Abstract: Multi-channel blind system identification is utilized to identify a patient's cardiac functions without catheterization. The approach is adaptive to each patient's cardiovascular system variations. The cardiac functions can be determined by formulating an auto-regression moving average model utilizing either finite impulse response systems or a group of infinite impulse response systems. Both of these models identify the system functions by solving a set of linear equations using the least-squares method. The system input is then identified by deconvolving the system output and the estimated impulse response of each channel. These models can be augmented to obtain an estimate of the maximum order of the cardiac functions when they are unknown a priori. The approach can also be modified to obtain the cardiac functions by first resolving the distinct dynamics associated with each channel, then determining the common dynamics and ultimately determining the system input.

Abstract: A differential Fick technique including a first phase in which baseline breathing parameters may be established and a second phase in which a change in the effective ventilation of a patient is induced. The durations of the first and second phases may be substantially the same and may be abbreviated relative to the durations of comparable phases of previously known differential Fick techniques. The disclosed differential Fick technique also lacks a recovery period in which the respiratory parameters of a patient are permitted to return to “normal” levels.

Abstract: Methods and devices for improving ventricular contractile status of a patient suitably exploit changes in ventricular pressure and/or dP/dtmax to provide and/or optimize a response to a patient. The ventricular pressure may be appropriately correlated to intracellular calcium regulation, which is indicative of contractile status. To assess ventricular contractile status, the device suitably observes a cardiac perturbation of the patient and measures force interval potentiation following the perturbation. The contractile potentiation can then be stored and/or quantified in the implantable medical device to determine the ventricular contractile status of the patient, and an appropriate response may be provided to the patient as a function of the ventricular contractile status. Examples of responses may include administration of drug or neuro therapies, modification of a pacing rate, or the like.

Abstract: A catheter for retrograde orientation in a blood flow is used to determine the blood flow rate by thermodilution measurements. The determination of the blood flow rate accommodates injectate induced thermal influences on a dilution thermal sensor, wherein the thermal influences can occur prior to introduction of the injectate into the blood flow.

Abstract: Heat exchanger-equipped catheters and related methods that are useable for changing or maintaining at least a portion of the body of a human or veterinary patient at a desired temperature and for the measurement of cardiac output or blood flow rate within a blood vessel, without the need for introduction of saline solution or any other foreign substance into the patient's blood.

Abstract: The segment volume of a cardiac chamber or blood vessel of a patient is determined by injecting a first indicator in the blood stream of a patient, which influences the conductance of the blood. The electrical conductance in the cardiac chamber or blood vessel is measured. An injected quantity of indicator is determined and the development of the concentration of this indicator in the blood is measured wherein the cardiac output is calculated from the injected quantity of indicator and the development of the concentration in the blood. Subsequently, the segment volume and electrical parallel conductance of a cardiac chamber or blood vessel are calculated from the calculated cardiac output, the injected quantity of conductance indicator and the measured conductance.

Abstract: A method for the measurement of post arteriolar pressure in a patient which is determined from information regarding the blood pressure (BP), systemic vascular resistance (R) and cardiac output (CO) by plotting the regression line for the equation BP=R×Q+c where c is the post arteriolar pressure, and determining the value of c from the regression line.

Abstract: This invention is a cannulation apparatus, and related methods for providing indirect access to a surgical site within a patient. The cannulation apparatus includes at least two fluid flow paths that are slidable coupled (40) (50) to one another, and selectively positional within the patient. The first, the second flow path s may be advanced through a single incision disposed remotely from the surgical field to first, and second predetermined locations within the patient. Exemplary sites for the incision include the groin region or in the neck region of the patient. The cannulation apparatus, and method of the present invention are particularly suited for use in providing cardiopulmonary support during cardiac surgery, including coronary artery bypass graft surgery. The cannulation apparatus of the present invention also provides an entry site for one or more support devices used in the surgical procedure.

Abstract: The present invention relates to a method and apparatus for monitoring haemodynamic function in animals and humans during anaesthesia and surgery. During anaesthesia and surgery the subject's haemodynamic, respiratory, neuromuscular and neurological functions are monitored as indicators of the condition of the health of the subject. Commonly, variations in blood pressure are used to imply corresponding variations in cardiac output, i.e. good blood pressure equals good cardiac output. The present invention utilizes a device to monitor changes of blood flow in peripheral blood vessels of the subject as an indicator of cardiac output. This is believed to provide a much more accurate indicator.

Abstract: A cardiac pacemaker has a pulse generator for delivering stimulation pulses to a patient's heart and a control unit for controlling the delivery of the stimulation pulses from the pulse generator. The control unit includes an altering unit for altering the AV-delay value from a predetermined first AV-delay value to a predetermined second AV-delay value, and back to the first AV-delay value. A sensor measures a parameter related to cardiac output of the patient, the sensor measuring this parameter in a time window within a time of operation with the first AV-delay value, and in a time window within the time of operation with said second AV-delay value, and in a time window within the time of operation after the return back to the first AV-delay value. A calculation unit calculates respective average values of the parameter during each of the time windows, and a determining unit determines from these average values which of the AV-delay values results in a higher cardiac output.

Abstract: The present invention concerns a catheter heating circuit for continuous cardiac output measurement. The circuit comprises a DC power source for supplying an operating voltage for the circuit, wherein the heating power from the heating circuit is fed to the catheter via an isolating transformer. Isolation is known per se and it is not described in detail. According to the invention the heating circuit further comprises means for generating a bipolar square wave with variable duty cycle, which square wave is supplied to said isolating transformer and further to the catheter filament.

Abstract: The invention comprises devices for noninvasively monitoring physiological characteristics of a patient's blood. Generally, probes having radiation emitters and detectors are used to determine absorbance of blood within the patient's tissue to determine various blood parameters. The device also has either a position sensor for determining the position of the probe with respect to the patient's heart or a movement generator for altering the position of the probe with respect to the patient's heart. The invention also comprises methods for noninvasively monitoring the physiological characteristics. In one embodiemnt, induced positional changes create differential hydrostatic pressures to facilitate measurement of blood parameters by absorbance. In a second embodiment, delays in pulse arrival times in coupled organs or members on opposite sides of the body are measured to determine cardiac output. The two methods are such that they can advantageously be used together.

Abstract: A technique for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.

Abstract: A body implantable system employs a lead system having at least one electrode and at least one thermal sensor at a distal end. The lead system is implanted within a patient's heart in a coronary vein of the left ventricle. The thermal sensor can be attached to a catheter that is disposed within an open lumen of the lead system. The thermal sensor senses a coronary vein temperature. The coronary vein temperature can be measured at a detector/energy delivery system and used as an activity indicator to adaptively control pacing rate. The measured coronary vein temperature can be also used with a left ventricular flow measurement to determine hemodynamic efficiency of the heart. A detected change in hemodynamic efficiency can be used by the detector/energy delivery system to modify the delivery of electrical pulses to the lead system.

Abstract: In order to determine the cardiac output of a patient, the patient's respiration cycle is determined and an indicator is injected into the patient's bloodstream over a period of at least substantially one respiration cycle. The change in the indicator value in the bloodstream downstream of the injection point is measured over a period of a number (n) of respiration cycles and the injected amount of indicator is established. The cardiac output is determined on the basis of the measured change in the indicator value, the injected amount of indicator blood and the initial value thereof. To this end a first variation in the indicator value is measured over at least substantially the period of one respiration cycle, directly prior to the injection, and the change in the indicator value caused by the injection is determined on the basis of the difference between the measured change in the indicator value measured over a period of n times that of the first variation and n times the measured first variation.

Abstract: A method of data management for optimizing the patient outcome from the provision of external counterpulsation (ECP) therapy is described. This method describes a process by which sets of dynamic cardiopulmonary dependent variables are measured during steady-state conditions, displayed, and translated into quantitative and qualitative measurements while the independent variables of ECP, cuff inflation duration and cuff inflation pressure settings of ECP systems, are altered by a physician. In combination with visual observation and computer-assisted ranking of the dependent variables, a physician can utilize the resulting information to render decisions on the optimal choice of the independent variables. The method will enable physicians to collect, view, track and manage complicated data using well-understood visualization techniques to better understand the consequences, acutely and chronically, of their therapeutic actions in general, and of their provision of ECP therapy in particular.

Abstract: An apparatus that continuously monitors the arterial pressure measured by a pressure sensor in an artery, which pressure is regarded as the reading Pao that approximately corresponds to the aortal pressure. In principle, the arterial pressure can be measured in the aorta, near the aorta, or in the arterial tree. To provide a second reading, the apparatus, via the input channel, continuously monitors the central venous pressure (CVP), which is regarded as the reading PIT that approximately corresponds to the intrathoracic pressure (ITP). The third reading is provided via the input channel as a reading Z which expresses the thoracic compliance.

Abstract: A system for evaluating the cardiovascular system parameters using indicator dilution and non-invasive or minimally invasive detection methods is disclosed. Intravascular indicators are stimulated, and emissions patterns detected for computation of cardiac output, cardiac index, blood volume and other indicators of cardiovascular health.

Abstract: A technique is disclosed for determining blood flow in a living body by changing the thermal energy level in the venous blood flow path and determining temperatures in both the venous and arterial blood flow paths. Blood flow is calculated as a function of the change in energy level and the temperature differences in the venous and arterial blood flow paths.

Abstract: Cardiac stroke volume and output are estimated using an arterial pressure signal, which may be obtained either invasively, using a catheter-mounted pressure sensor, or non-invasively, with an external plethysmographic sensor mounted with a finger cuff. Both pulsatile and non-pulsatile (continuous) components of the sensed pressure signal are analyzed. Stroke volume is estimated as a function of the ratio between the area under the entire pressure curve and a linear combination of various components of impedance. Depending on the embodiment, first and/or second time derivatives of the pressure signal are used to determine the impedance components. The estimated stroke volume is preferably corrected based on the amount of deviation from a reference pressure of the mean pressure, which itself is determined from the sensed pressure signal. The invention is thus able to estimate stroke volume and cardiac output from the pressure signal alone, with no need for calibration using other highly invasive techniques.

Abstract: A system and method is described for determining and graphically displaying oxygenation states of a patient in real time. The system is non-invasive and can display information to a physician that is intuitive. Various display objects are described for illustrating the output of oxygenation values. The display objects reflect the in vivo physiology that they measure, thus making interpretation of the measured values very intuitive.

Abstract: The invention comprises devices for noninvasively monitoring physiological characteristics of a patient's blood. Generally, probes having radiation emitters and detectors are used to determine absorbance of blood within the patient's tissue to determine various blood parameters. The device also has either a position sensor for determining the position of the probe with respect to the patient's heart or a movement generator for altering the position of the probe with respect to the patient's heart. The invention also comprises methods for noninvasively monitoring the physiological characteristics. In one embodiemnt, induced positional changes create differential hydrostatic pressures to facilitate measurement of blood parameters by absorbance. In a second embodiment, delays in pulse arrival times in coupled organs or members on opposite sides of the body are measured to determine cardiac output. The two methods are such that they can advantageously be used together.

Abstract: The invention concerns a system for the measurement of cardiac (1) output. The system comprises a heating resistor (2) placed in the vena cava (6), a temperature sensor (5) placed in the pulmonary trunk (4), an isolation interface (12) for separating an isolated side (14) and a non-isolated side according to patient potential, a power source (11) which is placed on the non-isolated side and produces the energy to be supplied to the heating resistor (2), and measuring elements (18, 19, 20) for the measurement of the power supplied to the heating resistor 92). According to the invention, the power measuring (18, 19, 20) elements are disposed on the isolated side (14), allowing the effective power supplied to the heating resistor (2) to be computed as accurately as possible.

Abstract: The segment volume of a cardiac chamber or blood vessel of a patient is determined by injecting a first indicator in the blood stream of a patient, which influences the conductance of the blood. The electrical conductance in the cardiac chamber or blood vessel is measured. An injected quantity of indicator is determined and the development of the concentration of this indicator in the blood is measured wherein the cardiac output is calculated from the injected quantity of indicator and the development of the concentration in the blood. Subsequently, the segment volume and electrical parallel conductance of a cardiac chamber or blood vessel are calculated from the calculated cardiac output, the injected quantity of conductance indicator and the measured conductance.

Abstract: Apparatus and methods for non-invasively determining cardiac output using partial re-breathing techniques are disclosed in which the apparatus is constructed with an instantaneously adjustable deadspace for accommodating differences in breathing capacities of various patients. The apparatus is constructed of inexpensive elements, including a single two-way valve which renders the apparatus very simple to use and inexpensive so that the unit may be readily disposable. The method of the invention provides a novel means of estimating cardiac output based on alveolar CO2 values rather than end-tidal CO2 values as previously practiced. A program for calculating cardiac output is also disclosed.

Abstract: The disclosed invention relates to systems and methods for obtaining physiological information from patients and displaying that information in an intuitive and logical format to a physician. Object displays are disclosed that are capable of visually displaying critical information in real time to allow physicians to quickly perceive the importance of changing patient values.

Abstract: A heart-sound analyzing apparatus, including a heart-sound microphone which is adapted to be worn on a living subject to iteratively detect a second heart sound II of the subject, a respiration-synchronous-signal detecting device which iteratively detects a respiration-synchronous signal of the subject, an inspiration-expiration judging device for judging, based on each of the respiration-synchronous signals iteratively detected by the respiration-synchronous-signal detecting device, whether the subject is in an inspiring state or in an expiring state, and an aortic-valve-closing-timing determining device for iteratively determining a timing when the aortic valve of the heart of the subject closes, based on each of second heart sounds II which are iteratively detected by the heart-sound microphone in time intervals, respectively, in each of which the subject is judged as being in the inspiring state by the inspiration-expiration judging device.

Abstract: Apparatus for ascertaining cardiac output of the heart of a patient comprising a control and display module. A venous probe is inserted into a vein in the forearm of the patient and is coupled into the control and display module and provides an electrical signal representing the dissolved oxygen in the venous blood. An arterial probe is inserted into an artery in the forearm of the patient and is coupled into the control and display module and provides an electrical output signal representing the dissolved oxygen in the arterial blood. The control and display module has a visible display that provides a continuous in vivo cardiac output that utilizes an arterial venous oxygen differential equation which includes an adjustment factor for adjusting for venous blood being sampled rather than mixed venous blood in the pulmonary artery of the patient.

Abstract: An electrical lead includes an elongate body having a proximal end, and a sensing unit capable of resolving a change in a spatial configuration of the electrical lead. A medical device includes a control unit, an elongate body having a proximal end coupled with the control unit, and a sensing unit capable of resolving a change in a spatial configuration of the electrical lead and relating it to the amount of blood ejected from the heart. A method includes receiving a signal transmitted from a lead disposed within a heart and determining a change in a dimension of the heart, due to the heart beating, based upon the signal.

Abstract: An improved apparatus and method for determining the cardiac output of a living subject. The improved apparatus generally comprises one or more electrode assemblies or patches affixed to the skin of the subject in the vicinity of the thoracic cavity. In one embodiment, the apparatus comprises a constant current source impedance cardiography (ICG) monitor adapted as a stand-alone system. In another embodiment, the apparatus comprises a module adapted for use with a host monitoring system, the latter providing ECG, blood pressure, and/or other inputs to the module. Method of detecting a loss of electrical continuity in one or more of the terminals of the electrode patch, and selecting between a plurality of signal inputs based on signal quality, are also disclosed.

Abstract: A plurality of radio frequency semi-passive transponders are attached to an animal's organ, such as the heart. Each semi-passive transponder may be attached to the surface of the organ or mounted on a stent that is implanted in a blood vessel of the organ. An interrogator periodically sends a signal to each semi-passive transponder which reacts by transmitting a reply signal. The interrogator processes the reply signals to derive information regarding activity of the organ. In one embodiment, the position of each semi-passive transponder is determined from the reply signals, thereby enabling information about organ movement and volume change to be derived. In another embodiment, data from a sensor on the semi-passive transponder is sent via the reply signal.

Abstract: The warming ability of skin has been measured by thermometer, which sensor was cooled upto 17-18 deg.C. before its contact with skin.

Abstract: The invention comprises methods for noninvasively monitoring physiological characteristics of a patient's blood. Determinations of blood constituent concentrations may be made by comparing absorbance of radiation at varying parameters, such as path length and blood pressure. Preferably, changes in pressure are effected by changing the height of the probes relative to the patient's heart. Determinations of blood pH may be made by comparing absorbance of the blood at different wavelengths. The temperature of the blood, and thus of the patient's core, may also be accurately determined. Further, cardiac output characteristics and blood pressures may be noninvasively determined using the methods of the invention.

Abstract: A technique for determining blood flow in a living body by changing the thermal energy level by a predetermined amount at a site in a blood flow path and detecting temperatures at locations upstream and downstream of the site. The temperature difference at such locations is determined and the blood flow is calculated as a function of the change in energy level and of the temperature differences measured prior to and following the change in energy level.

Abstract: An improved method and apparatus for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one exemplary embodiment, the invention comprises a method of measuring cardiac output (CO) using impedance waveforms (and ECG waveforms) which are analyzed via discrete wavelet transforms. These transforms aid in identifying fiducial points within the waveforms, the fiducial points being used to calculate various parameters relating to cardiac stroke volume (such as LVET and dZ/dtmax), from which cardiac output may be determined. The use of wavelet transforms for fiducial point detection increases the accuracy of the CO determination by reducing cross-term artifact, and also significantly reduces the amount and complexity of processing required as compared to prior art time-frequency distribution or empirical techniques. Improved methods of QRS complex detection within the ECG waveform, and median filtering of an input waveform, are also disclosed.

Abstract: A method is disclosed for diagnosing, monitoring and treating cardiovascular pathologies. Among the hemodynamic parameters of interest are peripheral resistance, compliance, and cardiac (left ventricular) output. Peripheral resistance determined according to the present invention has been found to be a reliable indicator, not only of hypertension, but also of the cause of the hypertension. The determined peripheral resistance can be compared against a predetermined threshold value. This comparison helps to foster a diagnosis of a hypertensive condition.

Abstract: A computer system (104) is connected to an injection means (107) to inject at a first place (101 ) a bolus warmer or colder than patient's blood. The travelling temperature deviation thus introduced to the patient's vascular system (103) passes the pulmonary circulation (111), where an extravascular thermovolume (112) may be present. When the temperature deviation reaches the second place (102), where blood temperature is measured by a sensor device (117) connected to the computer system (104), it is recorded as Thermodilution Curve (15), from which the computer system (104) determines an extravascular thermovolume estimate. Depending on that result the computer system (104) calculates a new amount of bolus to be injected by the injection means (107). The higher the extravascular thermovolume estimate, the higher the new amount of bolus.

Abstract: Apparatus for ascertaining cardiac output of the heart of a patient comprising a control and display module. A venous probe is inserted into a vein in the forearm of the patient and is coupled into the control and display module and provides an electrical signal representing the dissolved oxygen in the venous blood. An arterial probe is inserted into an artery in the forearm of the patient and is coupled into the control and display module and provides an electrical output signal representing the dissolved oxygen in the arterial blood. The control and display module has a visible display that provides a continuous in vivo cardiac output that utilizes an arterial venous oxygen differential equation which includes an adjustment factor for adjusting for venous blood being sampled rather than mixed venous blood in the pulmonary artery of the patient.

Abstract: The invention relates to an apparatus and a method for determining an approximate value for the stroke volume and the cardiac output of a person's heart. The apparatus and method employ a measured electrical impedance, or admittance, of a part of a person's body, namely, the thorax. This part of a person's body is chosen because its electrical impedance, or admittance, changes with time as a consequence of the periodic beating of the heart. Accordingly, the measured electrical admittance or impedance can provide information about the performance of the heart as a pump.

Abstract: In a means for support of the performance of a heart (1) in which fluid is taken from blood vessels via an external pump (7) and is returned to the blood vessels, the amount of fluid being controlled as a function of the measured values, a catheter in the ventricle is equipped with sensors (4) for measuring the volume of fluid per unit of time. The sensors (4) are connected to an evaluation circuit in which the ratio of the diastolic volume to the systolic volume per heartbeat or unit of time, especially the output rate and/or the deviation of the volume which has been delivered by the heart per unit of time from a defined setpoint, for example the setpoint which has been computed from body-specific data for the cardiac output (HZV), is evaluated and a signal is generated. The pump (7) via which fluid is withdrawn from the ventricle is controlled depending on the generated signal.

Abstract: The invention comprises devices for noninvasively monitoring physiological characteristics of a patient's blood. Generally, probes having radiation emitters and detectors are used to determine absorbance of blood within the patient's tissue to determine various blood parameters. The device also has either a position sensor for determining the position of the probe with respect to the patient's heart or a movement generator for altering the position of the probe with respect to the patient's heart. The invention also comprises methods for noninvasively monitoring the physiological characteristics. In one embodiemnt, induced positional changes create differential hydrostatic pressures to facilitate measurement of blood parameters by absorbance. In a second embodiment, delays in pulse arrival times in coupled organs or members on opposite sides of the body are measured to determine cardiac output. The two methods are such that they can advantageously be used together.

Abstract: The present invention is directed to an apparatus and method for injecting an injectate fluid into a blood vessel of a patient for carrying out thermodilution or dye-dilution measurements in order to determine hemodynamic parameters of the patient. The apparatus includes sensing means for sensing a change of pressure and/or flow rate and/or temperature inside the injection channel, and a computer coupled to the sensing means for determining the time instants of start and finish of the injection process.

Abstract: A thermodilution catheter having a heating filament which is fabricated so as to be thin and flexible enough to avoid contact with the patient's blood. The heating filament is either inserted in a preformed catheter lumen, incorporated into a wall of the catheter body itself, or wrapped around the catheter body wall and surrounded by an external sheath. Generally, the covering of the heating filament is minimally thin so as to allow the heat from the heating filament to be transferred to the surrounding blood and to minimally increase the overall cross-sectional area. Since the heating filament does not directly touch the patient's blood, the outer surface may be made smooth so as to prevent inducement of blood clots. In addition, the heating filament may be maintained at a safe temperature by forming the heating element of a flexible material having a high temperature coefficient of resistance, low thermal capacitance and high thermal conductivity.

Abstract: A method and apparatus determines continuously mean cardiac output by measuring the arterial pressure e.g. at a finger and calculating therefrom the mean arterial pressure and the time constant of the arterial system (in diastole). Compliance values are provided from a table. Mean cardiac output is then the product of mean arterial pressure and compliance divided by the time constant. Changes in cardiac output can be used for diagnostic purposes. A pressure cuff or pressure tonometer can be used to measure the arterial pressure with a microcomputer providing the necessary calculations.

Abstract: A vital sign monitoring apparatus has estimated blood pressure calculation means 30 for calculating estimated systolic blood pressure and estimated diastolic blood pressure from information relevant to blood pressure successively measured based on the relationship between information relevant to blood pressure and systolic blood pressure and the relationship between information relevant to blood pressure and diastolic blood pressure, systolic and diastolic duration measurement means 20 for successively measuring a systolic duration and a diastolic duration, and blood flow volume calculation means 40 for calculating a blood flow volume based on the estimated systolic blood pressure and the estimated diastolic blood pressure successively calculated and the systolic duration and the diastolic duration successively measured.

Abstract: An implantable blood flow monitoring system for providing synchronized blood vessel flow and myocardial wall contractility data to an external monitor independent of transcutaneous leads. Synchronized electrocardiogram data allows and provides comprehensive monitoring. A means is provided for transmitting synchronized cardiac function data and blood flow data to a distant remote location to facilitate continual physician monitoring.

Abstract: An improved method and apparatus for non-invasively assessing one or more hemodynamic parameters associated with the circulatory system of a living organism. In one exemplary embodiment, the invention comprises a method of measuring cardiac output (CO) using impedance waveforms (and ECG waveforms) which are analyzed via discrete wavelet transforms. These transforms aid in identifying fiducial points within the waveforms, the fiducial points being used to calculate various parameters relating to cardiac stroke volume (such as LVET and dZ/dtmax), from which cardiac output may be determined. The use of wavelet transforms for fiducial point detection increases the accuracy of the CO determination by reducing cross-term artifact, and also significantly reduces the amount and complexity of processing required as compared to prior art time-frequency distribution or empirical techniques. Improved methods of QRS complex detection within the ECG waveform, and median filtering of an input waveform, are also disclosed.

Abstract: A central venous cather (1) is placed in the vena cava superior (2) and equipped with a heating coil (3) for emitting heat pulses in the immediate proximity of the distal end (5) of the catheter (1) in order to introduce travelling temperature deviations to the patient's circulation. The power transferred to the blood stream during emission of each heat pulse represents an input signal for modified thermodilution measurements. Each travelling temperature deviation is detected as a system response corresponding to an input signal, when it reaches an arterial catheter (14) which additionally comprises a pressure sensor (17) for measuring the local blood pressure in the arteria femoralis (16) as a function of time.

Abstract: A method and apparatus for monitoring the hemodynamic status of a patient is provided. It comprises an implantable monitor with one or a plurality of sensors configured for extravascular placement, electronic circuitry that is coupled to the sensors and processes their output, a transmitter/receiver for conveying information between the monitor and an external unit, and a patient alert which notifies the patient if medical attention should be sought. The extravascular sensors include vascular plethysmography, heart and lung sounds, thoracic impedance, and ECG. In the preferred embodiment, the radio frequency transmitter/receiver provides for the automatic telemetry of data, without requiring the active participation of the patient or clinician. Thus data can be conveyed routinely and automatically, allowing more computationally demanding analysis to be done by an external device, or allowing human review at a central location. The monitor is particularly applicable to patients with heart failure.

Abstract: The present invention relates to a method for determining the cardiac output of a subject by thermodilution measurements by providing a predetermined amount of thermal indicator in a blood vessel with the thermal indicator having a temperature different from the temperature of subject's blood, thus exhibiting an indicator temperature difference. By measuring the temperature of subject's blood at a second place downstream the cardiac output (CO) and the extravascular thermovolume can be determined as a function of the time for the thermodilution curve. As a function of the thermodilution curve the measurements of the amount of thermal indicator and/or thermal indicator volume temperature difference are adjusted to provide a more accurate determination of cardiac output.