Thermodilution device

Claim 2

An arrangement for determining certain body properties of a patient which involve the blood, such as blood flow, from input data relating to preselected body activity of the patient and from sensing via a thermal sensor the temperature change in the circulating blood resulting from injecting into the blood stream at a predetermined rate a known quantity of an indicator fluid having a known temperature differential relative to the blood by way of a thermal sensor-equipped catheter arrangement introduced into the body, comprising: a control assembly and a sterile disposable assembly operatively connected to said control assembly but isolated from the latter in terms of sterilization, said sterile disposable assembly being connected to the catheter and including first means for providing the known quantity of indicator fluid within a temperature-regulated environment, said first means including second means for introducing the known quantity of indicator fluid thermally regulated by said environment into the catheter at the predetermined rate, and said control assembly including third means response to the input data relating to the preselected body activity of the patient for providing the temperature-regulated environment, fourth means coupled to said third means and to said first means for controlling said third means and for controlling the introduction of the known quantity of indicator fluid via the catheter into the patient''s blood stream at the predetermined rate and fifth means operatively connected to the thermal sensor and responsive to said third means for calculating the desired body property of the patient from information derived via the thermal sensor.

Claim 3

The arrangement according to claim 1 wheRein the catheter arrangemnt is part of the sterile disposable assembly.

Claim 4

The arrangement according to claim 1 further including a source of indicator fluid connected to said first means and wherein said source of indicator fluid is part of said sterile disposable assembly.

Claim 5

An arrangement for determining certain body properties of a patient which involve the blood, such as blood flow, from sensing, via a thermal sensor mounted on a catheter arrangement introduced into the body, the temperature change in the circulating blood resulting from injecting into the blood stream at a predetermined rate a known quantity of an indicator fluid having a known temperature differential relative to the blood, comprising: a control assembly and a sterile disposable assembly operatively connected to said control assembly but isolated from the latter in terms of sterilization, said sterile disposable assembly including heat exchanging means having a source of supply of indicator fluid, a syringe mechanism, and a valve arrangement, interconnecting said heat exchanging means and said syringe mechanism with the catheter, and having predetermined directional effect on the flow of indicator fluid, and said control assembly indluding a thermostabilized unit substantially enclosing said sterile disposable assembly for providing a temperature-controlled environment for the latter, first means coupled to said syringe mechanism for effecting a controlled application of motive power to said syringe mechanism, a programmer, coupled to said thermostabilized unit and to said first means for controlling said unit and for controlling the injection into the blood stream of the predetermined quantity of the indicator fluid of known temperature at the predetermined rate, and calculator means responsive to said programmer and to the thermal sensor contained in the catheter for calculating the desired body property of the patient following the injection.

Claim 6

An arrangement for determining certain body properties of a patient which involve the blood, such as blood flow, from sensing, via a thermal sensor mounted on a catheter arrangement introduced into the body, the temperature change in the circulating blood resulting from injecting into the blood stream at a predetermined rate a known quantity of an indicator fluid having a known temperature differential relative to the blood, comprising: a control assembly and a sterile disposable assembly operatively connected to said control assembly but isolated from the latter in terms of sterilization, said sterile disposable assembly including heat exchanging means having a source of supply of indicator fluid, a syringe mechanism, and a valve arrangement, interconnecting said heat exchanging means and said syringe mechanism with the catheter, and having predetermined directional effect on the flow of indicator fluid, and said control assembly indluding a thermostabilized unit substantially enclosing said sterile disposable assembly for providing a temperature-controlled environment for the latter, first means coupled to said syringe mechanism for effecting a controlled application of motive power to said syringe mechanism, a programmer, coupled to said thermostabilized unit and to said first means for controlling said unit and for controlling the injection into the blood stream of the predetermined quantity of the indicator fluid of known temperature at the predetermined rate, and calculator means responsive to said programmer and to the thermal sensor contained in the catheter for calculating the desired body property of the patient following the injection.

Claim 7

An arrangement for measuring blood flow in the circulatory systems of a patient, in which there is injected into the blood stream via a catheter arrangement a known amount of an indicator fluid having a known thermal difference relative to the patient''s blood, followed by measurement of the temperature difference obtained in the circulating blood effected by the injected indicator fluid at a point below the site of injection via a thermal sensing device mounted on the catheter arrangement, wherein the arrangement comprises two main assemblies which are operatively interconnected but which are separate in terms of sterilization, the first assembly including a programer (17) for controlling the injection of indicator fluid, a thermostabilized unit (3) connected to said programmer, first means (12, 13) for effecting a pumping action connected to said programmer, and a calculator (16) connected to said programmer and to the thermal sensing device, the other main assembly comprising a sterile disposable unit operatively connected to a reservoir means (1) containing indicator fluid, said disposable unit including heat exchanging means (2) extending within said thermostabilized unit, a syringe mechanism (7) situated within said thermostabilized unit and operatively connected to said first means for providing indicator fluid intake and injection modes, and a valve arrangement (4,5,8) with a directional effect connected between said syringe mechanism and said heat exchanging means and connected to the catheter, whereby upon a controlled pumping provided by said first means governed by said programmer, indicator fluid flows from said reservoir means via said heat exchanging means and said valve arrangement to said syringe mechanism and thereupon via said valve arrangement and the catheter to the patient.

Claim 8

An arrangement for measuring blood flow in the circulatory systems of a patient, in which there is injected into the blood stream via a catheter arrangement a known amount of an indicator fluid having a known thermal difference relative to the patient''s blood, followed by measurement of the temperature difference obtained in the circulating blood effected by the injected indicator fluid at a point below the site of injection via a thermal sensing device mounted on the catheter arrangement, wherein the arrangement comprises two main assemblies which are operatively interconnected but which are separate in terms of sterilization, the first assembly including a programer (17) for controlling the injection of indicator fluid, a thermostabilized unit (3) connected to said programmer, first means (12, 13) for effecting a pumping action connected to said programmer, and a calculator (16) connected to said programmer and to the thermal sensing device, the other main assembly comprising a sterile disposable unit operatively connected to a reservoir means (1) containing indicator fluid, said disposable unit including heat exchanging means (2) extending within said thermostabilized unit, a syringe mechanism (7) situated within said thermostabilized unit and operatively connected to said first means for providing indicator fluid intake and injection modes, and a valve arrangement (4,5,8) with a directional effect connected between said syringe mechanism and said heat exchanging means and connected to the catheter, whereby upon a controlled pumping provided by said first means governed by said programmer, indicator fluid flows from said reservoir means via said heat exchanging means and said valve arrangement to said syringe mechanism and thereupon via said valve arrangement and the catheter to the patient.

Claim 9

The arrangement according to claim 5 further comprising means (14) coupled to said programmer for detecting gas bubbles in the indicator fluid to be injected.

Claim 10

The arrangement according to claim 6 wherein said means for detecting air bubbles is adapted to be positioned relative to said sterile disposable unit to detect bubbles between said syringe mechanism and said valve arrangement.

Claim 11

The arrangement according to claim 6 wherein said programmer includes means responsive to said bubble detecting means for preventing the injection for preventing the injection of indicator fluid whenever a gas bubble is detected in the indicator fluid.

Claim 12

The arrangement according to claim 8 wherein said first means includes second means for causing said mechanism to change from the injection mode to the intake mode whenever a gas bubble is detected, and further comprising chambers means (6) disposed between said syringe mechanism and said valve arrangement, and having a volume which corresponds to at least the volume of indicator fluid ejected from said syring mechanism during the time interval required for said first means to cause said syringe mechanism to change from the injection mode to the intake mode.

Claim 13

The arrangement according to claim 6 wherein said programmer includes means responsive to said bubble detecting means for inhibiting said syringe mechanism during injection of indicator fluid into the patient whenever a gas bubble is detected in said indicator fluid.

Claim 14

The arrangement according to claim 6 wherein said bubble detecting means includes means for responding to a change in light transmitted through the indicator fluid effected by the procession of gas bubbles in the fluid passing said bubble detecting means.

Claim 15

The arrangement according to calim 6 wherein said bubble detecting means includes means for responding to changes in the dielectric constant of the indicator fluid due to the existence of gas bubbles in the fluid passing said detecting means.

Claim 16

The arrangement according to calim 6 wherein said bubble detecting means includes means for responding to changes in the dielectric constant of the indicator fluid due to the existence of gas bubbles in the fluid passing said detecting means.

Claim 17

The arrangement according to claim 3 wherein said heat exchanging means includes a hose arrangement.

Claim 18

The arrangement according to claim 13 wherein said hose arrangement partially extends within said thermostabilized unit.

Claim 19

The arrangement according to claim 5 wherein said first means includes a pneumatic cylinder.

Claim 20

The arrangement according to claim 5 wherein said first means includes an electric motor.

Claim 21

The arrangement according to claim 5 further comprising third means providing pre-injection of at least some of the known quantity of indicator fluid for enabling the catheter to be filled with the indicator fluid at the desired temperature and be cooled before the injection of the remainder of the known quantity of indicator fluid.

Claim 22

The arrangement according to claim 17 wherein the injection rate of said third means during pre-injection is less at the termination thereof than at the commencement thereof.

Claim 23

The arrangement according to claim 5 further comprising circuit means for providing the integration of temperature changes derived from the thermal sensor relative to a variable reference which reference varies during the integration in compensation for the natural variations of the patient''s blood temperature.

Claim 24

The arrangement according to claim 19 further including circuit means for providing the compensatory variation of said reference, including means for recording blood temperature prior to an injection of indicator fluid and following the completion of said integration, and further includes means for providing a correction factor to be subtracted from the integrated value, which is a factor of the integration time and of the blood temperature prior to the injection and after the completed injection.

Claim 25

The arrangement according to claim 19 wherein said calculator means includes circuit means for controllably actuating the integration for a period predeterminably related to the time interval defined by the time at which the indicator fluid is injected to when the first temperature change is determined from the thermal sensor.

Claim 26

The arrangement according to claim 19 further including an electric oscillator, coupled to sAid circuit means and controlled in frequency, phase and amplitude relative to the natural variation in blood temperature which obtains immediately before injection, for generating an oscillating reference signal for said circuit means.