US-12616385-B2 - Fluid circuit and blood pressure measurement device

US12616385B2US 12616385 B2US12616385 B2US 12616385B2US-12616385-B2

Abstract

A fluid circuit of a blood pressure measurement device includes a first cuff connected to a secondary side of a pump that supplies a fluid to a secondary side, a second cuff connected to a secondary side of the first cuff, a first valve provided between the first cuff and the second cuff, the first valve that closes when a differential pressure between the first cuff and the second cuff reaches a predetermined differential pressure, and a fluid resistor provided between the first valve and the second cuff.

Inventors

Yuki Takano
Yoshihide Tokko

Assignees

OMRON HEALTHCARE CO., LTD.

Dates

Publication Date: 20260505
Application Date: 20220909
Priority Date: 20200316

Claims (5)

1 . A fluid circuit, comprising: a first cuff connected to a secondary side of a pump that supplied a fluid to said secondary side of the pump; a second cuff connected in series to a secondary side of the first cuff, such that fluid flows sequentially from the pump to the first cuff, then to the first valve, then to a fluid resistor, and then to the second cuff.
2 . The fluid circuit according to claim 1 , comprising a second valve provided in parallel with the first valve and the fluid resistor, the second valve opening when a pressure of the first cuff is lower than a pressure of the second cuff.
3 . A blood pressure measurement device, comprising: the fluid circuit according to claim 1 ; an on-off valve provided between the pump and the first cuff, the on-off valve opening and closing a flow path to an atmosphere; a pressure sensor connected to the second cuff; and a control unit that controls the pump and the on-off valve based on a pressure detected by the pressure sensor.
4 . The blood pressure measurement device according to claim 3 , comprising a device body that houses the pump, the on-off valve, the pressure sensor, and the control unit, wherein the first valve and the fluid resistor are integrally provided with the first cuff.
5 . A blood pressure measurement device, comprising: the fluid circuit according to claim 2 ; an on-off valve provided between the pump and the first cuff, the on-off valve opening and closing a flow path to an atmosphere; a pressure sensor connected to the second cuff, and a control unit that controls the pump and the on-off valve based on a pressure detected by the pressure sensor.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is the U.S. national stage application filed pursuant to 35 U.S.C. 365(c) and 120 as a continuation of International Patent Application No. PCT/JP2021/005505, filed Feb. 15, 2021, which application claims priority to Japanese Patent Application No. 2020-045403, filed Mar. 16, 2020, which applications are incorporated herein by reference in their entireties. TECHNICAL FIELD The present invention relates to a fluid circuit and a blood pressure measurement device used for blood pressure measurement. BACKGROUND ART In recent years, blood pressure measurement devices used for measuring a blood pressure are being used as means to check health status at home, as well as in medical facilities. A blood pressure measurement device detects vibration of the artery wall to measure blood pressure by, for example, inflating and contracting a cuff wrapped around the upper arm or the wrist of a living body and detecting the pressure of the cuff using a pressure sensor. As such a blood pressure measurement device, there is known a technique that the blood pressure measurement device includes a sensing cuff for measuring a blood pressure and a plurality of cuffs including a pressing cuff that presses the sensing cuff against a living body. The blood pressure measurement device includes a pump and supplies a fluid, for example, air to the cuff by the pump to inflate the cuff. For example, JP 2009-22477 A discloses a technique of the blood pressure measurement device that disposes an orifice as a fluid resistor between a pressing cuff and a sensing cuff and includes a fluid circuit that reduces an amount of air injection. In such a blood pressure measurement device, a flow rate changes in proportion to a pressure difference between the pressing cuff on a primary side of the orifice and the sensing cuff on a secondary side of the orifice. Citation List—Patent Literature: Japanese Patent Application No.: JP 2009-22477 A. SUMMARY OF INVENTION Technical Problem In the blood pressure measurement device described above, the flow rate of air supplied from a pump changes in proportion to the pressure difference between the pressing cuff on the primary side of the orifice and the sensing cuff on the secondary side of the orifice. Therefore, a change in pressurizing time of a living body during blood pressure measurement changes an amount of air inflow to the sensing cuff, causing an error in the amount of air injection to the sensing cuff. Similarly, in a configuration including three or more cuffs, providing a fluid resistor, such as an orifice, between the cuff on the primary side and the cuff on the secondary side changes the amount of air inflow to the cuff on the secondary side. In addition, the pressurization time of the living body during blood pressure measurement changes depending on, for example, a thickness of a measurement site of a subject, a state of winding of an arm band, and a pump property. Further, the amount of air injection supplied to the sensing cuff needs to be smaller than an amount of intake air supplied to the pressing cuff. Therefore, as the orifice provided between the pressing cuff and the sensing cuff, an orifice having a large fluid resistance needs to be used. Such an orifice requires a fine pinhole and requires expensive and highly accurate processing technique. Thus, an object of the present invention is to provide a fluid circuit and a blood pressure measurement device that allow controlling an amount of air injection to a cuff to be constant. Solution to Problem According to an aspect, there is provided a fluid circuit that includes a first cuff, a second cuff, a first valve, and a fluid resistor. The first cuff is connected to a secondary side of a pump that supplies a fluid to a secondary side. The second cuff is connected to a secondary side of the first cuff. The first valve is provided between the first cuff and the second cuff. The first valve closes when a differential pressure between the first cuff and the second cuff reaches a predetermined differential pressure. The fluid resistor is provided on a secondary side of the first valve between the first valve and the second cuff. Here, the fluid includes a liquid and air. The cuff includes a bag-like structure that is wound around, for example, an upper arm and a wrist of a living body when a blood pressure is measured and inflates by supply of a fluid. When the fluid is air, the bag-like structure is an air bag inflated by, for example, air. According to this aspect, the fluid supplied to the secondary side by the pump is supplied to the first cuff, passes through the fluid resistor, and is supplied to the second cuff, and thus a flow rate of air supplied to the second cuff is smaller than a flow rate of air supplied to the first cuff. Therefore, a pressure of the first cuff is larger than a pressure of the second cuff. Further, when the differential pressure between the first cuff and t