DE19914437A1 - Determination of volume blood flow into aortic section over heart beat cycle from impedance curve of cardiogram by derivation of equation from Seifert and Kubieck's equation - Google Patents
Determination of volume blood flow into aortic section over heart beat cycle from impedance curve of cardiogram by derivation of equation from Seifert and Kubieck's equationInfo
- Publication number
- DE19914437A1 DE19914437A1 DE19914437A DE19914437A DE19914437A1 DE 19914437 A1 DE19914437 A1 DE 19914437A1 DE 19914437 A DE19914437 A DE 19914437A DE 19914437 A DE19914437 A DE 19914437A DE 19914437 A1 DE19914437 A1 DE 19914437A1
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- Prior art keywords
- equation
- curve
- impedance
- seifert
- tau
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- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Links
- 230000017531 blood circulation Effects 0.000 title description 2
- 238000009795 derivation Methods 0.000 title 1
- 239000008280 blood Substances 0.000 claims abstract description 7
- 210000004369 blood Anatomy 0.000 claims abstract description 7
- 210000001765 aortic valve Anatomy 0.000 claims abstract description 5
- 210000000115 thoracic cavity Anatomy 0.000 claims description 6
- 210000000038 chest Anatomy 0.000 abstract description 2
- 230000000630 rising effect Effects 0.000 abstract 1
- 238000010586 diagram Methods 0.000 description 3
- 239000012620 biological material Substances 0.000 description 2
- 238000002847 impedance measurement Methods 0.000 description 2
- 238000002489 impedance cardiography Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000002861 ventricular Effects 0.000 description 1
Classifications
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/026—Measuring blood flow
- A61B5/029—Measuring or recording blood output from the heart, e.g. minute volume
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/02—Detecting, measuring or recording pulse, heart rate, blood pressure or blood flow; Combined pulse/heart-rate/blood pressure determination; Evaluating a cardiovascular condition not otherwise provided for, e.g. using combinations of techniques provided for in this group with electrocardiography or electroauscultation; Heart catheters for measuring blood pressure
- A61B5/026—Measuring blood flow
- A61B5/0295—Measuring blood flow using plethysmography, i.e. measuring the variations in the volume of a body part as modified by the circulation of blood therethrough, e.g. impedance plethysmography
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/05—Detecting, measuring or recording for diagnosis by means of electric currents or magnetic fields; Measuring using microwaves or radio waves
- A61B5/053—Measuring electrical impedance or conductance of a portion of the body
- A61B5/0535—Impedance plethysmography
Landscapes
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Hematology (AREA)
- Heart & Thoracic Surgery (AREA)
- Molecular Biology (AREA)
- Veterinary Medicine (AREA)
- Biophysics (AREA)
- Pathology (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Cardiology (AREA)
- Medical Informatics (AREA)
- Physics & Mathematics (AREA)
- Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- General Health & Medical Sciences (AREA)
- Public Health (AREA)
- Physiology (AREA)
- Nuclear Medicine, Radiotherapy & Molecular Imaging (AREA)
- Radiology & Medical Imaging (AREA)
- Measurement And Recording Of Electrical Phenomena And Electrical Characteristics Of The Living Body (AREA)
Abstract
Description
Die Erfindung betrifft eine mathematische Formel zur Berechnung des Herzschlagvolumens aus der ΔZ-Kurve des Impedanzkardiogramms nach dem Oberbegriff des Hauptanspruchs.The invention relates to a mathematical formula for calculation of the heartbeat volume from the ΔZ curve of the Impedance cardiogram according to the preamble of the main claim.
Bei der Berechnung des Herzschlagvolumens aus dem
Impedanzkardiogramm wird überwiegend die Formel von Kubicek
angewendet, die lautet:
When calculating the heartbeat volume from the impedance cardiogram, the Kubicek formula is mainly used, which reads:
SVKubicek = ρL2/Zo2.LVET dZ/dtmax
SVKubicek = ρL2 / Zo2.LVET dZ / dtmax
mit
ρ dem spezifischen Blutwiderstandswert
L der Distanz zwischen den inneren Bandelektroden
Zo der thorakalen Grundimpedanz
LVET der Austreibungszeit (left ventricular ejection period)
dZ/dtmax Maximum der ersten Ableitung der ΔZ-Kurve.With
ρ the specific blood resistance value
L the distance between the inner band electrodes
Zo of basic thoracic impedance
LVET of the expulsion period (left ventricular ejection period)
dZ / dt max Maximum of the first derivative of the ΔZ curve.
Die Formel nach Kubicek hat den Nachteil, daß eine Validierung mit anderen anerkannten Meßmethoden wie dem Fick'schen Prinzip oder der Thermodilutionsmethode umstritten ist, da es sich um eine heuristische Formel handelt. Auch zeigt sich eine signifikante Änderung des so errechneten Herzschlagvolumens, wenn zwischen die beiden inneren Bandelektroden ein diskreter Widerstand geschaltet wird, wo das errechnete Herzschlagvolumen davon eigentlich unbeeinflußt sein müßte.The Kubicek formula has the disadvantage of being validated with other recognized measurement methods such as Fick's principle or the thermodilution method is controversial since it is is a heuristic formula. One also shows up significant change in the heartbeat volume calculated in this way, if a discrete between the two inner band electrodes Resistance is switched where the calculated heartbeat volume should actually be unaffected by this.
Aus der Diplomarbeit von Seifert, gefertigt am Institut für
Biomedizinische Technik der Universität Stuttgart geht eine
Formel zur Berechnung des Herzschlagvolumens aus der ΔZ-Kurve
des Impedanzkardiogramms hervor, die diese Nachteile nicht hat,
die aus einem vereinfachten Modell für die
Kontinuitätsgleichung abgeleitet ist und die lautet:
From the diploma thesis by Seifert, produced at the Institute for Biomedical Engineering at the University of Stuttgart, a formula for calculating the heartbeat volume from the ΔZ curve of the impedance cardiogram emerges, which does not have these disadvantages, which is derived from a simplified model for the continuity equation and is as follows :
mit
ρ dem spezifischen Blutwiderstandswert
L dem Abstand der inneren Bandelektroden
ZTo dem Impedanzwert im Maximum der ΔZ-Kurve
Zo der thorakalen Grundimpedanz
Ts der Zeit bis zum Aortenklappenschluß
To der Zeit bis zum Maximum der ΔZ-Kurve
το der Anstiegszeitkonstanten
τ1 der Abfallszeitkonstanten.With
ρ the specific blood resistance value
L the distance between the inner band electrodes
ZTo the impedance value in the maximum of the ΔZ curve
Zo of basic thoracic impedance
Ts of time until aortic valve closure
To the time to the maximum of the ΔZ curve
το the rise time constant
τ1 the fall time constant.
Die Formel von Seifert geht davon aus, daß die ΔZ-Kurve als eine Überlagerung zweier Exponentialfunktionen mit zwei unterschiedlichen Zeitkonstanten τo und τ1 interpretierbar ist, wobei die Anstiegszeitkonstante τo kleiner als die Abfallszeitkonstante τ1 ist.Seifert's formula assumes that the ΔZ curve as a superposition of two exponential functions with two different time constants τo and τ1 can be interpreted, where the rise time constant τo is smaller than that Fall time constant τ1.
Die aus der Diplomarbeit von Seifert hervorgehende Formel enthält den Term 1/ZTo - 1/Zo, der die Differenz von Leitwerten widergibt, wobei nach dem physikalischen Modell der Fig. 4 und dem elektrischen Ersatzschaltbild der Fig. 5 die den Aortenabschnitt umgebende Gewebeimpedanz auf diese Differenz keinen Einfluß hat.The formula resulting from the diploma thesis by Seifert contains the term 1 / ZTo - 1 / Zo, which reflects the difference of the conductance values, whereby according to the physical model of FIG. 4 and the electrical equivalent circuit diagram of FIG. 5, the tissue impedance surrounding the aortic section on these Difference has no influence.
Der Term 1/ZTo - 1/Zo ist aber etwas "unhandlich".The term 1 / ZTo - 1 / Zo is somewhat "unwieldy".
Deshalb liegt der vorliegenden Erfindung die Aufgabe zugrunde eine Formel zur Berechnung des Herzschlagvolumens aus der ΔZ- Kurve des Impedanzkardiogramms anzugeben, die leichter handhabbar ist und die trotzdem den Vorteil hat, daß die den Aortenabschnitt umgebende Gewebeimpedanz nahezu keinen Einfluß auf das so berechnete Herzschlagvolumen hat.The present invention is therefore based on the object a formula for calculating the heartbeat volume from the ΔZ Curve of the impedance cardiogram to indicate the lighter is manageable and which still has the advantage that the Tissue impedance surrounding the aortic section has almost no influence on the calculated heartbeat volume.
Diese Aufgabe wird durch den kennzeichnenden Teil des Hauptanspruchs gelöst.This task is carried out by the characteristic part of the Main claim solved.
Die erfindungsgemäße Formel hat den Vorteil, daß sie leicht handhabbar ist und einen Analogieschluß zur Formel nach Kubicek zuläßt.The formula according to the invention has the advantage that it is light is manageable and an analogy to the formula according to Kubicek allows.
Die dabei auftretende Abweichung gegenüber der aus der Diplomarbeit von Seifert hervorgehenden Formel liegt im Prozentbereich.The deviation that arises from that from the Diploma thesis of Seifert resulting formula lies in Percentage range.
Die erfindungsgemäße Formel lautet:
The formula according to the invention is:
mit
ρ dem spezifischen Blutwiderstandswert
L der Distanz zwischen den inneren Bandelektroden
ΔZmax dem maximalen Differenzbetrag der ΔZ-Kurve
Zo der thorakalen Grundimpedanz
Ts der Zeit bis zum Aortenklappenschluß
To der Zeit bis zum Maximum der ΔZ-Kurve
τo der Anstiegszeitkonstanten
τ1 der Abfallszeitkonstanten.With
ρ the specific blood resistance value
L the distance between the inner band electrodes
ΔZmax is the maximum difference in the ΔZ curve
Zo of basic thoracic impedance
Ts of time until aortic valve closure
To the time to the maximum of the ΔZ curve
τo the rise time constant
τ1 the fall time constant.
Aus der Tatsache, daß die absoluten ΔZ-Werte im Bereich um 0,2
bis 0,4 Ohm liegen, kann für den Term 1/ZTo - 1/Zo gebildet
werden:
From the fact that the absolute ΔZ values are in the range of 0.2 to 0.4 ohms, the following can be formed for the term 1 / ZTo - 1 / Zo:
(Zo - ZTo)/(ZTo.Zo) =∧ ΔZmax/Zo2(Zo - ZTo) / (ZTo.Zo) = ∧ ΔZmax / Zo2
Erläuterungen zum Meßprinzip und den mathematischen Formeln können den Figuren entnommen werden.Explanations of the measuring principle and the mathematical formulas can be seen in the figures.
Es zeigen:Show it:
Fig. 1 das Prinzip der Impedanzmessung Fig. 1 shows the principle of impedance measurement
Fig. 2 den Verlauf der ΔZ-Kurve mit den Meßgrößen für die Formel nach Kubicek Fig. 2 shows the course of the ΔZ curve with the measured variables for the formula according to Kubicek
Fig. 3 den Verlauf der ersten Ableitung dZ/dt mit den Meß größen für die Formel nach Kubicek Fig. 3 shows the course of the first derivative dZ / dt with the measurands for the formula according to Kubicek
Fig. 4 ein physikalisch vereinfachtes Modell als Grundlage für für die Impedanzkardiographie Fig. 4 is a physically simplified model as a basis for the impedance cardiography
Fig. 5 ein elektrisches Ersatzschaltbild zum Modell der Fig. 4 Fig. 5 is an electrical equivalent circuit diagram for the model of Fig. 4
Fig. 6 den approximierten Verlauf des einfließenden Volumens mit der Anstiegszeitkonstanten τo Fig. 6 shows the approximate course of the influent volume with the rise time constants τo
Fig. 7 den approximierten Verlauf des ausfließenden Volumens mit der Abfallszeitkonstanten τ1 Fig. 7 shows the approximate course of the effluent volume with the fall time constants τ1
Fig. 8 die Überlagerung der Kurven der Fig. 6 und 7 Fig. 8 shows the superposition of the curves of FIGS. 6 and 7
Die Fig. 1 zeigt das Prinzip der Impedanzmessung. Dabei wird eine Wechselspannungsquelle von ca. 100 kHz und einer konstanten Stromstärke von ca. 5 mA an die Elektroden 1 und 4 angelegt, welche einen Strom mit einer konstanten Stromstärke durch das biologische Material treibt. Die Meßelektroden 2 und 3 sind in dem definierten Abstand L zwischen den Elektroden 1 und 4 angebracht. Der Spannungsabfall an den Meßelektroden 2 und 3 wird einem Differenzverstärker mit sehr hohem Eingangswiderstand zugeführt. Aus dem konstanten Wechselstrom und dem Spannungsabfall an den Meßelektroden 2 und 3 kann die Impedanz des biologischen Materials bestimmt werden. Durch die Frequenz von ca. 100 kHz hat die Impedanz, gemessen am menschlichen Körper, nahezu rein ohmschen Charakter. Fig. 1 shows the principle of the impedance measurement. An AC voltage source of approximately 100 kHz and a constant current of approximately 5 mA is applied to electrodes 1 and 4 , which drives a current with a constant current through the biological material. The measuring electrodes 2 and 3 are attached at the defined distance L between the electrodes 1 and 4 . The voltage drop across the measuring electrodes 2 and 3 is fed to a differential amplifier with a very high input resistance. The impedance of the biological material can be determined from the constant alternating current and the voltage drop at the measuring electrodes 2 and 3 . Due to the frequency of approx. 100 kHz, the impedance, measured on the human body, has an almost purely ohmic character.
Die Fig. 2 zeigt einen typischen Impedanzverlauf der ΔZ-Kurve mit den für die Berechnung des Herzschlagvolumens nach Kubicek charakteristischen Größen. FIG. 2 shows a typical impedance curve of the ΔZ curve with the quantities characteristic for the calculation of the heartbeat volume according to Kubicek.
Die Fig. 3 zeigt die erste Ableitung dz/dt des Impedanzverlaufs mit den für die Berechnung des Herzschlagvolumens nach Kubicek charakteristischen Größen. FIG. 3 shows the first derivative dz / dt of the impedance curve with the quantities characteristic for the calculation of the heartbeat volume according to Kubicek.
Die Fig. 4 zeigt ein vereinfachtes physikalisches Röhrenmodell des Thorax und des von Blut durchströmten Aortenabschnitts. FIG. 4 shows a simplified physical tube model of the thorax and the aortic section through which blood flows.
Die Fig. 5 zeigt das zu Fig. 4 gehörige elektrische Ersatzschaltbild mit Z1 der Blutimpedanz, Z2 der Gewebeimpedanz und Zt der Thoraximpedanz. FIG. 5 shows the corresponding to Fig. 4 electrical equivalent circuit diagram with the blood impedance Z1, Z2 of the tissue impedance Zt and the thoracic impedance.
Die Fig. 6 zeigt den approximierten angenommenen Verlauf des in den Aortenabschnitt einfließenden Volumens mit der Anstiegszeitkonstanten τo. FIG. 6 shows the approximated assumed course of the volume flowing into the aortic section with the rise time constant τo.
Fig. 7 zeigt den Verlauf des approximierten angenommenen Verlaufs des aus dem Aortenabschnitt ausfließenden Volumens mit der Abfallszeitkonstanten τ1. Fig. 7 shows the course of the approximated curve assumed the effluent from the aortic volume with the fall time constants τ1.
Fig. 8 zeigt die Überlagerung der Kurven der Fig. 6 und 7 sowie einen typischen gemessenen Impedanzverlauf der ΔZ-Kurve mit den für die Berechnung des Herzschlagvolumens nach Seifert charakteristischen Größen. FIG. 8 shows the superimposition of the curves of FIGS. 6 and 7 and a typical measured impedance curve of the ΔZ curve with the variables characteristic of the calculation of the heartbeat volume according to Seifert.
ρ spezifischer Blutwiderstandswert
L Distanz zwischen den inneren Bandelektroden
ΔZmax Maximum der ΔZ-Kurve
Zo thorakale Grundimpedanz
Ts Zeit bis zum Aortenklappenschluß
To Zeit bis zum Maximum der ΔZ-Kurve
τo Anstiegszeitkonstante
τ1 Abfallszeitkonstante
ZTo ρ specific blood resistance value
L Distance between the inner band electrodes
ΔZmax maximum of the ΔZ curve
Zo thoracic basic impedance
Ts time until aortic valve closure
To time to the maximum of the ΔZ curve
τo rise time constant
τ1 fall time constant
Z To
Impedanzwert im Maximum der ΔZ-Kurve
Impedance value in the maximum of the ΔZ curve
Claims (1)
wobei ist:
SV das Herzschlagvolumen
ρ spezifischer Blutwiderstandswert
L Distanz zwischen den inneren Bandelektroden
ΔZmax Maximum der ΔZ-Kurve
Zo thorakale Grundimpedanz
Ts Zeit bis zum Aortenklappenschluß
To Zeit bis zum Maximum der ΔZ-Kurve
τo Anstiegszeitkonstante
τ1 AbfallszeitkonstanteMathematical formula for calculating the heartbeat volume from the ΔZ curve of the impedance cardiogram according to H. Seifert and D. Kubicek, characterized in that:
where is:
SV the heartbeat volume
ρ specific blood resistance value
L Distance between the inner band electrodes
ΔZmax maximum of the ΔZ curve
Zo thoracic basic impedance
Ts time until aortic valve closure
To time to the maximum of the ΔZ curve
τo rise time constant
τ1 fall time constant
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19914437A DE19914437A1 (en) | 1999-03-30 | 1999-03-30 | Determination of volume blood flow into aortic section over heart beat cycle from impedance curve of cardiogram by derivation of equation from Seifert and Kubieck's equation |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE19914437A DE19914437A1 (en) | 1999-03-30 | 1999-03-30 | Determination of volume blood flow into aortic section over heart beat cycle from impedance curve of cardiogram by derivation of equation from Seifert and Kubieck's equation |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| DE19914437A1 true DE19914437A1 (en) | 2000-10-05 |
Family
ID=7902969
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| DE19914437A Withdrawn DE19914437A1 (en) | 1999-03-30 | 1999-03-30 | Determination of volume blood flow into aortic section over heart beat cycle from impedance curve of cardiogram by derivation of equation from Seifert and Kubieck's equation |
Country Status (1)
| Country | Link |
|---|---|
| DE (1) | DE19914437A1 (en) |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1247487A1 (en) * | 2001-04-03 | 2002-10-09 | Osypka Medical GmbH | Apparatus and method for determining an approximate value of the stroke volume and the cardiac output of the heart |
| WO2003003920A2 (en) * | 2001-07-05 | 2003-01-16 | Gennady Gedevanishvili | Method and device for non-invasive research of blood distribution and its circulatory characteristics in warm-blooded organism |
| US7822470B2 (en) | 2001-10-11 | 2010-10-26 | Osypka Medical Gmbh | Method for determining the left-ventricular ejection time TLVE of a heart of a subject |
| US10470718B2 (en) | 2005-08-17 | 2019-11-12 | Osypka Medical Gmbh | Method for digital demodulation and further processing of signals obtained in the measurement of electrical bioimpedance or bioadmittance in a human subject |
-
1999
- 1999-03-30 DE DE19914437A patent/DE19914437A1/en not_active Withdrawn
Cited By (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP1247487A1 (en) * | 2001-04-03 | 2002-10-09 | Osypka Medical GmbH | Apparatus and method for determining an approximate value of the stroke volume and the cardiac output of the heart |
| WO2003003920A2 (en) * | 2001-07-05 | 2003-01-16 | Gennady Gedevanishvili | Method and device for non-invasive research of blood distribution and its circulatory characteristics in warm-blooded organism |
| WO2003003920A3 (en) * | 2001-07-05 | 2003-04-17 | Gennady Gedevanishvili | Method and device for non-invasive research of blood distribution and its circulatory characteristics in warm-blooded organism |
| US7822470B2 (en) | 2001-10-11 | 2010-10-26 | Osypka Medical Gmbh | Method for determining the left-ventricular ejection time TLVE of a heart of a subject |
| US7904141B2 (en) | 2001-10-11 | 2011-03-08 | Osypka Medical Gmbh | System and apparatus for determining the left-ventricular ejection time TLVE of a heart of a subject |
| US8562538B2 (en) | 2001-10-11 | 2013-10-22 | Osypka Medical Gmbh | System for determining the left-ventricular ejection time TLVE of a heart of a subject |
| US10470718B2 (en) | 2005-08-17 | 2019-11-12 | Osypka Medical Gmbh | Method for digital demodulation and further processing of signals obtained in the measurement of electrical bioimpedance or bioadmittance in a human subject |
| US11642088B2 (en) | 2005-08-17 | 2023-05-09 | Osypka Medical Gmbh | Method and apparatus for digital demodulation and further processing of signals obtained in the measurement of electrical bioimpedance or bioadmittance in an object |
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