HEART REFERENCE UNIT AND BLOOD PRESSURE MONITOR COMPRISING A HEART REFERENCE UNIT

Abstract

The present invention relates to a blood pressure monitor for non-invasive blood pressure measurement comprising a blood pressure sensor for measuring peripheral arterial pressure and a heart reference unit that comprises a first fluid column, with a first end positionable at blood pressure sensor level, and a second fluid column, with a first end positionable at a reference level, preferably the heart level, and at least one heart reference sensor for sensing the pressure prevailing in the first fluid column and the second fluid column. The invention further relates to a heart reference unit for a blood pressure monitor according to the invention.

Claims

1. A blood pressure monitor for blood pressure measurement, the blood pressure monitor comprising: a blood pressure sensor configured to measure a peripheral arterial pressure; and a heart reference unit, the heart reference unit comprising: a first fluid column with a first end positionable at a level of the blood pressure sensor, a second fluid column with a first end positionable at a reference level, and at least one heart reference sensor configured to sense pressures prevailing in the first fluid column and the second fluid column, wherein a second end of the first fluid column and a second end of the second fluid column, each at an end of its respective fluid column opposite the corresponding first end of each said fluid column, are configured for positioning at a predetermined elevation relative to each other.

2. A blood pressure monitor according to claim 1, wherein the heart reference unit comprises a differential pressure transducer configured to determine a hydrostatic pressure difference between the first fluid column and the second fluid column based on the pressures sensed by the at least one heart reference sensor.

3. A blood pressure monitor according to claim 2, wherein the blood pressure monitor further comprises a processor configured to derive a central arterial pressure from the peripheral arterial pressure and the hydrostatic pressure difference.

4. A blood pressure monitor according to claim 1, wherein the heart reference sensor is positioned at the second ends of the fluid columns.

5. A blood pressure monitor according to claim 4, wherein the heart reference unit comprises at least two heart reference sensors, respectively positioned at the second end of the first and the second fluid columns

6. A blood pressure monitor according to claim 1, wherein the second ends of the first fluid column and the second fluid column are positioned at a corresponding elevation.

7. A blood pressure monitor according to claim 1, wherein the second ends of the first fluid column and the second fluid column are connected through a connector housing.

8. A blood pressure monitor according to claim 7, wherein the connector housing houses the at least one heart reference sensor.

9. A blood pressure monitor according to claim 1, wherein the at least one heart reference sensor is a bidirectional differential pressure sensor configured sense a difference in pressures prevailing in the first fluid column and the second fluid column

10. A blood pressure monitor according to claim 9, wherein second ends of the first fluid column and second fluid column are mutually connected with the differential pressure sensor interposed between them.

11. A blood pressure monitor according to claim 1, wherein each of the first and second fluid columns is in communication with at least one expansion bladder, which expansion bladder is configured to compensate for non-hydrostatic pressure components.

12. A blood pressure monitor according to claim 11, wherein at least one expansion bladder is attached to the first end of each of the first and second fluid columns.

13. A blood pressure monitor according to claim 11, wherein each of the fluid columns and the at least one bladder in communication therewith form a gastight system that is closed off from its surrounding environment.

14. A blood pressure monitor to claim 1, wherein the at least one heart reference sensor is configured to register both positive and negative pressure differences between the first and second ends of the fluid columns.

15. A blood pressure monitor according to claim 1, wherein the fluid columns comprise fluid-filled flexible tubes.

16. A blood pressure monitor according to claim 1, wherein the fluid in each of the fluid columns has the same density.

17. A blood pressure monitor according to claim 16, wherein the density of the fluid contained in the fluid columns is substantially equal to the density of human blood.

18. A heart reference unit for use with a blood pressure monitor including a blood pressure sensor, the heart reference unit comprising: a first fluid column with a first end positionable at a level of the blood pressure sensor, a second fluid column with a first end positionable at a reference level, and at least one heart reference sensor configured to sense pressures prevailing in the first fluid column and the second fluid column, wherein a second end of the first fluid column and a second end of the second fluid column, each at an end of its respective fluid column opposite the corresponding first end of each said fluid column, are configured for positioning at a predetermined elevation relative to each other.

Description

DESCRIPTION OF THE DRAWINGS

[0020] The invention will now be elucidated into more detail with reference to a non-limitative exemplary embodiments shown in the following figures, wherein:

[0021] FIG. 1 shows a perspective view of a blood pressure monitor according to the invention, and

[0022] FIG. 2 shows a schematic view of another blood pressure monitor according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0023] In FIG. 1, a blood pressure monitor (1) is shown, comprising a blood pressure sensor (2) and a heart reference unit (3). The blood pressure sensor (2) comprises two pressure cuffs (4), placed around a body extremity, in the depicted case a finger (5). The blood pressure sensor (2) further comprises a pressure controller (6) for controlling the pressure in the pressure cuffs (4), which pressure cuffs are connected to the pressure controller (6) by means of fluid lines (7). The pressure controller (6) is connectable to a power source through a power cable (8), which power cable may double as a data cable for the transfer of measurement data to a data processor and/or display device. The pressure cuffs (4) exert a pressure on the blood vessel walls in the body extremity, which pressure is controlled based on the signal of a plethysmograph build into the pressure cuffs (4). Although the blood pressure sensor (2) employs two pressure cuffs (4) that allow alternate measurements between two fingers (5), the use of a blood pressure sensor using a single cuff is likewise possible. The cuff pressure is controlled such that the signal of the plethysmograph, which is a measure of the volume of blood inside the blood vessels under the cuff, is kept constant. The counter pressure exerted by the pressure cuff (4) is then a direct measure for the actual blood pressure inside the blood vessel. This method is commonly applied for performing a continuous non-invasive blood pressure measurements, for which the blood pressure monitor (1) according to the invention is eminently suited. The invention however also includes blood pressure monitors utilizing different types of blood pressure sensors that for example use auscultatory or oscillometric methods for deriving blood pressures. Furthermore, the blood pressure sensor could be suited to be positioned at different locations on the body, such as a wrist or an upper arm, without deviating from the scope of the invention. The heart reference unit (3) comprises a first fluid column (9) with a first end (10) positioned at blood pressure sensor level and a second fluid column (11) with a first end (12) positioned at heart level. The fluid columns (9, 11) are formed by flexible, fluid-filled tubes, which at their first ends (10, 12) are connected to separate expansion bladders (13). The position of these expansion bladders (13) may however be chosen differently based on a preferred layout of the blood pressure monitor (1) and the heart reference unit (3) in particular. The second ends (14, 15) of the fluid columns (9, 11) opposing the first ends (10, 12) of said fluid columns (9, 11) are connected through a connector housing (16). This connector housing (16) houses a heart reference sensor (not shown) for sensing the hydrostatic pressure exerted by the first and second fluid column. The connector housing (16) further houses a differential pressure transducer (not shown) for determining a hydrostatic pressure difference between the first fluid column (9) and the second fluid column (11). The connector housing is connectable to a power source and/or a data processor by means of a (combined) power/data cable (17). The connector housing (16) may also comprise a wireless transmitter, for transmitted data and/or comprise its own power, for instance in the form of a battery.

[0024] FIG. 2 shows a schematic view of another blood pressure monitor (20) according to the invention. The blood pressure monitor (20) again comprises a blood pressure sensor (21) comprising a pressure cuff (22), via a fluid line (23) connected to a pressure controller (24). Pressure readings from the pressure controller (24) can be relayed to a processor (25) via a data cable (26). The blood pressure monitor further comprises a heart reference unit (27) comprising a first fluid column (28) and a second fluid column (29). The first end (30) of the first fluid column (28) and the first end (31) of the second fluid column (29) are respectively positioned at blood pressure measurement level (32) and at heart level (33). The fluid columns (28, 29) are at their first ends (30, 31) provided with a expansion bladder (34, 35). On the second ends (36, 37) of the fluid columns, heart reference sensors (38, 39) are provided for respectively sensing the hydrostatic pressure exerted by the first and second fluid columns (28, 29). The heart reference sensors (38, 39) are connected to a differential pressure transducer (40) for determining a hydrostatic pressure difference between the fluid columns (28, 29). The differential pressure transducer (40) is further connected to the processor (25) via a data cable (41). The processor (25) is configured for deriving a central arterial pressure from the peripheral arterial pressure as measured by the blood pressure sensor (21) and the hydrostatic pressure difference determined by the differential pressure transducer (40). The determined central arterial pressure can subsequently be displayed by means of display means (42).

[0025] It will be apparent that the invention is not limited to the exemplary embodiments shown and described here, but that within the scope of the appended claims numerous variants are possible which will be self-evident to the skilled person in this field.