RU67424U1 - PORTABLE APPNO EPISODE REGISTRATION DEVICE - Google Patents

Abstract

The device relates to medicine, in particular to pulmonology, and can be used for inpatient treatment for continuous or occasional monitoring of breathing, ambulance personnel during transportation of patients who are threatened with apnea, at home when caring for and monitoring patients. The device for recording episodes of apnea is distinguished by the use of a sensor element included in the bridge circuit of a thermistor that responds to changes in the temperature of the inhaled and exhaled air. Use a replaceable nozzle of the sensor, which is a nasal cannula with a tube for air flow during exhalation / inhalation through the mouth and a hole for air from the environment. The sensor is installed over the upper lip of the patient with. The main unit of the apparatus for registering apnea is decorated in a plastic case measuring 5 × 4 × 2 cm. It is attached to the patient’s forehead with a rubber strap equipped with Velcro straps for reliable fixation around the head.

Description

The device relates to medicine, in particular to pulmonology, and can be used for inpatient treatment for continuous or occasional monitoring of breathing, ambulance personnel during transportation of patients who are threatened with apnea, at home when caring for and monitoring patients.

The most common diagnostic method for obstructive apnea is polysomnography — a method for the long-term recording of various functions of the human body during night sleep (Pat RU No. 2197893 “Method for the diagnosis and correction of respiratory disorders during sleep” Babak SL, Brusov AV, 2000 .). Based on the results of the questionnaire and somnological registration, taking into account the previously established basic symptoms-markers of the disease and boundary values of the significance of polymnographic indicators, the symptoms are graded and the somnographic parameters are verified, the severity of the respiratory disorder is determined, and therapeutic, dental or surgical correction is carried out depending on the latter, and in case of extreme severe course of the disease - non-invasive ventilation of the lungs. Assessment of the severity of the disease and the volume of surgical and / or dental exposure is performed stepwise, changing the amount of exposure according to the level of the treatment level. The method involves determining the criteria for the appropriateness of the appointment and evaluating the effectiveness of non-invasive ventilation, surgical treatment, dental correction.

Polysomnography methods allow you to show the presence or absence of sleep apnea syndrome.

Known respiratory sensor on piezoelectrics (US Pat. RU No. 2218082 "Respiratory sensor Bakusova LM"), used to control respiration parameters in normal and pathological conditions. The sensor contains a sensing element connected through electrical contacts to the recorder. The sensitive element is a thin piezoelectric plate with metal electrodes deposited on its surface, at least one of the electrodes is made in the form of a deposited thin film, and the electrodes are made of dissimilar

conductive materials with different coefficients of thermal expansion.

Due to the implementation of the electrode with a thin-film and piezoceramic plate in the form of a thin layer with a thickness of not more than 0.1 mm, their heating and cooling takes place in a short time, significantly less than the respiratory cycle. As a result of this, the inertia of the sensitive element is small and practically does not affect the accuracy of registration of the respiration process.

A sensor for measuring the temperature of exhaled air (AC SU No. 974998 "Agarkov sensor for measuring the temperature of exhaled air", 1982).

The sensor is used in the apparatus for studying the function of external respiration, it allows carrying out functional-load pneumatic tests with expiration of cold and hot air in order to identify hidden forms of insufficiency of the conditioning function of the respiratory apparatus and thereby improves the quality of functional diagnostics.

The sensor contains a thermocouple, a thermoprotective chamber, a moisture protective mesh, a housing with a groove for teeth and a valve. To measure the temperature of exhaled air, the sensor is placed in the oral cavity and fixed with teeth at the location of the groove. Next, measure the temperature of the exhaled air at the end of the maximum exhalation.

The method of printing in a dream is time-consuming, requires expensive large-sized equipment and appropriate conditions for implementation.

Much attention is being paid to the importance of simplifying polysomnography, given the widespread prevalence of obstructive sleep apnea, when treatment is predominantly home-based and when patients themselves must monitor the effectiveness of therapy and protect themselves from sudden death in a dream.

Compact monitors are becoming increasingly common. These devices monitor various parameters during sleep (for example, respiratory efforts and their resulting air flow, pulse rate and oxygen saturation of the blood, the amount of continuous positive nasal pressure and body position). Domestic devices of this kind are unknown.

Existing breathing sensors have the following disadvantages:

the design does not allow their use for a long time due to skin irritation, noticeable marks on the skin, disturbances to the sleeping person;

- may be applicable only to devices and apparatus for treatment and examination in a hospital;

- used only in the structure of large non-portable devices;

- work from a network.

The purpose of creating a utility model is the development of a portable apparatus for registering apnea.

The device being developed was to provide quick and accurate recording of episodes of respiratory arrest, the sensor should be convenient and should not interfere with the sleeping person, should be easy to put on and take off, not irritate the skin, and not leave noticeable marks after itself even with regular and prolonged use.

The device is fixed on the patient's head, while the sensor should be above his upper lip.

When inhaling, external relatively cold air enters the sensor through a special side hole in the interchangeable nozzle, and enters the patient's respiratory tract. When exhaling, the movement of air heated in the respiratory tract occurs in the opposite direction.

The exhaled air heats the thermistor, which is in the path of air flow. In this case, the bridge is unbalanced, the unbalance signal is amplified by the operational amplifier. Inhaled air cools the thermistor, its resistance increases. The polarity of the bridge unbalance signal is reversed. After amplification, the signal is fed to the input of a comparator built into the microcontroller. The comparator compares the input signal with a threshold, the voltage of which is almost equal to zero. When the input signal voltage is less than or equal to the threshold, the timer-counter of the microcontroller monitors the duration of the absence of the input signal. If the input signal does not exceed the threshold for 10 seconds, the timer-counter generates a signal to the output of the microcontroller responsible for the sound signal, this indicates an episode of apnea.

During apnea, the temperature of the thermistor remains constant, there is no change in the temperature of the air surrounding the thermistor. When breathing stops for more than 10 seconds, an audible signal sounds that warns of the dangers of apnea and causes either awakening of the sleeping person or emergency measures by medical personnel to restore the patient's breathing.

We used a thermistor as a sensitive element of the sensor, included in the bridge circuit, which reacts to changes in the temperature of the inhaled and exhaled air.

The bridge circuit shown in FIG. 1 can be used for thermistors with R ₃ = R _t and with resistance R4 equal to the resistance of the thermistor in the middle of the measured temperature range.

In the developed device for registering apnea, the sensor is a S861 vitrified bead thermistor manufactured by SIEMENS & MATSUSHITA. It is a miniature sensor for precision temperature measurements and medical technology with nickel-insulated fluoroplastics.

To convert the resistance of the thermistor to voltage, which is then fed to the ADC of the controller, a bridge circuit with a thermistor is used. Since the thermistor is remote from the main unit of the device (from the amplifier and power source), to eliminate the influence of the connecting wires, the bridge circuit of the converter shown in FIG. 2 is used. In this scheme, the influence of the resistance of the connecting wires R _p1 , R _p2 , R _p3 and the initial resistance of the sensor are compensated.

A

At point A of the bridge circuit, a reference voltage E _op is supplied (using a follower to OS1). At the same time, voltage is maintained at point B using OS2

B

as a result, the potential of point B is equal to zero. The transfer function for this circuit has the form

(T)

B

It follows that the resistance of the wires R _p1 -R _p4 do not affect the conversion result. To exclude resistance R _p5 at the output of the Converter, you can turn on the voltage follower. In this scheme, the thermistor can be included in any shoulder of the bridge, however, the transfer function will be linear only with respect to the shoulder R ₂ .

This scheme should ensure the fulfillment of two conditions:

the current flowing through the sensor should not exceed 0.1 A; the output voltage level should correspond to the input level of the ADC.

To increase the differential voltage of the unbalance of the bridge to the level of the ADC input signal, the OPA643U operational amplifier is used, designed for use with the ADC. The main criteria for his choice were high performance and a low level of internal noise.

We suggest using a replaceable nozzle of the sensor, which is a nasal cannula with a tube for air flow during exhalation / inhalation through the mouth and a hole for air from the environment. The sensor is mounted above the patient’s upper lip.

As a basis for the manufacture of a replaceable sensor nozzle, you can take, for example, a nasal cannula from APEXMED (Figure 3). It is intended for single use, made of non-toxic polyvinyl chloride, has straight thermoplastic nose teeth, the edges of the cannula are smooth rounded.

The thermistor is fixed at the end of a flexible hollow tube coming from the main unit of the device. The thermistor wires connecting it to the conversion unit are insulated inside this tube. The replaceable nozzle is fixed by means of a clamp with a tube, at the end of which a thermistor is fixed, which measures the temperature of the inhaled and exhaled air.

The main unit of the apparatus for registering apnea is decorated in a plastic case with a size of not more than 5 × 4 × 2 cm. It is attached to the patient’s forehead with a rubber strap equipped with Velcro for reliable fixation around the head (Figure 4).

For the device, you can use the case for handheld devices of the ERW-CASE series from OKW.

Claims (6)

1. Apparatus for recording episodes of apnea, characterized in that as a sensitive element of the sensor include a thermistor in the bridge circuit, responding to changes in temperature of the inhaled and exhaled air. 2. The device according to claim 1, characterized in that they use a replaceable nozzle of the sensor, which is a nasal cannula with a tube for air flow during exhalation / inhalation through the mouth and an opening for air from the environment. 3. The device according to claim 2, characterized in that the sensor is installed above the upper lip of the patient. 4. The device according to claim 1, characterized in that the replaceable nozzle is fixed using a clamp with a tube, at the end of which a thermistor is fixed. 5. The device according to claim 1, characterized in that the main unit of the apparatus for registering apnea is decorated in a plastic case measuring no more than 5 × 4 × 2 cm. 6. The device according to claim 1, characterized in that the device is mounted on the forehead of the patient using a rubber strap equipped with Velcro for reliable fixation around the head.