Title of the Invention Anti-Reflux Feeding Tube Related Application This application claims the priority of United States Provisional Application Serial No. 60/403,050, filed on August 13,2002 and Provisional Application Serial No. 60/434,531 filed on December 19,2002. The aforementioned provisional applications are incorporated by reference herein for all purposes.
Field of the Invention The present invention pertains to an enteral feeding tube, specifically an enteral feeding tube designed to prevent reflux of the feeding contents.
Background of the Invention In medicine there are a variety of chronic and acute conditions resulting in the need to nutritionally supplement a patient. Typically, if a patient is going to be without food for greater than one week, then they will require some sort of nutritional supplementation.
Currently, the only two options for nutritional supplementation involve feeding the patient through their gastrointestinal tract or through an intravenous route. The gastrointestinal route is associated with superior immunity and fewer complications, and, as such, is used more frequently.
Enteral tube feeding is delivered to an estimated 900,000 patients in the U. S. each year for conditions including ventilator dependence, trauma, and various forms of dysphagia.
While usually effective in the restoration of nutritional status of the patient, enteral tube feeding has been associated with serious complications. One of the most serious and, unfortunately, one of the most common problems with enteral tube feeding is the development of aspiration pneumonia. Studies have shown that up to 50% of patients on chronic enteral feeds develop findings consistent with aspiration. Despite the alarming rate of this potentially fatal complication, existing devices for the delivery of enteral tube feeds have failed to adequately address or solve this problem.
Several recent studies have established that duodenogastric reflux, gastric colonization with intestinal bacteria, and gastroesophageal regurgitation may be the primary factors leading to the development of pulmonary aspiration and the morbidity attributable to that condition.
Summary of the Invention The present invention has grown out of a body of existing research demonstrating that tube feed reflux persists regardless of the site of tube feed delivery. The present invention addresses the need for prevention of tube feed reflux through the use of a gastric evacuator and the incorporation of a rigid or temporarily inflatable barrier. When inflated, this barrier prevents the retrograde flow of the delivered tube feeds to the stomach and the lungs. The inflatable barrier is easily positioned during the tube feeding and deflated once the intestine has been emptied of the delivered nutrients. To ensure that the pressures generated in the intestine remain below the threshold at which mucosal damage occurs, multiple safety mechanisms are preferably incorporated into either the inflatable barrier, or the feeding tube, or both. The gastric evacuator component preferably decompresses the stomach to prevent reflux of gastric secretions.
Brief Description of the Drawings Fig 1-A cross-sectional view of the device being inserted percutaneously.
Fig 2A-C-Cross-sectional views of the Anti-Reflux Bulb (ARB) of the present invention in three stages of expansion and inflation.
Fig 3-A cross-sectional view of the device after gastric insertion, but prior to release of the vacuum seal on the ARB.
Fig 4-A cross-sectional view of the device after gastric insertion, with partial release of the vacuum seal on the ARB to encourage transpyloric migration of the tip of the device.
Fig 5A-C-A cross-sectional view of the function of the inserted device, including: A) Transpyloric passage, B) Full expansion of the foam in the distal balloon, and D) Inflation of the ARB across the pyloric valve.
Fig 6A-B-A cross-sectional view of the two different mechanisms of insertion of the device: A) Nasal insertion and B) Percutaneous Insertion.
Fig 7A-C-A cross-sectional view of three possible alternative embodiments of the device including A) An hourglass- shaped balloon that requires retraction against the pyloric valve for proper placement, B) A permanent flanged tube structure designed to be anchored in place across the pyloric valve with sutures, staples and C) The device of Figure 2 in which a proximal, gastrically-retained balloon is utilized in order to ensure proper placement of the inflating ARB.
Detailed Description of the Preferred Embodiments The Anti-Reflux Feeding Tube design of the present invention consists of a triple-lumen tube, manufactured from any biocompatible material, which preferably interfaces with a programmable pump. The various components of the Anti-Reflux Feeding Tube System are as follows.
The first lumen serves as the route of administration of tube feeds to the patient. The first lumen optionally, but preferably, incorporates some of the safety mechanisms below.
The second lumen will terminate in a perforated sleeve in the stomach. Optionally, the perforated sleeve may be substituted with a mesh, or another suitable method for preventing solids from clogging the tube, or left off entirely. When connected to suction, the perforated sleeve provides effective evacuation of gastric secretions during the delivery of the tube feeds.
The third lumen terminates in an inflatable balloon just prior to the opening of the larger lumen. This lumen, which will be the port of entry for the air required to inflate and deflate the anti-reflux balloon, may optionally slide freely within the optional Anti-Reflux Feeding Tube sheath allowing for the extension and retraction of the attached distal anti-reflux balloon (ARB).
The ARB envisioned by the inventor entails a long thin balloon which when inflated is larger than the diameter of the relaxed pyloric sphincter, but which is still smaller than the intestinal lumen. The balloon diameter will be between 0.5mm and 75mm, preferably between 5mm and 15mm. An additional, optional, embodiment of the balloon includes ridges, ribs, or bumps along the surface of the balloon to increase the balloon's ability to form an effective, stationary, seal with the pyloric valve.
The ARB contains a self-expanding mass of foam in the distal portion of its preferably long cylinder shaped balloon which, when connected to a vacuum and sealed, is compressed facilitating insertion into the stomach and then duodenum. Once the duodenal position of the ARB is confirmed, the vacuum can be released allowing the foam to expand to a size large enough to prevent return of the fully expanded tip back through the pyloric valve. Even fully expanded, the volume of the foam within the balloon is preferably small enough to not interfere with the flow of solid contents through the duodenum. The foam in the balloon can also be partially expanded in order to encourage transpyloric passage of the tip of the device from the stomach to the duodenum. Once in the duodenum, it can then be fully expanded to retain its position beyond the pyloric valve.
In this conformation, the fully inflated ARB is long enough to interface with the pyloric valve as long as the foam-filled tip of the ARB is in the duodenum (see Fig. 7A). Additionally, the proximal portion of the device residing in the stomach may incorporate a larger positional balloon, as well, which is large enough to prevent pyloric passage (see Fig. 7C), but small enough to allow comfortable retention in the gastric space.
This feature will allow the inflatable portion of the ARB to be accurately located in the pyloric sphincter at all times.
In a second manifestation, the ARB straddles the pyloric valve when inflated. In this embodiment, the ARB is hourglass shaped with a distal and a proximal bulb which can be inflated across the sphincter. Thus, once it is confirmed that the foam- filled tip is in the duodenum and the ARB is retracted against the pyloric sphincter and inflated, the pyloric sphincter is successfully occluded.
A third modality envisioned by the inventor involves an endoscopically placed flanged tube design in which the two flanges of the tube are designed to be placed on either side of the pyloric valve then sutured or stapled together. Thus, this design provides a relatively permanent mechanism for preventing duodenogatsric reflux, even with tube feeds. Preferably there will be an opening or flap valve that will allow drainage of- gastric secretions which will be closed with influx of tube feeds into the tube. This configuration may remain in the pyloric valve position indefinitely and would be useful in patients requiring relatively long-term nutritional support.
The preferred application of the device entails placement of the feeding tube either nasally or percutaneously with the feeding tube outlet in the intestine. After placement in the duodenum, the vacuum seal on the ARB will be fully removed and the self-expanding foam inside the distal portion of the balloon will increase in size until it can no longer pass the pyloric valve.
The tube feed delivery rate can vary from bolus feeding to nearly continuous feeding. It is expected, though, that for patients with healthy gastrointestinal tracts the tube feed will be delivered as a bolus due to the fact that this is the most physiologic and convenient delivery format for the patient and their caregivers.
The Anti-Reflux Feeding Tube design also optionally, but preferably, contains two important safety features to ensure that undue pressure is not applied to the intestinal wall. The first optional, but preferable, safeguard involves regulation of the inflation pressure of the occlusive balloon through the use of small balloon with increased compliance at the proximal end of the tube. This small, compliant safety balloon, placed externally and in-line with the air-containing lumen through which the occlusive balloon is inflated, will begin to expand once an adequate occlusive pressure of about 15-50 mmHg has been reached. This pressure is considered safe with respect to intestinal mucosa and musculature, even with prolonged exposure.
If, for some reason, inflation continues beyond the adequate pressure level, the safety balloon is also designed to rupture prior to reaching a critical pressure of about 60-100 mmHg, which is the maximum average pressure associated with physiologic peristalsis. The second optional, but preferable, safeguard is a similar area of increased compliance at the proximal end of the tube feed lumen. If the pressure in the tube feed lumen increases beyond 15-50 mmHg, this area of increased compliance will begin to warn the healthcare provider by expanding and, if the pressure reaches 60-100 mmHg, rupturing. Thus, as with the inflation lumen, the pressure will be relieved prior to damaging the intestinal mucosa. Used together, these safety features provide a redundant safeguard against excess intraluminal pressures.
Description of the Drawings As can be seen in Fig 1, the present invention provides a feeding tube 1 which can be advanced into the stomach 7 either nasally, or, as illustrated in Fig 1, percutaneously. The tube has multiple elements including: an Anti-Reflux Bulb (ARB) 2, a feeding tube lumen 3, an inflation lumen 4, a lumen provided for evacuation of the gastric contents 5, and a perforated tip 6 on the end of 5. When inserted percutaneously, the tube 1, is inserted through the skin 10 into the stomach 7 through the use of a guide wire 11. After placement in the stomach 7, the tube 1 will then be advanced beyond the pyloric valve 8 into the duodenum 9.
Fig 2 shows three conformations of the preferred embodiment of the invention. First, the ARB 2 is configured to have two bulbs on its terminal tip, a distal bulb 12, and a long proximal bulb 13. Once the ARB 2 is positioned across the pyloric valve 8, bulb 12 would reside in the duodenum, while bulb 13 would span the pyloric valve 8. The gastric portion of the balloon 13 also has an aperture 14 to allow air to move in and out of the ARB 2. The feeding tube lumen 3 is continuous through the center of the ARB 2 and terminates in a soft tip 15, preferably designed to not irritate the bowel wall. The intestinal bulb 12 of the balloon also preferably incorporates expanding foam within the balloon. This foam, when allowed to expand as shown in Fig. 2B, results in retention of the feeding tube outlet in the duodenum 9 due to the fact that the foam preferably expands to a volume that does not permit it to reflux past the pyloric valve 8. The foam, though, preferably does not expand to a size large enough to interfere with the flow of duodenal contents.
The fully inflated ARB, Fig 2C, is shown with its two bulbs fully expanded, so as to span the pyloric valve 8 when positioned correctly.
As can be seen in Fig 3, the feeding tube 1 is advanced into the stomach 7 before passage into the duodenum.
Fig 4 illustrates the removal of vacuum on the ARB 2 and the partial expansion of the foam balloon 12 to promote transpyloric passage int the duodenum 9.
Fig 5A-C illustrate the transpyloric passage of the ARB 2 and its positioning. As can be seen in Fig 5B, once the ARB 2 is in place in the duodenum 9, the foam-filled tip 12 is allowed to fully expand trapping the ARB in the duodenum. In Fig 5C, the ARB 2 is retracted to the pyloric valve 8 at which point it is inflated, spanning the pyloric valve and tube feed and gastric evacuation can commence according to the programmed protocol of the complementary pump. In addition, Fig. 5C shows the gastric fluid being drained from the stomach 16, and the tube feeds being deposited 17 into the duodenum 9.
As can be seen in Fig 6, the present invention may be inserted nasally Fig 6A or percutaneously Fig 6B.
Lastly, additional embodiments contemplated by the inventor are illustrated in Fig 7A-C. In Fig 7A, an alternative embodiment, which employs a hourglass-shaped balloon 18 spanning the pyloric valve 8 is shown. The advantage of this embodiment is the snug fit on the pyloric valve while the disadvantage is the requirement for precise placement not necessary in the preferred embodiment. The embodiment illustrated Fig 7B shows a relatively permanent tube 19, fitted securely across the pyloric valve by flanges 20 that are optionally sutured, stapled or affixed 21 in place. This embodiment would remain in place and optionally incorporates a valve to prevent reflux of duodenal contents, but which will allow drainage of gastric secretions into the duodenum. In Fig 7C, the preferred embodiment is equipped with an additional proximal foam-filled balloon 22 which has been designed to be retained in the gastric space.
This will allow the pyloric-occlusion balloon to be snugly held across the pyloric valve while not requiring permanent fixation and occlusion of the pylorus as in Fig 7B.
Not shown, but also envisioned by the inventor are the embodiments employing an inner and outer catheter for the feeding tube 1, which, when agitated will break deposits free from the inner lumen. Also envisioned but not illustrated is the catheter valve component which may consist of a mechanism such as a flap of flexible material or ball valve over the terminal end 15 of the feeding tube 1 or even an active valve opened and closed through EMF or radio wave communication.
While these are the preferred embodiments in which the pyloric valve is occluded to encourage antegrade flow of gastrointestinal contents, the device could employ any mechanism that provides unidirectional flow of enteral feeding contents within the gastrointestinal tract.
As considered above, this could involve an electronic valve triggered via communication across the tissues of the human body through EMFs, or other means of communication, allowing opening of the aperture 15 only at selected times. The valve of the device can take many shapes and the device can be manufactured from any of a variety of materials with the only requirement being that of biocompatibility.
