Patent Publication Number: US-2004054350-A1

Title: Enteral feeding unit having a reflux device and reflux method

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
     [0001] This application relates to the following co-pending commonly owned patent application: U.S. patent application Ser. No. 09/665,194, filed on Sep. 18, 2000, entitled “Apparatus and Method for Relieving Gastric Pressure During Enteral Feeding.”  
    
    
     
       BACKGROUND OF THE INVENTION  
       [0002] Enteral nutrition is a form of hyperalimentation and metabolic support in which nutrient formulas or medicaments are delivered directly to the gastrointestinal tract, either the stomach or the duodenum. Nutrient administration is accomplished through use of an enteral feeding system or device. Certain enteral feeding devices include pumps which deliver feeding fluid to the patient. Other enteral feeding devices rely upon gravity to move the feeding fluid from a container (suspended above patient level) to the patient.  
       [0003] During enteral feeding, excessive gastric pressure may result from the accumulation of gas or liquid resulting from stomach contractions, movement of the patient&#39;s abdomen, crying or through normal formation of gas. From time to time, the body relieves such excess gastric pressure by expelling gas or liquid or reflux fluid. The term, “reflux fluid” as used herein includes any gas, any liquid, any partially solid and liquid substance or any material which the body can expel.  
       [0004] Typically the expulsion of reflux fluid occurs during a burping response in which reflux fluid is expelled upward from the stomach through the esophagus and is expressed out of the mouth, where the enteral feeding tube is orally intubated or through the nasal passages, where naso-pharyngeal intubation has been utilized.  
       [0005] When the patient expels reflux fluid, the reflux fluid often flows out of the patient&#39;s mouth or the nose because the enteral feeding device is not adapted to receive the back flow of reflux fluid. Specifically, the feeding fluid pressure in the enteral feeding device prevents reflux fluid from flowing from the patient into the patient feeding tube. Though gastric reflux pressure created by even limited episodes of stomach movement or crying may exceed several feet of water, such reflux pressure can be inadequate to overcome the greater forward fluid pressure present within the patient feeding tube. As a result, expelled reflux fluid can accumulate in or around the nasal or oral passages.  
       [0006] This accumulation of reflux fluid is undesirable because the patient loses feeding fluid, and moreover, it is possible for the patient to inhale the reflux fluid into the lungs with possible risk of aspiration pneumonia or other ailments. The problem of gastric reflux pressure and reflux fluid is most acute in neonates, infants and small children in which gastric pressure may rapidly accumulate through periodic episodes of crying and because such patients have yet to develop control over the burping response as a means of gastric pressure relief. However, it is not unusual for adult patients undergoing enteral feeding to experience occasional difficulties with gastric reflux pressure relief.  
       [0007] There is a known gastric pressure relief device which is used in conjunction with enteral feeding devices. Such relief device includes a bag connected to a tube which is in fluid communication with the feeding device tube and the patient feeding tube. The bag vents to the atmosphere. If a patient expels enough reflux fluid, the bag eventually fills with reflux fluid, and any gas can escape to the atmosphere. Depending upon the pressure conditions during feeding, the reflux fluid can remain in the bag or flow back to the patient for feeding. One disadvantage with such relief device is the difficulty or inability for users to measure the amount of reflux fluid. Another disadvantage with such relief device is the difficulty in tracking changes of volume in the bag due to the irregular shape and the size of the bag. This adversely impacts accurate enteral administration of fluid nutrient formula, particularly since a selected quantity of nutrient formula is administered over a given period of time. Therefore, there is a need to overcome such disadvantages.  
       SUMMARY OF THE INVENTION  
       [0008] The enteral feeding unit, in one embodiment of the present invention, includes an administration device, such as a feeding bag and pump set, connected to a reflux device which, in turn, is connected to a feeding tube received by the patient. In one embodiment, the reflux device includes a relatively large, cylindrical reservoir tube, preferably non-collapsible, which collects and returns reflux fluid to patients. The reservoir tube bears a plurality of volumetric marks which enable users to track the amount of reflux fluid which patients expel over time. Since the reflux device is comprised completely of tubes and tube connectors, the reflux device is relatively simple to manufacture, assemble and use. Specifically, the cylindrical shaped reservoir tube facilitates a user&#39;s reading and tracking of changes in the volume of reflux fluid.  
       [0009] In one embodiment, the reflux device of the present invention includes a reservoir tube having a first end defining at least one opening, a body having a predetermined diameter and a second end defining an opening. The delivery tube includes a first end connected to the second end of the reservoir tube, a branch adapted for connection to an administration tube and a second end received directly or indirectly by a patient. The delivery tube has a diameter which is less than the diameter of the body of the reservoir tube. The reservoir tube is preferably non-collapsible and large enough to receive all of the reflux fluid expelled by a patient during an entire enteral feeding process.  
       [0010] In operation of one embodiment, a user enterally feeds a patient by delivering feeding fluid from a feeding source through a delivery tube to a patient, receiving reflux fluid from the patient through the delivery tube, channeling the received reflux fluid to a reservoir tube and enabling any gaseous portion of the reflux fluid to vent to the atmosphere.  
       [0011] It is therefore an advantage of the present invention to provide an enteral feeding unit having a reflux device and reflux method.  
       [0012] Another advantage of the present invention is to provide a non-collapsible, cylindrical reservoir for reflux fluid expelled during enteral feeding.  
       [0013] Yet another advantage of the present invention is to provide a volumetrically marked reservoir for reflux fluid which is relatively simple and convenient to read during enteral feeding.  
       [0014] Still another advantage of the present invention is to provide a reflux device which is relatively simple to construct and manufacture.  
       [0015] Yet another advantage of the present invention is to provide a reflux device which provides a relatively high level of convenience and accuracy in gauging volume and volume changes in reflux fluid during enteral feeding.  
       [0016] Another advantage of the present invention is to enable users to provide enhanced health care during enteral feeding in the areas of gastric pressure relief, the measurement of reflux fluid and the recovery and return of reflux fluid to patients, such as neonatal patients.  
       [0017] Additional features and advantages of the present invention are described in, and will be apparent from, the following Detailed Description of the Invention and the figures.  
     
    
    
     BRIEF DESCRIPTION OF THE FIGURES  
     [0018]FIG. 1 is a side elevation view of the enteral feeding unit in one embodiment of the present invention.  
     [0019]FIG. 2 is a fragmentary side elevation view of a multi-way connector of the reflux device of the enteral feeding unit in one alternative embodiment of the present invention.  
     [0020]FIG. 3 is a side elevation view of the enteral feeding unit in one alternative embodiment of this present invention.  
     [0021]FIG. 4 is a fragmentary side elevation view of a multi-way connector of the reflux device of the enteral feeding unit in one alternative embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE INVENTION  
     [0022] Referring now to the drawings, FIG. 1 illustrates one embodiment of enteral feeding unit  10  which includes an administration device  12  removably connected to a reflux device  14 . The administration device  12  is used for administering feeding fluid to a patient, and the reflux device  14  receives, retains and returns reflux fluid to the patient. The administration device  12  can include any suitable device or mechanism which distributes or delivers feeding fluid to the patient. In one embodiment, the administration device  12  includes: (a) a feeding bag  16  connected to administration tubing  18  having administration tubes  18   a  and  18   b ; (b) a pump  20  which produces a suction force within administration tubing  18  (preferably by regularly stretching and releasing a portion of administration tubing  18 ); and (c) a slideable tube set clamp  22  connected to the administration tube  18   a  utilized to cause the administration device  12  to become inoperative.  
     [0023] The pole  24  supports the feeding bag  16  and the pump  20 . In operation, the feeding bag  16  contains a supply of feeding fluid, and the pump  20  draws the feeding fluid from feeding bag  16  and forces the feeding fluid through the administration tubing  18 . It should be appreciated that enteral feeding unit  10  can include any suitable type of administration feeding device or pump device other than the administration feeding device  12 . For example, alternate administration feeding devices may not include a pump but instead such devices may rely upon gravity to distribute feeding fluid to the patient.  
     [0024] The reflux device  14 , removably connected to the administration device  12 , includes: (a) a reservoir tube  26  which receives reflux fluid from the patient, retains the reflux fluid and returns the reflux fluid to the patient; and (b) a delivery tube  28  connected to the reservoir tube  26  which brings the reservoir tube  26  into fluid communication with the administration tubing  18  and the feeding tube  30 .  
     [0025] The reservoir tube  26  includes: (a) a cover or vent member  32  connected to the upper end of reservoir tube  26  for controlling the entrance of debris and other material into the reservoir tube  26  and for enabling reflux gas to escape to the atmosphere; (b) a hook or other engaging member  34  attached to the upper end of the reservoir tube  26  for hanging the reservoir tube  26  from the pole  24 ; (c) a plurality of markings  36  along the reservoir tube  26 ; and (d) a funnel-shaped portion or adapter member  38  which enables the reservoir tube  26  to be rigidly connected to the delivery tube  28 .  
     [0026] The reservoir tube  26  is preferably non-collapsible, cylindrical in shape, transparent or translucent, and constructed of a suitable flexible plastic, such as polyethylene. The diameter of reservoir tube  26  is preferably in the range of five to ten times the diameter of the feeding tube  30 . In one embodiment, the reservoir tube  26  is sixty-four inches in length and has a diameter size of thirty-three Fr. on the French scale and a volume of one hundred forty cubic centimeters.  
     [0027] The cover or vent member  32  includes a surface which overlays the upper, open end of the reservoir tube  26 . The cover or vent member  32  preferably is a suitable filter which prevents dust and debris from entering the reservoir tube while enabling gastric and reflux gases to escape to the atmosphere. It should be appreciated that in other embodiments, the cover member can include a vent, a valve or any porous material. It should also be appreciated that the present invention need not include a cover member. For example, in one embodiment, the reservoir tube&#39;s upper end can be downwardly curved so that the opening of the upper end is pointed downward. This curved construction minimizes the entrance of dust or debris into the reservoir tube  26  while enabling gastric gases to freely escape to the atmosphere.  
     [0028] In another embodiment, the upper end of the reservoir tube  26  can be fully enclosed with a stopper or cap, and one or more holes or orifices can be constructed within the wall of the upper portion of the reservoir tube  26 . Such a construction minimizes the entrance of dust or debris into the reservoir tube  26  while enabling gastric gases to freely escape to the atmosphere.  
     [0029] The hook or engaging member  34 , which enables the reservoir tube  26  to connect to and hang from the device pole  24 , is rigidly connected to the outer wall of the upper portion of the reservoir tube  26 . Preferably, the engaging member  34  is a hook member constructed of a suitable rigid-forming plastic, and the engaging member  34  is connected to the reservoir tube  26  through a molding or adhesive process. The engaging member  34  can, however, be constructed of any suitable size, shape and material, and the engaging member  34  can be fastened to reservoir tube  26  in any suitable fashion.  
     [0030] The delivery tube  28 , connected to the lower end of the reservoir tube  26 , includes a multi-way connector, three-way connector or Y-port connector  40  positioned between an upper delivery tube portion  42  and a lower delivery tube portion  44 . The delivery tube  28  also includes a step connector  39  at the proximal end of the lower delivery tube portion  44  for removably connecting the delivery tube  28  to the feeding tube  30 . Preferably, the upper delivery tube portion  42 , Y-port connector  40  and lower delivery tube portion  44  are permanently connected to one another through a suitable adhesive or molding technique.  
     [0031] The Y-port connector  40  includes an administration branch  41  which receives administration tube  18   b . The Y-port connector  40  also has flexible arms  46  and  48 . Flexible arm  46  has a cap or stopper  47  for sealing and unsealing administration branch  41 . Flexible arm  48  has a converter or adapter member  49  which enables administration tubes  18   b  of different sizes to be connected to administration branch  41 .  
     [0032] The upper delivery tube portion  42  of the delivery tube  28  functions as an extension which facilitates the connection of the reservoir tube  26  to the feeding tube  30 . It should be appreciated, however, that the present invention need not include the upper delivery tube portion  42  of the reflux tube  28 . In such case, the reservoir tube  26  can be connected directly to the Y-port connector  40 .  
     [0033] The feeding tube  30  includes a three-way connector or Y-port connector  52  connected to the distal end  30   a  of the feeding tube  30 , and the proximal end  30   b  of the feeding tube  30  is received by the nasal or oral passages of a patient  54 . The Y-port connector  52  includes a multi-purpose branch  52   a  which enables users to flush out the feeding tube  30 , administer medication to patients or conduct other enteral feeding-related activities. Y-port connector  52  also includes two flexible arms  56  and  58  having stoppers  56   a  and  58   a , respectively. Stopper  56   a  can be used to seal and unseal the multi-purpose branch  52   a , and stopper  58   a  can be used to seal and unseal the distal end  30   a  of the feeding tube  30 .  
     [0034] It should be appreciated that in one alternative embodiment of the present invention, the reflux device does not need to include the Y-port connectors or the feeding tube. Instead, the reflux device can include the reservoir tube which is suitably in fluid communication with one delivery tube or a series of connected delivery tubes. The distal end of the delivery tube or delivery tube series is connected to the reservoir tube, and the proximal end of the delivery tube or delivery tube series is received by the patient. Such delivery tube or delivery tube series is in suitable fluid communication with the administration tube  18   b . The term “delivery tube,” as used herein, includes any tube which can direct the flow of fluid.  
     [0035] It should also be appreciated that in the embodiment illustrated in FIG. 1, the reflux device  14  can be used with different types of administration devices  12  with different sized administration tubes  18   b . To change administration devices  12 , the user can remove the administration tube  18   b  from the administration branch  41 . The user can then connect the administration tube of the new administration device to the administration branch  41 . Depending upon the diameter of the new administration tube, the user may or may not need to use adapter member  49  to make the connection to the administration branch  41 .  
     [0036] Accordingly, in this embodiment, the administration device and reflux device can be distributed and commercialized separately or as a combination.  
     [0037] In addition, it should be understood that the feeding tube  30  is merely one example of the type of feeding tube which can be used in conjunction with the reflux device of the present invention. The reflux device of the present invention can be used in conjunction with any suitable feeding tube or patient delivery tube.  
     [0038] In one embodiment, illustrated in FIG. 2, the administration device  12  and the reflux device  14  are permanently connected to each other. Instead of Y-port connector  40 ,  25  the reflux device  14  includes the Y-port connector  60 . The Y-port connector  60  is permanently connected to the administration tube  18   b , preferably through a suitable adhesive, molding process or other suitable fastening technique. Accordingly, in this embodiment, the administration device and reflux device can be distributed and commercialized together as a combination or kit.  
     [0039] Referring back to FIG. 1, the reservoir tube  26  includes a plurality of volumetric markings  36  which enable the user to measure the volume of reflux fluid expelled by a patient. These markings  36  also enable the user to measure changes in the amount of reflux fluid flowing to and from the patient. With this measurement information, users can determine the amount of feeding fluid a patient has ingested without expulsion. Because the reservoir tube  26  may carry a meaningful quantity of formula, particularly, for neonatal patients, the markings  36  enable the user to monitor the amount of refluxed formula to ensure that the neonatal patient is receiving the prescribed amount of formula. It should also be appreciated that the present invention can include markings for fluid measurement purposes on any of the delivery tubes, including, but not limited to, the feeding tube.  
     [0040] The markings  36  can include or incorporate any suitable marking or marking system. In one embodiment, markings  36  are lines printed or painted on the reservoir tube  26 . In another embodiment, markings  36  are suitable decals affixed to the reservoir tube  26  or suitable impressions, engravings, grooves or other shape modifications to the reservoir tube  26  which a user can use to measure the volume or volume change of reflux fluid.  
     [0041] To install and use the enteral feeding unit  10  of the present invention, the user suspends the feeding bag  16  from the pole  24  and feeds the administration tubing  18  into the pump  20 . The user then suspends the reservoir tube  26  from the pole  24 . The user inserts the step connector  19  of the administration tube  18   a  into the administration branch  41  of the Y-port connector  40 . Next, the user inserts step connector  39  into the Y-port connector  52  of the feeding tube  30 . The user then seals off the multi-purpose branch  52   a  of the Y-port connector  52  using the stopper  56   a  of the arm  56 . The user then primes the feeding tube  30  by delivering a relatively small amount of feeding fluid to ensure there are no occlusions blocking the flow of feeding fluid to the patient. After any occlusions have been overcome, the user administers feeding fluid to the patient using the pump  20 .  
     [0042] The reflux device  14  is essentially an open system because the reservoir tube  26  is vented to ambient atmospheric pressure. Therefore, to prevent air from entering into the feeding tube  30  and reaching the patient, the reflux device  14  is preferably oriented so that there is a constant presence of a relatively small column of feeding fluid (i.e., nutrient formula) located above the Y-port connector  40 .  
     [0043] One way in which this can be accomplished is by positioning the Y-port connector  40  at or slightly below the level of the patient&#39;s diaphragm or stomach. This patient level is illustrated in FIG. 1 by broken line  64 . By positioning the Y-port connector  40  in this manner, the distal end of the delivery tube  28  is preferably located at or slightly below the patient level. With the delivery tube  28  having this position, a small column of feeding fluid remains suspended within a distal portion of delivery tube  28  with the meniscus of the column below the patient level, as illustrated by wavy line  66   a  in FIG. 1. This column of fluid prevents air from being drawn into the enteral feeding tube  30  and ultimately reaching the patient.  
     [0044] Another unique aspect of maintaining the fluid column is that the height of such column has been observed to fluctuate in response to greater or lesser gastric pressure (ambient atmospheric pressure being a relative constant). Increases in gastric pressure or partial occlusions of the feeding tube may cause the height of the fluid column to increase. Accordingly, by reading the markings  36  a user can gather valuable information about the performance of the enteral feeding unit  10 , the patient&#39;s gastric pressure and reflux responses and the overall enteral feeding process for a particular patient.  
     [0045] In one alternative embodiment illustrated in FIG. 3, the enteral feeding unit  110  includes the administration device  12  removably connected to the reflux device  112 . The reflux device  112  includes a reservoir tube  114  which receives reflux fluid from the patient, retains the reflux fluid and returns the reflux fluid to the patient. The reservoir tube  114  includes: (a) a cover or vent member  116  connected to the upper end of reservoir tube  114  for controlling the entrance of debris and material into the reservoir tube  114  and enabling reflux gas to escape to the atmosphere; (b) a hook or other engaging member  118  attached to the upper end of the reservoir tube  114  for hanging or suspending the reservoir tube  114  from the pole  24 ; (c) a plurality of markings  120  along the reservoir tube  114 ; and (d) a funnel-shaped portion or adapter member  122  which enables the reservoir tube  114  to be connected to the Y-port connector  124  of the delivery tube  126 . The adapter member  122  can be removably or permanently connected to the body of the reservoir tube  114  using any suitable fastening technique, including, but not limited to, adhesion, molding, step-connection or press-fitting.  
     [0046] The reservoir tube  114  is preferably non-collapsible, cylindrical in shape, transparent or translucent, and constructed of a suitable flexible plastic, such as polyethylene. The diameter of reservoir tube  114  is preferably in the range of five to ten times the diameter of the feeding tube  128 . In one embodiment, the reservoir tube  114  has a suitable length and a diameter size of thirty-three Fr. on the French scale and a volume of one hundred forty cubic centimeters.  
     [0047] The cover or vent member  116  includes a surface which overlays the upper, open end of the reservoir tube  114 . The cover or vent member  116  preferably is a suitable filter which prevents dust and debris from entering the reservoir tube while enabling gastric and reflux gases to escape to the atmosphere. It should be appreciated that in other embodiments, the cover member can include a vent, a valve or any porous material. It should also be appreciated that the present invention need not include a cover member. For example, in one embodiment, the reservoir tube&#39;s upper end can be downwardly curved so that the opening of the upper end is pointed downward. This curved construction minimizes the entrance of dust or debris into the reservoir tube  114  while enabling gastric gases to freely escape to the atmosphere.  
     [0048] In another embodiment, the upper end of the reservoir tube  114  can be fully enclosed with a stopper or cap, and one or more holes or orifices can be constructed within the wall of the upper portion of the reservoir tube  114 . Such a construction minimizes the entrance of dust or debris into the reservoir tube  114  while enabling gastric gases to freely escape to the atmosphere.  
     [0049] The engaging member  118 , which enables the reservoir tube  114  to connect to and hang from the pole  24 , is rigidly connected to the outer wall of the upper portion of the reservoir tube  114 . The delivery tube  126 , connected to the reservoir tube  114 , includes a sleeve, multi-way connector or Y-port connector  124  at the distal end of the delivery tube  126  for fluid communication with the administration tube  18   a . The delivery tube  126  has a step connector  130  at the proximal end of the delivery tube  126  for removably connecting the delivery tube  126  to the feeding tube  128 . Preferably, the Y-port connector  124  and step connector  130  are permanently connected to the delivery tube  126  through a suitable adhesive or molding technique.  
     [0050] The Y-port connector  124  can be removably or permanently connected to the adapter member  122  of the reservoir tube  114  using any suitable fastening technique, including, but not limited to, adhesion, molding, step-connection or press-fitting. The Y-port connector  124  includes an administration branch  132  which receives administration tube  18   b , and the Y-port connector  124  has flexible arms  134  and  136 . Flexible arm  136  has a cap or stopper  138  for sealing and unsealing administration branch  132 . Flexible arm  134  has a converter or adapter member  140  which enables administration tubes  18   a  of different sizes to be connected to administration branch  132 .  
     [0051] The feeding tube  128  preferably includes a Y-port connector  129  at the distal end of the feeding tube  128 , and the proximal end of the feeding tube  128  is received by a patient  54 . The Y-port connector  129  includes a multi-purpose branch  129   a  for flushing and other purposes and two flexible arms  129   b  having stoppers  131   a  and  131   b . The stopper  131  a can be used to seal and unseal the multi-purpose branch  129   a , and the stopper  131   b  can be used to seal and unseal the distal end of the feeding tube  128 . It should be understood that the feeding tube  128  is merely one example of the type of feeding tube which can be used in conjunction with the reflux device of the present invention. The reflux device of the present invention can be used in conjunction with any suitable feeding tube or patient delivery tube.  
     [0052] It should be appreciated that in the embodiment illustrated in FIG. 3, the reflux device  112  can be used with different types of administration devices  12  with different sized administration tubes  18   b . To change administration devices  12 , the user can remove the administration tube  18   b  from the administration branch  132 . The user can then connect the administration tube of the new administration device to the administration branch  132 . Depending upon the diameter of the new administration tube, the user may or may not need to use adapter member  140  to make the connection to the administration branch  132 . Accordingly, in this embodiment, the administration device and the reflux device can be distributed and commercialized separately or as a combination.  
     [0053] In one embodiment, illustrated in FIG. 4, the administration device  12  and the reflux device  112  are permanently connected to each other. Instead of Y-port connector  124 , the reflux device  112  includes the Y-port connector  142 . The Y-port connector  142  is permanently connected to the administration tube  18   b , preferably through a suitable adhesive, molding process or other suitable fastening technique. Accordingly, in this embodiment, the administration device and reflux device can be distributed and commercialized together as a combination or kit.  
     [0054] Referring back to FIG. 3, the reservoir tube  114  includes a plurality of volumetric markings  120  which enable the user to measure the volume of reflux fluid expelled by a patient. The markings  120  also enable the user to measure changes in the amount of reflux fluid flowing to and from the patient. With this measurement information, users can determine the amount of feeding fluid a patient has ingested without expulsion. Because the reservoir tube  114  may carry a meaningful quantity of formula, particularly, for neonatal patients, the markings  120  enable the user to monitor the amount of refluxed formula to ensure that the neonatal patient is receiving the prescribed amount of formula. It should also be appreciated that the present invention can include markings for fluid measurement purposes on any of the delivery tubes, including, but not limited to, the feeding tube.  
     [0055] The markings  120  can include or incorporate any suitable marking or marking system. In one embodiment, the markings  120  are lines printed or painted on the reservoir tube  114 . In another embodiment, the markings  120  are suitable decals affixed to the reservoir tube  114  or suitable impressions, engravings, grooves or other shape modifications to the reservoir tube  114  which a user can use to measure the volume or volume change of reflux fluid.  
     [0056] To install and use the enteral feeding unit  110  of the present invention, the user suspends the feeding bag  16  from the pole  24  and feeds the administration tubing  18  into the pump  20 . The user then suspends the reservoir tube  114  from the pole  24 . The user inserts the step connector  19  of the administration tube  18   b  into the administration branch  132  of the Y-port connector  124 . Next, the user inserts the step connector  130  into the Y-port connector  129  of the feeding tube  128 . The user then seals off the multi-purpose branch  129   a  of the Y-port connector  129  using the stopper  131   a  of an arm  129   b . The user then primes the feeding tube  128  by delivering a relatively small amount of feeding fluid to ensure there are no occlusions blocking the flow of feeding fluid to the patient. After any occlusions have been overcome, the user administers feeding fluid to the patient using the pump  20 .  
     [0057] The reflux device  112  is essentially an open system because the reservoir tube  114  is vented to ambient atmospheric pressure. Therefore, to prevent air from entering into the feeding tube  128  and reaching the patient, the reflux device  112  is preferably oriented so that there is a constant presence of a relatively small column of feeding fluid (i.e., nutrient formula) located above the Y-port connector  124 .  
     [0058] One way in which this can be accomplished is by positioning the Y-port connector  124  at or slightly below the level of the patient&#39;s diaphragm or stomach. This patient level is illustrated in FIG. 3 by broken line  64 . By positioning Y-port connector  124  in this manner, the distal end of the delivery tube  126  is preferably located at or slightly below the patient level.  
     [0059] With the delivery tube  126  having this position, a small column of feeding fluid remains suspended within a distal portion of delivery tube  126  with the meniscus of the column below the patient level  64 , as illustrated by wavy line  66   b  in FIG. 3. This column of fluid prevents air from being drawn into the enteral feeding tube  128  and ultimately reaching the patient.  
     [0060] Another unique aspect of maintaining the fluid column is that the height of such column has been observed to fluctuate in response to greater or lesser gastric pressure (ambient atmospheric pressure being a relative constant). Increases in gastric pressure or partial occlusions of enteral feeding tube may cause the height of the fluid column to increase. Accordingly, by reading the markings  120  a user can gather valuable information about the performance of the enteral feeding unit  110 , the patient&#39;s gastric pressure and reflux responses and the overall enteral feeding process for a particular patient.  
     [0061] In the course of normal operation of the enteral feeding unit of the present invention, the height of the column of fluid within the reservoir tube may fluctuate when the enteral feeding tube becomes occluded during feeding or when the patient accumulates excessive gastric pressure, fluid, gas or other reflux fluid. In the latter case, the reflux fluid flows from the patient&#39;s stomach through the feeding tube into the reservoir tube. Any gas within the reflux fluid will separate and escape through the cover member of the reservoir tube.  
     [0062] The enteral feeding unit of the present invention, in one embodiment, includes a relatively large, cylindrical, non-collapsible reservoir tube which bears volumetric markings. The reservoir tube collects reflux fluid expelled by a patient, and the reservoir tube returns the reflux fluid to the patient when predetermined pressure conditions are satisfied. This reservoir tube, which is used in conjunction with an administration device, facilitates the accurate measurement and assessment of the amount of feeding fluid ingested by a patient (without expulsion), the amount of reflux fluid expelled by a patient and the change in the amount of reflux fluid expelled or recovered by a patient over time. The enteral feeding unit of the present invention enables users to enhance the effectiveness of enteral feeding, accommodate reflux fluid, minimize ailments and health risks caused by reflux fluid and accurately and conveniently measure the quantity of reflux fluid expelled by a patient.  
     [0063] It should be understood that various changes and modifications to the presently preferred embodiments described herein will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the present invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the appended claims.