WO2002024053A2 - Procede de controle et d'optimisation de la pression veineuse centrale et du volume intravasculaire - Google Patents

Procede de controle et d'optimisation de la pression veineuse centrale et du volume intravasculaire Download PDF

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Publication number
WO2002024053A2
WO2002024053A2 PCT/US2001/029582 US0129582W WO0224053A2 WO 2002024053 A2 WO2002024053 A2 WO 2002024053A2 US 0129582 W US0129582 W US 0129582W WO 0224053 A2 WO0224053 A2 WO 0224053A2
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Prior art keywords
pressure
volume
cuff
cvp
invasive
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PCT/US2001/029582
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English (en)
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WO2002024053A9 (fr
WO2002024053A3 (fr
Inventor
Kevin R. Ward
Robert W. Barbee
Rao R. Ivatury
Bruce D. Spiess
James A. Arrowood
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Virginia Commonwealth University
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Application filed by Virginia Commonwealth University filed Critical Virginia Commonwealth University
Priority to US10/380,347 priority Critical patent/US7118534B2/en
Priority to AU9291901A priority patent/AU9291901A/xx
Publication of WO2002024053A2 publication Critical patent/WO2002024053A2/fr
Publication of WO2002024053A3 publication Critical patent/WO2002024053A3/fr
Publication of WO2002024053A9 publication Critical patent/WO2002024053A9/fr

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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
    • A61B5/41—Detecting, measuring or recording for evaluating the immune or lymphatic systems
    • A61B5/412—Detecting or monitoring sepsis
    • 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
    • A61B5/021—Measuring pressure in heart or blood vessels
    • A61B5/022—Measuring pressure in heart or blood vessels by applying pressure to close blood vessels, e.g. against the skin; Ophthalmodynamometers
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/0059—Measuring for diagnostic purposes; Identification of persons using light, e.g. diagnosis by transillumination, diascopy, fluorescence
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves 
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00—Measuring for diagnostic purposes; Identification of persons
    • A61B5/103—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
    • A61B5/1073—Measuring volume, e.g. of limbs

Definitions

  • the invention is generally related to medicine, hi particular, the invention relates to intravascular volume and central venous pressure (CVP) measurement.
  • CVP central venous pressure
  • intravascular volume i.e., the volume of blood within blood vessels
  • Manipulation of intravascular volume is an important tool in the treatment of many disease states including but not limited to dehydration, congestive heart failure, renal failure, cardiogenic shock, traumatic and hemorrhagic shock, and septic shock in both their compensated and uncompensated states.
  • dehydration congestive heart failure
  • renal failure renal failure
  • cardiogenic shock traumatic and hemorrhagic shock
  • septic shock in both their compensated and uncompensated states.
  • the physical examination and medical history of a patient have not been demonstrated to produce accurate assessments of a patient's intravascular volume status.
  • the rate of venous return to the heart equals the rate of blood pumped out of the heart and the amount of blood pumped by the right ventricle equals the amount of blood pumped by the left ventricle.
  • This principle states that within physiologic limits, the heart will pump whatever amount of blood enters the right atrium and will do so without excessive backup of blood or fluid in the veins or tissues.
  • central or intracardiac volume plays an important role in the diagnosis and management of many chronic and acute disease states, it is helpful to have some measure of it.
  • the major measure of central vascular volume has been to measure pressure either within the right atrium (or superior or inferior vena cava) or in the pulmonary artery.
  • CVP central venous pressure
  • PAP pulmonary artery pressure
  • PAOP pulmonary artery occlusion pressure
  • PAOP is believed to reflect the pressure within the left atrium which is in turn believed to represent the pressure within the left ventricle.
  • pressure measurements in these cases are not volume measurements. Conventionally it has been considered that these pressure measurements reflect volume within their respective areas where the measurement is being made. CVP, PAP, and PAOP have been used to assess the volume status of patients and specifically the "preload" of the heart.
  • Preload is a concept relating to the Frank-Starling law in which the volume status of the patient is adjusted (usually increased) to produce an optimal increase in cardiac output that can be induced by fluid administration alone. This fluid administration distends the contracting fibers of the heart to a length which optimizes the contractile force. It is considered optimal to follow both cardiac output and volume status simultaneously as to create cardiac output-volume/pressure curves in which CVP, PAP, or PAOP is used as a surrogate of volume. Fluid is administered until no further increase in cardiac output is noted. The CVP, PAP, or PAOP is noted and additional volume is provided to keep one or more of these pressures the same.
  • RVEDVI right ventricular end-diastolic volume index
  • volume status and cardiac preload being beneficial in many disease states for both diagnosis and treatment purposes, it would be valuable if such a measure could be made less invasively than with present methods, especially noninvasively.
  • Too-distal measurements such as those of Blazek et al, have not conventionally been usable in determining central intravascular pressure and volumes, because overestimation would result.
  • the overestimation would have two sources: 1) pressure in veins distal to the axillary and brachial vein will be higher and 2) as a vein is occluded (prior to collapse) venous return will begin to be impeded.
  • U.S. Patent No. 5,040,540 discloses measuring central venous pressure (CVP) based on changes in the dimensions of the neck.
  • CVP central venous pressure
  • Sackner discloses a neck set-up and another stocking cap transducer set-up.
  • the methods proposed by Sackner are not usable in patients over about 18 months due to the physiological basis for the CVP measurement no longer being present after cranial bones fuse in normal growth.
  • Sackner recognizes that neck volume changes detected by his transducers may be from breathing, not just from changes in blood volume, and he resorts to various methods for removing the breathing-related component, making Sackner' s CVP measurements of dubious accuracy.
  • U.S. Patent No. 5,904,143 (issued May 18, 1999 to Policastro et al.) discloses a non-invasive pointer-device for estimating CVP.
  • the Policastro pointer device is not particularly accurate, and, as the inventors refer to the technology themselves, is more along the lines of an estimate.
  • While the PAC or CVP catheter can accurately measure central intravascular pressure (right atrial and right ventricular pressures, pulmonary artery pressures, and pulmonary artery occlusion or "wedge" pressure), use of this catheter constitutes an invasive tehcnique associated with numerous complications (infections, clots, arrhthmias, etc.).
  • invasive tehcnique associated with numerous complications (infections, clots, arrhthmias, etc.).
  • Health benefits to patients would be seen by removing the disadvantages of invasive CVP measurement while maintaining the accuracy of such invasive measurements.
  • the present invention non-invasively determines CVP and provides information concerning relative changes in intravascular volume. To do so, certain curves are plotted based on non- invasively determined patient information obtained by applying a controllable variable (such as degree of incremental inflation/deflation of a non-distally-applied vascular cuff (such as voltage applied)), taking certain measurements (such as pressure measurements) from the patient, plotting a curve based on the datapoints (such as a volume increase curve or a volume decline curve). Pertinent, accurate CVP and/or blood volume information is obtained from at least one feature (especially such as slope) of the non-invasive-based curve. Thus, the invention advantageously provides accurate CVP information without the risks and disadvantages of invasive measurement.
  • a controllable variable such as degree of incremental inflation/deflation of a non-distally-applied vascular cuff (such as voltage applied)
  • measurements such as pressure measurements
  • Pertinent, accurate CVP and/or blood volume information is obtained from at least one feature
  • An important purpose of the present invention is to noninvasively measure CVP and indicators of intravascular central volume and preload, such as for diagnostic and treatment.
  • the invention provides an intravascular pressure and volume-based non-invasive diagnostic method, comprising: (a) from a patient, taking non-invasive intravascular pressure and volume measurements; (b) plotting the non-invasive intravascular measurements as pressure and volume change curves; and (c) determining (i) an overall slope of the volume change curve, (ii) a maximum slope of the volume change curve and/or (iii) when the volume change curve is a volume decline curve, a threshold of the volume decline curve.
  • the invention in a second preferred embodiment provides a method of non-invasively determining CVP from an identified pressure measurement during a cuff inflation and/or deflation procedure from which is subtracted a baseline cuff, to determine CVP, comprising at least the step of determining CVP ⁇ P ⁇ x slope — P 0 .
  • P 0 is a measured initial pre-inflation pressure in an inflatable vascular cuff applied at a non-distal part of the patient.
  • P mxs i ope is a measured pressure at a maximally sloping part of a curve consisting of data points (x,y), with x being a volume variable (an exemplary example being variable x controlled by using voltage used in inflating the vascular cuff) and y being time.
  • the invention provides a system for non-invasively measuring intravascular central pressure and/or volume, comprising: (a) a non-invasive inflatable cuff supplying data to a data processing system; (b) a non-invasive cuff inflator receiving control instructions form and/or sending data to the data processing system and (c) a non-invasive volume sensitive detector sending data to the data processing system.
  • the inflatable cuff is sized for surrounding an extremity in an upper region.
  • volume change curve may be related to right ventricular compliance and venous return; that changes in the overall slope of the volume change curve are related to ventricular compliance and venous return, etc.
  • the CVP determination may be based on the cuff pressure at the volume change curve maximum slope or on the volume decline curve threshold.
  • such methods, devices and systems may include one or more of the following: absolutely determining CVP; inflating and/or deflating a vascular cuff surrounding an extremity upper part; determining the rate of venous volume change upon deflation of a vascular cuff surrounding an extremity upper part; determining the rate of venous volume change upon inflation of the vascular cuff; determining the threshold of venous volume change upon deflation of a vascular cuff surrounding an extremity upper part; measuring pressure for a large vein; surrounding an upper extremity with an inflatable cuff, and inflating the cuff while taking pressure and volume measurements; data-processing by a computer comprising an analogue-digital converter and a data acquisition system; pressure monitoring by providing a sensor between the cuff and skin overlying the vessel being monitored; and/or placing an occlud
  • a particularly preferred embodiment of the invention provides for non-invasively detecting volume sensitive data for a distal part of the extremity by operating a volume sensitive detector selected from the group consisting of a mercury-in-silastic strain gauge, a bioimpedance device, a photo device, a plethysmography device, a laser Doppler device and a spectroscopic volume detection device.
  • a volume sensitive detector selected from the group consisting of a mercury-in-silastic strain gauge, a bioimpedance device, a photo device, a plethysmography device, a laser Doppler device and a spectroscopic volume detection device.
  • an inflatable cuff is electrically and pneumatically connected to a programmed cuff inflator device; a computer processor receives pressure measurements from a cuff; the volume sensitive detector sends information to a computer via a signal amplifier; etc.
  • inventive methods, devices and systems in further embodiments may include one or more of the following: determining whether intraabdorninal pressure is elevated by determining pressure in large leg veins; titration of fluid resuscitation, positive end-expiratory pressure (PEEP), and/or titrating fluid therapy; applying non-invasively determined central venous pressure along with non- invasive measures of cardiac output (such as carbon dioxide rebreathing, Doppler, bioimpedance, arterial waveform analysis, etc.); fluid therapy titration based on a magnitude of non-invasively determined volume changes during deep inspiration; applying non-invasive measures of extravascular lung water to differentiate lung injury from fluid excess and or titrate fluid therapy; applying non-invasive measures of extravascular water to differentiate total body fluid excess and/or titrate fluid therapy; applying a non-invasive measure of extravascular lung water or of extravascular water (such as impedance cardiography (ICH) data or bioimpedance vector analysis (BJ A) data), etc.
  • ICH impedance cardiography
  • the inventive methods, systems and devices may include a first non-invasive cuff and at least one additional occluding cuff, the additional occluding cuff sized to an ankle and/or a wrist.
  • Figure 1 is a diagrammatic representation of a system according to the invention for noninvasive measurement of CVP, and/or monitoring and/or optimizing central vascular volume and preload.
  • Figure 2 is a graphical demonstration of simultaneous cuff pressure, invasively measured CVP and forearm mercury-in-Silastic strain gauge volume % recording.
  • Figure 3 is a graphical detail during cuff deflation, with the derivative of the strain-gauge slope being the point of maximal flow through the vein and hence pressure within the vein or mean CVP.
  • Figure 4 is a graphical comparison of noninvasive CVP (NICVP) versus invasive CVP.
  • Figure 5 is a graph of strain-gauge measurement of forearm intravascular volume represented by change in voltage during baseline (V) and during deep inspiration (DB).
  • Figure 6 is a graph of NICVP versus CVP, based on actual clinical data points from forearms of human patients.
  • Figures 7A-7I are graphs demonstrating cuff pressure/ forearm volume changes on a human subjected to various tilts and maneuvers.
  • FIGS. 8A-8C are block diagrams of exemplary non-invasive CVP monitoring systems according to the invention.
  • the invention provides a system for non-invasively measuring intravascular central pressure and/or relative volume changes, comprising: (a) a non-invasive inflatable cuff supplying data to a data processing system; (b) a non-invasive cuff inflator receiving control instructions from and or sending data to the data processing system and (c) a non-invasive volume sensitive detector sending data to the data processing system.
  • the invention preferably may use devices already commercially available and in use in other medical work, such as a combination of cuff and inflator devices conventionally used for arterial blood pressure measurement and a device conventionally used to perform venous plethysmography for forearm arterial blood flow. Such devices are newly used in the present invention for non-invasively measuring intravascular central pressure and/or volume.
  • non-invasive inflatable cuff supplying data to a data processing system may be used any mechanically, controllably inflatable and deflatable cuff, e.g., devices conventionally used to measure arterial blood pressure, such as Hokanson SC10 or SCI 2.
  • the cuff may contain an area for directing pressure over a vein of interest (such as an axillary vein, a brachial vein or a femoral vein), and/or may include a pressure fransducer that measures force between the cuff and skin overlying the vein of interest.
  • a vein of interest such as an axillary vein, a brachial vein or a femoral vein
  • non-invasive cuff inflator receiving control instructions from and/or sending data to the data processing system may be mentioned cuff inflators conventionally used to measure arterial blood pressure, such as Hokanson TD312.
  • the non-invasive volume sensitive detector sending data to the data processing system may be used any distal sensor capable of measuring small volume (i.e., on the order of 0.5 to 1%) changes in the extremity or its parts distal to the point of occlusion, e.g., devices conventionally used to perform venous plethysmography for forearm arterial blood flow, such as a Hokanson EC-4 plethysmography device.
  • Signal amplifiers such as Biopac DA100C
  • interfaces such as Biopac UMIOOC
  • curve-plotting may be performed in a non-computerized embodiment, most preferably in practicing the invention a data processing system is used.
  • the data processing system may be any system that controls and/or receives and processes information from the cuff and receives and/ processes information from the volume sensitive detector, e.g., a computer with analogue to digital converting capabilities and software for controlling cuff inflation and deflation while simultaneously assessing volume changes.
  • a multi channel physiologic recording instrument such as an AR-6 SIMUTRACE.
  • pressure vascular cuff and/or pressure sensor between the skin and cuff
  • a non-distal point on the patient such as at an upper extremity (such as on the upper arm such as along the axillary or brachial vein or on the upper thigh such as along the femoral vein).
  • Examples of such non-invasive monitoring are to apply an inflatable cuff and to measure pressure inside the cuff with a transducer; to attach or incorporate a pressure transducer onto the surface of the cuff that is in contact with that area of the skin overlying the brachial, axillary, or femoral vein, etc.
  • a transducer is used to measure pressure within the cuff, preferably this value is constantly reported to a computer during inflation and deflation.
  • the inventive method provides for inflating the vascular cuff above the central venous pressure but below arterial diastolic pressure.
  • a vascular cuff pressure of 30-40 mm Hg can be used since central venous pressures of this magnitude are usually inconsistent with life and diastolic arterial pressure is usually higher than this range.
  • a preferred example of cuff inflation is to inflate the cuff rapidly to a pressure of 40 mm Hg. At 40 mm Hg, venous outflow from the arm or leg is halted because this pressure is above the CVP and hence the axillary, brachial, or femoral vein pressure.
  • the length of venous occlusion from the vascular cuff can be maintained for various lengths of time but is usually maintained until no further significant changes in volume are noted.
  • An example of no further significant changes in volume is a plateau of the volume signal such that the volume signal changes less than 5% over 30 seconds.
  • the vascular cuff When no further significant changes in volume are observed, the vascular cuff is deflated. Once the pressure occluding the axillary, brachial or femoral vein is reduced below its closing pressure, the volume in the limb distal to the point of occlusion begins to rapidly decrease signaling restoration of venous flow. Analysis of the slope of this volume drop reveals that the derivative of the curve (e.g., the slope) represents venous flow and hence the cuff pressure at the maximal slope represents mean pressure within the brachial, axillary or femoral vein, which represents CVP.
  • the derivative of the curve e.g., the slope
  • the pressure as measured within the vascular cuff 1 or by a pressure transducer between the cuff 1 and skin overlying the axillary, brachial, or femoral vein at this point thus represents CVP. See, e.g., Figure 2.
  • Figure 2 As shown in Figure 2, as vascular cuff pressure is increased, the volume in the distal arm increases, as noted by the strain gauge. When the vascular cuff pressure is decreased, the volume in the forearm is decreased as noted by the strain gauge.
  • the vascular cuff 1 may be slowly inflated.
  • the point of maximum rise in slop (volume over time) distal to the cuff represents the occluding pressure within the vein, which in turn represents the CVP.
  • the measurements may be made more sensitive by inflation of an additional vascular cuff around the wrist or ankle above arterial systolic pressure to reduce the time lag of volume increase in the forearm or calf that may occur from venous filling of the hand or foot respectively.
  • the inflation of the wrist or ankle vascular cuff can be done in several seconds and does not add significant additional time to the measure of venous pressure.
  • the rate of inflation and deflation can be varied such as inflation and deflation at a rate of 1 mm Hg/sec.
  • the preferred method is rapid inflation while holding the inflation for 30-60 seconds followed by rapid deflation. This routine is demonstrated in Figures 2 and 3 in a subject who was undergoing invasive CVP monitoring as a part of prescribed care.
  • a non-invasive CVP monitoring system 200 may comprise a sensor for measuring volume change 201 (such as a mercury-in silastic or other sensitive device for measuring volume change) receiving data from and sending data to a processing system 220, the processing system 220 receiving data from a vascular cuff 211.
  • a sensor for measuring volume change 201 such as a mercury-in silastic or other sensitive device for measuring volume change
  • the processing system 220 receiving data from a vascular cuff 211.
  • the vascular cuff 211 are inflatable vascular cuffs which can be placed at a non-distal part of a patient, such as on the upper arm or leg.
  • the processing system 220 of Figure 8 A is discussed below with regard to Figures 8B and 8C in which exemplary processing systems according to the invention are shown.
  • a sensor for measuring volume change 201 (such as a mercury-in silastic or other sensitive device for measuring volume change) is connected to a hardware-software interface 202 (such as a plethysmograph or other hardware-software interface depending on the type of sensor).
  • a hardware-software interface 202 such as a plethysmograph or other hardware-software interface depending on the type of sensor.
  • interface 202 may be used any interface which can be zero balanced to detect and quantitate volume increases or decreases for the lower extremity (such as forearm, or other limb or digit) to which the sensor 201 is applied.
  • Particularly preferred as interface 202 is a plethysmograph, especially a signal-amplifying plethysmograph.
  • the signal received by the interface 202 is sent (via A-D (analogue - to digital) interface 203) to an A-D board 204 which digitizes the data and then sends the data to a processor 205 (such as a microprocessor unit (computer)), where the data may be stored and/or displayed (such as display 206 on Figure 8C).
  • a processor 205 such as a microprocessor unit (computer)
  • the vascular cuff 211 which can be placed on the upper arm or leg, is inflated 'and deflated via an inflator 212, preferably an inflator with a pressure transducer (such as the inflator with a pressure transducer 212A in Figure 8C), most preferably an automated inflator operating at a controlled rate determined by the processor 205.
  • This inflator 212 preferably also monitors the pressure in the vascular cuff 211 as measured via a pressure transducer, with the output from this transducer first amplified (at the amplifier 213) and then sent (via the A-D interface 203) to the A-D board, after which the output may be sent to the vascular cuff 211.
  • the processor 205 (such as a microprocessor and associated software) examines the rate of volume decline (venous outflow) following the onset of cuff 211 deflation and finds the maximum slope. The pressure in the vascular cuff 211 at this point is measured. The baseline cuff 211 pressure (before inflation) is subtracted, and this difference is used as an estimate of central venous pressure.
  • an inventive system may non-invasively determine CVP as follows: v if ⁇ i max slope — l ⁇ , where P 0 is a measured initial pressure in the vascular cuff 211 before inflation and P m a x slope is a measured pressure at a maximally sloping point of a curve consisting of data points (x,y), with x being the volume variable and y being time.
  • variable x may be controlled by using voltage used in inflating the cuff.
  • a display 206 may be used to report values and offer menu guidance.
  • vascular cuff pressure instead of using vascular cuff pressure, a sensor may be placed between the cuff and the tissues of the arm or leg to measure the pressure that the vascular cuff exerts on the tissue overlying the axillary, brachial, or femoral vein. This transduced pressure is amplified and sent to the A-D interface followed by the A-D board and then the computer.
  • a distal measurement (such as volume measurement, impedance measurement, flowmetry, spectroscopy, etc.) is carried out on an area distal to the upper extremity pressure measurement (such as, when an upper arm area is being measured, a distal area thereof including hands, fingers; when an upper leg area is being measured, a distal area thereof including feet, toes), or combinations of distal areas.
  • the upper extremity pressure measurement such as, when an upper arm area is being measured, a distal area thereof including hands, fingers; when an upper leg area is being measured, a distal area thereof including feet, toes
  • mercury-in-Silastic strain gauges such as, when an upper arm area is being measured, a distal area thereof including hands, fingers; when an upper leg area is being measured, a distal area thereof including feet, toes
  • mercury-in-Silastic strain gauges such as, when an upper arm area is being measured, a distal area thereof including hands, fingers; when an upper leg area is being measured, a distal area thereof including feet
  • a distal measurement-taking sensor (such as a volume or impedance based sensor, etc.) is connected to a computer system.
  • a computer system receives measurement data of distal volume changes and upper extremity pressure data.
  • a computer system that relates distal volume changes to upper extremity pressure data, such as comparing distal volume changes in response to inflation and deflation of a vascular cuff applied to an upper extremity.
  • a computer-data acquisition system with analogue to digital converter capabilities and control mechanisms to allow for timed and controlled inflation and deflation of the proximal arm or leg vascular cuff with simultaneous detection and analysis of volume changes in the limb distal to the inflated vascular cuff during inflation and deflation of the cuff.
  • Intravascular volume may be determined from a strain-gauge measurement of the lower part of the extremity, with the lower extremity (such as forearm) intravascular volume represented by change in voltage during baseline (V) and during deep inspiration (DB). An example of such measurements is shown in Figure 5. A volume decrease may be detected through increase in venous return by deep inspiration.
  • An exemplary device for noninvasive measurement of CVP may be seen with reference to Figure 1.
  • An inflatable vascular cuff 1 is non-invasively applied to surround a patient's extremity at an upper part.
  • the inflatable vascular cuff 1 preferably is formed to ensure pressure to be focused on a particular vascular structure(s) (such as a relatively large vein) as the cuff is inflated and pressure is circumferentially produced.
  • the inflatable external device 1 is shown applied to an upper arm 100, but as mentioned above, may also be applied to a thigh.
  • Inflatable vascular cuffs for pressure measurement are known to those skilled in the art, see, e.g., U.S. Patent No. 4,566,462 (Janssen).
  • the inflatable cuff 1 optionally includes an embedded pressure sensor, such as a Milar brand button pressure transducer.
  • the cuff 1 may be manually inflatable or confrollably inflated by a computer, preferably inflatable by a computer.
  • a fransducer may measure pressure within the cuff 1 with the measured pressure reported (preferably constantly reported) to the computer during inflation and deflation.
  • a pressure transducer may be attached or incorporated onto the surface of the cuff 1 that is in contact with that area of the skin overlying the brachial, axillary, or femoral vein, with pressure as measured by this transducer is reported (preferably continuously) to the computer.
  • the cuff 1 is electrically connected to a programmed cuff inflator 2 that reports pressures to a processing system 3 (such as a computer with analogue-digital converter and a data acquisition system).
  • a processing system 3 such as a computer with analogue-digital converter and a data acquisition system.
  • the computer 3 provides information to a signal amplifier 4 which is connected to a volume sensitive detector 5 (such as a mercury-in-silastic strain gauge, a bioimpedance device, photo or other plethysmography device, laser Doppler, spectroscopic volume detection device, etc.).
  • a volume sensitive detector 5 such as a mercury-in-silastic strain gauge, a bioimpedance device, photo or other plethysmography device, laser Doppler, spectroscopic volume detection device, etc.
  • peripheral veins such as the axillary, brachial, and antecubital vein are almost equivalent to those measured in the right atrium as CVP.
  • the present invention both makes absolute determinations of central venous pressure as well as observes changes in rate of venous runoff when the vascular cuff is deflated.
  • the axillary vein will collapse.
  • the arterial diastolic pressure normally about 80 mm Hg
  • the volume of the arm distal to the cuff will increase.
  • the change in forearm circumference (and hence volume) at a pressure is measured (such as with a mercury-in-Silastic strain gauge, a water displacement plethsymograph, photoplethysmography, etc.).
  • the cuff pressure will be noted as a reasonable estimate of CVP.
  • a miniaturized pressure transducer may be placed between the inner surface of the vascular cuff and skin or in the subcutaneous tissue or muscle for a closer measure of true vascular collapse pressure.
  • the invention has many uses, especially in medical measurements, diagnosis, treatment, etc.
  • devices and methods according to the invention may be used on patients whose volume status is unclear, such as patients with suspected compensated or uncompensated shock state (traumatic, cardiogenic, septic), congestive heart failure, renal failure, etc.
  • the inventive devices may be used as an initial tool in assessing volume status of a patient. This assessment may occur in the prehospital setting, hospital ward, operating room, intensive care unit, emergency department, special care unit, cardiologists' offices, other places where progression/treatment of heart failure is measured, dialysis clinics, nursing homes, residences, etc.
  • Devices according to the invention preferably are used as part of a multiparametric monitoring system that noninvasively monitors multiple physiological parameters in shock and critically ill patients.
  • a multiparametric monitoring system provides more information than conventionally-used PACs and can be applied significantly earlier in a patient encounter. This feature in turn increases the potential to obtain information that would allow diagnostic and therapeutic decisions early enough in patient care to improve outcome.
  • the invention provides a new use for equipment commonly used to measure forearm blood flow (by measuring the rate of forearm volume increase), venous outflow obstruction (forearm volume decrease following handgrip exercise) and venous compliance (forearm volume changes following step changes in cuff pressure).
  • the inventive methods herein permit examination of the slope of venous return from an extremity during cuff deflation. When this measure is repeated in the same individual after repetitive fluid administration, there may be detected a decrease in the point at which the maximum slope had been previously occurring. The time at which the slope changes is identified as signaling the maximum amount of fluid the right heart is able to receive while still maintaining a maximum cardiac output. It may thus be interpreted that the CVP at which this occurs is the point of optimal preload. This strategy also may be used to indicate at which point fluid removal, afterload manipulation, or inotropic manipulation of the heart is optimal.
  • the system as diagrammed in Figure 1 can be incorporated into other monitoring systems such as those which noninvasively measure cardiac output without the need for pulmonary artery catheterization.
  • Such a system advantageously allows for production of Frank-Starling pressure- cardiac output curves in which volume was provided or reduced to produce maximum cardiac output while noting the level of CVP at which this maximum cardiac output is obtained. Additional fluid administration or fluid reduction is provided to maintain this CVP.
  • other subsequent maneuvers to improve cardiac output such as use of inotropic agents, or manipulation of arterial blood pressure may reduce CVP.
  • the system could indicate that additional fluid administration should be provided to return CVP to the level previously shown to produce maximum fluid increases in cardiac output.
  • Repetitive examination may be performed of the slopes of venous run-off from the limb during vascular cuff deflation in response to fluid administration or fluid reduction as an internal response to optimize preload.
  • a human is challenged with additional intravascular volume that increases the right ventricular or central venous pressure, an increase in cardiac output results.
  • This increase in cardiac output prevents accumulation of fluid in the venous bed of the tissues by essentially maintaining the rate of venous return.
  • movement of fluid from the right heart matches movement of fluid from the left heart.
  • the point at which fluid administration is not matched by changes in cardiac output means that fluid will begin to accumulate in the venous system of tissue beds. This in turn will be reflected by decreases in venous return to the right side of the heart since venous pressures are elevated out of proportion to cardiac output.
  • RVEDI right ventricular end-diastolic volume index
  • PEEP positive end-expiratory pressure
  • volume sensitive measures are sensitive enough to detect respiratory variation in the extremity volume during spontaneous inspiration. Deep inspiration increases the rate and volume of venous return to the right atrium and ventricle by reducing intrathoracic pressure.
  • a mercury in-Silastic strain gauge may be used to detect a decrease in limb volume associated with deep inspiration (see Figure 5). Intravenous administration until no further decrease in volume during inspiration may be indicative of optimal preload. The noninvasively measured CVP at that point would be kept by providing additional fluid (such as by intravenous provision of fluid, etc.). Conversely, the subsequent use of inotropes or afterload manipulation which changes preload resulting in reappearance of inspiratory pressure- induced changes in limb volume signals the need to administer additional volume (such as by the intravenous route) to maintain optimal preload.
  • Non-invasive CVP determination also may be useful to determine the presence of raised intra-abdominal pressure when measurements are taken from both the leg and arm.
  • Abdominal compartment syndrome is a well-known complication of trauma which can cause splanchnic ischemia.
  • the pressure within the abdomen is expected to be transmitted to the inferior vena cava which in turn is detected by measurement of pressure and venous return in the femoral vein using the non-invasive techniques of the invention.
  • the measure may be made even more sensitive to the presence of increased infra-abdominal pressure by simultaneous comparison to a non-invasive measure of CVP made in the upper extremity.
  • the invention may be used to determine the precise pressure at which the axillary vein occludes.
  • This pressure will reflect CVP, resulting in a non-invasive method to monitor volume status, such as by using the finger(s) as a structure in which volume changes are made since volume changes at this location may occur first in response to axillary vein occlusion, such as with the use of mercury in silastic strain gauges on the finger or photoplethsmography techniques (with motion artifact rejection technology).
  • a button transducer may be placed under the finger against the skin of the arm or leg and applied with pressure.
  • the use of non-circumferential pressure is considered less preferred.
  • Another use of non-invasive measurement of CVP according to the present invention is in combination with currently available noninvasive measurements of cardiac output to optimize volume status in conditions such as circulatory shock or congestive heart failure.
  • the invention may be used in further and additional medical contexts than simply as a substitute for invasive CVP measurement. That is, in some contexts CVP measurement may be desired but invasive CVP would not have been ordered because of the relative risks and disadvantages.
  • the invention makes CVP measurement possible in circumstances where previously it had been desired but would not have been conducted.
  • a noninvasive method or device according to the invention may be used on more patients earlier in their care. Such increased CVP measurement makes possible improvements in patient outcome.
  • plethysmography with mercury in silastic strain gauges was used to measure changes in forearm volume.
  • the strain gauge was placed around the greatest circumference of the forearm.
  • a pediafric endofracheal (ET) tube with a water manometer was placed over the axillary vein under the blood pressure cuff, with an initial balloon pressure of 30 cm H 2 0 (22.1 mm Hg).
  • the output from the blood pressure cuff was connected to a pressure transducer placed at the level of the right atrium.
  • a wrist cuff was inflated to 140 mm Hg.
  • the pressure transducer and plesythmograph were connected to an AR-6 SMUTRACE (a multi channel physiologic recording instrument) with a thermal processed paper that gives black and white recording.
  • AR-6 SMUTRACE a multi channel physiologic recording instrument
  • the subject was placed on a tilt table, which was changed from head up 90° (standing) to head down 30 °.
  • V volume at constant pressure without any maneuvers.
  • Trials 4 through 7 clearly show that changes in CVP cause a concomitant change in forearm volume, hi all three positions, deep breathing (decrease in CVP) caused a decrease in forearm volume relative to the control (V). Similarly, a valsalva maneuver (increase in CVP) caused a drastic increase in forearm volume.
  • Trials 6 and 7 demonstrate that a valsalva maneuver causes a smaller change in forearm volume when CVP is higher (head down 20°).
  • Li trial 8 ( Figure 7H)
  • a pressure of 11.0 mm Hg was required to raise forearm volume from 0-1.0V, while 30.1 mm Hg were needed during valsalva (increased CVP).
  • Figures 7A-7I provide evidence that a threshold/critical change in forearm volume is sensitive to changes in CVP. This includes even negative pressure changes. Also, the data show that increasing or decreasing pressures were required to occlude the axillary vein as CVP increased or decreased respectively in response to tilting. Additionally, the data show that these pressures can be accurately quantitated and are within the expected clinical ranges of CVP changes in response to tilting and other maneuvers performed as reported above.
  • FIGS. 7A-7I show that a noninvasive method of measuring CVP may be a medically sound alternative to direct intravenous measurement of this variable.
  • this noninvasive CVP measurement will help in optimizing the volume status during medical and surgical emergencies and resuscitation.
  • the device will also decrease the need for invasive instrumentation of patients in the intensive care unit setting while aiding in their hemodynamic management.
  • the device also can be seen to be useful in the office or clinic setting for optimal management of such diseases as congestive heart failure or chronic renal failure.
  • EXAMPLE 2 EXAMPLE 2
  • non-invasive CVP was taken from the upper extremity using a system according to Figure 1 herein. Data from these 14 subjects (four readings from each subject) are depicted in Figure 4.
  • noninvasive CVP was taken from the upper extremity and is compared to the invasively measured CVP.
  • the correlation is over 0.9 (specifically, 0.97). In no instance would the values have differed to the magnitude that different patient management would have been indicated for the noninvasively measured CVP versus the invasively measured CVP.
  • FIG. 3 is a detailed analysis of the recording from Figure 2 during deflation of the vascular cuff. The steepest portion of the slope (derivative) was located. The cuff pressure at this time was noted. In this case it was exactly the same as the mean CVP noted during the time indicated between the two solid bars in the CVP tracing.
  • Baseline (BL) inspiration for a patient was observed and recorded, as shown in Figure 5.
  • Deep inspiration (DB) by a patient also was observed, as shown in Figure 5.
  • Figure 5 shows relative decrease in volume noted on deep inspiration as measured by a mercury-in-Silastic strain gauge.

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  • Health & Medical Sciences (AREA)
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  • Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)

Abstract

L'invention se rapporte à un procédé de détermination non invasive de la pression veineuse centrale avec une précision comparable à celle des techniques de mesure invasives. Ledit procédé consiste à tracer des courbes à partir de données relatives au patient déterminées de manière non invasive et obtenues par application d'une grandeur variable contrôlable (la pression) à une veine d'intérêt, en un point non distal et par prise de certaines mesures (telles que des mesures de pression et de volume) sur le patient. Un exemple de grandeur variable controlâble est la tension appliquée lors du gonflage/dégonflage incrémental d'un manchon périvasculaire. Une courbe est tracée en fonction des points de données (telle qu'une courbe d'accroissement du volume ou une courbe de réduction du volume). La pente de cette courbe de données établies de manière non invasive, permet d'obtenir des informations pertinentes et précises sur la pression veineuse centrale et/ou le volume sanguin. Des informations précises relatives à la pression veineuse centrale sont ainsi obtenues sans encourir les risques ni supporter les désavantages des techniques de mesure invasives.
PCT/US2001/029582 2000-09-21 2001-09-21 Procede de controle et d'optimisation de la pression veineuse centrale et du volume intravasculaire WO2002024053A2 (fr)

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Cited By (5)

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EP1366708A2 (fr) * 2002-05-07 2003-12-03 Colin Corporation Appareil d'inspection de l'arteriosclérose et appareil de mesure de la pression sanguine au niveau de la cheville
US7011631B2 (en) 2003-01-21 2006-03-14 Hemonix, Inc. Noninvasive method of measuring blood density and hematocrit
EP1793733A2 (fr) * 2004-09-15 2007-06-13 Itamar Medical (C.M.) 1997 Ltd. Procede et appareil permettant de mesurer de façon non invasive des parametres physiologiques, notamment le flux sanguin et la capacite veineuse
EP2892582A4 (fr) * 2012-09-10 2016-11-09 Univ Vanderbilt Dispositif d'accès intraveineux comportant un système de réanimation hémodynamique intégré et méthodes associées
US10842395B2 (en) 2011-11-24 2020-11-24 Itamar Medical Ltd. Apparatus for monitoring arterial pulse waves in diagnosing various medical conditions

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US5343868A (en) * 1992-04-02 1994-09-06 Hewlett-Packard Company Method and apparatus for detecting artifacts in a blood pressure measuring system
US6120459A (en) * 1999-06-09 2000-09-19 Nitzan; Meir Method and device for arterial blood pressure measurement

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US5343868A (en) * 1992-04-02 1994-09-06 Hewlett-Packard Company Method and apparatus for detecting artifacts in a blood pressure measuring system
US6120459A (en) * 1999-06-09 2000-09-19 Nitzan; Meir Method and device for arterial blood pressure measurement

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1366708A2 (fr) * 2002-05-07 2003-12-03 Colin Corporation Appareil d'inspection de l'arteriosclérose et appareil de mesure de la pression sanguine au niveau de la cheville
EP1366708A3 (fr) * 2002-05-07 2004-03-03 Colin Corporation Appareil d'inspection de l'arteriosclérose et appareil de mesure de la pression sanguine au niveau de la cheville
US6796946B2 (en) 2002-05-07 2004-09-28 Colin Medical Technology Corporation Arteriostenosis inspecting apparatus and ankle-blood-pressure measuring apparatus
US6923771B2 (en) 2002-05-07 2005-08-02 Colin Medical Technology Corporation Arteriostenosis inspecting apparatus and ankle-blood-pressure measuring apparatus
CN100453034C (zh) * 2002-05-07 2009-01-21 欧姆龙健康医疗事业株式会社 动脉狭窄检查设备和踝血压测量设备
US7011631B2 (en) 2003-01-21 2006-03-14 Hemonix, Inc. Noninvasive method of measuring blood density and hematocrit
EP1793733A2 (fr) * 2004-09-15 2007-06-13 Itamar Medical (C.M.) 1997 Ltd. Procede et appareil permettant de mesurer de façon non invasive des parametres physiologiques, notamment le flux sanguin et la capacite veineuse
US9474453B2 (en) * 2004-09-15 2016-10-25 Itamar Medical Ltd. Measuring blood flow and venous capacitance
EP1793733B1 (fr) * 2004-09-15 2017-05-17 Itamar Medical (C.M.) 1997 Ltd. Procede et appareil permettant de mesurer de façon non invasive des parametres physiologiques, notamment le flux sanguin et la capacite veineuse
US10842395B2 (en) 2011-11-24 2020-11-24 Itamar Medical Ltd. Apparatus for monitoring arterial pulse waves in diagnosing various medical conditions
EP2892582A4 (fr) * 2012-09-10 2016-11-09 Univ Vanderbilt Dispositif d'accès intraveineux comportant un système de réanimation hémodynamique intégré et méthodes associées

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