RU2231285C1 - Device for selecting and recognizing korotkoff tones - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: device has phonendoscope head, acoustic chamber of which is connected to soundproof shell via flexible tube. The soundproof shell is protected with microphone from external noise. The microphone is connected to acoustic chamber with 10-100 mm long flexible tube.

EFFECT: high level of noise immunity; high accuracy and reliability in measuring arterial blood pressure.

1 dwg

Description

The invention relates to medical equipment and is intended to isolate and convert Korotkov tones into an electrical signal, and can be used in devices for measuring blood pressure and in devices for listening and recording sounds of the heart and lungs.

A device for isolating and converting Korotkov's tones [1], a prototype that contains a cup-shaped element having a rim and a base, an acoustic diaphragm (membrane) mounted on top of the rim of the cup-shaped element, a miniature microphone that forms electrical signals is installed in the center of the base of the cup-shaped element.

This device (prototype) is sensitive to relative displacements and to ambient noise and does not allow to reliably distinguish Korotkov tones. During blood pressure measurements, the acoustic diaphragm (membrane) is affected by the signal of Korotkov tones, vibrational interference from movement and tremor of the hands, and extraneous noise in the room. Since the microphone is located in the center of the base of the cup-shaped element, it perceives and amplifies all these signals.

These shortcomings with a large amplification of the electric signal (if the signal of the Korotkov tones is comparable with the noise level) practically leads to overloading of the amplifying and recording path of the equipment or to the appearance of unpleasant, deafening sounds in the headphones of the phonendoscope. In addition, the high sensitivity of the microphone located in the center of the cup-shaped element during loud-speaking reproduction of the studied sounds causes self-excitation of the entire electro-acoustic path.

The aim of the invention is to improve the accuracy of measuring blood pressure by increasing the reliability of the allocation of Korotkov tones by reducing the influence of vibrational noise and increasing the signal-to-noise ratio.

This goal is achieved due to the fact that in the proposed device for the selection and conversion of Korotkov tones, the microphone is moved outside the head of the phonendoscope, enclosed in a soundproof shell that protects it from external noise and is connected to the acoustic chamber of the phonendoscope using an elastic tube, the length of the elastic tube between the microphone inlet and the phonendoscope head outlet is less than 100 mm. This can significantly reduce the effect of noise and increase the signal-to-noise ratio.

Thus, the implementation of the device for highlighting and converting Korotkov tones, in which the microphone is placed outside the phonendoscope head, is enclosed in a soundproof shell that protects it from external noise and is connected to the phonendoscope acoustic chamber using an elastic tube, is new and this solution meets the criterion " novelty".

The above set of distinguishing features is unknown from the prior art at the moment and does not follow from the well-known rules for designing a device for highlighting and converting Korotkov tones, and this proves compliance with the criterion of "inventive step".

The constructive implementation of the device for the selection and conversion of Korotkov tones with the specified set of essential features does not represent any structural, technical, technological and implementation difficulties, which allows us to conclude that the criterion of "industrial applicability" is met.

The drawing shows a General view of the device for the selection and conversion of Korotkov tones and a sectional view along AA.

A device for isolating and converting Korotkov tones comprises a phonendoscope head 1, a membrane 2, an elastic tube 3, a microphone 4, a sleeve 5, a soundproof shell 6, a sealing sleeve 7, a plasticizer 8, a signal wire 9.

The device operates as follows.

A device for isolating and converting Korotkov tones is installed, for example, over an artery in the patient's elbow cavity. Sound vibrations are perceived by the sensitive membrane 2 and transmitted through the airspace of the acoustic chamber of the phonendoscope head 1 and elastic tube 3 to the microphone 4, which converts their amplitude and shape into an electrical signal.

Since the microphone is isolated: firstly, it is enclosed in a soundproof shell that protects it from external noise, and secondly, there is no direct contact of the microphone body with the walls of the phonendoscope head through which vibrational noise can be transmitted, and is located at some distance from it, then signals with reduced vibrational noise will be perceived due to the fact that the elastic tube (the length of the elastic tube is optimally selected) effectively dampens low-frequency vibrations, for example, from hand tremors, transmitted to the body of the phonendoscope head. This design allows you to:

- increase the stability of the conversion characteristics;

- increase the accuracy and resolution of the device;

- increase noise immunity;

- achieve an increase in signal to noise ratio;

- calculate blood pressure based on a more reliable selection of Korotkov’s tones.

1. Pat. USA No. 5406953, 04/18/95, A 61 V 5/0225 (MKI6).

Claims (1)

A device for isolating and converting Korotkov tones containing a phonendoscope head made in the form of a cup-shaped element with a base and a rim having an acoustic chamber and a sensitive membrane, and a microphone connected to an electronic signal amplifier, characterized in that the microphone is placed outside the phonendoscope head into a soundproof shell and is connected to the phonendoscope acoustic chamber with an elastic tube, the length of which is 10-100 mm.