RU2676654C1 - Inhalation anesthesia apparatus - Google Patents

Abstract

FIELD: medicine.SUBSTANCE: invention relates to medical technology, namely to the apparatus of inhalation anesthesia. Device contains an oxygen dosimeter connected to the inlet of a low resistance evaporator connected to a backup bag and an adsorber, an air compressor and a check valve connected in parallel to the inlet of the evaporator and communicated with the atmosphere, breathing indicator and breathing circuit with safety valve, characterized in that the breathing indicator is made in the form of a backup bag of anesthesia adequacy indicator located horizontally on a bracket and equipped with an anesthetic concentration reduction indicator placed on the front of the bag, and an indicator of increasing concentration placed behind the bag on the vertical wall of the bracket.EFFECT: technical result is the expansion of the scope of use of portable devices for inhalation anesthesia and the implementation of cost-effective and environmentally-friendly low-flux anesthesia for various types of animals in virtually any environment.3 cl, 5 dwg

Description

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

The well-known IN devices (Drager, Penlon, Ohmeda) are equipped with high-precision precision evaporators (VOC - evaporators outside the respiratory circuit), multi-function artificial ventilation devices and gas analyzers (monitors) of the composition of the respiratory mixture, and this leads to significant dimensions (weight about 50 kg ) and cost ($ 50,000). They are characterized by slow regulation of the composition of the respiratory mixture (respirable concentration of anesthetic and oxygen) when 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; Baum JA. Low Flow Anesthesia. Drager 2004].

Also known is an anesthetic unit (IN device) containing a dosimeter and an oxygen source connected to the input of a low resistance anesthetic vaporizer connected to a backup bag of the respiratory circuit and equipped with a position switch inside or outside the respiratory circuit [RU patent No. 2372947]. This unit is selected as a prototype.

This rather simple device due to the inclusion of the evaporator inside the respiratory circuit allows you to quickly regulate the respirable concentration of anesthetic and, accordingly, the depth of anesthesia (within 1-2 minutes). The disadvantage of the prototype is the rapid change in the parameters of anesthesia, which must be carried out only under the supervision of a monitor of the composition of the respiratory mixture (concentration of anesthetic), equipped with appropriate signaling devices and limiters of the amount of supplied anesthetic. The cost of such a monitor is 5-10 times higher than the cost of the anesthesia block under consideration, which practically excludes its safe use for an ordinary anesthetist.

This device also does not allow you to adjust the oxygen concentration regardless of its supply by the dosimeter, which greatly complicates the use of economical and environmentally friendly low-flow anesthesia in small hospitals and clinics.

These disadvantages make it difficult to use the known advantages of inhalation anesthesia relative to intravenous (less metabolism and consequently inertia, less trauma and the natural route of administration of drugs with oxygen) and, accordingly, limit its use.

The technical result of the patented invention is as follows:

- the scope of application of portable IN devices is expanding significantly due to compatibility with any existing sources of oxygen (including mini-concentrators) and air (low-power compressors of medical devices, including inhalers); at the same time, a flexible modular system in combination with wide standard sizes of the main units of the device (vaporizer, respiratory circuit and chambers for anesthesia) provides adequate anesthesia for a wide standard size of animals.

- provides the possibility of operational regulation of oxygen concentration during optimal NPA;

- increases the safety and effectiveness of the NPA due to the ability to evaluate and quickly adjust the respirable concentration of anesthetic on the evaporator scale even in the absence of a scarce and expensive gas analyzer of anesthetics;

- 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;

- the mass of the apparatus is reduced due to the minimization of the main blocks and elements (evaporator, dosimeter, adsorber) and the exclusion of metal-intensive case parts for their fastening;

- the presence of a camera in the form of a self-expanding bag with elastic walls, connected to the outlet of the evaporator and the inlet of the adsorber, allows you to use the apparatus for anesthesia of small animals (weighing less than 300 grams) without special devices. The technical result of the invention is achieved by the differences set forth in the claims.

The invention is illustrated by illustrations, which represent:

FIG. 1 is a schematic diagram of an IN device;

FIG. 2 - indicator of the adequacy of anesthesia for spontaneous breathing:

a - with an excessive concentration of anesthetic;

b - with insufficient concentration of anesthetic;

FIG. 3 - anesthesia with an animal apparatus up to 30 kg, a Vega “Samy Kitten” children's inhaler is used as an air compressor;

FIG. 4 - anesthesia by animal apparatus up to 400 kg;

FIG. 5 - chamber for anesthesia of small animals:

a - the induction of sevoflurane mouse in the Ambu chamber 300 ml;

b - maintenance of anesthesia with Ambu bag.

The IN device contains an MINIVAP low resistance evaporator 1, an oxygen dosimeter (rotameter) 2, connected to the inlet of the anesthetic evaporator 1, connected to the backup bag 3 of the breathing circuit, which includes an adsorber 4, a safety valve 5, and inspiration 6 and exhalation valves 7. The apparatus is connected in parallel to the inlet of the evaporator 1 by an air compressor 8 with a rotameter 9 and a check valve 10 connected to the atmosphere, and is equipped with an indicator of the adequacy of anesthesia during spontaneous breathing.

As a compressor 8, a medication inhaler was used, for example, a Vega “Samy Kitten” pediatric inhaler.

The indicator is made in the form of a backup bag 3 of the respiratory circuit, located horizontally on the bracket 11 and equipped with a pointer 12 to reduce the concentration of the anesthetic “LESS C _A ”, located on its front part, and a pointer 13 to increase the concentration of the anesthetic “MORE C _A ”, placed behind the bag on vertical wall 14 of the bracket 11.

The apparatus is equipped with a camera for anesthesia of small animals in the form of a self-expanding bag 15 with elastic walls (Ambu type) and a removable cover 16 connected instead of the patient's tee 17 to the outlet of the evaporator 1 through valve 6 via a plug-in connection 18 and to the input of the adsorber 4 through valve 7 by detachable connection 19; while the small "patient b" is placed inside the bag 15 Ambu.

The device is equipped with a monitor 20 (gas analyzer) of the concentration of anesthetic vapor C _A and oxygen C _O2 .

Depending on the working conditions and anesthesia technique, the IN device can be equipped with low resistance evaporators MINIVAP / 1 (for patients up to 30 kg) and MINIVAP / S (for patients over 200 kg) for various anesthetics (sevoflurane, isoflurane, halotane or enflurane) and different concentration ranges. Also, depending on the size of the small “patients b,” choose a 15Ambu bag volume (300, 600 or 1200 ml).

The mass of the proposed IN device and the volume of its respiratory circuit are minimal due to the minimum sizes of the main components: evaporator 1 (MINIVAP-20/1, weight 400 g), dosimeter 2 (Dwyer mini-rotameter, weight 200 g), compressor 5 (1.5 kg), adsorber 4 (150 g with a volume of 0.6 l), and the absence of massive body parts.

So, the mass of such a Hummingbird device in FIG. 3 about 4 kg together with the compressor, and the volume of the respiratory circuit together with the adsorber and ∅15 mm inhalation and exhalation hoses is about 1.5 l. The volume of the backup bag 3 is selected based on the mass of patients: from 50 ml (mice, small birds) to 5 or more liters (horses).

The mass of the device IN "Hummingbird" in Fig. 4 in a set for large animals (MINIVAP-20 / S vaporizer weighing 1.5 kg, adsorber 4 with a volume of 1.2 l) less than 10 kg.

The device ID works as follows.

After standard preparation and testing of the IN device, oxygen is supplied to the respiratory circuit 4 and the patient is connected to it. Gradually (within half a minute) increase the respirable concentration of anesthetic C _A to 2-3 MAC (minimum alveolar concentration) on a scale of evaporator 1.

After reaching the required depth of anesthesia (the duration of induction for isoflurane is about 5 minutes, for sevoflurane - 2 minutes), the patient is intubated, then spontaneous respiration is restored or transferred to mechanical ventilation (depending on the surgical procedure, anesthesia technique and the patient's condition).

The oxygen consumption by dosimeter 2 is kept low (1-2 l / min for a 60 kg patient) in the first 15 minutes, while the oxygen concentration of C _{O2 is} adjusted to 30 vol. %, after which the dosimeter 9 is opened, the inhaler compressor 8 is turned on, the dosimeter 2 is closed and the air flow rate is set at 2-2.5 l / min. In this case, the amount of bleed gas through the safety valve 5 is set so that at the end of the inhalation the bag does not "stick together", and at the end of the exhalation it does not overflow.

In the phase of maintaining anesthesia, the concentration of the anesthetic C _{A of the} evaporator is set at 1-1.5 MAC, while the readings of the gas analyzer 20 gradually approach the concentration on the scale of the evaporator 1, and the oxygen concentration does not fall below 21 vol. %

With a decrease in the depth of anesthesia or an increase in the degree of surgical exposure, minute ventilation reflexively increases so that after a few breathing cycles, bag 3 is completely empty by the end of the patient’s inspiration and completely opens indicator 13 with a warning inscription on the need to increase the concentration of anesthetic: “MORE C _A ”. At the same time, at the end of the inspiration, the pressure drops abruptly below atmospheric pressure in case of gas deficiency in the respiratory circuit, the check valve 10 opens and the patient inhales additional air that enters the respiratory circuit through evaporator 1. In accordance with the warning “MORE C _A ”, an anesthetist incrementally increases the concentration of anesthetic on the evaporator scale, for example, up to 3 MAC, and after stabilizing breathing returns the concentration of anesthetic to a level of 1.5 MAC in accordance with the stage of surgical operation walkie-talkie.

With an increase in the depth of anesthesia or a decrease in traumatic effects, minute ventilation reflexively decreases so that bag 3 increases in volume and remains inflated throughout the entire respiratory cycle. In this case, the warning inscription “LESS C _A ” of the pointer 12 is constantly in front of the eyes of the anesthetist, and the pointer 13 with the opposite inscription is closed with a swollen bag 3.

Based on this warning, the anesthetist reduces the concentration of the anesthetic on the evaporator scale, for example, to 0.8 MAC until the minute ventilation is restored.

At the same time, the oxygen concentration in the inhaled mixture is monitored by monitor 20, maintaining it at an adequate level. So, to increase the oxygen concentration, the air compressor 8 is turned off and oxygen, respectively, is supplied through the rotameter 2 instead of air.

Anesthesia of small animals weighing less than 300 grams. carried out using a bag of 15 Ambu. The patient (mouse) is placed in a chamber (300 ml bag, Fig. 5 _a ), after opening the cover 16, close the cover 16, the scale of the evaporator 1 is set to the desired concentration of anesthetic (from 0 to 6 vol.%), After which the anesthetic mixture is pumped through the camera, periodically squeezing the elastic walls of the Ambu bag with your finger or hand. After induction, the mouse is removed from the chamber and the necessary surgical procedures are performed.

To maintain anesthesia, the Ambu exit (directly or through a soft mouthpiece) is pressed tightly against the muzzle of the mouse (Fig. 5 _b ).

Similarly, other small animals (rodents, birds, reptiles) are anesthetized with any anesthetics, including isoflurane and halothane, using larger Ambu bags (600 or 1200 ml).

At the same time, the volume and frequency of ventilation are similarly regulated by periodically compressing the Ambu bag and, accordingly, setting the minimum allowable oxygen flow rate through the rotameter for a half-closed (low-flow) circuit, the safety valve 5 of the device must be closed.

The correspondence between minute ventilation and oxygen consumption is established by excursion of the backup bag 3 of the apparatus.

Thus, the proposed apparatus provides optimal inhalation anesthesia in district hospitals, veterinary clinics and remote regions with minimal capital and operating costs:

- provides a safe and effective anesthesia due to the timely adequate regulation of the respirable concentration of anesthetic according to the readings of the indicator of the adequacy of anesthesia during spontaneous breathing;

- provides the ability to maintain optimal oxygen concentration throughout the operation due to the use of cheap portable low-pressure sources of oxygen and air;

- differs in the minimum weight, dimensions and cost due to the minimum dimensions of the main components (evaporator, compressor, adsorber) and the absence of massive body parts.

So, the mass of the Hummingbird IN device for small patients (up to 30 kg) together with a compressor is about 4 kg, and for large patients (over 200 kg) - 10 kg together with an adsorbent.

Claims (3)

1. An inhalation anesthesia apparatus containing an oxygen dosimeter connected to the inlet of a low resistance evaporator connected to a backup bag and an adsorber, an air compressor and a check valve connected in parallel to the evaporator inlet and connected to the atmosphere, a breathing indicator and a breathing circuit with a safety valve, characterized the fact that the respiratory indicator is made in the form of a backup bag of an anesthesia adequacy indicator located horizontally on the bracket and equipped with a pointer to reduce the ntratsii anesthetic, placed on the front of the bag, and a pointer to increase the concentration of a bag placed on the vertical wall of the bracket. 2. The apparatus according to claim 1, characterized in that the inhaler of drugs is used as a compressor. 3. The apparatus according to claim 1, characterized in that it contains a monitor of concentrations of anesthetic and oxygen.

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