The invention relates to an enteral feeding catheter for channelling flowable nutrient into a patient's digestive tract, such as into patient's stomach, duodenum or jejunum, said catheter being adapted to be advanced through patient's esophagus, said catheter having a proximal end, a distal end, and a first lumen, said first lumen having an opening at said proximal end adapted to be connected to a supply for receiving said nutrient from said supply and channelling said nutrient from said proximal end to said distal end, said distal end being provided with several radial outlets for the exit of said nutrient.
Feeding catheters of this type are used for instance in feeding of a patient who is unable to swallow nutrients in the natural manner or in postoperative or critical care. Especially in critical care it is important to monitor the intra-abdominal pressure in order to avoid intra-abdominal hypertension or abdominal compartment syndrome, which may impede blood circulation and perfusion in the abdominal region and may be hazardous to the patient.
DE 35 00 822 A1 discloses a device for measuring the pressure in the human or animal body. The device comprises a balloon which is attached at the distal end of a multi-luminal catheter and which is only partially filled with a gaseous medium. The pressure in the balloon is transferred over a lumen of the catheter to a pressure gauge. DE 35 00 822 A1 does not disclose an enteral feeding catheter.
It is therefore an object of the invention to provide an enteral feeding catheter device which allows reliable continuous determination of patient's intra-abdominal pressure and keeps the additional burden related to the pressure measurement for the critical ill patient as low as possible.
It is a further object of the invention to provide a computer system and a computer program which allow for calibration and recalibration of the measurement equipment and allow continuous determination of the intra-abdominal pressure with good accuracy.
According to the invention an enteral feeding catheter as mentioned above is provided with a second lumen, adapted to be connected to a source/sink of gas and a gas pressure gauge at its proximal end and being connected to an inflatable and deflatable distal balloon provided on said catheter body near said distal end. The balloon will be named “distal balloon” in the following just for the sake to give it a name and to distinguish it from other balloons (described later) which are situated proximally with respect to the distal balloon. “Distal” must not be understood in the sense that the distal balloon is situated at the very distal end of the catheter body.
The distal balloon has preferably a high degree of gastightness allowing relatively long recalibration intervals.
Preferably the enteral feeding catheter has a third lumen adapted to be connected to a source/sink of air and a gas pressure gauge at its proximal end and being connected to an inflatable and deflatable proximal balloon provided on said catheter body at an axial, position such that said second balloon is positioned in the patient's thorax when the catheter is inserted. The balloon will be named “proximal balloon” in the following just for the sake to give it a name and to distinguish it from the distal balloon which is situated distally with respect to the proximal balloon. “Proximal” must not be understood in the sense that the balloon is situated close to the proximal end of the catheter body. Providing the catheter with a proximal balloon which is situated in the thorax region of the patient, i.e. above the diaphragm when the catheter is properly inserted in place, allows to monitor not only the intra-abdominal pressure but also the intra-thoracic pressure which has an importance in monitoring cardiovascular parameters of the patient which cannot be overestimated.
According to another preferred embodiment of the invention the enteral feeding catheter has a fourth lumen adapted to be connected to a source/sink of gas or fluid at its proximal end and being connected to a blocking balloon provided on said catheter body at an axial position such that said blocking balloon is positioned in patients stomach when the catheter is inserted. This blocking balloon, which is preferably filled with air or water, is very useful to assist in placing the catheter precisely and correctly without applying x-ray imaging. The catheter is advanced through the patient's esophagus with the blocking balloon being empty until the operator can be sure that the blocking balloon has entered the stomach. The balloon is then filled with air or water and the catheter is withdrawn until the blocking balloon abuts the cardia of patient's stomach, thus ensuring that the catheter is placed precisely with respect to the stomach. Additionally the blocking balloon prevents the catheter from being withdrawn further from its place. In order to avoid accidental overpressure the pressure inside the balloon could be limited and/or monitored. An overpressure would indicate falsely positioning of the blocking balloon in the esophagus.
Alternatively or additionally the feeding catheter, may be provided with several radioopaque marking rings distributed over its length and/or nearby the balloons and/or a radioopaque stripe extending axially over its length to allow observing the placement of the catheter under X-ray-imaging.
Insertion marks distributed over the length of the catheter may inform the operator on how far the catheter has been advanced into the patient's body.
Additionally the feeding catheter ray be provided with two or more electrodes placed near the distal end of the catheter for impedance measurement to determine the acidity of the gastric juice and to carry out gastric volume measurements. The gastric volume is negative correlated with the bio-electrical impedance i.e. impedance decreases if gastric volume increases. The gastric volume could be calculated with a empirical estimated function of the impedance. Additionally or alternatively the feeding catheter may provide two or more electrodes sufficiently proximal before or after the proximal balloon 8. These electrodes should be placed above diaphragm in the esophagus in order to estimate transthoracic bioimpedance which measures cardiac stroke volume and cardiac output and thoracic fluid content. Additionally the feeding catheter may provide pulse densitometry means placed in the esophagus in order to measure arterial oxygen saturation or indo cyanine green dye concentration. It was found that this would be more reliable than common non invasive pulse densitometry means e.g. on the finger or ear.
A computer system which provides for calibration and recalibration of the measurement equipment and allows continuous determination of the intra-abdominal pressure with good accuracy comprises first connection means adapted to connect said computer system to pump driving means adapted to drive a pump for increasing/decreasing the gas volume inside at least one balloon of an enteral feeding catheter and second connection means adapted to connect said computer system to a pressure gauge adapted to determine the pressure p prevailing in said at least one balloon, calculation means for calculating the mathematical derivative dp/dV of pressure p with respect to volume V displaced by the pump and accessing means to access executable instructions to cause said computer system to cause said pump driving means to adjust the gas volume inside said balloon for initial setting such that said mathematical derivative dp/dV of pressure p with respect to volume V is zero or as close to zero as possible.
Preferably the computer system further comprises third connection means adapted to connect said computer system to valve means adapted to connect for initial settings said pressure gauge to ambient air and disconnect it from ambient air, said accessing means access instructions to cause said computer system to connect said pressure gauge to ambient air and to adjust said pressure gauge to zero.
Advantageously the computer system further comprises alarm means alerting of a blocked or occluded catheter lumen, in case that the absolute mathematical derivative dp/dV of pressure p with respect to volume exceeds a certain upper threshold at a certain pressure.
The computer system may further comprise alarm means alerting of a leakage in case that the absolute mathematical derivative dp/dV of pressure p with respect to volume V fails to reach a lower threshold at a certain pressure.
A computer program which provides for calibration and recalibration of the measurement equipment and allows continuous determination of the intra-abdominal pressure with good accuracy comprises instructions executable by a computer system to cause said computer system for initial settings to drive a pump for increasing/decreasing the gas volume inside at least one balloon of said enteral feeding catheter and collecting pressure readings of pressure p prevailing in said at least one balloon, calculating the mathematical derivative dp/dV of pressure p with respect to volume V and adjusting the gas volume inside said balloon such that said mathematical derivative dp/dV of pressure p with respect to volume V is zero or as close to zero as possible.
Preferably the computer program comprises the steps of connecting said pressure gauge to ambient air, adjusting said pressure gauge to zero and disconnecting said pressure gauge from ambient air.
Advantageously the computer program comprises the step of activating alarm means alerting of a blocked or occluded catheter lumen, in case that the absolute mathematical derivative dp/dV of pressure p with respect to volume V exceeds a certain upper threshold at a certain pressure.
Preferably the computer program further comprises the step of activating alarm means alerting of a leakage in a catheter lumen, in case that the absolute mathematical derivative dp/dV of pressure p with respect to volume V fails to reach a lower threshold at a certain pressure.
Preferably the computer program further comprises the steps of continuously collecting pressure readings after initialization has been accomplished.
Preferably the computer program further comprises the step of activating an alarm when the pressure exceeds a certain threshold.
The invention including its construction and method of operation will be illustrated in the drawings in which
In the middle part M the body of the catheter 1 is surrounded by a proximal balloon 8 which is internally connected to the opening 5a, so that the proximal balloon 8 may be inflated by pressing air into the opening 5a or may be deflated by sucking air out of opening 5a which will be explained in detail later. The balloon 8 is named “proximal balloon” just for the sake to give it a name and to distinguish it from a balloon which is situated distally with respect to the proximal balloon which will be described later. “Proximal” is not to be understood that the balloon is situated at the proximal end of the catheter body.
In the distal part D the body of the catheter 1 is surrounded by a distal balloon 6 which is internally connected to the opening 7a, so that the distal balloon 6 may be inflated by pressing air into the opening 7a or may be deflated by sucking air out of the opening 7a which will be explained in detail later. The balloon 6 is named “distal balloon” just for the sake to give it a name and to distinguish it from the proximal balloon 8 which is situated proximally with respect to the distal balloon 6 mentioned before. “Distal” must not be understood that the balloon is situated at the very distal end of the catheter body.
Distally with respect to the distal balloon 6 there are provided radial openings 4 which serve as outlets to allow flowable nutrients or medications, which have been introduced into the catheter 1 through its opening 3, to exit into patient's digestive tract.
Before and after balloons the catheter has radio opaque marking rings 9, an axially extending radio opaque stripe 10, and optically visible insertion marks 11, supporting the operator in determining the position of the catheter in patient's body, especially during the time when it is advanced through the digestive tract of the patient. The marks 10 extent from balloon 8 up to the Y-junction 15 at equal distances (e.g. 5 cm).
The details of the structure of catheter 1 will become more apparent from
A side hose 14 is connected to the main part of the catheter 1 via a Y-junction 15. The distal end of the side hose 14 is closed by a connector 16, which has two openings 5a and 7a. The side hose 14 is connected to a second lumen 5 and a third lumen which is not visible in
As may be best understood from
As becomes apparent from
Close to the distal tip of the catheter 1 the first lumen 2 is provided with several radial outlets 4 which allow nutrient to flow out of the first lumen 2. At the outer wall of the catheter 1 there are further provided two electrodes 12 and 13 spaced apart from each other. The electrodes are connected by electric wires 20 and 21 to the connector 16 (
The catheter system is operated as follows:
The catheter 1 is advanced with its distal tip ahead through the mouth or the nose of a patient into the esophagus of the patient until its tip reaches the stomach, the duodenum or the jejunum of the patient depending on the medical requirements. The axial position of the distal balloon is such that the distal balloon will be placed in the stomach (or duodenum or jejunum), while the axial position of the proximal balloon on the body of the catheter 1 is such that it will be placed in the patient's thorax. The movement of the catheter 1 is monitored by means of the radioopaque marking rings 9, radioopaque stripe 10 and/or by counting visible insertion marks 11 outside the patient.
Once the distal tip of the catheter 1 has reached its final destination in the patient's digestive tract, the computerized system as shown in
During the inflation process the pressure inside the proximal balloon 8 increases and the balloon 8 unfolds. After the balloon 8 has been unfolded the pressure inside the balloon increases rapidly, in other words the absolute amount of mathematical derivative of pressure p with respect to displacement x of the piston is high and exceeds a predetermined threshold at a certain positive pressure, causing the program to stop the inflation process and to start a deflation in other words the piston will be moved in the opposite direction whereby the balloon 8 is evacuated. At the beginning of the deflation process the pressure falls rapidly until the balloon 8 begins to collapse. During the process of collapsing the balloon 8 the pressure changes only slightly or remains constant, in other words dp/dV and equally dp/dx are zero or at least very close to zero. When the balloon 8 has reached the state of being completely collapsed further movement of the piston will cause rapid pressure drop, in other words dp/dV and dp/dx respectively will have large absolute amounts. When the absolute amount of the derivative with respect to volume exceeds a predetermined threshold at a certain negative pressure the evacuation action will be stopped by the computer 28.
The diagram shown in
The pressure inside the stomach can however be assessed reliably when it is independent of the filling state of balloon 8, i.e. in the range between point b and point c.
After having collected the pressure readings and having calculated the derivative dp/dx (or dp/dV) the computer determines a position between points b and d preferably the middle between points b and d, and moves the piston to this position to finalize the initial setting of the system.
In order to minimize leakage, valve 25 is closed after this calibration phase. If leakage is negligible valve 25 could be omitted. Then the patients thoracic pressure can be assessed continuously. After some time due to inavoidable leakage e.g. of the balloon a recalibration may become indicated.
Assumed now that the balloon 8 or any other part as for example the connector 16 has a leakage. In this case the pressure p and its mathematical derivative dp/dV with respect to volume V will remain low during the process of inflation and the pressure and its derivative will remain below a predetermined threshold. This will be recognized by the computer system and an alarm will be given.
Further it may occur that a lumen may be occluded or intentionally blocked because the catheter used has only one balloon. This situation as well will be recognized by the computer system because in this case the pressure during the inflation process will go high very rapidly.
Needless to say that the initial adjustment for the distal balloon 6 is done in the same way; by connecting the opening 7a to the computerized system and proceeding in the same way as described above with respect to the proximal balloon 8 in order to determine the patient's intra abdominal pressure. The computer may then calculate also the difference between abdominal and thoracal pressure and monitor this difference value.
While an embodiment has been described in which a catheter with two balloons is employed it goes without saying that only one balloon may be employed if the measurement of the pressure at only one site in patient's body is regarded to be sufficient. One of the two balloons and the catheter lumen pertaining to it may be left away.
The catheter of
The catheter 1 is advanced with its distal tip ahead through the mouth or the nose of a patient into the esophagus of the patient until its tip reaches the stomach, the duodenum or the jejunum of the patient depending on the medical requirements. The axial position of the distal balloon 6 is such that the distal balloon 6 as well as the blocking balloon 33 will then be situated in the stomach. The movement of the catheter 1 is monitored by means of counting the visible insertion marks 11 to make sure that the blocking balloon has entered the stomach. Then the blocking balloon 33 is filled with water and the catheter will be retracted until the blocking balloon 33 abuts the cardia of the patient's stomach, thus ensuring that the catheter is placed precisely with respect to the stomach and balloon 8 will be situated in the patient's thorax. Additionally the blocking balloon prevents the catheter 1 from being withdrawn from its place. This blocking balloon is very useful to assist in placing the catheter precisely and correctly without applying X-ray imaging.
The further operation of the catheter 1 is same as described for the catheter of the first embodiment and may be omitted therefore.
Number | Date | Country | Kind |
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05101465.2 | Feb 2005 | EP | regional |
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/EP06/50009 | 1/3/2006 | WO | 00 | 11/14/2007 |