Method and device for long-term monitoring of arterial vascular stiffness and vascular calcification of a patient

• US 10,016,138 B2
• Filed: 04/11/2013
• Issued: 07/10/2018
• Est. Priority Date: 04/11/2012
• Status: Active Grant

• Current Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius SE & Co. KGaA)
• Original Assignee: Fresenius Medical Care Deutschland GmbH (Fresenius SE & Co. KGaA)
• Inventors: Zhang, Wei
• Primary Examiner(s): Cheng, Jacqueline
• Assistant Examiner(s): PORTILLO, JAIRO H
• Application Number:
  US13/860,666
• Publication Number:
  US 20130274620A1
• Time in Patent Office: 1,916 Days
• Field of Search: None
• CPC Class Codes: A61B 5/02007 Evaluating blood vessel condition, e.g. elasticity, compliance
• CPC Class Codes: A61B 5/02125 of pulse wave propagation time
• CPC Class Codes: A61B 5/02225 using the oscillometric method

Abstract

The present invention proposes a method and a device for long-term monitoring of the arterial vascular stiffness and vascular calcification on a particular patient, wherein a characteristic variable for the arterial vascular stiffness is determined exclusively from the shape and/or the characteristic of at least one pressure pulse wave caused by a cardiac contraction as a function of time and is stored as a time series for the particular patient. In particularly preferred embodiments, the characteristic variable is represented as a trend and serves the physician as a basis for long-term monitoring of the arterial vascular stiffness.

Claims

1. A method for long-term monitoring arterial vascular stiffness of a patient comprising the steps of:

non-invasive measurement of a pressure pulse wave as a function of time, caused by a cardiac contraction of the patient, in a plurality of successive intervals of time based on at least one pressure pulse wave occurring per interval of time and corresponding to a series of successive extracorporeal blood treatment sessions of the patient or including a series of successive extracorporeal blood treatment sessions of the patient,

non-invasively determining one time the length of the descending aorta of the patient, characterized in that the length of the descending aorta of the patient (L₂) defined as the distance between the tip of the aortic arch and the aortic bifurcation is calculated according to at least one of the equations

L₂=k_JS·

L_JS, where 0.6≤

k_JS≤

1,

wherein

L₂ denotes the length of the descending aorta of the patient,

k_JS denotes a first dimensionless correction factor, and

L_JS denotes the distance between the jugular and the pubic symphysis of the patient lying down,

L₂=k_JBS·

L_JBS, where 0.8≤

k_JBS≤

1.2,

wherein

L₂ denotes the length of the descending aorta of the patient,

k_JBS denotes a second dimensionless correction factor, and

L_JBS denotes the distance between the jugular and the umbilicus of the patient, and

L₂=α

·

H−

β

, where α

=3.10 and β

=7.00,

wherein

L₂ denotes the length of the descending aorta of the patient in mm and

H denotes the height of the patient, standing up, in cm,

storing the determined length of the descending aorta of the patient on a non-transitory computer readable medium unambiguously assigned to the patient,

evaluation of the measured pressure pulse waves as a function of time in the plurality of successive intervals of time based on the at least one pressure pulse wave per interval of time and calculating a pulse wave transit time (PTT) in the descending aorta of the patient from a smoothing of the measured pressure pulse waves as a function of time for the at least one pressure pulse wave per interval of time, wherein the pulse transit time (PTT) in the descending aorta is calculated as the difference between the time of a detected peak of the reflection wave or a detected turning point of the reflection wave in the at least one pulse pressure wave and the time of a systolic peak in the at least one pulse pressure wave,

saving the calculated pulse wave transit time for a majority of successive measurement intervals,

calculating a trend of the pulse wave transit time from the saved pulse wave transit times,

storing the trend of the pulse wave transit time as a time series on the non-transitory computer readable medium unambiguously assigned to the patient, and

monitoring the stored trend of the pulse wave transit time for a change in the pulse wave transit time indicating a change in the arterial vascular stiffness of the patient.

2. The method according to claim 1, characterized in that the first dimensionless correction factor k_JS has a value of 0.75≤

k_JS≤

0.85.

3. The method according to claim 1, characterized in that the pulse wave transit time is calculated under the assumption that the length is determined for the descending aorta of the patient.

4. The method according to claim 1, characterized in that the calculation of the pulse wave transit time includes a calculation of a pulse wave velocity (PWV) of the descending aorta of the patient according to the equation

5. The method according to claim 4, further comprising the step of

continuously calculating and monitoring at least one of

the blood pressure of the patient in the interval of time according to the equation

BP(t)=m·

PWV(t)+n,

the absolute change in blood pressure of the patient in the interval of time according to the equation

Δ

BP(t)=m·

[PWV(t)−

PWV(t₀)]+n, and

the relative change in blood pressure of the patient in the interval of time according to the equation

6. A measurement and computation unit, for non-invasively determining at least one characteristic variable pertaining to arterial vascular stiffness of a patient, comprising

a blood pressure measuring unit including a pressure sensor and configured for measuring pressure pulses at a measurement site on the patient'"'"'s wrist or at a measurement site on the patient'"'"'s upper arm and conversion into electrical pressure pulse signals,

an evaluation unit having a computation and memory unit having a computer program with program code for ordering the steps of the method according to claim 1, when the program code is running in the computation and memory unit.

7. The measuring and computation unit according to claim 6 further comprising

a data input unit for entering the length of the descending aorta of the patient or for input of data for calculating the length of the descending aorta of the patient in the computation and memory unit.

8. The measuring and computation unit according to claim 6, characterized in that the blood pressure sensor is a piezoelectric pressure pickup for non-invasive measurement of pressure pulses on the patient'"'"'s wrist or a sphygmomanometer cuff for non-invasive measurement of pressure pulses on the patient'"'"'s upper arm.

9. The measuring and computation unit according to claim 6 integrated into a control and computation unit of a blood treatment device for extracorporeal blood treatment or connected to a control and computation unit of a blood treatment device for extracorporeal blood treatment.

10. The measuring and computation unit according to claim 6 further comprising a read/write unit for storing the trend of the pulse wave transit time as a time series on the computer readable medium.

11. A blood treatment device for extracorporeal blood treatment in combination with the measuring and computation unit according to claim 6.

12. The blood treatment device for extracorporeal blood treatment according to claim 11 selected from the group consisting of dialysis machines, hemofiltration machines, and hemodiafiltration machines.

13. A computer program product comprising a program recorded on a non-transitory computer readable medium and coded to perform the method of claim 1 when under control of a computer running the program and incorporated in a computation and memory unit of a device comprising a blood pressure measuring unit including a pressure sensor and configured for measuring pressure pulses at a measurement site on the patient'"'"'s wrist or at a measurement site on the patient'"'"'s upper arm and conversion into electrical pressure pulse signals, and an evaluation unit containing the computation and memory unit.

14. The method according to claim 1, characterized in that the first dimensionless correction factor k_JS=8.