WO2016200334A1 - Système et procédé de détermination de la position de tubes médicaux insérés - Google Patents

Système et procédé de détermination de la position de tubes médicaux insérés Download PDF

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Publication number
WO2016200334A1
WO2016200334A1 PCT/SG2016/050195 SG2016050195W WO2016200334A1 WO 2016200334 A1 WO2016200334 A1 WO 2016200334A1 SG 2016050195 W SG2016050195 W SG 2016050195W WO 2016200334 A1 WO2016200334 A1 WO 2016200334A1
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WO
WIPO (PCT)
Prior art keywords
tube
patient
distal end
transmitter
location
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/SG2016/050195
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English (en)
Inventor
Ajay Ogirala
Ashley John Vaz
Khai Pang LEONG
Ravinder SINGH SACHDEV
Hui Leng Isabel NG
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Venia Medical Systems Pte Ltd
Tan Tock Seng Hospital
Original Assignee
Venia Medical Systems Pte Ltd
Tan Tock Seng Hospital
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Application filed by Venia Medical Systems Pte Ltd, Tan Tock Seng Hospital filed Critical Venia Medical Systems Pte Ltd
Publication of WO2016200334A1 publication Critical patent/WO2016200334A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/06—Devices, other than using radiation, for detecting or locating foreign bodies ; Determining position of diagnostic devices within or on the body of the patient
    • A61B5/061—Determining position of a probe within the body employing means separate from the probe, e.g. sensing internal probe position employing impedance electrodes on the surface of the body
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6867—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive specially adapted to be attached or implanted in a specific body part
    • A61B5/6871—Stomach
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B34/00—Computer-aided surgery; Manipulators or robots specially adapted for use in surgery
    • A61B34/20—Surgical navigation systems; Devices for tracking or guiding surgical instruments, e.g. for frameless stereotaxis
    • A61B2034/2046—Tracking techniques
    • A61B2034/2051—Electromagnetic tracking systems
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B2560/00—Constructional details of operational features of apparatus; Accessories for medical measuring apparatus
    • A61B2560/04—Constructional details of apparatus
    • A61B2560/0431—Portable apparatus, e.g. comprising a handle or case
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/68—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient
    • A61B5/6846—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive
    • A61B5/6847—Arrangements of detecting, measuring or recording means, e.g. sensors, in relation to patient specially adapted to be brought in contact with an internal body part, i.e. invasive mounted on an invasive device
    • A61B5/6852—Catheters

Definitions

  • the present invention relates generally to nasogastric tubes used in medical systems, and, more specifically, to a system and method for determining the location of the distal end of a nasogastric tube in a person where the proximal end of the tube remains outside the body.
  • a nasogastric tube (“NG tube”) is a flexible tube that is inserted through a patient's nose, past the throat and down to the stomach. It can be used to remove contents from the stomach, including air, to decompress the stomach, or to remove small solid objects and fluid, such as poison, from the stomach.
  • An NG tube can also be used to put substances into the stomach. Nutrients can be sent directly into the stomach when a patient cannot take food or drink by mouth (i.e. enteral feeding). NG Tubes are also commonly used to administer drugs and other oral agents such as activated charcoal.
  • Nasogastric intubation is a medical procedure wherein the end of the NG tube is inserted into the stomach.
  • NG tube intubation must be administered with utmost caution.
  • the NG tube must be carefully passed down the nose, through the esophagus and into the stomach of the patient. Appropriate care and procedure must be observed to ensure that the tube has not passed through the larynx into the trachea and down into the bronchi.
  • the health care provider should also be careful to avoid folding or coiling of the tube. Serious complications can arise due to improper insertion of the NG tube. If improperly inserted, an NG tube can lead to aspiration pneumonia and death.
  • one or more tests are used to confirm the proper placement of the NG tube into the stomach of the patient. Moreover, if the tube is to remain in place, a tube position check is recommended before each feeding and at least once per day. There are several tests that can be performed to check the location of an NG tube.
  • One test entails injecting air into the tube after it is inserted.
  • the clinician injects air into the NG tube while carefully listening for sounds in the abdomen with a stethoscope.
  • the tube should be in the correct position if air is heard in the stomach.
  • this method is unreliable and prone to error. Air sounds can be difficult to hear and interpret, particularly in a busy setting. Further, this method can be ineffective when treating obese patients.
  • Another test entails aspirating a sample of fluid from the tube to analyze after it is inserted.
  • the clinician draws a sample of fluid from the tube with a syringe.
  • the clinician can then check the pH of the sample. Because the fluid in the stomach is acidic, the sample should have a pH of 5.5 or lower to if the tube is in the correct position.
  • this method can also be unreliable.
  • the test results will vary depending on stomach contents. Moreover, acid-inhibiting drugs can cause misleading test results.
  • a more reliable test entails the use of an x-ray machine.
  • the clinician takes an x-ray of the chest and abdomen of the patient after inserting the tube to confirm its location. While effective, this method is generally avoided because of risks associated with exposure to x-rays. It is well acknowledged that any form of x-ray exposure (radiation) carries risks and the patient should be carefully monitored and controlled to minimize exposure. Further, a fetus, embryo, baby or child is more vulnerable to x-ray damage so the clinician should take extra precautions with younger patients and pregnant women.
  • the x-ray method also requires the use of expensive, heavy equipment in a specialized clinical environment. Administering the scan and preparing images is time consuming and can require 30 minutes or more to confirm proper placement of the tube. This is particularly impractical when repeated tests are necessary for a tube that must remain in place for an extended period of time.
  • Radio frequency identification is used in other methods wherein a tag or chip that contains electronically stored information is attached to a medical tube.
  • RFID Radio frequency identification
  • U.S. Patent App. No. 11/993,218 uses an electronic system and an RFID sensor embedded on an NG tube to determine its location. The test requires electromagnetic (EM) energy to pass from an external module (outside the human body) to a sensor module (inside the human body attached to the NG Tube) and then from the sensor module back to the external module. The system exposes the patient to a high amount of electromagnetic energy. Many recent studies have raised questions regarding the safety of exposure to electromagnetic energy. Moreover, the RFID sensor can interfere with other medical tests, including MRI scans.
  • the invention recognizes that there exists a long felt need for a safe and effective system and method for determining and verifying the position of medical tubes, catheters, syringes and other devices that are inserted into patients.
  • the invention enables accurate and economical bio-positioning using minimal amounts of radio- frequency electromagnetic (RF-EM) energy from an external source. This provides a safe, effective and reliable method for confirming the location of the distal end of a nasogastric tube. Further, the invention is less expensive and faster than traditional methods.
  • RF-EM radio- frequency electromagnetic
  • a transmitter module is connected to the gastric tube and is composed of a power source, a transmitter, a receiver, an analyzer and a user interface.
  • Electromagnetic (EM) energy transmitted from the transmitter is absorbed by one or more receiving antenna and analyzed to determine the location of the distal end of the medical tube. The location can be displayed to the user on an interface.
  • EM Electromagnetic
  • the medical tube system includes one or more receiving antenna (embedded or connected to the distal end of the NG tube) that do not transmit electromagnetic energy.
  • a transmitter includes more than one transmitting antennae, each capable of transmitting independently of one another.
  • the transmitter can include a plurality of transmitting antennae for determining the location of the distal end of the nasogastric tube using antennae diversity.
  • the analyzer of the medical tube system can use an algorithm to accurately determine the location of a nasogastric tube inside a patient.
  • the user e.g. health care provider or care giver
  • the medical tube detection system uses only EM energy that is transmitted from outside a patient. That is, there is no EM energy radiated from components that are inside the patient. The amount of EM energy that is transmitted can be adjusted to accommodate for the size of a patient. For example, a stronger signal may be necessary with an obese patient.
  • a method of confirming the presence of a medical tube in a patient's stomach comprising the steps of (1 ) placing the distal end of a medical tube in the stomach a patient, wherein the medical tube has a receiving antenna near the distal end, (2) connecting the proximal end of the medical tube to an external transmitter module, (3) placing the external transmitter module near the surface of the stomach of the patient, (4) analyzing the parameters of energy in the area near the stomach to determine the presence or absence of the distal end of the medical tube and (5) conveying information to a user through an interface.
  • the external transmitter module can include a transmitter, a receiver, an analyzer and a user interface
  • the receiving antenna (inside the patient) does not transmit EM energy.
  • the location of the distal end of a medical tube is determined using EM energy that is transmitted from outside the patient.
  • the external transmitter can include more than one transmitting antennae, each capable of operating
  • a plurality of transmitting antennae can be used for determining the location of the distal end of said nasogastric tube using antennae diversity.
  • the analyzer can use an algorithm to determine the location of a medical tube inside a patient.
  • the method can be used for a nasogastric tube, an orogastric tube, a percutaneous endoscopic gastrostomy tube, a percutaneous jejunostomy tube, an endotracheal tube, a chest tube, a urinary catheter, an intravenous catheter, an arterial catheter, a gastric decompression tube, a suction tube, a drainage tube, an intracranial pressure monitor, a catheter or a syringe.
  • a position-sensing medical tube for minimizing a patient's exposure to EM energy. It is comprised of (1 ) a medical tube having a proximal end and a distal end, wherein the distal end includes a receiving antenna and is placed inside a patient and (2) an external transmitter module connected to the proximal end of the medical tube that includes a power source, a transmitter, a receiver, an analyzer and a user interface.
  • the transmitter radiates energy to the receiving antenna.
  • the receiver detects radiation patterns and the analyzer uses an algorithm to determine the presence or absence of the distal end of the medical tube.
  • the receiving antenna of the system does not transmit EM energy.
  • the external transmitter can include more than one transmitting antennae, each capable of operating independently of one another. Further, the external transmitter can include a plurality of transmitting antennae for determining the location of the distal end of the nasogastric tube using antennae diversity. The distal end of a nasogastric tube can be detected by holding the external transmitter module over a person's stomach and observing a signal. The amount of EM energy transmitted can be adjusted to accommodate for the size of a patient.
  • a first aspect of the invention is an improved system and method for determining the location of the distal end of an NG tube inserted into the human body where the proximal end is outside the human body.
  • a second aspect of the invention is an NG tube system that is portable and more economical, reliable, safe and effective than traditional methods and can be used in both surgical and bed-side settings.
  • a third aspect of the invention is an intelligent NG tube system that includes a transmitter module, an antenna (or antenna array) connected to a transmitter, a receiver, an analysis module and one or more tube antennae.
  • a fourth aspect of the invention is an NG tube system in which an external transmitter module radiates electromagnetic (EM) energy through one or more antennae to detect the location of an NG tube. The system reduces the patient's exposure to EM energy compared to traditional tests.
  • a fifth aspect of the invention is an intelligent NG tube system in which a receiver and analyzer module evaluate incident energy as a separate external entity (i.e. no analysis or radiated energy from the internal antenna) to determine the position of a nasogastric tube. The amount of transmitted energy can be adjusted to
  • a sixth aspect of the invention is an intelligent NG tube system that uses an algorithm with one or more transmitting antennae to accurately determine the location of a nasogastric tube while eliminating ambiguous signals.
  • a seventh aspect of the invention is a system and method of determining the position of an NG tube that minimizes the limitations and risks associated with electromagnetic (EM) energy travelling through the human body.
  • the invention uses low amounts of radio-frequency electromagnetic (RF-EM) energy from an external source yet enables accurate and economical bio-positioning.
  • RF-EM radio-frequency electromagnetic
  • the invention has greater electromagnetic compatibility than conventional systems that use EM energy.
  • a eighth aspect of the invention is a system and method of determining the position of an NG tube that can operate in three modes such that (1) energy is transmitted from one antenna of the transmitter module, (2) energy is transmitted from two antennae of the transmitter module and (3) energy is transmitted from all three antennae of the transmitter module.
  • a ninth aspect of the invention is a portable NG tube system which allows a clinician or care giver to confirm proper placement of the distal end of a nasogastric tube by holding a device over a patient's abdomen or stomach and observing a signal.
  • the system is suitable for use outside of the clinical environment (i.e. home use) by providers or care givers with minimal training.
  • FIG. 1 is a schematic diagram of the NG tube assembly of the system, in accordance with the invention.
  • FIG. 2 is a schematic diagram the handheld module over the abdomen of a patient.
  • FIG. 3 is an illustration of the handheld module.
  • FIG. 4 is an illustration of the assembled NG tube.
  • FIG. 5 is a schematic diagram showing the antenna radiation perpendicular to vertical orientation of body, in accordance with the invention.
  • FIG. 6 is a schematic diagram showing overlapping radiation patterns that occur when the nasogastric tube is in the stomach (recording strong signals) in accordance with the invention.
  • FIG. 7 is a schematic diagram showing the radiation pattern mismatch that occurs when that nasogastric tube is in lungs (recording weak signals) in accordance with the invention.
  • FIG. 8 is a flow chart depicting the process of inserting and checking the location of a nasogastric tube, in accordance with the invention.
  • FIG. 9 is a flow chart depicting the process of verifying the location of an NG tube, in accordance with the invention.
  • NG nasogastric
  • the invention is not so limited and may be used to assist in properly inserting and verifying the location of other objects, including medical tubes, orogastric tubes, nasogastric tubes, percutaneous endoscopic gastrostomy tubes, percutaneous jejunostomy tubes, endotracheal tubes, chest tubes, urinary catheters, intravenous catheters, arterial catheters, gastric decompression tubes, suction tubes, drainage tubes, intracranial pressure monitors, catheters, syringes and other objects.
  • Other applications include, for example, but not limited to, using the invention in veterinary practices as well as outside of the medical/clinical setting.
  • embodiment/aspect means that a particular feature, structure, or characteristic described in connection with the embodiment/aspect is included in at least one embodiment/aspect of the disclosure.
  • antenna refers to an electrical device which converts electric power into radio waves, and vice versa.
  • a typical antenna is an arrangement of metallic conductors (elements), electrically connected (often through a transmission line) to the receiver or transmitter.
  • An oscillating current of electrons forced through the antenna by a transmitter will create an oscillating magnetic field around the antenna elements, while the charge of the electrons also creates an oscillating electric field along the elements.
  • antenna array refers to a geometrical arrangement of more than one antenna elements with a deliberate relationship between their currents, usually to achieve a desired radiation pattern
  • aspirate refers to the removal by suction of fluid and cells through a needle or syringe. The term may also refer to the accidental sucking in of food particles or fluids into the lungs.
  • catheter refers to a flexible tube inserted through a narrow opening into a body cavity, for example, the bladder.
  • clinical care refers to a health professional, such as a physician, psychologist, or nurse, who is directly involved in patient care.
  • coaxial cable refers to a transmission line that includes a tube of electrically conducting material surrounding a central conductor held in place by insulators that can be used to transmit telegraph, telephone and television signals
  • distal refers to the portion that is situated away the point of origin or attachment, as of a limb or bone. It can also refer to the portion that is situated away from a point of reference.
  • electrical envelope (of a modulated carrier wave) refers to a curve connecting the peaks of a graph of the instantaneous value of the electric or magnetic component of the carrier wave as a function of time.
  • Electromagnetic refers to the interrelation of electric currents or fields and magnetic fields.
  • EMC electromagnetic compatibility
  • electromagnetic radiation is the radiant energy released by certain electromagnetic processes. Visible light is one type of electromagnetic radiation. Other familiar forms are invisible electromagnetic radiations, such as radio waves, infrared light and X-rays.
  • incident energy refers to energy that falls upon or strikes something and then transfers some or all of its power into the object.
  • ISM band refers industrial, scientific and medical (ISM) radio bands (portions of the radio spectrum) reserved internationally for the use of radio frequency (RF) energy for industrial, scientific and medical purposes other than
  • loop antenna refers to an antenna shaped by one or more loops that is made of electrically conductive material with its end connected to an electromagnetic source.
  • Lumen refers to the canal, duct, or cavity of a tubular object or organ.
  • medical tube refers to a tube used in a medical procedure or method having one end internal and one end external to the body.
  • Examples of medical tubes include nasogastric tubes, orogastric tubes, percutaneous endoscopic
  • gastronomy tubes percutaneous jejunostomy tubes, endotracheal tubes, urinary catheters, intravenous catheters, arterial catheters, suction tubes, drainage tubes and intracranial pressure monitors.
  • nasogastric aspiration or “nasogastric suction” refers to the process of draining the stomach's contents via a tube.
  • PEP peak envelope power
  • proximal refers to the portion that is situated toward the point of origin or attachment, as of a limb or bone. It can also refer to the portion that is situated toward a point of reference.
  • radiation pattern refers to the directional (angular) dependence of the strength of the radio waves from the antenna or other source.
  • radio frequency refers to any of the electromagnetic wave frequencies that lie in the range extending from around 3 kHz to 300 GHz, which include those frequencies used for communications or radar signals. RF usually refers to electrical rather than mechanical oscillations.
  • radio frequency identification is a technology that incorporates the use of electromagnetic or electrostatic coupling in the radio frequency (RF) portion of the electromagnetic spectrum to uniquely identify an object, animal, or person.
  • signal diversity or “diversity scheme” refers to a method for improving the reliability of a message signal by using two or more communication channels with different characteristics.
  • miniature connector or "SMA” refers to a family of plugs or electrical connector that is commonly used in personal computers and components.
  • transmitter diversity refers to radio communication using signals that originate from two or more independent sources that have been modulated with identical information-bearing signals and that may vary in their transmission
  • Ultrasonic images also known as sonograms are made by sending pulses of ultrasound into tissue using a probe. The sound echoes off the tissue with different tissues reflecting varying degrees of sound. These echoes are recorded and displayed as an image to the operator.
  • x-ray or “x-radiation” refers to an electromagnetic wave of high energy and very short wavelength, which is able to pass through many materials opaque to light.
  • the invention includes an "intelligent" NG tube locating system which may be referred to as the "iNGT system.” It enables a clinician, health care provider or care giver to quickly and accurately confirm that the distal tip of a nasogastric tube is properly located in a patient's stomach.
  • the invention utilizes an internal antenna that is embedded or attached to the distal end of the NG tube. The antenna does not have electronic sensors or a power supply and does not emit energy. This bio-positioning technology is safe, portable, inexpensive and does not require extensive training or expertise for proper use.
  • the system includes a handheld transmitter module ("iNGT Transmitter Module” or “transmitter”) and an NG tube assembly.
  • the transmitter module includes (1) a transmitter, (2) a receiver and analyzer, (3) a power source, (4) a user interface and (5) one or more transmitting antennae.
  • the NG tube assembly includes (1) a tube antenna (receiving antenna), (2) a nasogastric tube, (3) a coaxial cable and (4) a connector.
  • a healthcare provider follows a standard procedure to insert the NG tube into a patient.
  • the NG tube antenna is imbedded or attached to one end (the distal end) of the NG tube assembly.
  • the NG tube is inserted into a patient by passing the distal end through the nose, through the esophagus and then to either the stomach or duodenum.
  • the clinician or caregiver can use the iNGT system to confirm that the distal end is properly placed in the patient's stomach. Because of the risk of
  • the user connects a coaxial cable from the NG tube assembly to the
  • the transmitter module can then be turned on.
  • the transmitter antennae transmits electromagnetic energy from the transmitter.
  • the transmitter has three antennae for this process. In typical use, all three will transmit electromagnetic energy which is captured by the NG tube antenna.
  • the user can hold or 'hover' the external hand-held device over the stomach area and observe a signal.
  • the electromagnetic signal is transferred to the receiver and analysis module through the coaxial cable.
  • the analysis module can use an algorithm to determine the location of the tube antenna inside the patient based on the
  • the system provides a signal to the user to indicate whether or not the distal end is in the stomach.
  • the NG tube may remain in place for an extended period of time. This may be necessary when the tube is used for regular patient feeding. It is essential to verify the position of the tube before each feeding and at least once per day. In such circumstances, the user can repeat the test as often as deemed practical or necessary.
  • FIG.1 is a schematic diagram of the nasogastric (NG) tube assembly 100 which has been properly inserted into a patient.
  • the system 100 includes an NG tube 102 and an external handheld device.
  • the NG tube 102 has an electromagnetic antenna (NG tube antenna) 103 at its distal tip and an embedded insulated conductor 102 that runs along the length of the tube.
  • the embedded insulated conductor 102 transmits an electromagnetic signal from the tube antenna 103 to the external receiver.
  • subminiature connector (SMA) 101 or similar connecting mechanism joins the NG tube antenna to the transmitter module.
  • the transmitter module 104 transmits/radiates electromagnetic energy that is absorbed/monitored by the receiving antenna 103 in the NG tube 102.
  • FIG. 2 is a schematic diagram of the handheld transmitter module 104 over the abdomen of a patient.
  • Transmitter antennae include the center antenna 201 , the "lungs” antenna 202 and the “stomach” antenna 203.
  • One or more antennae in the handheld module radiate EM energy to the NG tube antenna (receiving antenna) 103.
  • the NG tube antenna 103 absorbs the energy and it is converted into a binary value.
  • the signal is passed through the coaxial cable 102 to the receiver/analysis module in the handheld transmitter 104.
  • FIG. 3 is a diagram of the handheld transmitter module ("transmitter") 104.
  • the transmitter has three separate antennae.
  • the center antenna 201 is flanked by the "lungs” antenna 202 and the “stomach” antenna 203.
  • the "lungs” antenna 202 and the “stomach” antenna 203 are detachable as shown.
  • the transmitter can operate in three modes. The user can choose the mode by pressing one of three buttons 301.
  • the user interface 302, a buzzer or one or more indicator lights 303 alert the user to the proper (or improper) placement of the NG tube. An audio mechanism or buzzer can be located near the lights 303.
  • a coaxial cable (or similar) plugs into the transmitter 304. The modes of operation are described in detail below.
  • the transmitter includes a transmitter module 104.
  • the transmitter module can generate, amplify and transmit continuous EM radiation.
  • Such modules are commonly used in the electrical and engineering arts.
  • a preferred module for use in the transmitter has a multiple port output capable for transmitting three separate continuous
  • electromagnetic radiation streams at 13.56MHz between 17dBm to 20dBm.
  • Multiple sources can be used for antenna diversity to improve detection accuracy.
  • the transmitting antenna can be a small loop antenna.
  • the use of three separate transmitting antennae (“antenna array” or “phased array”) can be used to improve the accuracy of the system.
  • the signals from the antennae can be combined or processed in order to achieve improved performance over that of a single antenna.
  • the antenna array can be used to increase the overall gain, provide diversity reception, cancel out interference from a particular set of directions, "steer” the array so that it is most sensitive in a particular direction, determine the direction of arrival of the incoming signals and maximize the Signal to Interference Plus Noise Ratio (SINR)
  • SINR Signal to Interference Plus Noise Ratio
  • the user activates the power source and joins the SMA (or similar) connector 101 with the proximal end of the NG tube.
  • the provider can then choose the intended mode or operation.
  • EM radiation is transmitted from one or more transmitting antenna based on the mode.
  • the energy is absorbed by the NG tube antennae 103.
  • the receiver and analyzer module evaluate the incident energy of the tube antenna.
  • the receiver module can include amplifying circuitry, rectifier circuitry, an analogue to digital converter (ADC), a microcontroller (e.g. arduino uno board) that reads the signal strength from the ADC, an LCD screen to display the signal strength and a buzzer to provide real-time audio feedback on the signal strength.
  • ADC analogue to digital converter
  • microcontroller e.g. arduino uno board
  • the receiver module receives input RF signal, amplifies the signal and converts the signal strength to a numerical value for data processing.
  • the receiver module includes an analysis module that can use an algorithm to accurately locate the tip of the nasogastric tube.
  • the analyzer module determines if the NG tube is in the proper position (i.e. whether intubation was successful).
  • the electrical envelope of electromagnetic energy is digitized into a digital/binary value.
  • the digital output is analyzed and an audio/visual "pass" or "fail" is displayed on the interface to the user.
  • Mode 1 energy is transmitted from a single antenna of the transmitter module.
  • the module is held over the patient, specifically, the antenna labelled
  • the analyzer module Based on the energy received from the antennae, the analyzer module will determine whether the NG tube is present in the stomach.
  • Energy is detected and analyzed and a signal is sent to the user interface.
  • the user can visualize a green light indicating that the NG tube is properly placed.
  • a red light can indicate that the tube is improperly placed.
  • the clinician can hold or 'hover' the external hand-held device over the stomach area.
  • the external hand-held device can indicate whether the nasogastric tube is in the stomach by using a light, sound or text. For example, the device can display a green light. If the tube is not detected in the stomach, the device can give a signal to prompt the clinician to immediately remove or adjust the position of the tube. For example, the device can display a red light or emit a warning sound such as a beep.
  • FIG. 4 is a detailed illustration of the assembled NG tube.
  • the receiving antenna 103 is near the distal tip.
  • a catheter tube 104 extends across a substantial length of the tube.
  • the catheter tube is used for passing food or other substances into the stomach or aspirating material out of it.
  • the coaxial cable 102 links the antenna to a subminiature connector (SMA) 101 or other similar connector.
  • SMA subminiature connector
  • NG tubes must have small diameters to be effective and minimize discomfort during NG tube intubation. Accordingly, the NG tube antenna must be compact.
  • the iNGT system preferably includes a loop antenna of less than 3.0 mm with a ferrite core or similar design.
  • the selected frequency dictates the arrangement of the coil (i.e. number of rotations). This determines the inductance and capacitance of the coil and other characteristics of the antenna.
  • the transmitter antenna operates at a frequency of 13.56 MHz.
  • the receiving antenna is compact and receives the signal from the transmitter antenna.
  • a loop antenna design is preferable because of the size constraint.
  • the number of coils or turns is optimized for the preferred inductance, capacitance and other characteristics of the antenna. The number of loops therefore is chosen such that the antenna works well at the selected frequency.
  • the loop/receiving antenna can be composed of ferrite.
  • the coil antenna can be wound around a ferrite core to maximize the flux crossing through it and maximize the signal that is generated.
  • the receiver antenna preferably has a diameter of less than 3.0 mm to fit on the distal end of the NG tube. It preferably also has a short length improve so that the system can accurately pinpoint its location.
  • FIG. 5 is a schematic diagram showing the antenna radiation 401 perpendicular to the vertical orientation of the body.
  • the expected radiation pattern of the nasogastric tube antenna is donut shaped with its primary gain perpendicular to the vertical axis of the human body.
  • FIG. 6 shows how radiation patterns 500 overlap when the nasogastric tube is in stomach.
  • a radiation pattern 501 from external hand-held device is shown when placed over stomach area.
  • the radiation pattern from embedded antenna in the nasogastric tube is also shown 502.
  • the maximum energy is detected by the receiver and analyzer module (i.e. handheld device) when placed over the stomach of the patient. The system will detect less energy if the handheld device is placed over the lungs of the patient or elsewhere.
  • FIG. 7 shows the mismatch in radiation patterns 600 when the nasogastric tube is in lungs. Maximum energy will be recorded by the handheld device when the tube antenna is placed above the lungs of the patient. Significantly less energy is detected when the handheld device is placed over the stomach of the patient. A radiation pattern 601 from the external hand-held device does not overlap with that of the NG tube antenna 602. Here, the hand-held device will alert the clinician of the misplacement and indicate that the tube should be removed or adjusted.
  • An NG tube is often used for enteral feeding.
  • the tube is minimally invasive and relatively quick and easy to insert. It is particularly useful to avoid a surgical procedure to insert a gastrostomy device. However, because of the dangers of an improperly placed NG tube, the user must use caution in inserting and maintaining the position of the tube.
  • FIG. 8 is a flow chart depicting a process 800 of intubating a patient and verifying the position of a nasogastric tube using the invention.
  • the clinician selects a feeding tube suitable for the patient.
  • a clinic or hospital may have particular guidelines for choosing the appropriate type and size of NG tube.
  • the iNGT system can include different types of tubes of various sizes.
  • the healthcare provider selects the proper NG tube depending on considerations such as the desired procedure, patient's size and the anticipated length of time that an NG tube will remain in place. Further guidelines and considerations may be necessary when treating an infant or child.
  • the healthcare provider inserts the tube into the patient 802 according to an accepted protocol. He or she carefully inserts the NG tube into the patient by passing the distal end through the nose, down through the esophagus and then to the stomach. Thereafter, the proximal end of the tube may be secured with tape or held in place while checking its position.
  • a coaxial cable is attached to the proximal end of the NG tube.
  • the user connects a subminiature connector (SMA) on the end of the cable to the transmitter module.
  • SMA subminiature connector
  • the user confirms that the system has power by, for example, visualizing a "power on” button or light.
  • the user can confirm that the location of the distal end of the NG tube by moving the handheld apparatus ("transmitter") over the surface of the patient and watching the visual display.
  • the transmitter is "hovered” or placed over the patient's body to allow it to detect and analyze the emitted energy.
  • the user can guide the transmitter over the contour of the body, from the throat to the esophagus and then the stomach.
  • step 804 the device detects whether the tube is in stomach area. If the device is not detected in stomach area, then the handheld device is hovered over the lungs area of the patient 805. At step 807, the device determines whether the tube is in the area near the lungs.
  • the distal end will be in the stomach.
  • the detector module will sense the overlapping radiation patterns (see FIG.5). In this case, the interface on the transmitter will notify the caregiver with a signal such as a beep or icon on the screen. The user can proceed with nasogastric feeding or other patient care.
  • an NG tube will bend or form a coil when it is inserted, in which case, the distal tip may not reach the stomach. Other times, the tube may be misdirected into the lungs. If the NG tube is not properly inserted or is misplaced after insertion, the radiation patterns will not overlap (see FIG.6).
  • the interface on the transmitter will notify the user with a signal such as a buzzer or flashing icon on the screen. In this circumstance, the NG tube should be promptly removed.
  • the healthcare provider should return to the first step in the procedure.
  • the system will operate in Mode 3, wherein energy is transmitted from all three antennae of the transmitter module alternatively.
  • the antenna labelled “lungs” is placed over the lungs.
  • the antenna labelled “stomach” is placed over the stomach.
  • the third antenna is located between these two. Based on the energy received from the three antennae, the analyzer module can accurately determine whether the NG tube is present in the stomach.
  • the clinician can feed the patient if the device detects the tube in the stomach area 806. If the tube is in the lungs, as shown at step 809, the clinician checks whether the tube can be readjusted. If so, then the clinician readjusts the tube and proceeds to step 803. Otherwise, the clinician can remove and re-insert the tube 810.
  • FIG. 9 is a flow chart depicting the process 900 of verifying the location of a nasogastric tube using the invention. This process is appropriate when, for example, regular testing is necessary for an NG tube that remains in place.
  • the clinician checks the feeding tube and begins the process. The clinician places the handheld device over the stomach area of the patient 902. At step 903, the device determines whether the tube is in stomach area. If the device is not detected in the stomach area, then the clinician can place the handheld device over the lungs of the patient 905. At step 907, the device determines whether the tube is in lungs. If the tube is detected in the stomach or if the device is not detected in the lungs, the clinician can give food, fluid and medication as prescribed 904. As shown at step 907, the clinician can remove the tube and begin the process again if the tube is in the wrong location.
  • the system is safe, easy to use and is particularly well suited to repeated tests. Thus, it is conducive for use with an NG tube that is to remain in place for an extended period of time (e.g. a feeding tube). In such case, the position of the tube should be regularly confirmed prior to administering food and/or according to protocol.
  • an NG tube that is to remain in place for an extended period of time (e.g. a feeding tube). In such case, the position of the tube should be regularly confirmed prior to administering food and/or according to protocol.
  • the system is inexpensive and requires minimal training for use. It can be used in a clinical setting as well as a home environment. Mature patients and/or parents/care givers can be trained to use the iNGT system. It is also possible for a health care provider to conduct a second test (e.g. pH test) to confirm the results of the iNGT system.
  • a second test e.g. pH test
  • the invention can be used for inserting other tubes, catheters, probes or other objects into a patient, animal or subject.
  • the invention can be used for detecting the presence (or absence) of objects in a patient. It can also be used to follow one or more objects as they progress through a patient (e.g. through the digestive tract or circulatory system).

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Abstract

La présente invention concerne un système et un procédé de détermination de la position d'un tube naso-gastrique à l'intérieur d'un patient. Le système comprend module d'émetteur portatif et un système de tube. Le module d'émetteur comprend (1) un émetteur, (2) un récepteur et un analyseur, (3) une source d'alimentation, (4) une interface utilisateur et (5) une ou plusieurs antennes d'émission. Le système de tube comprend une antenne qui est fixée à ou intégrée dans un tube naso-gastrique. Le système peut déterminer précisément l'emplacement de l'extrémité distale du tube nasogastrique à l'intérieur du corps humain tout en réduisant au minimum l'exposition du patient à l'énergie électromagnétique.
PCT/SG2016/050195 2015-06-10 2016-04-26 Système et procédé de détermination de la position de tubes médicaux insérés Ceased WO2016200334A1 (fr)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190298222A1 (en) * 2016-12-09 2019-10-03 Stc.Unm Feeding tube visualization
CN110638659A (zh) * 2019-11-01 2020-01-03 广州驭林医药科技有限公司 一种胃肠管营养系统
US12036063B2 (en) 2020-07-31 2024-07-16 Avent, Inc. Airway detection using acoustic signals
US12220544B2 (en) 2020-07-31 2025-02-11 Avent, Inc. Airway detection using ultrasound

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Publication number Priority date Publication date Assignee Title
US5042486A (en) * 1989-09-29 1991-08-27 Siemens Aktiengesellschaft Catheter locatable with non-ionizing field and method for locating same
US5375596A (en) * 1992-09-29 1994-12-27 Hdc Corporation Method and apparatus for determining the position of catheters, tubes, placement guidewires and implantable ports within biological tissue
US20110098559A1 (en) * 2005-01-14 2011-04-28 William John Besz Guiding insert assembly for a catheter used with a catheter position guidance system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5042486A (en) * 1989-09-29 1991-08-27 Siemens Aktiengesellschaft Catheter locatable with non-ionizing field and method for locating same
US5375596A (en) * 1992-09-29 1994-12-27 Hdc Corporation Method and apparatus for determining the position of catheters, tubes, placement guidewires and implantable ports within biological tissue
US20110098559A1 (en) * 2005-01-14 2011-04-28 William John Besz Guiding insert assembly for a catheter used with a catheter position guidance system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20190298222A1 (en) * 2016-12-09 2019-10-03 Stc.Unm Feeding tube visualization
US11723552B2 (en) * 2016-12-09 2023-08-15 Unm Rainforest Innovations Feeding tube visualization
CN110638659A (zh) * 2019-11-01 2020-01-03 广州驭林医药科技有限公司 一种胃肠管营养系统
US12036063B2 (en) 2020-07-31 2024-07-16 Avent, Inc. Airway detection using acoustic signals
US12220544B2 (en) 2020-07-31 2025-02-11 Avent, Inc. Airway detection using ultrasound

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