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CN116236649B - Target drug concentration estimation method and system for inhalation anesthesia - Google Patents

Target drug concentration estimation method and system for inhalation anesthesia

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Publication number
CN116236649B
CN116236649B CN202211663893.9A CN202211663893A CN116236649B CN 116236649 B CN116236649 B CN 116236649B CN 202211663893 A CN202211663893 A CN 202211663893A CN 116236649 B CN116236649 B CN 116236649B
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concentration
patient
blood
unit
drug
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CN116236649A (en
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李帅飞
李长缨
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Beijing Aeonmed Co Ltd
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Beijing Aeonmed Co Ltd
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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/021—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes operated by electrical means
    • A61M16/022—Control means therefor
    • A61M16/024—Control means therefor including calculation means, e.g. using a processor
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/01—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes specially adapted for anaesthetising
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/1005—Preparation of respiratory gases or vapours with O2 features or with parameter measurement
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
    • A61M16/00—Devices for influencing the respiratory system of patients by gas treatment, e.g. ventilators; Tracheal tubes
    • A61M16/10—Preparation of respiratory gases or vapours
    • A61M16/1005—Preparation of respiratory gases or vapours with O2 features or with parameter measurement
    • A61M2016/102—Measuring a parameter of the content of the delivered gas
    • A61M2016/1035—Measuring a parameter of the content of the delivered gas the anaesthetic agent concentration
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02A—TECHNOLOGIES FOR ADAPTATION TO CLIMATE CHANGE
    • Y02A90/00—Technologies having an indirect contribution to adaptation to climate change
    • Y02A90/10—Information and communication technologies [ICT] supporting adaptation to climate change, e.g. for weather forecasting or climate simulation

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  • Health & Medical Sciences (AREA)
  • Anesthesiology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Engineering & Computer Science (AREA)
  • Pulmonology (AREA)
  • Biomedical Technology (AREA)
  • Emergency Medicine (AREA)
  • Hematology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
  • Measuring Pulse, Heart Rate, Blood Pressure Or Blood Flow (AREA)

Abstract

The invention belongs to the technical field of anesthesia machines, and particularly relates to a target drug concentration estimation method and system for inhalation anesthesia, wherein the method comprises the steps of obtaining parameters set by an anesthesia respirator; the method comprises the steps of obtaining basic information of a patient, inputting the data into a pre-established dynamic equation, calculating the concentration of inhaled medicine at the mouth end of the patient, the concentration of alveolar medicine and the concentration of an effector room by adopting a Dragon-Gregory algorithm, and estimating the target medicine concentration, wherein the dynamic equation is based on the dispersion process of a breathing circuit of an anesthesia respirator and the absorption and metabolism process of a human body, and is used for solving the relation between the concentration to be solved, the basic information of the patient and the setting parameters of the anesthesia respirator. The method is suitable for an anesthesia respirator and a volatile anesthetic, the established model parameters have physiological significance and can be self-adaptive along with individual attributes of patients, and the method can predict the time of the drug reaching an equilibrium state in an anesthesia loop and a respiratory system of the patients to obtain the alveolar concentration and the effector chamber concentration of the anesthetic.

Description

Target drug concentration estimation method and system for inhalation anesthesia
Technical Field
The invention belongs to the technical field of anesthesia machines, and particularly relates to a target drug concentration estimation method and system for inhalation anesthesia.
Background
The anesthetic machine sends anesthetic into alveoli of a patient through a mechanical loop to form partial pressure of anesthetic gas, and after the partial pressure of the anesthetic gas is dispersed into blood, the anesthetic machine directly inhibits a central nervous system, so that the effect of general anesthesia is generated. The anesthesia machine belongs to a semi-open anesthesia device. It mainly comprises an anesthesia evaporation tank, a flowmeter, a folding bellows respirator, a breathing circuit (comprising a suction and exhalation unidirectional valve and a manual air bag), a corrugated pipeline and the like.
During inhalation general anesthesia, volatile drugs are delivered to the patient's lungs by an anesthesia machine, the patient's inhaled drug concentration is determined by the fresh gas flow and the vaporizer setting drug concentration, and the time for the patient's alveolar gas drug concentration to reach the minimum alveolar gas effective concentration (Minimal Alveolar Concentration, MAC) value is also affected by the frequency of ventilation and tidal volume. In clinic, the requirement of anesthesia maintenance must be determined accurately by the patient's depth of anesthesia and the target concentration of the drug, and then the dosing concentration and ventilation parameter settings must be manually adjusted as required by the progress of anesthesia. For inhalation anesthesia, the target is alveoli, and the concentration distribution of anesthetic in the lung cannot be monitored and known by any instrument, so that the evaluation often depends on the experience knowledge of anesthesiologists, and although the traditional maintenance mode can meet the operation requirement, the process of experience judgment and manual operation is a tedious work for doctors, and the effort of the doctors to perform the operation is not dispersed. In order to meet the intelligent demand, it is necessary to develop a software tool for the anesthesia respirator, establish effective mathematical and physiological models, calculate the absorption condition of the anesthetic in the patient's lung and the distribution and metabolism condition of the anesthetic in the patient's body by receiving the setting and monitoring parameters of the anesthesia respirator, thereby estimating the maintenance level of anesthesia and assisting the doctor in adjusting the dosage.
Clinically, anesthesiologists rely on experience knowledge and monitoring indexes such as heart rate, blood pressure, electroencephalogram index and the like to infer the consciousness level or anesthesia depth of a patient, and estimate the concentration or supply rate of volatile drugs. To infer the target drug concentration, a mathematical model of the drug uptake into the metabolic process must be built and solved under conditions where the parameters are physiologically significant. At present, an automatic drug delivery system applied to controlling anesthesia depth is mostly based on a classical three-chamber drug generation/pharmacodynamics model, the system can only be used for intravenous injection type anesthesia, the drug delivery mode is stable, model parameters are easy to calculate, the drug delivery of inhalation type anesthetic is influenced by parameter setting of an anesthesia respirator, the breathing state of a patient and the like, and the classical model is not applicable in the situation.
Disclosure of Invention
The invention aims to overcome the defects of the prior art and provides a target drug concentration estimation method and system for inhalation anesthesia.
In order to achieve the above object, the present invention proposes a target drug concentration estimation method for inhalation anesthesia, the method comprising:
Acquiring parameters set by an anesthesia respirator;
Acquiring basic information of a patient;
inputting the data into a pre-established dynamic equation, and calculating to obtain the concentration of the inhaled medicine at the mouth end of a patient, the concentration of the alveolar medicine and the effect concentration by adopting a Dragon-Gregor algorithm, so as to realize the estimation of the target medicine concentration;
The dynamic equation is based on the dispersion process of the breathing circuit of the anesthesia respirator and the absorption and metabolism process of the human body, and is a relation between the concentration solved by 3 zones, the basic information of the patient and the setting parameters of the anesthesia respirator.
As an improvement of the above method, the parameters set by the anesthetic breathing apparatus include:
Fresh gas flow Q 0 in L/min, respiratory circuit input drug concentration C 0 in vol%, respiratory frequency f in 1/min, tidal volume V t in L.
As an improvement of the above method, the patient basic information includes the sex G of the patient, wherein, male, g=1, female, g=0, age y, height h in meters, and body weight m in kilograms.
As an improvement of the above method, the power equation satisfies the following formula:
Wherein, C ins、C1、Ceff respectively represents the concentration of inhaled medicine at the mouth end, the concentration of alveolar medicine and the effect concentration;
subscript i represents a value of 2-4, and C 2、C3、C4 represents the residual concentration of the drug in blood-rich tissues, muscles and fat respectively;
V 0 represents the total volume of the airway of the anesthesia respirator and the lung of the patient, and is constant, and the value is 7L-8L;
Δq represents the flow lost by the gas valve in the circuit, which is 0.1 times the fresh gas flow Q 0 in units of L/min;
V d represents the dead space of the lung in mL, the weight of the patient is 2.2 times that of the patient, the weight of the patient is in kg, V 1 represents the functional residual capacity of the lung, and the unit is L through BMI estimation;
Q 2、Q3、Q4 is the blood flow rate of human body blood-rich tissue, muscle tissue and fat tissue, and the unit L/min is satisfied with the following formula:
Q 2 = 75% heart discharging blood volume
Q 3 = 18% heart discharging blood volume
Q 4 = 6% heart amount of blood discharge
V 2、V3、V4 represents the total volume of human blood-rich tissue, muscle tissue, adipose tissue, respectively, and the unit L satisfies the following formula:
Wherein IBW is an ideal quality index, ibw=22h 2;
lambda 0 represents the blood gas distribution coefficient of the inhalation anesthetic, and is determined by the type of the drug;
Lambda 2 represents the liver/blood partition coefficient of the drug, lambda 3 represents the muscle/blood partition coefficient of the drug, lambda 4 represents the lipid of the drug
The blood partition coefficients are constant, k e0 is the rate constant of elimination of the effect chamber medicine, and k 20 is the constant.
In another aspect, the invention provides a target drug concentration estimation system for inhalation anesthesia, which comprises a parameter acquisition module, an information acquisition module and an output module, wherein,
The parameter acquisition module is used for acquiring parameter settings of the anesthesia respirator;
the information acquisition module is used for acquiring basic information of a patient;
The output module is used for inputting the data into a pre-established dynamic equation, calculating the concentration of the inhaled medicine at the mouth end of a patient, the concentration of the alveolar medicine and the effect concentration by adopting a Dragon-Gregory tower algorithm, and realizing the estimation of the target medicine concentration;
The dynamic equation is based on the dispersion process of the breathing circuit of the anesthesia respirator and the absorption and metabolism process of the human body, and is a relation between the concentration solved by 3 zones, the basic information of the patient and the setting parameters of the anesthesia respirator.
As an improvement of the above system, the parameters set by the anesthetic breathing apparatus include:
Fresh gas flow Q 0 in L/min, respiratory circuit input drug concentration C 0 in vol%, respiratory frequency f in 1/min, tidal volume V t in L.
As an improvement of the above system, the patient basic information includes the sex G of the patient, wherein, male, g=1, female, g=0, age y, height h in meters, and body weight m in kilograms.
As an improvement of the above system, the power equation satisfies the following formula:
Wherein, C ins、C1、Ceff respectively represents the concentration of inhaled medicine at the mouth end, the concentration of alveolar medicine and the effect concentration, the subscript i represents the value of 2-4, and C 2、C3、C4 respectively represents the residual concentration of the medicine in blood-rich tissues, muscles and fat;
V 0 represents the total volume of the airway of the anesthesia respirator and the lung of the patient, and is constant, and the value is 7L-8L;
Δq represents the flow lost by the gas valve in the circuit, which is 0.1 times the fresh gas flow Q 0 in L/min;
V d represents the dead space of the lung in mL, the weight of the patient is 2.2 times that of the patient, the weight of the patient is in kg, V 1 represents the functional residual capacity of the lung, and the unit is L through BMI estimation;
Q 2、Q3、Q4 is the blood flow rate of human body blood-rich tissue, muscle tissue and fat tissue, and the unit L/min is satisfied with the following formula:
Q 2 = 75% heart discharging blood volume
Q 3 = 18% heart discharging blood volume
Q 4 = 6% heart amount of blood discharge
V 2、V3、V4 represents the total volume of human blood-rich tissue, muscle tissue, adipose tissue, respectively, and the unit L satisfies the following formula:
Wherein IBW is an ideal quality index, ibw=22h 2;
lambda 0 represents the blood gas distribution coefficient of the inhalation anesthetic, and is determined by the type of the drug;
Lambda 2 represents the liver/blood partition coefficient of the drug, lambda 3 represents the muscle/blood partition coefficient of the drug, lambda 4 represents the lipid/blood partition coefficient of the drug, all constants, k e0 is the rate constant for elimination of the drug in the effector chamber, and k 20 is a constant.
Compared with the prior art, the invention has the advantages that:
1. the method is suitable for an anesthesia respirator and a volatile anesthetic;
2. the model parameters established by the method have physiological significance and can be self-adaptive along with the individual attribute of the patient;
3. The invention can predict the time for the medicine to reach an equilibrium state in the anesthesia loop and the respiratory system of a patient;
4. The output of the invention is the alveolar drug concentration of the patient, namely the effect concentration of the anesthetic can be obtained.
Drawings
FIG. 1 is a schematic diagram of an atrioventricular model of the absorption and metabolism of an inhaled anesthetic drug involved in the method;
FIG. 2 shows the trend of the inhalation concentration, alveolar concentration and effect concentration over the course of the process using the method of the present invention.
Detailed Description
Traditional inhalation anesthetic concentration control methods rely on the experience and intuitiveness of the physician, and existing anesthesia delivery systems are limited to intravenous anesthesia. In order to achieve accurate target administration of the inhalation anesthetic, the inhalation anesthetic (isoflurane, sevoflurane, desflurane and the like) needs to be combined with the dispersion process of the inhalation anesthetic in the breathing circuit of the anesthesia respirator and the absorption and metabolism process of the human body, and a mathematical model capable of simultaneously and accurately describing the two dynamic processes is established. The input variables of the model are the tidal volume, the respiratory rate, the fresh gas flow and the set concentration of the evaporating pot of the anesthesia respirator, the parameters of the model are the sex, the age, the height and the weight of a patient, the output result of the model is the alveolar drug concentration or the effector chamber concentration, and the final purpose is to calculate the output with guiding significance for an anesthesiologist through the model by the known input variables and parameters.
The technical scheme of the invention is described in detail below with reference to the accompanying drawings and examples.
Example 1
Embodiment 1 of the present invention proposes a target drug concentration estimation method for inhalation anesthesia.
As shown in fig. 1, the method relates to an atrioventricular model of absorption and metabolism of inhaled anesthetic drugs, wherein each box represents different human tissues, mainly comprising alveoli, blood-rich tissues (liver, kidney, etc.), muscles, fat and effector compartments (brain). The inhalation anesthetic enters the blood circulation of the human body mainly through alveoli, and then is distributed in various tissues, and enters the alveolar gas through the blood circulation to be discharged out of the human body, so that the lung is the center of the whole atrioventricular model. Drug transfer exists between tissues and lungs, and the transfer rates of the parts are affected by multiple factors, with the main purpose of the model being to describe this dynamic process and to estimate the concentration of drug in the alveoli or effector compartments.
The method comprises the following specific steps:
The method comprises the steps of obtaining parameters set by an anesthesia respirator, wherein the parameters comprise fresh gas flow Q 0 in the unit of L/min, drug concentration C 0 input by a breathing circuit in the unit of vol%, breathing frequency f in the unit of 1/min and tidal volume V t in the unit of L.
Obtaining basic information of a patient, including sex (G, male: G=1, female: G=0), age (y), height (h, m) and weight (m, kg) of the patient,
Based on the dispersion process of the breathing circuit of the anesthesia respirator and the absorption and metabolism process of the human body, establishing a kinetic equation;
And combining parameters set by the anesthesia respirator and basic information of a patient, and adopting a Dragon-Greek tower algorithm to perform single-step calculation on a kinetic equation to obtain the concentration of the inhaled medicine at the mouth end of the patient, the concentration of the alveolar medicine and the effect concentration, so as to realize target medicine concentration estimation.
The following analysis was performed in detail:
firstly, establishing a kinetic equation of the whole system model, wherein the kinetic equation is as follows:
Secondly, input variables of the model are obtained, and the meaning and the determining method of the input variables are as follows:
Q 0, setting fresh gas flow through an anesthesia machine interface, wherein the fresh gas flow is L/min;
c 0 the concentration of the medicine is input into the breathing circuit, and the medicine evaporation tank of the anesthesia machine is operated by a doctor to set the concentration, the unit is vol%;
f, respiratory frequency, namely setting the respiratory frequency by an anesthesia machine interface, wherein the respiratory frequency is 1/min;
v t, tidal volume, unit, L through the interface of the anesthesia machine;
then, parameters of the model are acquired. The parameters of the model are actually the sex (G, men: g=1, women: g=0), age (y), height (h, m) and weight (m, kg) of the patient, and the parameters of the differential equation set are calculated by the four terms, and the meaning and calculation method of the parameters in the equation set are as follows:
V 0 the total volume of the entire respiratory system (including the anesthetic breathing apparatus airways and the patient's lungs) is generally a constant, about 7L to 8L;
ΔQ is the lost flow rate of the air valve and the like in the loop, which is generally 0.1 time of the fresh gas flow rate Q 0, and is in units of L/min;
vd, the dead space of the lung, can be estimated by 2.2 times of the weight (kg), unit, mL;
V1. functional residual capacity of the lung can be estimated from the BMI index (body mass index, bmi=m/h 2), in L;
Q 2、Q3、Q4 is the blood flow of the blood-rich tissue, the muscle tissue and the fat tissue of the human body, the unit is L/min, Q 2、Q3、Q4 is about 75 percent, 18 percent and 6 percent of the heart blood discharge amount, and the heart blood discharge amount can be estimated by age, sex, height and weight (heart blood discharge amount=5.84+0.08 BMI-0.03 y-0.62G). V 2、V3、V4 represents the total volume of human blood-rich tissue, muscle tissue and adipose tissue respectively, the unit L is that the relation between the three and IBW is:
Wherein IBW is an ideal quality index, ibw=22h 2;
lambda 0 the blood gas distribution coefficient of inhalation anesthetic is a constant determined by the kind of drug;
lambda 2,λ3,λ4 the tissue/blood partition coefficient of inhalation anesthetics is generally a known constant.
Lambda 2 represents the liver/blood partition coefficient of the drug, lambda 3 represents the muscle/blood partition coefficient of the drug,
Lambda 4 represents the lipid/blood partition coefficient of the drug.
K 20, the constant, the value is 0.009 when the drug is sevoflurane or isoflurane;
Finally, the differential equation set is subjected to single-step solution by adopting a Dragon-Kutta algorithm (Runge-Kutta), and three results with guiding significance for anesthesiologists, namely C ins、C1、Ceff, are finally obtained, wherein the results respectively represent the concentration of inhaled medicine at the mouth end of a patient, the concentration of alveolar medicine and the effect concentration (brain). And C 2、C3、C4 in the equation set respectively represents the residual concentration of the drug in blood-rich tissues, muscles and fat, and the three are regarded as intermediate variables of the whole system and are not taken as output results.
The drug metabolic process may employ finer physiological modeling.
FIG. 2 is a simulation result of the model on sevoflurane anesthesia, setting fresh gas flow rate to 4L/min, initial administration concentration to 3%, respiratory rate to 12 times per minute, tidal volume to 0.5L, and administration concentration to 0 at 15 minutes, the graph showing the trend of inhalation concentration, alveolar concentration and effect concentration throughout the process.
Example 2
The embodiment 2 of the invention provides a target drug concentration estimation system for inhalation anesthesia, which is realized based on the method of the embodiment 1 and comprises a parameter acquisition module, an information acquisition module and an output module, wherein,
The parameter acquisition module is used for acquiring parameter settings of the anesthesia respirator;
the information acquisition module is used for acquiring basic information of a patient;
The output module is used for inputting the data into a pre-established dynamic equation, calculating the concentration of the inhaled medicine at the mouth end of a patient, the concentration of the alveolar medicine and the effect concentration by adopting a Dragon-Gregory tower algorithm, and realizing the estimation of the target medicine concentration;
The dynamic equation is based on the dispersion process of the breathing circuit of the anesthesia respirator and the absorption and metabolism process of the human body, and is a relation between the concentration solved by 3 zones, the basic information of the patient and the setting parameters of the anesthesia respirator.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and are not limiting. Although the present invention has been described in detail with reference to the embodiments, it should be understood by those skilled in the art that modifications and equivalents may be made thereto without departing from the spirit and scope of the present invention, which is intended to be covered by the appended claims.

Claims (2)

1. A method of estimating target drug concentration for inhalation anesthesia, the method comprising:
Acquiring parameters set by an anesthesia respirator;
Acquiring basic information of a patient;
inputting the data into a pre-established dynamic equation, and calculating to obtain the concentration of the inhaled medicine at the mouth end of a patient, the concentration of the alveolar medicine and the effect concentration by adopting a Dragon-Gregor algorithm, so as to realize the estimation of the target medicine concentration;
The dynamic equation is based on the dispersion process of the breathing circuit of the anesthesia respirator and the absorption and metabolism process of the human body, and is a relation between the concentration solved for 3 zones, the basic information of the patient and the setting parameters of the anesthesia respirator;
The parameters set by the anesthesia respirator comprise:
The fresh gas flow Q 0 is in unit of L/min, the breathing circuit input drug concentration C 0 is in unit of vol%, the breathing frequency f is in unit of 1/min, and the tidal volume V t is in unit of L;
The basic information of the patient comprises the sex G of the patient, wherein G=1 for men, G=0 for women, age y, height h in meters and weight m in kilograms;
The power equation satisfies the following equation:
The method comprises the steps of (1) respectively representing the concentration of inhaled medicine at the mouth end, the concentration of alveolar medicine and the effect concentration, wherein a subscript i represents the value of 2-4, C 2、C3、C4 represents the residual concentration of the medicine in blood-rich tissues, muscles and fat, V 0 represents the total volume of an airway of an anesthesia respirator and the lung of a patient, and is constant, the value of 7L-8L, V t is the tidal volume, the unit of the tidal volume is L, the delta Q represents the flow lost by an air valve in a loop and is 0.1 times of fresh air flow Q 0, the unit of the flow is L/min, V d represents the dead space of the lung, the unit of the weight of the patient is 2.2 times, the unit of the weight of the patient is kg, V 1 represents the functional residual air volume of the lung, the unit of the blood flow of the blood-rich tissues, the muscle tissues and the adipose tissues of a human body is L through BMI estimation, and the unit of L/min are satisfied, and the following formula is satisfied:
Q 2 = 75% heart discharging blood volume
Q 3 = 18% heart discharging blood volume
Q 4 = 6% heart amount of blood discharge
V 2、V3、V4 represents the total volume of human blood-rich tissue, muscle tissue, adipose tissue, respectively, and the unit L satisfies the following formula:
Wherein IBW is an ideal quality index, ibw=22h 2;
lambda 0 represents the blood gas distribution coefficient of the inhalation anesthetic, and is determined by the type of the drug;
Lambda 2 represents the liver/blood partition coefficient of the drug, lambda 3 represents the muscle/blood partition coefficient of the drug, lambda 4 represents the lipid/blood partition coefficient of the drug, all constants, k e0 is the rate constant for elimination of the drug in the effector chamber, and k 20 is a constant.
2. A target drug concentration estimation system for inhalation anesthesia is characterized by comprising a parameter acquisition module, an information acquisition module and an output module, wherein,
The parameter acquisition module is used for acquiring parameter settings of the anesthesia respirator;
the information acquisition module is used for acquiring basic information of a patient;
The output module is used for inputting the data into a pre-established dynamic equation, calculating the concentration of the inhaled medicine at the mouth end of a patient, the concentration of the alveolar medicine and the effect concentration by adopting a Dragon-Gregory tower algorithm, and realizing the estimation of the target medicine concentration;
The dynamic equation is based on the dispersion process of the breathing circuit of the anesthesia respirator and the absorption and metabolism process of the human body, and is a relation between the concentration solved for 3 zones, the basic information of the patient and the setting parameters of the anesthesia respirator;
The parameters set by the anesthesia respirator comprise:
The fresh gas flow Q 0 is in unit of L/min, the breathing circuit input drug concentration C 0 is in unit of vol%, the breathing frequency f is in unit of 1/min, and the tidal volume V t is in unit of L;
The basic information of the patient comprises the sex G of the patient, wherein G=1 for men, G=0 for women, age y, height h in meters and weight m in kilograms;
The power equation satisfies the following equation:
The method comprises the steps of (1) respectively representing the concentration of inhaled medicine at the mouth end, the concentration of alveolar medicine and the effect concentration, wherein a subscript i represents the value of 2-4, C 2、C3、C4 represents the residual concentration of the medicine in blood-rich tissues, muscles and fat, V 0 represents the total volume of an airway of an anesthesia respirator and the lung of a patient, and is constant, the value of 7L-8L, V t is the tidal volume, the unit of the tidal volume is L, the delta Q represents the flow lost by an air valve in a loop and is 0.1 times of fresh air flow Q 0, the unit of the flow is L/min, V d represents the dead space of the lung, the unit of the weight of the patient is 2.2 times, the unit of the weight of the patient is kg, V 1 represents the functional residual air volume of the lung, the unit of the blood flow of the blood-rich tissues, the muscle tissues and the adipose tissues of a human body is L through BMI estimation, and the unit of L/min are satisfied, and the following formula is satisfied:
Q 2 = 75% heart discharging blood volume
Q 3 = 18% heart discharging blood volume
Q 4 = 6% heart amount of blood discharge
V 2、V3、V4 represents the total volume of human blood-rich tissue, muscle tissue, adipose tissue, respectively, and the unit L satisfies the following formula:
Wherein IBW is an ideal quality index, ibw=22h 2;
lambda 0 represents the blood gas distribution coefficient of the inhalation anesthetic, and is determined by the type of the drug;
Lambda 2 represents the liver/blood partition coefficient of the drug, lambda 3 represents the muscle/blood partition coefficient of the drug, lambda 4 represents the lipid/blood partition coefficient of the drug, all constants, k e0 is the rate constant for elimination of the drug in the effector chamber, and k 20 is a constant.
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