RU2421250C1 - Method of fast inhalation induction of general anaesthesia with constant positive breathing system pressure - Google Patents

Abstract

FIELD: medicine.

SUBSTANCE: invention refers to medicine, namely to anesthesiology, and can be used in inhalation anaesthesia. That is ensured by inhalation induction with adjusting constant positive pressure 5 cm Aq in a breathing system of an anaesthesia apparatus.

EFFECT: method allows reducing narcosis induction time and thereby reducing the adverse actions of the anaesthetic with simultaneous partial inhalation anaesthetic pressure increase due to choosing an optimum value of constant positive breathing system pressure.

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Description

The present invention relates to medicine, namely to anesthesiology and intensive care, and is intended for use in surgical and resuscitation departments of medical and diagnostic institutions.

It is known that the most dangerous stages of anesthetic management are the introduction to anesthesia (induction) and exit from it (awakening). During the induction of anesthesia with the introduction of anesthetic and narcotic drugs into the patient's body, the functioning of almost all vital systems and organs is rearranged. Undoubtedly, reducing the time of induction of anesthesia can significantly reduce the duration of the negative impact of anesthesia drugs on the physiological functions and the psycho-emotional sphere of the patient, reduce the duration of the anesthetic allowance and, accordingly, the economic costs.

The rate of inhalation induction of anesthesia depends on the physicochemical and pharmacological properties of the anesthetic used, as well as on its partial pressure in the gas-narcotic mixture. It is known that the higher the partial pressure of an inhaled anesthetic in the alveolar gas, the faster the induction of anesthesia.

The vapor and gaseous inhalation anesthetics currently used are used with individual vaporizers and rotameters (dispensers) under normal conditions when the airway pressure is equal to the atmospheric pressure corresponding to the place of anesthesia (Stachnik J. Inhaled anesthetic agents. - Am J Health Syst Pharm. 2006. Apr 1; v. 63, No. 7, p.623-34. Jöhr M, Berger TM. Paediatric anaesthesia and inhalation agents. - Best Pract Res Clin Anaesthesiol. 2005. Sep; v. 19, No. 3, p. 501-22).

The aim of the invention is to reduce the time of induction of anesthesia and, accordingly, the negative impact of the anesthesia drug on the patient and his psycho-emotional sphere, reducing economic costs by reducing the time of the anesthetic benefit.

This goal is achieved by the fact that in a closed respiratory circuit, where the gas-narcotic mixture is supplied during inhalation induction of anesthesia, a constant increased pressure is created up to 5 cm of water. Art. using the exhalation valve of the anesthesia apparatus.

The method is illustrated by the following clinical examples.

Example 1

Patient P., 3 years old, medical history 13978/07, with a diagnosis of congenital pronounced cleft palate 3a degree. The child was admitted for planned surgical treatment - plastic of the palate and frenulum of the upper lip.

Before the operation, the condition was satisfactory, according to laboratory and instrumental examinations, there were no violations. Premedication was not performed.

Under operating conditions, the anesthesia apparatus circuit was previously filled with a gas-narcotic mixture with an anesthetic (sevoflurane), for which a gas flow of 8 l / min was injected into it and an 8% sevoflurane vaporizer was opened with a triple filling and subsequent emptying of the respiratory bag in the apparatus circuit. After that, the face mask was hermetically placed on the child’s face, a constant increased pressure of 5 cm of water was installed in the circuit using the exhalation valve. Art. and with quiet spontaneous breathing of the patient, anesthesia was started by inhalation of the indicated gas-narcotic mixture at an anesthetic concentration of 8% at a gas flow of 8 liters per minute. After 2 minutes from the start of induction of anesthesia, the concentration of sevoflurane in the supplied fresh gas-narcotic mixture was reduced to 4% by turning the handle of the evaporator. Then, after the next 1 minute, a maintenance concentration of sevoflurane was set at 1.5% on the evaporator. Thus, the time of induction of anesthesia was 3.5 minutes, the time of loss of consciousness was 12 seconds, which was confirmed by the monitoring of the electroencephalogram (EEG), processed and presented by the values of the BIS-index (bispectral index).

On the graph (Fig. 1), according to the BIS index, the level of consciousness of depression (sleep depth), expressed in arbitrary units (cu), is indicated on the Y axis, and time is indicated on the X axis. The moment of the start of inhalation of the narcotic drug mixture is marked by arrow 1. The level of consciousness, which was clear at the moment, corresponded to the value of the BIS index - 92 cu 12 seconds after the start of inhalation of the gas-narcotic mixture, on 4 breaths, the child lost consciousness on clinical grounds, which according to the BIS-index corresponded to 63 cu, and by the end of the first minute of inhalation - 44 cu (arrow 2), which testified to a deep degree of sedation (oppression of consciousness).

Thus, the period of conscious negative psycho-emotional perception by the child of the performed procedure was no more than 12 seconds from the start of the manipulation, which was an important component of the prevention of psychogenic stress.

Example 2

Patient R., 8 years old, medical history number 14553/07, with a diagnosis of congenital cataract, was admitted for planned surgical treatment - cataract extraction.

According to laboratory and instrumental examinations before surgery and anesthesia, there were no violations of the functions of organs and systems outside the correctable pathology, the condition was assessed as satisfactory. Premedication was not performed.

Under operating conditions, the anesthesia apparatus circuit was previously filled with a gas-narcotic mixture with sevoflurane, for which a gas flow of 8 l / min was supplied to it and an 8% sevoflurane vaporizer was opened with threefold filling and subsequent emptying of the respiratory bag in the apparatus circuit. After that, the face mask was hermetically placed on the child’s face, a constant increased pressure of 5 cm of water was installed in the circuit using the exhalation valve. Art. and with quiet spontaneous breathing of the patient, anesthesia was started by inhalation of the indicated gas-narcotic mixture at an anesthetic concentration of 8% at a gas flow of 8 liters per minute. After 2 minutes from the start of induction of anesthesia, the concentration of sevoflurane in the supplied fresh gas-narcotic mixture was reduced to 4% by turning the handle of the evaporator. Then, also after 2 minutes, a maintenance concentration of sevoflurane - 1.5% was established on the evaporator. Thus, the time of induction of anesthesia was 3 minutes, the time of loss of consciousness was 10 seconds, which was confirmed by the monitoring indications of the BIS-index and clinical signs (lack of speech contact, reactions to sound, visual and tactile stimuli).

On the graph (figure 2) according to the BIS index on the Y axis, the level of depression of consciousness (depth of sleep), expressed in arbitrary units (cu), is indicated on the X axis, time. The moment of the start of inhalation of the narcotic drug mixture is marked by arrow 1. The level of consciousness that was clear at the moment corresponded to the value of the BIS index - 90 cu 10 seconds after the start of inhalation of the gas-narcotic mixture, on 3 breaths, the child lost consciousness on clinical grounds and according to the BIS index, which corresponded to 58 cu, and by the end of the first minute of inhalation - 40 cu (arrow 2), which testified to a deep degree of sedation (oppression of consciousness).

Thus, the proposed method for the rapid inhalation induction of anesthesia has reduced the time of this period of anesthetic management, reduce the effect on the psycho-emotional sphere of patients, increase the profitability of the operating room, and reduce the risk of complications.

In total, at the moment, the described method has performed induction of inhalation anesthesia in 763 children with various surgical interventions. At the same time, the time of induction of anesthesia was reduced on average by 15%, compared with the common method of stepwise inhalation induction of anesthesia using a similar anesthetic.

Despite the apparent simplicity, the invention was developed as a result of lengthy scientific research related to the study of the optimal constant positive pressure in the respiratory circuit during induction of anesthesia, the time intervals for achieving adequate levels of sedation and the depth of anesthesia.

Since the rate of occurrence of the equilibrium concentration (pressure) of gases between different containers has a direct dependence on their partial pressure in these tanks, accordingly, the higher this pressure in one of the tanks, the faster it will increase in the desire to equalize in another tank. Thus, the number of molecules will also increase in a container with a lower content, the faster, the higher the pressure gradient between these containers. Mathematically, this dependence is determined by the formula p1V1 / T1 = p2V2 / T2, where p is the pressure in the tank (1 and 2), V is the volume of the tank (1 and 2), T is the temperature of the gas (vapor) in the tank (1 and 2). From this formula it is seen that, ceteris paribus and the initial equilibrium (equality) between the systems (capacities), when the values of V and T remain unchanged, an increase in pressure in one of the containers should inevitably lead to a similar increase in it in the other (Landsberg G. C. An Elementary Textbook of Physics. M., 1975, in 3 volumes, vol. 1, 656 pp., Ch. 8). If on the one hand we take the alveolar space, where the gas-narcotic mixture is located, and on the other hand, the blood, where the anesthetic from the alveolar space enters, then with increasing pressure in the respiratory circuit and accordingly in the alveolar space, the partial pressure of gases and vapors and their entry into the blood. With regard to the induction of anesthesia, this will contribute to a more rapid saturation of the body with an anesthetic, and, accordingly, a reduction in the time of this period of the anesthetic benefit.

We first developed a method for the rapid induction of inhalation anesthesia by increasing the partial pressure of a volatile anesthetic in a gas-narcotic mixture by creating a constant positive pressure in the respiratory circuit using the exhalation valve of the anesthesia apparatus.

The method is fully ready for use in the departments of anesthesiology and intensive care of healthcare institutions if there are specialists of the first and highest qualification categories, as well as the availability of appropriate equipment, and in particular anesthetic apparatus with vaporizers for the use of volatile anesthetics.

The claimed method is successfully used in the Russian Children's Clinical Hospital and the Children's City Clinical Hospital No. 13 named after N.F. Filatov, Moscow. The technique of rapid induction of inhalation anesthesia with a constant positive pressure in the respiratory circuit allows you to increase the patient's safety during anesthesia, namely at the stage of introduction into anesthesia.

The method has important socio-economic importance in terms of reducing the number of complications and the negative impact on the psycho-emotional sphere of patients arising from the induction of anesthesia, as well as reducing economic costs due to increased operating room efficiency.

Claims (1)

The method of rapid inhalation induction of anesthesia with constant positive pressure in the respiratory circuit, characterized in that the inhalation induction is started and performed with the establishment of a constant positive pressure of 5 cm of water in the respiratory circuit of the anesthesia apparatus. Art., which allows you to increase the partial pressure of an inhaled anesthetic and reduce the time of induction of anesthesia.

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