inlet of the pump manifold  20 . The pump manifold outlet adapter  22  is shown protruding upwardly from the pump manifold  20  with the proximate end of the delivery tube  26  pressed over the adapter. Note that the elements of the pump assembly comprising not only the pump manifold  20 , but also the pump motor  62 , and pump drive transfer  64  located below and sealed in the component chamber and below the bulkhead plate  18 . The drive transfer  64  provides a magnetically coupling with the gear pump heads located in the pump manifold  20 . The user control panel  34  protrudes from the opening in the polymer cylinder into the component chamber and is fashioned to provide a watertight fitting. Note also that the fine sieve filter  24  and pump manifold  20  are positioned in the bulkhead plate  18  towards the outside circumference of the fluid reservoir so as to provide mounting space for the pump motor  62  and also to allow a user to tip the device to collect fluid over the fine sieve filter thus providing a means to reduce the residual fluid in the reservoir to a minimum. 
         [0036]    Now in  FIG. 3 , showing a bottom plan view according to the present invention, the circular base  32  is comprising a disc shaped element having a plurality of round recesses, typified at  52 , wherein feet, being constructed of rubberized or anti-skid material, typified at  54 , are inserted and secured. A battery compartment cover  56  is secured in the base  32  by threads presented around the circumference of the cover and received by threads in the base  32 . Finger cut outs  66  and  68  in the cover  56  provide a grip for the user to unscrew and remove the cover  56 . 
         [0037]    A cross-section view provided in  FIG. 4  reveals the internal arrangement of the apparatus. Watertightness of internal is achieved by o-ring seals between all of the major structural elements with the exception of the user control panel  34  which is secured by water resistant adhesives. The relationship between the base  32  and the cover  56  are illustrated wherein the circumference threads  72  of the cover  56  are received by the threads  74  of the base  32 . Base o-ring  76  is retained in a recess of the base  32  thereby providing a watertight seal around the battery  70 . The base  32  has a mounting recess  78  to fit snuggly within the polymer cylinder  12  and an o-ring recess  82  to accommodate o-ring  80  thereby providing for the polymer cylinder  12  to receive the base  32  by pressing the base  32  into the bottom opening of the polymer cylinder  12 . Similarly, the bulkhead plate  18  is press fit into the inside of the polymer cylinder  12  by means of bulkhead plate o-ring  84  retained by plate outside recess  86  around the circumference of the bulkhead plate  18 . Also, similarly, the top portion of the pump manifold  20  is pressed into the bulkhead plate pump o-ring  90  retained by plate inside recess  88  forming a watertight seal between the pump manifold and the bulkhead plate  18 . Pump manifold mount  132  located between the pump manifold  20  and the base  32  is constructed from a resilient material being compressed upon insertion of the base  32  in the polymer cylinder to insure that the pump manifold  20  remains secured to the bulkhead plate  18 . 
         [0038]    In the preferred embodiment, the pump control module  92  is mounted to the back of the user control panel  34  by standoffs  94  and  96  within the watertight component chamber  16  as illustrated in  FIG. 4 . The pump control module  92  is comprising a programmable processor and suitable interface electronic components to be in direct electrical communication with the user activation switch  36 , the battery condition indicators  40 ,  42 ,  44  and  46 , the power indicator  48 , the power adapter  38 , the battery  70 , an optical fluid level sensor  98 , and the pump motor  62 . The battery condition indicators  40 ,  42 ,  44  and  46  show conditions of completely full, full, satisfactory and low while the apparatus is active or charging. The power indicator is visible when the apparatus is active. Non-rechargeable or rechargeable batteries may be utilized wherein the pump control module  92  is capable of detecting of rechargeable batteries are inserted and manages the recharging of the batteries when power is presented to the power adapter  38 . The rechargeable batteries have unique connectors to facilitate detection. A specialized battery holder is provided for non-rechargeable batteries. The number of cells in the battery  70  is used to limit the maximum power to transfer to the pump thereby performing as a safety limiting mechanism dependent on the particular patient. For example, when issued to a child, a battery with fewer cells is utilized than if the apparatus were issued to an adult. The pump control module  92  is further engineered to reduce the total power transfer when non-rechargeable batteries are detected to prevent users from inadvertently applying high power as non-rechargeable batteries are intended for emergency use only. 
         [0039]    The pump control module  92  is also operable to direct the automatic sequencing of the apparatus. When the user directs the apparatus to start pumping by pressing the user activation switch  36 , the pump motor, being electric is started at a predetermined speed commensurate to satisfy the pressure and volume flow rate for the particular patient as determined by the preselected capacity of the battery and drives the gear pump drive gears  118  and  120  to rotate within the gear pump cavity  108  to draw fluid through the pump cavity inlet path  106  and out through the pump cavity outlet path  142 . The intermeshed drive gears  118  and  120  are magnetically coupled to the pump drive transfer mechanism thereby isolating the fluid pathways from external contamination. As the fluid is drawn through the pump cavity  108  and out through the pump cavity outlet path  142 , a back flow restrictor  110  in direct fluid communication with the pump cavity outlet path  142  is comprising a back flow restrictor valve seat  116 , a valve ball  114 , and a back flow flow restrictor spring  112  secured by the outlet adapter  22  positioned in the same respective order such that the fluid flow from the pump cavity  108  forces the valve ball  114  to lift from the valve seat  116  and to flow to the pump manifold outlet. The valve ball  114  re-seats by spring  112  against the valve seat  116  when the flow stops or attempts to reverse to the pump cavity. The valve ball  114  is preferably constructed of glass so as to minimize build up of deposits. 
         [0040]    The pump control module  92  begins to monitor the optical level sensor  98  for indications of low fluid level after a 3 to 5 second delay from the beginning of activation so as to allow sufficient time to evacuate the fluid recess chamber of air. When the optical level sensor  98  indicates no fluid in the chamber, the pump control module  92  deactivates the pump motor and deactivates the power indicator  48  thereby completing the sequence. The pump control module  92  further monitors the pump motor current to indicate the fluid pressure such that the delivery of the fluid is stopped if the pressure exceeds predetermined levels for the particular patient or if an obstruction occurs preventing fluid flow. 
         [0041]    Of particular import in the present invention, the fluid recess chamber  100 , in  FIG. 4 . The fluid recess chamber  100  having a top, width, bottom, and height forms the fluid receiving portion of the inlet of the pump manifold  20  comprising a cylindrically shaped expansion opening of the pump manifold  20  inlet being open on the top and having an outlet bore in the bottom wherein a vertical draw tube  102  is removably press fit into the bore having a length such that the top of the tube  124  is near the top of the chamber and also having a small bore  122  in the side of the tube  102  tangent to the bottom of the chamber  100  comprising seal  104 . The draw tube seal  104  is constructed of resilient material formed in a disk shape having a diameter of the recess chamber and an opening to receive the vertical draw tube  102 . A recess  144 , as illustrated in  FIG. 5 , around the top of the fluid recess chamber  100  receives the fine sieve filter  34 . The fine sieve filter  34 , the vertical draw tube  102  and the seal  104  are therefore all removable for cleaning. 
         [0042]    The fluid recess chamber  100  is critical to the proper operation of the device and facilitates a number of significant advantages over the prior art. Firstly, as illustrated in  FIG. 5 , the chamber permits the use of a removable fine sieve filter  34  presented to the reservoir at the pump manifold  20  inlet. Drawing fluid through a fine filter, as opposed to pushing fluid through a filter at the pump outlet, can be problematic due to air being trapped by surface tension below the filter, as indicated the air bubbles at  126 , or during conditions prior to pump priming when the fluid recess chamber  100  may be empty resulting in the optical level sensor  98  detecting no fluid level in the fluid reservoir. The vertical draw tube  102 , with the top  124  positioned proximate to the fine sieve filter  124 , is provided to draw trapped air bubbles  126  away from regions near to the bottom of the fine sieve filter  34  when the pump motor is first started at which time the optical level sensor output is briefly disregarded by the pump control module to accomplish the procedure. 
         [0043]    Secondly, the chamber improves the reliability of the method of detection of an empty fluid reservoir as illustrated in  FIG. 6 . Sensing the presence of fluid utilizing mechanical means is often unreliable and prone to failure; however, optical level sensors are generally highly reliable. Using optical level sensors, however, are sensitive to ambient light levels. For example, sun light or bright lighting can falsely trigger an optical level sensor. According to the present invention, the fluid recess chamber is comprising an optical level sensor within the cylindrical wall of the chamber  100  and below the fine sieve filter  34 , thus the filter shades the sensor from ambient light conditions. Because the top  124  of the vertical draw tube  102  is positioned proximate to the fine sieve filter  34 , a tube drain hole  122  positioned adjacent to the bottom of the recess chamber  100  permits the chamber to drain fully reducing the fluid level below the optical level sensor  98  as the final volumes of fluid are drawn, as shown by the fluid flow at  128 , into the pump. Absence of the tube drain hole  122  would result in fluid to be retained in the fluid recess chamber at levels indicated at  130 . 
         [0044]    Thirdly, incorporation of the fluid recess chamber minimizes retention of the fluid in the reservoir as the recess chamber represents the lowest point in the fluid reservoir system. Consequently the fluid reservoir must be completely empty first before the optical level sensor detects a low fluid level. As the diameter of the fluid recess chamber is small relative to the fluid reservoir, the volume of retained fluid is necessarily smaller then accomplished by other methods. 
         [0045]    The structural elements of the apparatus may be constructed of any suitable material; however, materials contacting the instillation fluid should not leach, slough or be prone to retain deposits. Further, materials contacting the instillation fluid should be resistant to corrosion. 
         [0046]    So as to efficiently and effectively administer an antegrade colonic enema, the pump control module is programmed, pumping mechanisms are sized, and a sufficient power supply provided to deliver fluid pressures in the range of 2 mm H2O to 500 mm H2O and fluid flow rates in the range of 50 ml/minute to 600 ml/minute as measured at the standard reference pressure and temperature conditions of 1 kPa and 0 degrees Celsius. 
         [0047]    Returning to  FIG. 4 , a reservoir cover  134  is fitted to the top opening of the fluid reservoir  14  for purposes of storage and transport. During transport, the stoma catheter, adapter and flexible delivery tube are stowed within the fluid reservoir  14 . The user pulls a centrally position cover knob  136  upwardly relative to the cover resulting in the cover o-ring  138  to be reduced in circumference as the o-ring retainer mechanism  140  reduces in diameter responsive to the knob  136  position. The user places the cover  134  into the top of the reservoir  14 , then by pressing the cover knob  136  downwardly relative to the cover, the o-ring retainer mechanism  140  expands in diameter thereby compressing the cover o-ring  138  against the inside circumference of the reservoir  14  thereby providing a snug and watertight fit suitable for storage and transport of the apparatus. 
         [0048]    Use of the portable instillation apparatus is very simple and can be managed by a patient or caregiver with very little training As many patients use tap water as the flushing fluid for antegrade colonic enemas, the open reservoir system provides easy filling direction from a sink faucet as well as easy access for cleaning. The graduation marks provide an easy means for selecting the total volume to be administered. 
         [0049]    More over, the present system provides facile utilization due to: (1) minimal patient training, (2) no filling of fluid reservoir bags or other sealed containers, (3) open and bottom drawn reservoir system provides easy filling and minimal air entrainment, (4) high availability and reliability, and (5) ready portability. 
         [0050]    In view of the foregoing, it will be seen that the several objects of the invention are achieved and other advantages are attained. Although the foregoing includes a description of the best mode contemplated for carrying out the invention, various modifications are conceivable.