Abstract:
A gastric pressure relief apparatus for incorporation within an enteral feeding system, including an enteral feeding container, an administrative tube and an enteral feeding tube. The apparatus comprises a gas and liquid-receiving reservoir with a gas vent to ambient atmosphere, a length of tube secured to the reservoir at one end and joined to the enteral feeding tube at another end and connector means for joining the administrative tube to the length of tube to be oriented at a point below that of an enterally-fed patient&#39;s stomach. The length of tube includes volumetric indicia to allow for measurement of refluxed fluid and subsequent adjustment of fluid administration.

Description:
TECHNICAL FIELD 
     The present invention generally relates to enteral nutrition wherein fluid nutrients are administered to the human gastrointestinal tract through an enteral feeding tube and, in particular, to improvements to a device for relieving gastric pressure in neonatal and pediatric patients during enteral feeding. 
     BACKGROUND OF THE INVENTION 
     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 generally comprising an enteral feeding container, usually a distensible bag suspended above patient level, joined to a length of flexible administration tubing. The proximal end of the administration tubing, which is joined to an outlet port in the enteral feeding bag, may include a drip chamber-tube clamp arrangement for determining flow rate. The distal end of the administration tubing carries a male luer adaptor for coupling with a female luer adaptor disposed on a distal end of an enteral feeding tube. U.S. Pat. No. 4,490,143 generally discloses the arrangement of elements utilized in an enteral feeding system. Intubation of the enteral feeding tube may be through naso-pharyngeal passage or through oral intubation. The flow rate of fluid nutrient through the enteral feeding tube is achieved through either gravity feed or use of an enteral feeding pump disposed at a generally intermediate position along the administration tubing. 
     During enteral feeding excessive gastric pressure may result through accumulation of gas or liquid resulting from stomach contractions, movement of the patient&#39;s abdomen, crying or through normal formation of gas. Typically the body relieves such excess gastric pressure through expulsion of accumulated gas or liquid through a burping response. However, in a patient undergoing enteral feeding in which fluid nutrients are being continually fed to the gastrointestinal tract, upward expulsion of gastric reflux materials is highly undesirable. More importantly, reflux of gas or liquid through the enteral feeding tube cannot occur. Though gastric reflux pressure created by even limited episodes of stomach movement or crying may exceed several feet of water, such reflux pressure is inadequate to overcome the greater forward fluid pressure present within the enteral feeding tube. This greater fluid pressure is developed because the height of the column of fluid nutrient in the enteral feeding system stands well above the level of the patient&#39;s stomach. Fluid pressure is further increased through the use of the enteral feeding pump. In addition, tube set clamps along the administration tubing also prevent reflux of excessive gastric gas or liquid through the enteral feeding tube. 
     Because gastric reflux pressure cannot overcome the greater forward fluid pressure within the enteral feeding tube, reflux materials are expelled upward from the stomach through the esophagus and are 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. In the latter, it is possible for the patient to inhale the reflux materials into the lungs with possible risk of aspiration pneumonia. The problem of relief of gastric reflux pressure is most accute 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. 
     Gastric pressure relief devices such as device  10  in FIG. 1 have been developed to permit relief of gastric reflux pressure through the enteral feeding tube to avoid uncontrolled upward expulsion of reflux materials through the burping response. Device  10  also prevents introduction of air into any portion of the enteral feeding system, particularly the enteral feeding tube. Further, because the fluid refluxed by a patient generally comprises the nutrient formula being administered to the patient, after device  10  relieves gastric reflux pressure, the refluxed fluid nutrient is returned to the enteral feeding tube for delivery to the patient. However, the quantity of refluxed fluid nutrient, particularly fluid which collects within tube line  18  is often unknown. This adversely impacts accurate enteral administration of fluid nutrient, particularly since a selected quantity of nutrient is administered over a given period of time. Hence, prior to the development of the improvements to device  10  as disclosed herein, a need existed for a gastric reflux pressure relief device which temporarily collects, accurately measures and returns refluxed nutrient formula to the enteral feeding tube. 
     SUMMARY OF THE INVENTION 
     According to the present invention improvements to a gastric reflux pressure relief device have been developed for in-line incorporation into an enteral feeding system. The pressure relief device is interposed between the distal end of an administration tubing and proximal end of the enteral feeding tube for capturing refluxed fluid. 
     The pressure relief device includes a selected length of pressure relief tubing having a fluid collection reservoir on a proximal end. A male luer adaptor is disposed at a distal end of the relief tubing for coupling with a female luer adaptor at a proximal end of an enteral feeding tube. Joined along a selected position on the relief tubing is a Y-connector for receiving the male luer adaptor commonly utilized on the distal end of enteral administration tubing. Hence, the relief tubing is in fluid communication with both a source of fluid nutrient and the enteral feeding tube. The Y-connector is interposed at a position about ⅔ of the length of the relief tubing so that the segment of tubing proximal to the Y-connector defines a pressure relief segment while the segment of the tubing distal to the Y-connector delivers fluid nutrient received from the administration tubing to the enteral feeding tubing. The reflux material collection reservoir, preferably a flexible plastic tail-feeding bag, is vented to the ambient atmosphere. Where reflux materials include gas, the gas is released from the present pressure relief apparatus through the vent. On the other hand, where the reflux materials include fluid, then the reservoir temporarily collects and retains the fluid before gradual return and delivery to the patient. Though the collection reservoir is vented to the ambient atmosphere, so long as the Y-connector is positioned at or below the patient&#39;s stomach level, a standing column of fluid nutrient will be maintained above the Y-connector, thereby preventing suction of air into the enteral feeding system through the reservoir gas vent. 
     It has been found that because the reservoir has inner dimensions larger than the relief tubing, the reservoir best functions to receive and expel refluxed gas. Though the reservoir has volumetric markings, refluxed formula rarely enters the reservoir. Instead, formula most commonly is refluxed into the relief tubing above the Y-connector. As a result, the relief tubing may carry a meaningful quantity of formula, particularly, for neonatal patients. Hence, the relief device has been improved by providing the relief tubing with volumetric indicia or markings. 
     The present invention will be more fully described in the following detailed description with reference being made to the drawings and the Claims appended thereto. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a gastric pressure relief device known in the art set off by bracket, incorporated within an enteral feeding system; and, 
     FIG. 2 is a fragmented perspective view of the known pressure relief device with the improvements thereto. 
    
    
     DETAILED DESCRIPTION 
     The term “fluid” as used herein shall refer to and include both gas and liquid physical states. Referring now to the drawings, FIGS. 1 and 2 disclose a gastric pressure relief device known in the art generally referenced by  10 . As will later be explained in greater detail, relief apparatus  10  is interposed between a distal end of enteral feeding administration tubing and a proximal end of an enteral feeding tube. Relief apparatus  10  generally comprises at a proximal end a reflux material collection reservoir  12 , preferably a distensible bag to receive gas or fluid materials refluxed during gastric pressure relief. Reservoir  12  is vented to the ambient atmosphere through gas vent  14  and is suspended from a support standard by a hanger tab  16 . Reservoir  12  is joined to a length of tubing  18  placing reservoir  12  in fluid communication with both the enteral feeding tube and the administration tubing. Disposed preferably at about ⅔ the length of tubing  18  is a connector  20  for joining tube  18  with a distal portion of the administration tubing. Preferably, connector  20  is a Y-shape connector which separates tubing  18  into two segments, although any shaped connector known or used in the art is suitable so long as the fluid continuity of tube  18  can be maintained. For example, a small sleeve molded into an opening cut in the side wall of tubing  18  to receive a distal portion of administration tubing without severing tubing  18  into segments may also be suitable. 
     As best disclosed in FIG. 2, connector  20  apportions tubing  18  to define a pressure relief segment  18   a  proximal to connector  20  and seated within area  20   a  of connector and a fluid delivery segment  18   b  distal to connector  20  and seated within arm  20   b  of connector  20 . Preferably carried on relief segment  18   a  is a slideable tube set clamp  22  utilized to close relief segment  18   a  causing pressure relief apparatus  10  to become inoperative. 
     A proximal end of fluid delivery segment  18   b  is joined to arm  20   b  of connector  20 . A distal end of fluid delivery segment  18   b  carries a male luer adaptor  24  to be inserted into a female luer adaptor carried on a proximal end of the enteral feeding tube, which will be discussed later in greater detail. Fluid delivery segment  18   b  serves to receive fluid nutrient from administration tubing and deliver such fluid to the enteral feeding tube. In addition, in conditions of excessive gastric pressure, fluid delivery segment  18   b  passes reflux materials, gas or liquid, through connector  20  into pressure relief segment  18   a , and, if necessary, into collection reservoir  12  as well. Any reflux gas which passes through fluid delivery segment  18   b  which is channeled into relief segment  18   a  continues to pass upward through collection reservoir  12 , through gas vent  14  and into the ambient atmosphere. 
     Reservoir  12  is a distensible bag preferably made from a flexible elastomeric plastic such as polyethylene or polyvinylchloride. However, it is conceivable that reservoir  12  could also embody a more shape-retentive container such as a polyethylene plastic bottle. Reservoir  12  must have adequate capacity to receive a substantial amount of reflux material in the event of repeated episodes of excessive gastric pressure. For example, when relief apparatus  10  is utilized in enteral feeding of infants, reservoir  12  should have a fluid capacity of approximately 500 ml. 
     The use and operation of relief apparatus  10  is disclosed in FIG.  1 . As previously discussed, the distal portion of relief apparatus  10  is joined to an enteral feeding tube  38  of a selected length and diameter suited for the particular patient. Specifically, male luer adaptor  24  disposed on the distal end of fluid delivery segment  18   b  seats within a female luer adaptor  40  disposed on a proximal end of enteral feeding tube  38 . Next, a distal end of an administration tubing  42  is joined to relief apparatus  10  through connection with open arm  20   a  of connector  20 . Specifically, a male luer adaptor  44  disposed on the distal end of administration tubing  42  seats within open arm  20   c  of connector  20 . Finally, reservoir  12  is suspended by hanger  16  from an available arm of a common intravenous suspension standard A. Clamp  22  disposed on pressure relief segment  18   a  would be in a closed position so as to maintain relief apparatus  10  in an inoperative mode. 
     An enteral feeding container  46  containing a selected nutrient formula is also suspended from support standard A preferably at the same height and level as reservoir  12 . The flow rate for delivery of nutrient formula from enteral feeding container  46  through administration tubing  42  may be accomplished through use of an enteral feeding pump  48  in combination with use of a tube set clamp  50 , preferably a roller-type clamp as disclosed in FIG.  1 . Fluid flow rate may also be achieved through gravity feed controlled through the combination of a drip chamber and a tubing clamp (not shown). 
     Enteral feeding begins after priming of administration tubing  42 . In order to insure that there are no occlusions within feeding tube  38 , a small amount of nutrient formula is initially administered to the patient. After any occlusions have been overcome, clamp  22  of relief apparatus  10  is opened, thereby activating pressure relief apparatus  10 . 
     Relief apparatus  10  is essentially an open system, i.e., reservoir  12  is vented to ambient atmospheric pressure. Hence, to avoid introduction of air into enteral feeding tube  38  through tubing  18 , pressure relief apparatus  10  must be oriented in such a manner so as to assure the presence of a small column of nutrient formula within pressure relief segment  18   a . This is accomplished by positioning connector  20 , and as a result the distal end of relief segment  18   a  at or slightly below the level of the patient&#39;s stomach. For reference purposes, patient level is indicated in FIG. 1 by broken line B. So long as connector  20  maintains the distal end of pressure relief segment  18   a  at or below patient level, then a small column of nutrient formula is developed and remains suspended within a distal portion of relief segment  18   a  with the miniscus of the column generally at a position marked by broken line C in FIG.  1 . This column of fluid prevents air from being drawn into fluid delivery segment  18   b  and, ultimately, into enteral feeding tube  38 . 
     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). When the height of the fluid column has increased within relief segment  18   a , the cause may be increased gastric pressure or partial occlusion of enteral feeding tube  38 . 
     In the course of normal operation of apparatus  10 , the height of the column of fluid within relief segment  18   a  may rise and enter collection reservoir  12  in two situations. First, fluid will rise and enter reservoir  12  if enteral feeding tube  38  becomes occluded during feeding. Secondly, if the patient accumulates excessive gastric pressure, fluid or gas will reflux from the patient&#39;s stomach through enteral feeding tube  38  to fluid delivery segment  18   b , then to segment  18   a  for collection in reservoir  12 . Any gas within the reflux materials will separate and escape through vent  14 . 
     Because the relief tubing  18   a  may carry a meaningful quantity of formula, particularly, for neonatal patients, the relief device  10  has been improved by providing the relief tubing  18   a  with volumetric markings  52 . This allows the monitoring of refluxed formula to ensure that the patient is receiving the prescribed amount. 
     While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof Therefore, it is intended that the invention not be limited to a particular embodiment disclosed as the best mode contemplated for carrying out the invention, but that the invention will include all embodiments falling within the scope of the appended claims.