ENTERAL FEEDING TUBE SYSTEM USED TO ASSIST IN TUBE PLACEMENT

Abstract: A system and method are described in which myoelectric signals within a patient's body are detected by electrodes secured to the distal end of a tube, and are promptly displayed by some means and made available to a medical care provider while placing the tube in the patient. The signals detected indicate where the distal end of the tube is located within the gastrointestinal tract at any moment during the insertion of the tube into a patient's body.

Description: ENTERAL FEEDING TUBE SYSTEM USED TO ASSIST IN TUBE PLACEMENT BACKGROUND ANO SUMMARY OF THE INVENTION In many patients, gastrointestinal feeding is the preferred route of nutrient delivery with either the stomach or the small intestine being the areas of major importance. Proper positioning of the feeding end of an enteral feeding tube in the desired area of the gastrointestinal tract has always been a problem. Even after proper positioning of the feeding end of a feeding tube in either the stomach or the small intestine, it is possible that the feeding end of the tube may unknowingly migrate from the selected area, whereupon the patient may be subjected to a risky feeding situation. A common method of initially positioning and then monitoring the position of the feeding end of such a gastrointestinal feeding tube has been to use an x-ray. To repeatedly verify proper placement in this manner is not only cumbersome, time consuming, and expensive, but it also subjects the patient to unnecessary x-ray exposure. Post-pyloric feeding is often desirable in critically ill patients. Some studies have shown that only about 5 to 15% of feeding tubes pass spontaneously into the small bowel in critically ill patients. Post-pyloric feeding tube placement is difficult, frequently requiring time consuming blind attempts, transport to radiology for fluoroscopic guidance or a bedside endoscopic procedure. Proper placement and verification of a feeding tube can take an hour or more depending on all of the circumstances involved. Erythromycin is a motilin analog which promotes gastric motility by stimulating the gastric migrating motor complex. Use of erythromycin has been demonstrated to facilitate spontaneous post-pyloric passage in patients. Recording of an electromyogram (EMG) from the wall of the gastrointestinal tract allows differentiation between gastric and small bowel location. The results of an EMG recorded from the stomach compared to the results of an EMG recorded from the duodenum will show a sharp contrast. For example, signals originating from the stomach will have a dominant frequency of approximately 3 cpm (cycles per minute) whereas signals originating from the duodenum will have a dominant frequency of about 11 or 12 cpm. The present invention takes advantage of the contrast between the electrical signals that can be detected from the stomach and the signals that can be detected from the small bowel. The present invention comprises a feeding tube having at least one electrode secured on an end of the feeding tube. By detecting signals received from the electrode(s) on the end of the feeding tube, a physician can know the location of the feeding tube without resorting to x-rays or other cumbersome procedures. Erythromycin may be administered to enhance gastric motor activity during insertion of the feeding tube. With the electrode(s) placed at the distal tip of the feeding tube, the feeding tube is first guided into the stomach. The signals obtained from the stomach are generally about 3 cpm in frequency and have relatively large amplitude. As the distal tip of the feeding tube passes into the small bowel, the resident signals increase generally to about 10 to 13 cpm in frequency at a much lower amplitude. Frequency and amplitude of the signals can be monitored in substantially real time at the bedside of the patient using, for example, a computer monitor or a printer to show the graphical representation of the frequency and/or amplitude of the signals. The present invention offers several advantages. First, the present invention allows for substantially real time feedback of the location of the feeding tube tip as it is being guided into the patient's body. Second, the present invention minimizes radiation exposure, since x-rays are no longer needed or can be minimized by use of the present invention. A third advantage of the present invention is that the elapsed time from the beginning of the insertion of the feeding tube to the time in which feeding can begin may be substantially less than when using prior methods, especially if the present invention is used along with a prokinetic agent. It should also not be overlooked that the present invention is beneficial in that it may cause less discomfort to the patient since the feeding tube may be placed much more quickly. A final consideration is cost, which may be significantly lower using the method of the present invention. The assignee of the present invention is also the owner of U.S. Patent No. 4,921,481 which issued on May 1, 1990, and is entitled Enteral Feeding System Utilizing Gastrointestinal Myoelectrography. U.S. Patent No. 4,921,481 is hereby incorporated by reference into the present application. Other objects and advantages of the present invention will become more apparent when considered in view of the following detailed description and drawings. BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is a plan view of the feeding tube of a preferred embodiment of the present invention; Figure 2 is an end view taken in the direction of lines 2-2 of Figure i; Figure 3 is a perspective view of one embodiment of a data acquisition system of the present invention; Figure 4A is a view of an electromyogram signal from the stomach of a patient, showing, generally, a 3 cpm frequency; Figure 4B is a view of an electromyogram signal from the small bowel of a patient, which generally reveals a 10 cpm frequency; Figure 4C is a view of an electromyogram signal in transition, reflecting the real time contrast between Figures 4A and 4B; Figure 5 shows a schematic representation of a portion of a patient's digestive tract; Figure 6 is a schematic representation of the feeding tube of the present invention with its distal end located within a patient's stomach; Figure 7 is a diagrammatical representation of a preferred signal acquisition system of the present invention; and Figure 8 is a diagrammatical representation of another embodiment of the present invention in which a large physiological signal acquisition monitor system incorporates the signal acquisition of the present invention. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS Referring now to the drawings, in Figure 1 a feeding tube 10 is shown that may be used in the present invention. A Flexiflo 10F feeding tube with internal stylet 12 such as made by Ross Products Division of Abbott Laboratories in Columbus, Ohio, is shown modified by the placement of three silver wire electrodes 14, preferably arranged at four, six and eight centimeters from the tip 13 (shown in Figure 2) to record EMG signals by contact with the mucosa. As shown in Figure 7, the signal transmitted from the electrode(s) is filtered and amplified by an amplifier, such as a R1000 research amplifier 16 made by Ross Products Division of Abbott Laboratories. The signal may be conditioned by a bandpass filter that may operate from 0.03 to 15 Hz with a 40 dB per decade roll-off. Signal gain may be controlled by an internal switch. A 2 pole high pass filter may be incorporated with a cut off frequency of 0.03 Hz and a 6 pole low pass filter may be set with a cut off frequency of 1 Hz. A variety of electrode configurations may be used containing, preferably two or more electrodes 36, 38 to obtain a signal. One of the electrodes would be used to provide a reference. Three or more electrodes may be used at the distal end of the tube to offset naturally occurring noise levels in the gut. The myoelectrical gastrointestinal signal may be digitized, preferably, by a 12 bit A/D board on a personal computer 20 and can be stored on disc or printed as a real time amplitude-time plot. Gastric signals 40 in the stomach are generally of relatively high amplitude with a frequency of 3 cycles per minute as shown in Figure 4A, while the duodenal signals 42 are generally low amplitude with frequencies of 10 to 13 cycles per minute as shown in Figure 4B. Erythromycin lactobionate may be infused at initiation of the procedure of inserting the feeding tube 10 into a patient 11, at a preferred dose of 3 mg/Kg given over ten minutes. The erythromycin enhances the gastric migratory motor complex activity and accelerate gastric emptying, which may result in a more rapid duodenal placement of the feeding tube tip. The feeding tube 10 may be of a nasoenteric type to be ultimately located in the stomach 30 or small bowel 32, and its position confirmed by auscultation and EMG real time printout. The tube is then slowly advanced into the patient until the duodenal EMG is detected on a continuous record. If the small bowel 32 signal is not detected, the feeding tube 10 is withdrawn and advanced again until it is successfully located in a postpyloric position. Figures 5 and 6 show the placement of a feeding tube 10 within a patient 11. A medical care provider, such as a physician, may carefully monitor the progression of the feeding tube into the patient, by viewing a display monitor 26 or a continuous printout 25 from a chart printer 24 for example, as shown in Figure 3. The monitor 26 or printer 24 may be placed on a mobile cart 27 and moved to a patient's bedside prior to introducing the feeding tube. The feeding tube is electrically connected to the monitor or printer so that signals detected by the electrodes on the feeding tube are received by the display device. The medical care provider would be trained to look for the characteristic signals on the display monitor or printout which reveal the location of the feeding tube during the insertion procedure. As the feeding tube enters the patient's stomach, the medical care provider will be able, simultaneously, to see the frequency and amplitude characteristics of stomach signals 40, on the monitor or real-time printout. Figure 4A is a representation of what the medical care provider would see on a monitor or printout as the feeding tube enters the patient's stomach. As the feeding tube continues to be inserted, it will arrive in the duodenum. The medical care provider will be able, simultaneously, to see the frequency and amplitude characteristics of duodenum signals 42, on the monitor or real-time printout. Figure 4B is a representation of what the medical care provider would see on a monitor or printout as the feeding tube enters the patient's duodenum. Figure 4C shows the transition over time (i.e. - over several seconds or a few minutes, depending on the rate at which the medical care provider is inserting the feeding tube) as the feeding tube moves from the patient's stomach to the patient's duodenum. The noticeable change in the frequency and amplitude of the signal shown in Figure 4C is an indication that the feeding tube has moved from the stomach to the duodenum. With this live source of up-to-the-minute, accurate, bedside information, medical care providers can quickly and properly place a feeding tube within a patient. The feeding tubes may be initially inserted into a patient 11 through the nose, but may also be inserted through the mouth or even through the skin in the abdominal region of the patient. An enteral tube can be used for feeding the patient, for checking food absorption levels, as a means for inputting drugs, and as a means for degassing the stomach, among other uses known to those of skill in the art. In a preferred embodiment of the present invention erythromycin is used as a motility agent to assist in the advancement of the tube into the small bowel of the patient; however, other prokinetic agents may be used which would also stimulate the gut. The tube may be physically advanced by a medical care provider carefully guiding the tube into the patient until the distal end 13 of the tube 10 arrives at its intended location. The tube may also be inserted into the patient and then allowed to naturally migrate into the region where it is intended to supply its function. Figure 8 shows the present invention as a part of a physiological patient monitor system in which multiple signals are obtained from a plurality of different data monitors. A total patient condition record may be stored at a channel bank 50 which forms a part of the system. While there has been shown and described several possible embodiments of the invention, it will be obvious to those of skill in the art that changes and modifications may be made without departing from the invention, and it is intended by the appended claims to cover all such changes and modifications as fall within the true spirit and scope of the invention.

Claims: WHAT IS CLAIMED IS: 1. A method for placing a feeding tube within a patient, comprising the steps of: providing means for obtaining signals from a distal end of said feeding tube; introducing said feeding tube distal end into said patient; monitoring signals naturally occurring within a first location within a patient's body as said feeding tube distal end enters said first location; monitoring signals naturally occurring within a second location of a patient's body as said feeding tube distal end enters said second location; stopping the insertion of said feeding tube into said patient, when said signals at said second location are detected. 2. The method of claim 1, wherein said means for obtaining signals from said feeding tube includes placing at least one electrode on a distal end of said feeding tube. 3. The method of claim 1, wherein said monitoring of signals includes providing a display monitor and displaying on said monitor a graphical representation of said signals. 4. The method of claim 3, wherein said displaying of said graphical representation is done in a substantially continuous manner throughout the time in which said feeding tube is being placed within said patient. 5. The method of claim 1, wherein said monitoring of signals naturally occurring within a first location and said monitoring of signals naturally occurring within said second location are accomplished visually with a display monitor. 6. The method of claim 1, wherein said monitoring of signals naturally occurring within a first location and said monitoring of signals naturally occurring within a second location is accomplished with a strip chart printer providing substantially continuous graphical output representing said signals. 7. The method of claim 1, wherein said monitoring is accomplished by providing a bedside monitor means adapted to indicate said signals in a substantially real time manner. 8. A method for monitoring a feeding tube placement within a patient, comprising the steps of: providing means for obtaining signals from a distal end of said feeding tube; and monitoring in real time, from said patient's bedside, said signals naturally occurring from a location within a patient's body. 9. A system for enteral feeding utilizing gastrointestinal myoelectrography, comprising: a feeding tube having a proximal end and a distal end; at least one electrode secured to said distal end of said feeding tube; a monitor in electrical communication with said at least one electrode at said proximal end of said feeding tube; means in association with said monitor and said at least one electrode for detecting and promptly displaying a naturally occurring signal within said patient's stomach in substantially real time when said distal end is in said stomach, and for detecting and promptly displaying a naturally occurring signal in said patient's small bowel in substantially real time when said distal end is in said small bowel. 10. The system of claim 9, wherein said means and association with said monitor and said at least one electrode includes a signal conditioner plus amplifier. 11. The system of claim 9, wherein said monitor is a personal computer display monitor. 12. The system of claim 9, wherein said monitor is a strip chart printer. 13. The system of claim 9, wherein said feeding tube is a nasoenteric tube. 14. The system of claim 9, wherein said signal within said patient's stomach is about 3 cycles per minute in frequency. 15. The system of claim 9, wherein said signal in said small bowel is about 10 to 13 cycles per minute in frequency.

Inventors: HAYES JAMES P, LEVY HOWARD, TOMBA TODD C, HAYES, JAMES, P., LEVY, HOWARD, TOMBA, TODD, C.
Applicants: ABBOTT LAB, ABBOTT LABORATORIES
Application year: 1996
Main classification: A61J15
IPC codes: A61B5, A61J15