Surgery – Diagnostic testing – Detecting nuclear – electromagnetic – or ultrasonic radiation
Reexamination Certificate
1998-05-14
2001-03-06
Lateef, Marvin M. (Department: 3737)
Surgery
Diagnostic testing
Detecting nuclear, electromagnetic, or ultrasonic radiation
C600S429000, C600S431000, C600S435000, C128S899000, C607S122000, C607S156000
Reexamination Certificate
active
06198963
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of intrabody tubes, i.e., tubes used internally in the medical care of patients, and specifically to location confirmation of medical tubes within a human body.
BACKGROUND OF THE INVENTION
In many instances medical tubes are inserted into a patient's body for short-term or long-term infusion of medicine, blood products, nutrition or other fluids. Such tubes are inserted, for example, into the patient's venous, arterial or digestive system. Sometimes it is important to insert the medicine or other fluid into a particular point in the patient's body. For example, in cancer chemotherapy and antibiotic therapy, an outlet of the tube infusing the medicine must be positioned in an area of high volume blood flow. As another example, patients who cannot eat on their own have a feeding tube inserted through their nose or mouth into their stomach. A feeding solution is inserted into the patient's stomach through an end of the feeding tube outside of the patient's body. The feeding solution naturally must be inserted into the stomach and not into other areas of the body. Other intrabody tubes include dilating tubes to widen esophageal stricture, colonic decompression tubes and urological tubes.
In many cases, an intrabody tube is used periodically over a long period of time. Therefore, to avoid the need to repeatedly insert new tubes, the tube is left within the patient's body. This is especially important when the patient is in home care, where there is nobody who can insert the tube. Home care of patients is a widespread and growing field, mainly due to the rising cost of hospital fees and the lengthening of care periods.
Generally, there is no simple method of keeping an intrabody tube fixed in place, and the tubes do not always remain in their original place. The outlet of the tube may drift out of place within the patient's body. Using the tube when its outlet is not in its proper place may cause serious damage. For example, the tip of a feeding tube may curl up and drift to the patient's lungs. Inserting a feeding solution through the tube in such a case could cause the death of the patient. Likewise, a chemotherapy infusion tube must be placed in a suitable location with a large stream of blood, such as the superior vena-cava in the heart. Otherwise, the medicine may damage the lining of the vascular system. It has been found that of patients who receive medicine in their hearts through infusion tubes, a significant portion suffer from complications due to unnoticed drift of the infusion tube.
There are other cases in which it is desired to follow up on the location of objects, other than tubes, within a patient's body. For example, it may be desired to follow up on the location of a screw, staple, electrode, shunt or any other object implanted in a patient's body. A specific example involves a Murphy button, which is used to connect a torn part of the intestine. The Murphy button is implanted in the intestine, and should remain in place until the intestine heals. After the intestine heals, the Murphy button should drift along the intestine out of the patient's body. Medical staff usually follow up on the movements of the button in case it gets stuck within the patient.
Various methods of confirming the location of medical tubes have been shown in the art. X-ray imaging is the most commonly used location confirmation system. Position determining systems can also be used for this purpose.
U.S. Pat. No. 5,425,382, whose disclosure is incorporated herein by reference, describes apparatus and method for locating a medical tube. The tube is located using a detection apparatus which senses the static magnetic field strength gradient of a magnet associated with the tube. The user locates the tube according to the gradient magnitude at points along the patient's body.
Another method is disclosed in U.S. Pat. Nos. 5,099,845 and 5,325,873, whose disclosures are incorporated herein by reference, wherein a radiating resonant element is associated with the tube. Apparatus is provided to indicate the distance from the apparatus to the tube, according to the radiation levels at different points, whereby the position of the tube is determined.
Another type of position-sensing apparatus is described in U.S. Pat. Nos. 4,905,698 and 5,425,367, whose disclosures are incorporated herein by reference. Such apparatus generates AC currents which induce an electromagnetic field, which in turn induces currents within a coil at the tip of a catheter. According to these currents, the relative location of the catheter is determined.
The use of the above described apparatus is time consuming and therefore complicates the use of intrabody tubes. Also, to operate such apparatus, a certain level of skill and experience is required. Therefore, such apparatus needs to be operated by clinical staff, and is not fit for widespread home care use.
SUMMARY OF THE INVENTION
It is an object of some aspects of the present invention to provide simple verification devices and methods for confirmation of intrabody tube location, which can be operated by nonprofessionals.
It is an object of some aspects of the present invention to provide simple verification devices and methods for quick confirmation of intrabody tube location.
It is an object of some aspects of the present invention to provide a verification device for automatic confirmation of intrabody tube location.
It is a further object of some aspects of the present invention to provide verification devices for confirmation of intrabody tube location which prevent use of the tube unless it has been confirmed that the tube is properly located.
Another object of some aspects of the present invention is to allow simple follow-up of the movements of an object within a human body.
Israel patent application number 119262, filed on Sep. 17, 1996, and PCT patent application PCT/IL97/00058, filed Feb. 14, 1997, which are assigned to the assignee of the present invention and whose disclosures are incorporated herein by reference, disclose methods of determining whether a chemotherapy tube has remained in its original position.
In some preferred embodiments of the present invention, a verification device outside the body of a patient is used to confirm the location of a medical tube's outlet inside the body. Preferably, the verification device operates in two modes, a learn mode, which records the correct location of the tube's outlet, and a test mode, which confirms, at later times, that the outlet remains in the correct location. Preferably, in the learn mode, the verification device measures and records one or more parameter values, forming a parameter vector, which characterize the location of the tube's outlet relative to the verification device. In the test mode, the device confirms that the values of the parameter vector did not change significantly relative to the recorded values, i.e., the tested values are within an allowed range of the recorded values.
The allowed range is necessary in order to minimize false alarms due to inaccuracy in the measurement or slight movements of the outlet of the tube which are insignificant. Preferably, the allowed range is defined such that proper location of the outlet is not confirmed when the outlet is in a dangerous position. The allowed range corresponds generally to areas in the patient's body where the tube may safely be used and/or areas regarding which there is substantially no risk that harm could be caused to the patient.
In some preferred embodiments of the present invention, a sensor is fixed to the medical tube, preferably, near the tube's outlet. The sensor enables the verification device to determine the one or more parameter values.
In preferred embodiments of the present invention, the method of using the verification device includes two steps: the “learn” step of recording location information, and the “test” step of location confirmation before every use of the
Fenster Maier
Govari Assaf
Haim Shlomo Ben
Biosense Inc.
Capezzuto Louis J.
Lateef Marvin M.
Lin J.
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