RU2372947C1 - Narcosis block - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: narcosis block comprises a gas-flow stabilised low-resistance anaesthetic mini-evaporator, a breathing circuit with connectors for fresh gas mixture and tapered connectors for the evaporator, inhaled and exhaled gas mixture, inspiration and expiration hoses. An anaesthetic feed accelerator comprises a two-position two-contact switchboard connectable in introduced narcosis of the input of the evaporator to the socket for inhaled gas mixture, and its output - with the inspiration hose, and in narcosis maintenance - connecting the input of the evaporator with the connector for fresh gas mixture, and its output - with the breathing circuit. The anaesthetic feed accelerator is provided with a timer for sound and/or light signalling of termination of preset duration of introduced narcosis equipped with an actuating unit that switches between introduced narcosis and maintenance modes of the switchboard, and also standardised in introduced narcosis relative to maintenance of inhaled concentration, anaesthetic feed rate and time constant. The increase factor of inhaled concentration and anaesthetic feed rate is proportional to the relation of minute ventilation to fresh gas flow. The decrease factor of time constant is proportional to the relation of inspiration hose capacity to breathing circuit capacity, and gas flow to minute ventilation.

EFFECT: higher rate of anaesthesia management and improved anaesthesia safety.

3 cl, 2 dwg

Description

The invention relates to medical equipment, namely to equipment for inhalation anesthesia (IN).

The problem with most modern IN devices (Drager, Penlon, Ohmeda) equipped with precision evaporators outside the respiratory circuit (VOC) is the extremely slow regulation of respirable concentration using economical and environmentally friendly low-flow anesthesia (NPA) [Watney G. In - and out of circuit vaporizers. Anesthesia Equipment Resources ASE 2007. www.asevet.com/resources/circuits/circle.htm]. As a result, “the concentration inhaled by the patient is not determined on the evaporator scale until it stabilizes, which lasts for tens of minutes at low fresh gas flows (stabilization time is proportional to the volume of the respiratory circuit, including the patient’s lung volume, and inversely proportional to the difference between the intake and absorption of anesthetic vapor). Then the low fresh gas flow required for semi-closed and closed systems makes them impractical. ”

With a minimum oxygen flow rate of 250 ml / min, “this anesthetic delivery technique reaches its limit ... the absorption of isoflurane (and especially enflurane or halotane) by an adult exceeds its maximum flow to the respiratory circuit” [Baum JA. Low Flow Anesthesia. Drager 2004].

Anesthetic delivery rate can be increased by sequentially installing the evaporators outside the loop [Otero PE, Rebuelto M, Hallu RE, Aldrete JA. Increasing anesthetic concentration without modifying FGF by serial connection of vaporizers. ALFA 2003; 1-7]. When using 4 evaporators with a maximum mark of 5% sevoflurane, the result will be 16.1 vol.% Or 48 cm ³ / min of vapors of sevoflurane with a fresh gas flow of 250 ml / min. However, for clinical practice, the latter method is hardly acceptable due to the cumbersome and inconvenience of controlling 4 evaporators.

On the other hand, simple but unstable draw-over vaporizers (such as OMV, Goldman), installed inside a half-closed breathing circuit (VIC), allow you to quickly change the inhaled concentration even with minimal gas flow [Watney G. In- and out of circuit vaporizers]. In this case, the flow rate of the anesthetic into the circuit is proportional to minute ventilation and does not depend on fresh gas flow. However, the instability of draw-over evaporators leads to unpredictable changes in respirable concentration, which is extremely dangerous when using modern powerful halogen-containing anesthetics. So, the concentration of anesthetic monotonically increases with each respiratory cycle when a part of the gas exhaled by the patient passes through the vaporizer again and can instantly jump due to the instability of the latter (for example, with a sharp deepening of the breath). Therefore, draw-over anesthesia is still limited to veterinary medicine, district hospitals, hard-to-reach regions, emergency situations and military field conditions.

The present invention provides adequate inhalation anesthesia in a hospital, emergency situations and on an outpatient basis when using low-resistance evaporators stabilized by flow and temperature, such as MINIVAP [RF application No. 2006128439/14 (030886) dated 08/08/2006 “Anesthetics vaporizer”, solution on the grant of a patent on September 12, 2007] and portable “Hummingbird” devices built on their basis [operating manual 9444-17276657.001-06 RE, 2006].

The solution to this problem is achieved thanks to a combination of new and well-known technical solutions implemented in the patented invention.

Anesthetic block [operating manual 9444-17276657.001-06 OM Portable IN “Hummingbird” devices], containing a gas-stabilized mini-evaporator of low resistance anesthetic, breathing circuit with connectors for the fresh gas mixture and conical connectors for the evaporator inhaled and exhaled gas mixtures, inhalation and exhalation hoses, in accordance with the present invention, is equipped with an anesthetic feed accelerator made in the form of a two-position two-contact switch connecting the inlet a ventilator with a connector for the inhaled gas mixture, and its outlet with an inhalation hose; in the anesthesia maintenance mode, the evaporator inlet is connected to the fresh gas mixture connector, and its outlet is with the breathing circuit.

The accelerator is equipped with a timer that signals through the sound and / or light signal about the completion of a given duration of induction of anesthesia. The timer can be equipped with an actuator that transfers the switch from the induction anesthesia mode to the maintenance mode.

The invention provides for equipping the evaporator with a bypass with a check valve that opens when the permissible differential pressure is exceeded.

According to the invention, the conical sockets of the connectors for the evaporator and the inhaled gas mixture are placed in the switch housing orthogonally to each other and are equipped with clamps.

In all cases, the accelerator is normalized in the mode of induction of anesthesia relative to the regime of maintaining respirable concentration, anesthetic feed rate and time constant, while the coefficient of increase in respirable concentration and anesthetic feed rate is proportional to the ratio of minute ventilation to fresh gas flow, and the reduction constant of the time constant is proportional to the ratio of the hose volume inspiration to the volume of the respiratory circuit and gas flow to minute ventilation.

The technical result of the patented invention is as follows:

- increases the speed and effectiveness of the management of anesthesia during surgical operations;

- increases the safety of the NPA due to:

- - the ability to assess the respirable concentration of anesthetic on the evaporator scale, not only in a stable mode, but also with induction of anesthesia, even in the absence of a scarce and expensive gas analyzer of anesthetics;

- - the time limit of the regimen of induction anesthesia or emergency deepening by means of signaling and automation;

- - eliminating the possibility of dropping drops of liquid anesthetic from the evaporation chamber during an emergency supply of fresh gas mixture or increasing minute ventilation;

- the scope of application of the new anesthesia block is expanding significantly due to compatibility with any existing mechanical ventilation apparatus (IVL) and IN through standard ISO conical connections;

- reduced operating room air pollution by reducing the release of vapors of anesthetics, including halogen-containing;

- saves the use of expensive anesthetics, as well as medical gases;

- provides the ability to work with low-pressure sources of oxygen (for example, adsorption or membrane) through the use of a low resistance evaporator.

The invention is illustrated by drawings, which represent the following.

Figure 1 - Schematic diagram of the anesthesia block.

Figure 2 - Installation of anesthesia block on a standard horizontal ISO fitting for inhalation of the ventilator or ID.

An anesthetic block containing a low-resistance mini-evaporator 1 (Fig. 1) of low resistance stabilized by gas flow and temperature, a breathing circuit 2, including an adsorber 3 and a ventilator 4, with connectors for fresh 5 gas mixture from dosimeter 6 and conical connectors for evaporator 1 inhaled 7 and exhaled 8 gas mixture, inhalation hoses 9 and exhalation 10 for connection with the patient 11. The anesthetic block is equipped with an anesthetic feed accelerator made in the form of a two-position two-contact switch 12 connecting (see the dashed bold line) in the IV mode narcosis-stand inlet 13 of the evaporator 1 with the connector 7 to the inspired gas mixture, and its output 14 - with inhalation hose 9 (evaporator 1 within a breathing circuit - Status In). In the mode of maintaining anesthesia, the input 13 of the evaporator 1 is connected (see the solid bold line) with the connector 15 of the dosimeter 6, and its output 14 (figure 2) is connected to the connector 5 of the breathing circuit 2 (the evaporator 1 outside the breathing circuit is the Out position).

The anesthesia block accelerator is equipped with a timer 16, which signals through the sound and / or light signal about the completion of a given duration of induction of anesthesia.

In one embodiment, the timer 16 is equipped with an actuator 17 that automatically switches the switch 12 from the mode of induction of anesthesia (position In) to the maintenance mode (position Out).

The evaporator is equipped with a bypass 18 with a spring-loaded check valve 19, which opens when the permissible differential pressure is exceeded (for example, 300 Pa is an adjustable value).

In a portable design, the cone sockets of the connectors for the evaporator 1 and the inhaled gas mixture 7 are placed (see Fig. 2) in the switch housing 12 orthogonally to each other and are equipped with a latch 18 (for example, in the form of an annular clip around the base of the connector 7) and the latch the latch 19. The latch 19 provides a horizontal arrangement of the evaporator 1 both with horizontal and vertical (not shown) orientation of the connector 7 of the inhaled gas mixture. In the latter case, the switch 12 is rotated 90 ° counterclockwise around the axis of the evaporator 1 shown in figure 2, respectively, the evaporator 1 is rotated around its axis clockwise also 90 ° and is fixed in the new position by the latch 19.

The accelerator is normalized (table in figure 2) in the mode of induction of anesthesia relative to the maintenance mode for respirable concentration, anesthetic delivery rate and time constant. In this case, the coefficient of increase in respirable concentration and anesthetic supply rate is proportional to the ratio of minute ventilation to fresh gas flow MV / G _{K + Z} , and the coefficient of decrease in the time constant is proportional to the ratio of the volume of the inhalation hose to the volume of the respiratory circuit and gas flow to minute ventilation V _W G _{K + Z} / V _to MB.

Anesthesia block works as follows.

Insert the fitting tightly into the socket of the connector 7 of the inhaled mixture and fix the switch 12 and the evaporator 1 by means of the latches 18 and 19, respectively. A dosimeter 6 (through connector 15) and a breathing circuit 2 (through connector 5), as well as a inhalation hose 9, are connected to switch 12. Set switch 12 to the In position (evaporator 1 inside the loop, concentration scale at zero). Turn on the supply of oxygen and nitrous oxide in the required ratio with the total flow rate exceeding the minute ventilation of the patient during spontaneous breathing, and connect the patient 11 to the anesthesia unit. On timer 16, set the approximate duration of induction of anesthesia (usually 2-3 minutes), turn on the evaporator scale 1 and gradually (within half a minute) increase the respirable concentration of anesthetic to 2-3 MAK (minimum alveolar concentration), guided by the evaporator scale 1 or the tabular ratio to switchboard panels 12 (C _I ≈С _Ш MV / Г _{К + З} ). In this case, with fresh gas flow greater than or equal to minute ventilation, the inhaled concentration of anesthetic is equal to the concentration on the evaporator scale (C _I ≈ С _Ш ). Moreover, the stabilization time of the respirable concentration from the moment of switching the scale of the evaporator 1 is only a few seconds (≈V _W / MB). Upon reaching the required depth of anesthesia, patient 11 is either intubated and transferred to mechanical ventilation, or left to spontaneously breathe (with short-term interventions, operations on the limbs, etc., with adequate gas exchange parameters). In both cases, the switch 12 is manually or automatically (via mechanism 17) put in the Out position (evaporator 1 outside the breathing circuit 2), so that the inhaled concentration of the anesthetic is aligned with the concentration on the scale of the evaporator 1 (C _I ≈ С _Ш ). In this case, the fresh gas flow is reduced to a low (1-2 l / min) or minimum level (0.5 l / min for an adult patient) according to the NLA technique.

During the operation, which can last several hours, there is a need to urgently deepen anesthesia. In this case, without changing the flow rate of the fresh gas mixture, switch switch 12 to the In position and within a few seconds increase the respirable concentration to a predetermined level in accordance with the table ratio on the switch panel 12 (C _I ≈ СШ MV / Г _{К + З} ).

Example. For a short-term increase in the respirable concentration of sevoflurane from 1 to 2 vol.% In an oxygen-nitrous mixture (1: 2) for an adult patient with minute ventilation MB = 6 l / min and G _{K + 3} = 1 l / min, evaporator scale 1 ( "MINIVAP-20") in the In mode is set to (0.3-0.4) vol.%. In this case, the calculated respirable concentration C ₁ ≈0.35 × 6 = 2.1. An anesthetic gas analyzer connected to the patient’s tee shows 2% vol. Of sevoflurane.

After a short-term deepening of anesthesia, the anesthesia is maintained at the same level (C _I ≈ 1), for which the switch 12 is returned to the Out position, and the scale of the evaporator 1 is returned to the mark С _Ш = 1.

In the case of a sharp increase in minute ventilation, the pressure drop across the evaporator 1 located inside the breathing circuit (In mode) also increases sharply. So, with an average minute ventilation of 6 l / min, the maximum speed in the inspiratory phase of the patient can be 18 l / min and the pressure drop across the evaporator 1 will not exceed 200 Pa. When ventilation is 12 l / min, when the instantaneous speed reaches a value of about 25 l / min, the pressure drop increases to 300 Pa, so that the check valve 19 opens the bypass 18, bypassing the excess gas flow past the evaporator 1.

Quantitative standardization of the main parameters for controlling the depth of anesthesia (respirable concentration, feed rate and time constant characterizing the pharmacokinetics of the anesthetic) helps the anesthetist to implement an adequate pain management strategy during the surgical operation.

In cases of sudden violations of the centralized supply of compressed medical gases (primarily oxygen), the anesthesiologist can use low-pressure oxygen sources (adsorption or membrane, which are part of the standard equipment) and continue adequate inhalation anesthesia during the surgery due to the low resistance of the anesthetic vaporizer (less than 100 Pa at a gas flow rate of 10 l / min).

Thus, the proposed anesthetic block:

- increases the speed and effectiveness of anesthesia management during surgical operations; so, the transition process of stabilization of the respirable concentration is reduced by dozens of times (instead of minutes - seconds), which allows the anesthesiologist to quickly manage the depth of anesthesia without additional administration of intravenous anesthetics;

- increases the safety of anesthesia;

- - the ability to quickly assess the respirable concentration of anesthetic on the evaporator scale, not only in a stable mode, but with induction of anesthesia, even in the absence of a deficient anesthetic gas analyzer;

- - limiting the duration of induction anesthesia or emergency deepening anesthesia;

- - eliminating the possibility of dropping drops of liquid anesthetic from the evaporation chamber with an emergency increase in the supply of fresh gas mixture or minute ventilation of the patient;

- significantly expands the scope of inhalation anesthesia due to compatibility with any existing ventilation and IN devices;

- reduces the pollution of the operating room atmosphere by reducing the release of vapors of anesthetics and increases the savings in their use (together with medical gases) due to the implementation of the NLA methodology at all stages of anesthesia;

- provides the ability to work with low-pressure sources of oxygen (for example, adsorption or membrane) in the absence of sources of compressed gases due to the use of a low resistance evaporator.

Claims (3)

1. Anesthetic block containing a gas-stabilized mini-vaporizer of low resistance anesthetic, a breathing circuit with connectors for a fresh gas mixture and conical connectors for an evaporator, inhaled and exhaled gas mixture, inhalation and exhalation hoses, characterized in that it is equipped with an anesthetic feed accelerator made in the form of a two-position two-contact switch, with the possibility of connecting in the mode of induction anesthesia the input of the evaporator with the connector for the inhaled gas mixture, and its output with a hose and in the anesthesia maintenance mode - with the possibility of connecting the evaporator inlet with the connector for the fresh gas mixture and its outlet with the breathing circuit, while the anesthetic supply accelerator is equipped with a timer for signaling with the sound and / or light signal about the completion of the specified duration of induction anesthesia, equipped with an actuator capable of transferring the switch from the induction anesthesia mode to the maintenance mode, and is also normalized in the induction anesthesia mode relative to the maintenance mode blowhole concentration, feed rate and anesthetic time constant, wherein the magnification factor respirable concentration and feed rate of the anesthetic is proportional to the minute ventilation to fresh gazotoku, and reduce the time constant coefficient is proportional to the inspiratory hose relationship to the volume of the breathing circuit and gazotoka to minute ventilation. 2. Anesthetic block according to claim 1, characterized in that the evaporator is equipped with a bypass with a check valve that opens when the permissible differential pressure is exceeded. 3. Anesthesia block according to claim 1, characterized in that the conical slots of the connectors for the evaporator and the inhaled gas mixture are placed in the switch housing orthogonally to each other and are equipped with clamps.

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