WO2024009231A1 - Electric polarization catheter for calculating systemic cardiac output in critical area - Google Patents

Electric polarization catheter for calculating systemic cardiac output in critical area Download PDF

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Publication number
WO2024009231A1
WO2024009231A1 PCT/IB2023/056951 IB2023056951W WO2024009231A1 WO 2024009231 A1 WO2024009231 A1 WO 2024009231A1 IB 2023056951 W IB2023056951 W IB 2023056951W WO 2024009231 A1 WO2024009231 A1 WO 2024009231A1
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Prior art keywords
catheter
electrode
balloon
blood
sensing coil
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PCT/IB2023/056951
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French (fr)
Inventor
Giuseppe NASSO
Ignazio CONDELLO
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Nasso Giuseppe
Condello Ignazio
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Publication of WO2024009231A1 publication Critical patent/WO2024009231A1/en

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    • 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 
    • A61B5/053—Measuring electrical impedance or conductance of a portion of the body
    • A61B5/0538—Measuring electrical impedance or conductance of a portion of the body invasively, e.g. using a catheter
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
    • A61B5/026—Measuring blood flow
    • A61B5/029—Measuring or recording blood output from the heart, e.g. minute volume
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/107—Measuring physical dimensions, e.g. size of the entire body or parts thereof
    • A61B5/1072—Measuring physical dimensions, e.g. size of the entire body or parts thereof measuring distances on the body, e.g. measuring length, height or thickness
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—Detecting, measuring or recording devices for testing the shape, pattern, colour, size or movement of the body or parts thereof, for diagnostic purposes
    • A61B5/107—Measuring physical dimensions, e.g. size of the entire body or parts thereof
    • A61B5/1076—Measuring physical dimensions, e.g. size of the entire body or parts thereof for measuring dimensions inside body cavities, e.g. using catheters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/14503—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/14542—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue for measuring blood gases
    • 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
    • A61B5/6853—Catheters with a balloon
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/12—Diagnosis using ultrasonic, sonic or infrasonic waves in body cavities or body tracts, e.g. by using catheters
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B8/00—Diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/52—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves
    • A61B8/5215—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data
    • A61B8/5223—Devices using data or image processing specially adapted for diagnosis using ultrasonic, sonic or infrasonic waves involving processing of medical diagnostic data for extracting a diagnostic or physiological parameter from medical diagnostic data

Definitions

  • the extracorporeal ultrasound is not capable of determining CO with sufficient precision. It is necessary to perform intravascular measurements, but the prolonged intravascular measurements of blood flow in aorta involve serious risks.
  • the pulmonary artery catheter (PAC) or Swan-Ganz is still the gold standard for measuring CO. PAC is inserted in the venous system and it is made to advance through the atrium and the right ventricle in the pulmonary artery, which is not without risks. PAC allows to measure CO with thermodilution methods. However, its use was associated to various complications during and after the measuring procedure. This led to the development of several minimally invasive methods for monitoring CO based upon (combinations of) thermodilution, transthoracic or esophageal ultrasound (Doppler) and analysis of power and contour of the pressure pulses.
  • Doppler transthoracic or esophageal ultrasound
  • the present invention relates to a new apparatus (1) for determining cardiac output, comprising a percutaneous catheter (2) implantable in critical area, which exploits, instead of the thermodilution typical of the catheter di Swan Ganz, the transfer of a small amount of energy on a liquid carrier such as blood.
  • the delivered electric energy is lower than 10 Millivolt (mV), therefore it is not lethal and it is irrelevant on heart rhythm.
  • An advantage of the apparatus of the present invention is to comprise, directly connected to the catheter (2), an echocardiographic probe (9) for measuring the lumen of the pulmonary vessel, by allowing to perform a structural determination without using an extracorporeal ultrasound.
  • At least one electrode (3) connected to an electric current generator (4) positioned as first element starting from the proximal end (12), configured in such a way as to transfer a defined amount of electric charge;
  • an expandable balloon (6) positioned in proximity to the distal end of the catheter, equipped with an outlet valve (7) which allows said balloon (6) to be inflated and deflated, so as to anchor or disanchor said catheter (2) to the blood vessel;
  • At least one sensing coil (8) positioned before said balloon (6) and after said electrode (3), configured to detect an amount of electric charge
  • an ultrasound probe (9) positioned adjacent to the sensing coil (8), configured for detecting the real diameter of a vessel lumen;
  • Pressure transducer a device is meant converting the pressure into an analog electrical signal.
  • the pressure conversion into an electrical signal is obtained from the physical deformation of the strain gauges connected to the membrane of the pressure transducer and wired in a Wheatstone bridge configuration.
  • Electrode battery, dynamo, alternator, photovoltaic cell
  • a device capable of keeping constant over time the p.d. (potential difference) between the two extremes of a conductor.
  • Ultrasound probe an intravascular probe is meant allowing to obtain with ultrasounds a cross/longitudinal section of the lumen, by allowing to detect the vessel sizes.
  • Step releasing electrode one electrode is meant having, behind the tip, a space containing silicone gum impregnated with corticosteroid (usually dexamethasone sodium phosphate), which is gradually released over time towards outside by the electrode in the point of contact with myocardium.
  • corticosteroid usually dexamethasone sodium phosphate
  • right atrial pressure the right atrial pressure comprised between an average of 2 mmHg under physiological conditions is meant.
  • pulmonary artery (PAP) monitoring the monitoring of blood pressure of the pulmonary arterial circulation is meant.
  • capillary pressure WP
  • PCWP Pulmonary capillary wedge pressure
  • Figure 1 Structure of the apparatus (1) and specifically of the catheter (2) of electric polarization of the red blood cells for detecting cardiac output and for detecting the pressures of the right heart according to a preferred embodiment of the present invention.
  • Figure 3 Section structure of the catheter of electric polarization (2) according to a preferred embodiment of the present invention.
  • Figure 4 Structure exemplifying a steroid releasing electrode (3) according to a preferred embodiment of the present invention.
  • the present invention provides a new apparatus (1) for measuring physiological parameters for determining cardiac output, comprising:
  • At least one electrode (3) connected to an electric current generator (4) positioned as first element starting from the proximal end (12), configured in such a way as to transfer a defined amount of electric charge;
  • an expandable balloon (6) positioned in proximity to the distal end of the catheter, equipped with an outlet valve (7) which allows said balloon (6) to be inflated and deflated, so as to anchor or disanchor said catheter (2) to the blood vessel,
  • - at least one sensing coil (8) positioned before said balloon (6) and after said electrode (3), configured to detect an amount of electric charge;
  • an ultrasound probe (9) positioned adjacent to the sensing coil (8), configured for detecting the real diameter of a vessel lumen;
  • said apparatus is characterized in that said electrode (3) connected to said electric current generator (4) transfers a defined amount of electric charge to the blood in the section under examination, and said sensing coil (8) detects the electric charge of the blood in the point wherein it is positioned and sends the signals relating to the detected charges to a device for processing said measurements (11).
  • the body of said catheter (2) is hollow, and it is defined by at least two sections.
  • the body of said catheter (2) is defined by four sections (A, B, C, D in figure 3): section A is configured for the passage of polarization lines, electric reading lines and ultrasound probe; section B is configured for filling-in the balloon (6); line C is configured for the proximal infusion in right atrium; and section D is configured for the passage of the lines reading the atrial and pulmonary pressures.
  • said electrode (3) is a steroid releasing electrode.
  • said electrode (3) is connected to the proximal end (12) of said catheter.
  • said electrode (3) is configured for measuring the right atrial pressure (PVC).
  • PVC right atrial pressure
  • a pressure transducer (5) is required, converting the mechanical pulse of the lumen into electrical pulse to the processing device (11).
  • the line with transducer can be connected to the proximal end (12) of the catheter proximally to a saline solution bag inserted in a bag squeezer inflated so that it guarantees continuous washing of the lumen.
  • the transducer is positioned at the two extremes of line and detects the mechanical pulse of the blood from the lumen and transmits it in real time to the processing device (11) by providing a maximum, minimum and average value of PVC, and provides a sphygmic wave.
  • said electric current generator (4) delivers an electric potential in a range from 1 mV to 20 mV.
  • said pressure transducer (5) is configured for pulmonary artery (PAP) monitoring, capillary pressure (WP) detection and mixed venous blood sampling to determine the saturation of said blood (SVO2).
  • PAP pulmonary artery
  • WP capillary pressure
  • SVO2 mixed venous blood sampling
  • the balloon is inflated with a liquid.
  • liquids are physiological solution, crystalloid solutions (such as acetate ringer®, lactate ringer®), electrolytic solutions, double distilled solution.
  • said balloon (6) is made of a material selected from polyethylene terephthalate (PET), nylon, polyvinyl chloride (PVC).
  • PET polyethylene terephthalate
  • PVC polyvinyl chloride
  • said balloon (6) when inflated, is configured to occlude a branch of the pulmonary artery and determine through echocardiographic monitoring and/or modification of the pressure wave the pulmonary capillary wedge pressure (PCWP).
  • PCWP pulmonary capillary wedge pressure
  • the transesophageal echocardiography is exploited.
  • the monitoring of pressures changes in relation to the positioning of the catheter.
  • the passage and positioning of the catheter (2) from a structure to the other one in the right heart sections is discriminated through the different morphologies of the pressure waves in relation to the different values in mmHg.
  • the pressure wave of the right atrium has a morphology related to the systolic peak which does not exceed 5 mmHg, in right ventricle there is under normal physiological conditions a systolic peak of 25 mmHg and end-diastolic peak of 9 mmHg, whereas the pulmonary artery has an average pressure of 15 mmHg, a systolic peak of 25 mmHg and an end-diastolic pressure of 9 mmHg, the occlusion of the pulmonary artery (wedge of the pulmonary artery) has an average pressure of 9 mmHg.
  • said sensing coil (8) is a platinum-iridium metal alloy insulated by a sheath made of silicone or polyurethane.
  • said sensing coil (8) has a length from 0.5 to 1.5 cm and a thickness from 0.1 to 0.5 cm.
  • said sensing coil (8) has a length of 1 cm and a thickness of 0.3 cm.
  • said sensing coil (8) detects the electric charge at a distance of 3 to 5 cm from the distal end (13) of said catheter.
  • said ultrasound probe (9) is a piezoelectric ultrasound probe.
  • a piezoelectric ultrasound probe is an ultrasound probe (with ultrasounds), comprising piezoelectric elements which produce electromechanical microsystems (MEMS), so that said probe can transmit and receive ultrasounds by making a diaphragm comprising said piezoelectric element to vibrate.
  • MEMS electromechanical microsystems
  • a method for measuring physiological parameters for determining cardiac output comprising a step of using the apparatus according to any one of the herein described embodiments.
  • the catheter comprises:
  • a proximal lumen is at level of the right atrium, by allowing to monitor the right atrial pressure (PVC) and to determine cardiac output (CO) through the delivery of electric energy on the red blood cells through a steroid releasing electrode (cathode).
  • PVC right atrial pressure
  • CO cardiac output
  • PAP pulmonary artery
  • WP wedge pressure capillary pressure
  • SvO2 mixed venous blood sampling to determine its saturation
  • PCWP pulmonary capillary wedge pressure
  • sensing coil anode
  • an ultrasound probe is connected to detect the real diameter in short-axis of the vessel lumen.
  • the energy produced by a voltage generator is delivered by the catheter at the proximal end (cathode) aligned to the outflow tract and it is detected on the fluid in the distal portion of the catheter (anode).
  • the speed difference from the transfer to the energy detection on the fluid allows to calculate the output in preferred time ranges, for example every 5 seconds.

Abstract

The present invention relates to the field of measurement of physiological parameters for determining cardiac output, more specifically it relates to a new apparatus for determining cardiac output based upon determining the electric charges induced on the membrane of the red blood cells (electric polarization of the red blood cells).

Description

ELECTRIC POLARIZATION CATHETER FOR CALCULATING SYSTEMIC CARDIAC OUTPUT IN CRITICAL AREA
FIELD OF THE INVENTION
The present invention relates to the field of measurement of physiological parameters for determining cardiac output, more specifically it relates to a new apparatus for determining cardiac output based upon determining the electric charges induced on the membrane of the red blood cells (electric polarization of the red blood cells).
STATE OF ART
The measurement of the cardiac output (CO) is an important instrument for monitoring the hemodynamic status of patients during the surgical operations and their stay in the intensive care unit. The cardiac output is the volume of blood pumped by the heart in a determined period of time. Since the blood circulation is a closed system, this can designate both the volume of blood pumped in the aorta by the left ventricle, but also the volume of blood pumped in the pulmonary arteria by the right ventricle, or the volume of blood flowing in the right atrium (venous return) or in the left atrium.
The extracorporeal ultrasound is not capable of determining CO with sufficient precision. It is necessary to perform intravascular measurements, but the prolonged intravascular measurements of blood flow in aorta involve serious risks. The pulmonary artery catheter (PAC) or Swan-Ganz is still the gold standard for measuring CO. PAC is inserted in the venous system and it is made to advance through the atrium and the right ventricle in the pulmonary artery, which is not without risks. PAC allows to measure CO with thermodilution methods. However, its use was associated to various complications during and after the measuring procedure. This led to the development of several minimally invasive methods for monitoring CO based upon (combinations of) thermodilution, transthoracic or esophageal ultrasound (Doppler) and analysis of power and contour of the pressure pulses.
Blood speed alone is not sufficient to determine cardiac output, since it is also necessary to know the real internal cross-section area of the blood vessel. In past, the determination of real internal cross-section area was obtained by using transducer arrays and methods for range-gating or processing the signal-power ratio, which require intricate and meticulously constructed transducers and complex electronic processing units. In this regard, one relates to U.S. 3.542.014, Peronneau, 4.142.412, McLeod et al., 4.237.729, McLeod et al., 4.259.870, McLeod et al., e 4.232.373, Jackson et al. Although these methods are capable of providing higher accuracy and precision in determining cardiac output, the complexity and cost of the catheter and of the related signal-processing apparatus have significantly limited their widespread commercial application.
However, all these methods have disadvantages, both in terms of practicality (limited frequency of measurement, manual procedures, time required for measurement and/or patient discomfort) and accuracy in a wide range of hemodynamic conditions.
SUMMARY OF THE INVENTION
The present invention relates to a new apparatus (1) for determining cardiac output, comprising a percutaneous catheter (2) implantable in critical area, which exploits, instead of the thermodilution typical of the catheter di Swan Ganz, the transfer of a small amount of energy on a liquid carrier such as blood. The delivered electric energy is lower than 10 Millivolt (mV), therefore it is not lethal and it is irrelevant on heart rhythm.
The percutaneous catheter (2) is implantable percutaneously in right jugular vein and it exploits the principle of the electric polarization of the red blood cells, by allowing to calculate, at serial intervals depending upon medical needs, the systemic cardiac output, by considering the speed difference of the red blood cells charged electrically between two defined points of the catheter, in relation to the ultrasound diameter of the pulmonary lumen in short axis projection of the point.
The apparatus of the present invention is based upon an electrodynamic field system, consisting of one electrode (3) integrated in the catheter, aimed at releasing the electric energy in the order of tens of mV, by allowing to release electric charges on the membrane of the red blood cells, and of one sensing coil, integrated too in the catheter, allowing to read the charge on the membrane of the red blood cells in speed, then by exploiting a measurement of micrometric nature.
An advantage of the apparatus of the present invention is to comprise, directly connected to the catheter (2), an echocardiographic probe (9) for measuring the lumen of the pulmonary vessel, by allowing to perform a structural determination without using an extracorporeal ultrasound.
The calculation of the output through the catheter of the present invention will result from the formula:
Figure imgf000004_0001
Figure imgf000004_0002
Therefore, the present invention relates to an apparatus (1) for measuring physiological parameters for determining cardiac output, comprising:
- an implantable percutaneous catheter (2) for insertion into a blood vessel wherein blood flow is to be measured, wherein said catheter (2) comprises a proximal end (12) and a distal end (13) and:
- at least one electrode (3) connected to an electric current generator (4) positioned as first element starting from the proximal end (12), configured in such a way as to transfer a defined amount of electric charge;
- a pressure transducer (5) adjacent to said electrode (3);
- an expandable balloon (6) positioned in proximity to the distal end of the catheter, equipped with an outlet valve (7) which allows said balloon (6) to be inflated and deflated, so as to anchor or disanchor said catheter (2) to the blood vessel;
- at least one sensing coil (8) positioned before said balloon (6) and after said electrode (3), configured to detect an amount of electric charge;
- an ultrasound probe (9) positioned adjacent to the sensing coil (8), configured for detecting the real diameter of a vessel lumen;
- means (10) for connecting to a device for processing the raw measurements (11) detected by said sensing coil (8) and said probe (9);
- optionally a device for processing the measurements (11) detected by said sensing coil (8) and said probe (9); wherein said apparatus is characterized in that said electrode (3) connected to said electric current generator (4) transfers a defined amount of electric charge to the blood in the vessel under examination, and said sensing coil (8) detects the electric charge of the blood in the point wherein it is positioned and sends the signals relating to the detected charges to a device for processing said measurements (11). GLOSSARY
To the purposes of the present invention, under the expression “volume of the pulmonary vessel” the amount in litres per minute of blood passing in the pulmonary artery trunk is meant.
To the purposes of the present invention, under the expression “Sensing coil” a device is meant detecting and converting current having a measurable output voltage, proportional to the current passing through the measured path.
To the purposes of the present invention, under the expression “Pressure transducer” a device is meant converting the pressure into an analog electrical signal. The pressure conversion into an electrical signal is obtained from the physical deformation of the strain gauges connected to the membrane of the pressure transducer and wired in a Wheatstone bridge configuration.
To the purposes of the present invention, under the expression “Electric current generator” (battery, dynamo, alternator, photovoltaic cell...) a device is meant capable of keeping constant over time the p.d. (potential difference) between the two extremes of a conductor.
To the purposes of the present invention, under the expression “Ultrasound probe” an intravascular probe is meant allowing to obtain with ultrasounds a cross/longitudinal section of the lumen, by allowing to detect the vessel sizes.
To the purposes of the present invention, under the expression “Steroid releasing electrode” one electrode is meant having, behind the tip, a space containing silicone gum impregnated with corticosteroid (usually dexamethasone sodium phosphate), which is gradually released over time towards outside by the electrode in the point of contact with myocardium.
To the purposes of the present invention, under the expression “short axis of the point” a projection is meant allowing to highlight the cross section of the vessel.
To the purposes of the present invention, under the expression “right atrial pressure” the right atrial pressure comprised between an average of 2 mmHg under physiological conditions is meant.
To the purposes of the present invention, under the expression “pulmonary artery (PAP) monitoring” the monitoring of blood pressure of the pulmonary arterial circulation is meant.
To the purposes of the present invention, under the expression “capillary pressure (WP)” or Pulmonary capillary wedge pressure (PCWP) (also called pulmonary wedge pressure or pulmonary artery occlusion pressure) the pressure measured by the wedge of an inflated balloon catheter inserted into a small pulmonary arterial branch is meant.
To the purposes of the present invention, under the expression “blood saturation (SVO2)” the oxygen saturation in the mixed venous blood is meant.
To the purposes of the present invention, when one relates to the terms “before” and “after” with reference to elements arranged in the catheter (2), one considers as direction the one going from the proximal lumen to the distal lumen of said catheter.
DETAILED DESCRIPTION OF FIGURES
Figure 1. Structure of the apparatus (1) and specifically of the catheter (2) of electric polarization of the red blood cells for detecting cardiac output and for detecting the pressures of the right heart according to a preferred embodiment of the present invention.
Figure 2. Electric polarization catheter (2) in relation to the cardiac anatomy according to a preferred embodiment of the present invention.
Figure 3. Section structure of the catheter of electric polarization (2) according to a preferred embodiment of the present invention.
Figure 4. Structure exemplifying a steroid releasing electrode (3) according to a preferred embodiment of the present invention.
DETAILED DESCRIPTION
The present invention provides a new apparatus (1) for measuring physiological parameters for determining cardiac output, comprising:
- an implantable percutaneous catheter (2) for insertion into a blood vessel wherein blood flow is to be measured, wherein said catheter (2) comprises a proximal end (12) ed a distal end (13) and:
- at least one electrode (3) connected to an electric current generator (4) positioned as first element starting from the proximal end (12), configured in such a way as to transfer a defined amount of electric charge;
- a pressure transducer (5) adjacent to said electrode (3);
- an expandable balloon (6) positioned in proximity to the distal end of the catheter, equipped with an outlet valve (7) which allows said balloon (6) to be inflated and deflated, so as to anchor or disanchor said catheter (2) to the blood vessel,
- at least one sensing coil (8) positioned before said balloon (6) and after said electrode (3), configured to detect an amount of electric charge; - an ultrasound probe (9) positioned adjacent to the sensing coil (8), configured for detecting the real diameter of a vessel lumen;
- means (10) for connecting to a device for processing the raw measurements (11) detected by said sensing coil (8) and said probe (9);
- optionally a device for processing the measurements (11) detected by said sensing coil (8) and said probe (9); wherein said apparatus is characterized in that said electrode (3) connected to said electric current generator (4) transfers a defined amount of electric charge to the blood in the section under examination, and said sensing coil (8) detects the electric charge of the blood in the point wherein it is positioned and sends the signals relating to the detected charges to a device for processing said measurements (11).
In an embodiment, the body of said catheter (2) is hollow, and it is defined by at least two sections.
In a preferred embodiment, the body of said catheter (2) is defined by four sections (A, B, C, D in figure 3): section A is configured for the passage of polarization lines, electric reading lines and ultrasound probe; section B is configured for filling-in the balloon (6); line C is configured for the proximal infusion in right atrium; and section D is configured for the passage of the lines reading the atrial and pulmonary pressures.
In an embodiment, said electrode (3) is a steroid releasing electrode.
In an embodiment, said electrode (3) is connected to the proximal end (12) of said catheter.
In a preferred embodiment, said electrode (3) is configured for measuring the right atrial pressure (PVC). For determining PVC, a pressure transducer (5) is required, converting the mechanical pulse of the lumen into electrical pulse to the processing device (11). The line with transducer can be connected to the proximal end (12) of the catheter proximally to a saline solution bag inserted in a bag squeezer inflated so that it guarantees continuous washing of the lumen. The transducer is positioned at the two extremes of line and detects the mechanical pulse of the blood from the lumen and transmits it in real time to the processing device (11) by providing a maximum, minimum and average value of PVC, and provides a sphygmic wave. The PVC value allows to evaluate the circulating blood volume, the cardiac functionality and the venous return. Various factors affect the PVC values: hypovolemia or hypervolemia (decrease or increase in the circulating blood volume), cardiac insufficiency, mechanical obstacles to the cardiac circulation, changes in intrathoracic pressure (for example pneumothorax), drugs and mechanical ventilation. PVC is a parameter which is detected frequently within post-surgery monitoring. In an embodiment, said electric current generator (4) is a low voltage generator, for example the typical current generators of pacemakers and steroid releasing electrodes.
In an embodiment, said electric current generator (4) delivers an electric potential in a range from 1 mV to 20 mV.
In a preferred embodiment, said pressure transducer (5) is configured for pulmonary artery (PAP) monitoring, capillary pressure (WP) detection and mixed venous blood sampling to determine the saturation of said blood (SVO2). Through the capillary pressure (WP), it is possible to obtain an indirect measurement of the left atrial pressure. The standard gold is considered to determine the origin of the acute pulmonary oedema.
According to an embodiment, said balloon outlet valve (7) is equipped with a syringe (14) for inflating said balloon (6).
In a preferred embodiment, the balloon is inflated with a liquid. Examples of liquids are physiological solution, crystalloid solutions (such as acetate ringer®, lactate ringer®), electrolytic solutions, double distilled solution.
In an embodiment, said balloon (6) is made of a material selected from polyethylene terephthalate (PET), nylon, polyvinyl chloride (PVC).
In a preferred embodiment, said balloon (6), when inflated, is configured to occlude a branch of the pulmonary artery and determine through echocardiographic monitoring and/or modification of the pressure wave the pulmonary capillary wedge pressure (PCWP). In order to position correctly the balloon (6) to occlude the pulmonary artery branch, the transesophageal echocardiography is exploited. The monitoring of pressures changes in relation to the positioning of the catheter. In fact, the passage and positioning of the catheter (2) from a structure to the other one in the right heart sections is discriminated through the different morphologies of the pressure waves in relation to the different values in mmHg. The pressure wave of the right atrium has a morphology related to the systolic peak which does not exceed 5 mmHg, in right ventricle there is under normal physiological conditions a systolic peak of 25 mmHg and end-diastolic peak of 9 mmHg, whereas the pulmonary artery has an average pressure of 15 mmHg, a systolic peak of 25 mmHg and an end-diastolic pressure of 9 mmHg, the occlusion of the pulmonary artery (wedge of the pulmonary artery) has an average pressure of 9 mmHg.
The integration of the parameters “short axis of the point”, “right atrial pressure”, “PAP” and ”WP”, is useful to interpretate the right heart output in relation to the macro- circulatory and oxygen consumption and then metabolic parameters of the patient in critical area. In an embodiment, said sensing coil (8) is a platinum-iridium metal alloy insulated by a sheath made of silicone or polyurethane.
In an embodiment, said sensing coil (8) has a length from 0.5 to 1.5 cm and a thickness from 0.1 to 0.5 cm. Preferably, said sensing coil (8) has a length of 1 cm and a thickness of 0.3 cm.
In a preferred embodiment said sensing coil (8) detects the electric charge at a distance of 3 to 5 cm from the distal end (13) of said catheter.
In an embodiment, said ultrasound probe (9) is a piezoelectric ultrasound probe. A piezoelectric ultrasound probe is an ultrasound probe (with ultrasounds), comprising piezoelectric elements which produce electromechanical microsystems (MEMS), so that said probe can transmit and receive ultrasounds by making a diaphragm comprising said piezoelectric element to vibrate.
A method for measuring physiological parameters for determining cardiac output is also herein described, comprising a step of using the apparatus according to any one of the herein described embodiments.
EXAMPLES
In a preferred embodiment of the apparatus of the present invention, the catheter comprises:
- a proximal lumen is at level of the right atrium, by allowing to monitor the right atrial pressure (PVC) and to determine cardiac output (CO) through the delivery of electric energy on the red blood cells through a steroid releasing electrode (cathode).
- a distal lumen connected to a pressure transducer allowing to monitor in pulmonary artery (PAP), to detect the capillary pressure (WP wedge pressure) and mixed venous blood sampling to determine its saturation (SvO2).
- an output valve of the balloon provided with a syringe to inflate the balloon itself, by allowing to occlude a branch of the pulmonary artery and determine the pulmonary capillary wedge pressure (PCWP).
- a lumen for the connection to the electrical energy detector, sensing coil (anode), which detects the electrical charge at a distance of 4 cm from the tip of the catheter,
- an additional lumen in right atrium thereto an ultrasound probe is connected to detect the real diameter in short-axis of the vessel lumen.
The energy produced by a voltage generator is delivered by the catheter at the proximal end (cathode) aligned to the outflow tract and it is detected on the fluid in the distal portion of the catheter (anode). The speed difference from the transfer to the energy detection on the fluid allows to calculate the output in preferred time ranges, for example every 5 seconds.

Claims

1. An apparatus (1) for measuring physiological parameters for determining cardiac output, comprising:
- an implantable percutaneous catheter (2) for insertion into a blood vessel in which blood flow is to be measured, wherein said catheter (2) comprises a proximal end (12) and a distal end (13) and:
- at least one electrode (3) connected to an electric current generator (4) positioned as first element starting from the proximal end (12), configured in such a way as to release a defined amount of electric charge;
- a pressure transducer (5) adjacent to said electrode (3);
- an expandable balloon (6) placed in proximity to the distal end of the catheter, equipped with an outlet valve (7) which allows said balloon (6) to be inflated and deflated, so as to anchor or disanchor said catheter (2) to the blood vessel;
- at least one sensing coil (8) placed before said balloon (6) and after said electrode (3), configured to detect an amount of electric charge;
- an ultrasound probe (9) positioned adjacent to the sensing coil (8), configured for detecting the real diameter of a vessel lumen;
- means (10) for connecting to a device for processing the measurements (11) detected by said sensing coil (8) and said probe (9);
- optionally a device for processing the raw measurements (11) detected by said sensing coil (8) and said probe (9); wherein said apparatus is characterized in that said electrode (3) connected to said electric current generator (4) transfers a defined amount of electric charge to the blood in the vessel under examination, and said sensing coil (8) detects the electric charge of the blood in the point where it is placed and sends the signals relating to the detected charges to a device for processing said measurements (11).
2. The apparatus according to claim 1 , wherein the body of said catheter (2) is hollow, and it is defined by at least two sections.
3. The apparatus according to any one of claims 1 or 2, wherein said electrode (3) is a steroid releasing electrode.
4. The apparatus according to any one of claims 1 to 3, wherein said electrode (3) is connected to the proximal end (12) of said catheter.
5. The apparatus according to any one of claims 1 to 4, wherein said electrode (3) is configured for measuring the right atrial pressure (PVC).
6. The apparatus according to any one of claims 1 to 5, wherein said electric current generator (4) is a low voltage generator, preferably said electric current generator (4) delivers an electric potential in a range from 1 mV to 20 mV.
7. The apparatus according to any one of claims 1 to 6, wherein said pressure transducer (5) is configured for pulmonary artery (PAP) monitoring, capillary pressure (WP) detection and mixed venous blood sampling to determine the saturation of said blood (SVO2).
8. The apparatus according to any one of claims 1 to 7, wherein said balloon outlet valve
(7) is equipped with a syringe (14) for inflating said balloon (6) and for example with physiological solution, crystalloid solutions, electrolytic solutions, double distilled solution, preferably said balloon (6) is made of a material selected from polyethylene terephthalate (PET), nylon, polyvinyl chloride (PVC).
9. The apparatus according to any one of claims 1 to 8, wherein said balloon (6), when inflated, is configured to occlude a branch of the pulmonary artery and determine through echocardiographic monitoring and/or modification of the pressure wave the pulmonary capillary wedge pressure (PCWP).
10. The apparatus according to any one of claims 1 to 9, wherein said sensing coil
(8) is a platinum-iridium metal alloy, insulated by a silicone or polyurethane sheath and/or it has a length from 0.5 to 1.5 cm and a thickness from 0.1 to 0.5 cm and/or detects the electric charge at a distance of 3 to 5 cm from the distal end (13) of said catheter.
11. The apparatus according to any one of claims 1 to 10, wherein said ultrasound probe (9) is a piezoelectric ultrasound probe.
PCT/IB2023/056951 2022-07-07 2023-07-05 Electric polarization catheter for calculating systemic cardiac output in critical area WO2024009231A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20090177090A1 (en) * 2005-05-06 2009-07-09 Sorin Grunwald Endovascular devices and methods of use
US20170281023A1 (en) * 2016-03-30 2017-10-05 Zoll Medical Corporation Non-Invasive Blood Flow Measurement
US20180296162A1 (en) * 2003-02-21 2018-10-18 3Dt Holdings, Llc Luminal organ sizing devices and methods

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20180296162A1 (en) * 2003-02-21 2018-10-18 3Dt Holdings, Llc Luminal organ sizing devices and methods
US20090177090A1 (en) * 2005-05-06 2009-07-09 Sorin Grunwald Endovascular devices and methods of use
US20170281023A1 (en) * 2016-03-30 2017-10-05 Zoll Medical Corporation Non-Invasive Blood Flow Measurement

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