Author : Pulmonary Function Group of the Respiratory Disease Branch of the Chinese Medical Association
Corresponding Author: Song Yuanlin, Department of Respiratory and Critical Care Medicine, Zhongshan Hospital Affiliated to Fudan University; Zheng Jinping, Department of Respiratory and Critical Care Medicine, First Affiliated Hospital of Guangzhou Medical University
Cited this article: Pulmonary Function Group of the Respiratory Disease Branch of the Chinese Medical Association. Chinese Expert Consensus on Principles, Quality Control and Clinical Applications of Portable Pulmonary Functional Instruments [J]. Chinese Journal of Tuberculosis and Respiratory , 2022, 45(10): 970-979. DOI: 10.3760/cma.j.cn112147-20220302-00167.
Abstract
Portable Pulmonary Functional Device has the advantages of small size, portable, easy to operate and low cost compared to traditional laboratory pulmonary function instruments. It can be used as a supplement to laboratory lung function instruments and is suitable for community, grassroots and other health institutions. At present, there is still a lack of guiding documents related to portable pulmonary function instruments in China. This expert consensus will explain it from the aspects of equipment hardware, equipment quality requirements, operational principles, operation quality control, clinical application and personnel training. The portable pulmonary function meter consists of a spirometer and a computer system. Its core component is the flow sensor , which retains the core functions of the laboratory lung function instrument, namely conventional ventilation function and diastolic test, but does not have the ability to measure lung volume, residual volume and diffusion functions. Portable pulmonary function instrument products need to pass the quality inspection of national and international authoritative institutions and must meet the ISO26782:2009 standard. The quality control of portable lung function instruments includes equipment quality control, operation process quality control, reporting quality control, etc., and its technical details are consistent with the quality control requirements of laboratory lung function instruments. It can be used for early screening of respiratory diseases, epidemiological investigations, , physical examination screening, clinical trials, respiratory chronic disease management, and bedside examinations for people with reduced mobility. The operation technology training of portable lung function instruments is mainly aimed at grassroots community medical workers. The training methods are flexible and diverse, and focus on the combination of theoretical and practical operations. Portable lung function instruments have some high-tech technologies that laboratory lung function instruments do not have, such as intelligent data transmission, cloud database , big data management, biosensor , etc. The application of these technologies will make lung function instruments more intelligent and diversified, and will greatly improve the level of respiratory chronic disease management.
Pulmonary function examination is one of the important examination methods for respiratory diseases, mainly used to check lung ventilation and diffusion functions. It has important clinical value in the early diagnosis of lung and airway diseases, assessment of disease severity, prognosis judgment, judgment of drug efficacy, and assessment of surgical tolerance [1]. Large laboratory lung function detection instruments are huge, bulky, expensive and complex in operation. This traditional lung function determination generally needs to be carried out in secondary and above hospitals, resulting in serious insufficient rates of primary hospital and community lung function examinations, resulting in a large number of chronic respiratory diseases missed diagnosis.
In July 2020, the National Health Commission's Disease Control and Prevention Bureau issued the "Notice on Issuing the Central Anti-epidemic National Debt Disease Control Project Management Work Plan", focusing on the "Early Screening Intervention Capacity Improvement Project for Grassroots Respiratory Diseases". The project requires grassroots health institutions to configure lung function detector target 50%, and the lung function detection rate for residents over 40 years old in 2025 shall not be less than 25%. The portable pulmonary function instrument conforms to the strategic needs of the country. It has the characteristics of simple operation, low price, and easy to carry. It can be widely used in grassroots hospitals, community outpatient clinics, physical examination centers, , etc., which can effectively promote the improvement of early screening and intervention capabilities of chronic respiratory diseases. In addition, occupational lung disease diagnosis or lung function testing in remote areas may require it to be performed in factories or in wild environments, and portable lung function devices can provide elastic solutions. To this end, the Pulmonary Functional Group of the Respiratory Diseases Branch of the Chinese Medical Association organized relevant experts to write this expert consensus to facilitate the clinical use and promotion of portable pulmonary function devices.
1. Working principle of portable lung function instrument and product standards
(I) Working principle
According to the different flow measurement methods, portable lung function instruments are mainly divided into several methods: differential pressure type, ultrasonic type, turbine type, strain reed type, thermal-sensitive type (hot wire type), etc. [2].
1. Differential pressure sensor: The flow rate is measured using the correspondence between the pressure drop and the flow rate of the air flow in a certain shape of the flow pipeline. The differential pressure sensor includes two parts: a differential pressure generator and a differential pressure detector. The pressure differential sensor can be divided into various different forms such as orifice plate type, pitot tube type and venturi tube .
2. Ultrasonic sensor: Two sets of ultrasonic generators and receiver are used, and their arrangement directions are opposite. When the air flow passes through the flowmeter pipeline, the ultrasonic signal conduction in the same direction as the air flow accelerates, while the ultrasonic signal conduction in the opposite direction of the air flow slows down. Specifically, there are time difference method, Doppler effect method, etc.
3. Turbo sensor: Measured based on the rotation speed of the rotating component ( impeller or turbine) in proportion to the fluid speed.
4. Strain reed sensor: The airflow drives the strain reed deformation and vibration. The reed deformation affects the impedance of the strain gauge , and the gas flow rate is indirectly calculated by detecting the change in current.
5. Thermal conduction sensor: designed based on the principle of heat conduction and gas flow rate. The core part is a temperature-dependent resistive element. The resistance increases when the component temperature rises and the resistance decreases when the component temperature drops. Thermal conduction sensors are divided into different forms such as hotline and thermally sensitive.
The performance characteristics, service life, consumables use and maintenance costs of each type of instrument are different. The characteristics of commonly used detection techniques are compared in Table 1.
(II) Product performance standards
Lung function examination results are affected by many factors, such as the characteristics of the inspection instrument, the condition and degree of cooperation of the subjects, the professional quality of the inspectors and the guidance ability of the subjects, the standardization of the inspection process, and the quality control evaluation of the inspection results. Currently, the pulmonary function instrument refers to the following relevant standard documents.
1. ISO26782:2009: Anesthesia and respiratory equipment - International standard for spirometers for measuring the volume of people's forceful exhalation time.
2. ISO23747:2015: Anesthesia and respiratory equipment - International standard for peak expiratory flowmeters for evaluating lung function in spontaneous respirators.
3. YY/T 1438-2016: Anesthesia and respiratory equipment—a peak expiratory flowmeter for evaluating lung function in spontaneous respiratory patients.
4. JJF 1213-2008: Pulmonary function instrument calibration specifications.
comprehensive international standards and clinical needs. Usually, the performance standards of the pulmonary function instrument are: the product needs to pass the quality inspection of national and international authoritative institutions, the accuracy of the product is required to comply with the American Thoracic Science Society (ATS) and the European Respiratory Association (ERS) product quality standard , and the pulmonary function instrument must meet the ISO26782:2009 standards.
2. Portable pulmonary function instruments. Quality control of commonly used lung function examinations.
Portable pulmonary function instruments are currently most commonly used in clinical practice for pulmonary capacity , urgency pulmonary capacity and bronchodilation test . This chapter will no longer describe the standard operations in detail. For conventional quality control and sensor control requirements, please refer to the guide [3, 4, 5, 6, 7, 8], which is only explained for the core or update points of quality control for adults.
(I) Quality control before lung function examination
portable lung function instrument environmental calibration, volume calibration, calibration verification and other preparations before lung function examination can refer to the guide [3, 4, 5, 6, 7]. Two aspects need to be noted: ① When the environmental parameters change greatly, for example, when the ambient temperature change is greater than 3 ℃ within 30 min, re-calibrate [3, 4, 5]. ② After daily volume calibration, the sensor must be linearly verified at different flow rates. The capacity error must be controlled within ±2.5% of the reading [5]. The capacity error of the 3 L fixed cylinder for calibration must be less than ±15 ml.
(II) Quality control of pulmonary calcification
The specific standards for acceptability and repeatability of the pulmonary calcification curve are referred to the guide [5, 7, 8].The baseline of tidal breathing is stable, and the end-expiratory lung volume changes of at least 3 stable tidal breaths should be 15% tidal volume (VT) [5] ; the end-expiratory and end-inspiratory curves should reach the platform, and the volume change in the last second of the end-expiratory should be 0.025 L; the difference between the optimal and inferior values of pulmonary vital capacity (VC) is ≤10% VC or 0.150 L (take the larger value) [5, 7, 8] . VC selects the maximum value in the acceptable curve; deep inhalation volume (IC) takes the average of acceptable values; complementary exhalation volume (ERV) = VC-IC.
(III) Quality control of pulmonary dysfunction examination
The determination of pulmonary dysfunction is divided into 4 stages. After breathing evenly and calmly several times, perform maximum inhalation, and immediately use the maximum strength and fastest to exhale explosively, continue to exhale until the residual air level, and inhale well to the total lung level. The capacity-time curve and flow-volume curve were recorded simultaneously to obtain ventilation indicators such as the first second force exhalation volume (FEV1), force vital capacity (FVC) and maximum expiration flow (PEF), and quality control indicators such as force exhalation time (FET), extrapolated volume (BEV).
1. Acceptability of the force-exhausting pulmonary capacity curve: There are clear criteria for evaluating the start, process, end of each completed force-exhausting pulmonary capacity curve and the maximum suction after a strong exhausting. (1) The starting standard for exhaling force: ① Subjective standard: There is no hesitation at the beginning of exhalation, sufficient explosive force, the rising branch of the force exhalation curve is steep and straight, and there is a significant peak of maximum exhalation flow (PEF) flow. ② Objective standard: Extrapolated volume (BEV) is an objective indicator for evaluating the initial explosive force of exhalation. BEV should be ≤5% pulmonary capacity (FVC) or 0.100 L (to take the larger value) [5] . (2) Standards for exhalation process: no coughing in the first second of the first expiration, the entire exhalation curve is smooth, the door is closed, no early inhalation or leakage, and no tongue blockage. (3) End criteria for exhaling force: To obtain a satisfactory end of exhalation (EOFE), refer to Figure 1 to determine [5] in sequence: ① Determine whether the end of exhalation curve reaches the platform. If the volume change of 0.025 L in the last second of the exhalation, a satisfactory EOFE is obtained. ② If you encounter severe airway obstruction or older clinically, sometimes the exhalation time can be as long as 15 s or longer. Even if you continue to exhale vigorously, the curve still does not meet the platform period and does not meet the standard "①", but the force exhale time (FET) has reached 15 s. Regardless of whether the subject can continue to exhale, it is believed that a satisfactory EOFE is achieved. ③In clinical practice, some subjects who are younger, have increased lung elastic resistance or are restricted from lung thorax. Due to the decrease in lung volume, the force exhalation ends quickly and does not meet the standard "②". At the same time, when the change in the end volume of the force exhalation does not meet the standard "①", if it can be ensured that the FVC value is the maximum value, or ensure that the difference between the value and the maximum FVC value in the current measurement sequence is within the repetitive tolerance range, it is also considered that satisfactory EOFE [5] is achieved. (4) Maximum inhalation standard after exhaling force: Maximum inhalation after exhaling force is an important step to check whether the previous inhalation is complete. Therefore, the maximum inhalation lung capacity (FIVC) after exhalation force becomes an important indicator for judging the acceptability of the stress lung capacity curve. If the FIVC is greater than FVC, it is necessary (FIVC-FVC) ≤5%FVC or 0.100 L (take the larger value), otherwise the curve is unacceptable.
2.FEV1 and FVC acceptability standards and usability standards: In clinical work, some force-exhausting curves do not meet the acceptability standards, but their FEV1 or FVC measurements may be usable. For example, for acceptable FVC, obtaining a satisfactory EOFE and avoiding glottal closure during the entire forced expiration process are essential, but there is no requirement for no cough within the first second of the start of the forced expiration; however, for FEV1, no cough within the first second of the start of the forced expiration, no glottal closure and leak within the first second are necessary conditions for its acceptability and usability, while glottal closure after the first second or EOFE dissatisfaction does not affect its usability and acceptability [5]. In this way, for subjects who are not cooperating well, doctors can also obtain valuable data from the only graphs.
Author : Pulmonary Function Group of the Respiratory Disease Branch of the Chinese Medical Association
Corresponding Author: Song Yuanlin, Department of Respiratory and Critical Care Medicine, Zhongshan Hospital Affiliated to Fudan University; Zheng Jinping, Department of Respiratory and Critical Care Medicine, First Affiliated Hospital of Guangzhou Medical University
Cited this article: Pulmonary Function Group of the Respiratory Disease Branch of the Chinese Medical Association. Chinese Expert Consensus on Principles, Quality Control and Clinical Applications of Portable Pulmonary Functional Instruments [J]. Chinese Journal of Tuberculosis and Respiratory , 2022, 45(10): 970-979. DOI: 10.3760/cma.j.cn112147-20220302-00167.
Abstract
Portable Pulmonary Functional Device has the advantages of small size, portable, easy to operate and low cost compared to traditional laboratory pulmonary function instruments. It can be used as a supplement to laboratory lung function instruments and is suitable for community, grassroots and other health institutions. At present, there is still a lack of guiding documents related to portable pulmonary function instruments in China. This expert consensus will explain it from the aspects of equipment hardware, equipment quality requirements, operational principles, operation quality control, clinical application and personnel training. The portable pulmonary function meter consists of a spirometer and a computer system. Its core component is the flow sensor , which retains the core functions of the laboratory lung function instrument, namely conventional ventilation function and diastolic test, but does not have the ability to measure lung volume, residual volume and diffusion functions. Portable pulmonary function instrument products need to pass the quality inspection of national and international authoritative institutions and must meet the ISO26782:2009 standard. The quality control of portable lung function instruments includes equipment quality control, operation process quality control, reporting quality control, etc., and its technical details are consistent with the quality control requirements of laboratory lung function instruments. It can be used for early screening of respiratory diseases, epidemiological investigations, , physical examination screening, clinical trials, respiratory chronic disease management, and bedside examinations for people with reduced mobility. The operation technology training of portable lung function instruments is mainly aimed at grassroots community medical workers. The training methods are flexible and diverse, and focus on the combination of theoretical and practical operations. Portable lung function instruments have some high-tech technologies that laboratory lung function instruments do not have, such as intelligent data transmission, cloud database , big data management, biosensor , etc. The application of these technologies will make lung function instruments more intelligent and diversified, and will greatly improve the level of respiratory chronic disease management.
Pulmonary function examination is one of the important examination methods for respiratory diseases, mainly used to check lung ventilation and diffusion functions. It has important clinical value in the early diagnosis of lung and airway diseases, assessment of disease severity, prognosis judgment, judgment of drug efficacy, and assessment of surgical tolerance [1]. Large laboratory lung function detection instruments are huge, bulky, expensive and complex in operation. This traditional lung function determination generally needs to be carried out in secondary and above hospitals, resulting in serious insufficient rates of primary hospital and community lung function examinations, resulting in a large number of chronic respiratory diseases missed diagnosis.
In July 2020, the National Health Commission's Disease Control and Prevention Bureau issued the "Notice on Issuing the Central Anti-epidemic National Debt Disease Control Project Management Work Plan", focusing on the "Early Screening Intervention Capacity Improvement Project for Grassroots Respiratory Diseases". The project requires grassroots health institutions to configure lung function detector target 50%, and the lung function detection rate for residents over 40 years old in 2025 shall not be less than 25%. The portable pulmonary function instrument conforms to the strategic needs of the country. It has the characteristics of simple operation, low price, and easy to carry. It can be widely used in grassroots hospitals, community outpatient clinics, physical examination centers, , etc., which can effectively promote the improvement of early screening and intervention capabilities of chronic respiratory diseases. In addition, occupational lung disease diagnosis or lung function testing in remote areas may require it to be performed in factories or in wild environments, and portable lung function devices can provide elastic solutions. To this end, the Pulmonary Functional Group of the Respiratory Diseases Branch of the Chinese Medical Association organized relevant experts to write this expert consensus to facilitate the clinical use and promotion of portable pulmonary function devices.
1. Working principle of portable lung function instrument and product standards
(I) Working principle
According to the different flow measurement methods, portable lung function instruments are mainly divided into several methods: differential pressure type, ultrasonic type, turbine type, strain reed type, thermal-sensitive type (hot wire type), etc. [2].
1. Differential pressure sensor: The flow rate is measured using the correspondence between the pressure drop and the flow rate of the air flow in a certain shape of the flow pipeline. The differential pressure sensor includes two parts: a differential pressure generator and a differential pressure detector. The pressure differential sensor can be divided into various different forms such as orifice plate type, pitot tube type and venturi tube .
2. Ultrasonic sensor: Two sets of ultrasonic generators and receiver are used, and their arrangement directions are opposite. When the air flow passes through the flowmeter pipeline, the ultrasonic signal conduction in the same direction as the air flow accelerates, while the ultrasonic signal conduction in the opposite direction of the air flow slows down. Specifically, there are time difference method, Doppler effect method, etc.
3. Turbo sensor: Measured based on the rotation speed of the rotating component ( impeller or turbine) in proportion to the fluid speed.
4. Strain reed sensor: The airflow drives the strain reed deformation and vibration. The reed deformation affects the impedance of the strain gauge , and the gas flow rate is indirectly calculated by detecting the change in current.
5. Thermal conduction sensor: designed based on the principle of heat conduction and gas flow rate. The core part is a temperature-dependent resistive element. The resistance increases when the component temperature rises and the resistance decreases when the component temperature drops. Thermal conduction sensors are divided into different forms such as hotline and thermally sensitive.
The performance characteristics, service life, consumables use and maintenance costs of each type of instrument are different. The characteristics of commonly used detection techniques are compared in Table 1.
(II) Product performance standards
Lung function examination results are affected by many factors, such as the characteristics of the inspection instrument, the condition and degree of cooperation of the subjects, the professional quality of the inspectors and the guidance ability of the subjects, the standardization of the inspection process, and the quality control evaluation of the inspection results. Currently, the pulmonary function instrument refers to the following relevant standard documents.
1. ISO26782:2009: Anesthesia and respiratory equipment - International standard for spirometers for measuring the volume of people's forceful exhalation time.
2. ISO23747:2015: Anesthesia and respiratory equipment - International standard for peak expiratory flowmeters for evaluating lung function in spontaneous respirators.
3. YY/T 1438-2016: Anesthesia and respiratory equipment—a peak expiratory flowmeter for evaluating lung function in spontaneous respiratory patients.
4. JJF 1213-2008: Pulmonary function instrument calibration specifications.
comprehensive international standards and clinical needs. Usually, the performance standards of the pulmonary function instrument are: the product needs to pass the quality inspection of national and international authoritative institutions, the accuracy of the product is required to comply with the American Thoracic Science Society (ATS) and the European Respiratory Association (ERS) product quality standard , and the pulmonary function instrument must meet the ISO26782:2009 standards.
2. Portable pulmonary function instruments. Quality control of commonly used lung function examinations.
Portable pulmonary function instruments are currently most commonly used in clinical practice for pulmonary capacity , urgency pulmonary capacity and bronchodilation test . This chapter will no longer describe the standard operations in detail. For conventional quality control and sensor control requirements, please refer to the guide [3, 4, 5, 6, 7, 8], which is only explained for the core or update points of quality control for adults.
(I) Quality control before lung function examination
portable lung function instrument environmental calibration, volume calibration, calibration verification and other preparations before lung function examination can refer to the guide [3, 4, 5, 6, 7]. Two aspects need to be noted: ① When the environmental parameters change greatly, for example, when the ambient temperature change is greater than 3 ℃ within 30 min, re-calibrate [3, 4, 5]. ② After daily volume calibration, the sensor must be linearly verified at different flow rates. The capacity error must be controlled within ±2.5% of the reading [5]. The capacity error of the 3 L fixed cylinder for calibration must be less than ±15 ml.
(II) Quality control of pulmonary calcification
The specific standards for acceptability and repeatability of the pulmonary calcification curve are referred to the guide [5, 7, 8].The baseline of tidal breathing is stable, and the end-expiratory lung volume changes of at least 3 stable tidal breaths should be 15% tidal volume (VT) [5] ; the end-expiratory and end-inspiratory curves should reach the platform, and the volume change in the last second of the end-expiratory should be 0.025 L; the difference between the optimal and inferior values of pulmonary vital capacity (VC) is ≤10% VC or 0.150 L (take the larger value) [5, 7, 8] . VC selects the maximum value in the acceptable curve; deep inhalation volume (IC) takes the average of acceptable values; complementary exhalation volume (ERV) = VC-IC.
(III) Quality control of pulmonary dysfunction examination
The determination of pulmonary dysfunction is divided into 4 stages. After breathing evenly and calmly several times, perform maximum inhalation, and immediately use the maximum strength and fastest to exhale explosively, continue to exhale until the residual air level, and inhale well to the total lung level. The capacity-time curve and flow-volume curve were recorded simultaneously to obtain ventilation indicators such as the first second force exhalation volume (FEV1), force vital capacity (FVC) and maximum expiration flow (PEF), and quality control indicators such as force exhalation time (FET), extrapolated volume (BEV).
1. Acceptability of the force-exhausting pulmonary capacity curve: There are clear criteria for evaluating the start, process, end of each completed force-exhausting pulmonary capacity curve and the maximum suction after a strong exhausting. (1) The starting standard for exhaling force: ① Subjective standard: There is no hesitation at the beginning of exhalation, sufficient explosive force, the rising branch of the force exhalation curve is steep and straight, and there is a significant peak of maximum exhalation flow (PEF) flow. ② Objective standard: Extrapolated volume (BEV) is an objective indicator for evaluating the initial explosive force of exhalation. BEV should be ≤5% pulmonary capacity (FVC) or 0.100 L (to take the larger value) [5] . (2) Standards for exhalation process: no coughing in the first second of the first expiration, the entire exhalation curve is smooth, the door is closed, no early inhalation or leakage, and no tongue blockage. (3) End criteria for exhaling force: To obtain a satisfactory end of exhalation (EOFE), refer to Figure 1 to determine [5] in sequence: ① Determine whether the end of exhalation curve reaches the platform. If the volume change of 0.025 L in the last second of the exhalation, a satisfactory EOFE is obtained. ② If you encounter severe airway obstruction or older clinically, sometimes the exhalation time can be as long as 15 s or longer. Even if you continue to exhale vigorously, the curve still does not meet the platform period and does not meet the standard "①", but the force exhale time (FET) has reached 15 s. Regardless of whether the subject can continue to exhale, it is believed that a satisfactory EOFE is achieved. ③In clinical practice, some subjects who are younger, have increased lung elastic resistance or are restricted from lung thorax. Due to the decrease in lung volume, the force exhalation ends quickly and does not meet the standard "②". At the same time, when the change in the end volume of the force exhalation does not meet the standard "①", if it can be ensured that the FVC value is the maximum value, or ensure that the difference between the value and the maximum FVC value in the current measurement sequence is within the repetitive tolerance range, it is also considered that satisfactory EOFE [5] is achieved. (4) Maximum inhalation standard after exhaling force: Maximum inhalation after exhaling force is an important step to check whether the previous inhalation is complete. Therefore, the maximum inhalation lung capacity (FIVC) after exhalation force becomes an important indicator for judging the acceptability of the stress lung capacity curve. If the FIVC is greater than FVC, it is necessary (FIVC-FVC) ≤5%FVC or 0.100 L (take the larger value), otherwise the curve is unacceptable.
2.FEV1 and FVC acceptability standards and usability standards: In clinical work, some force-exhausting curves do not meet the acceptability standards, but their FEV1 or FVC measurements may be usable. For example, for acceptable FVC, obtaining a satisfactory EOFE and avoiding glottal closure during the entire forced expiration process are essential, but there is no requirement for no cough within the first second of the start of the forced expiration; however, for FEV1, no cough within the first second of the start of the forced expiration, no glottal closure and leak within the first second are necessary conditions for its acceptability and usability, while glottal closure after the first second or EOFE dissatisfaction does not affect its usability and acceptability [5]. In this way, for subjects who are not cooperating well, doctors can also obtain valuable data from the only graphs.Therefore, the acceptability and usability standards of FEV1 and FVC are different, as shown in Table 2 [5].
3. Repeatability of the pulmonary capacity curve: (1) Number of measurements and precision: Multiple measurements are separated by 1~2 min, try to obtain 3 acceptable curves, and check up to 8 times. For adults, the difference between the optimal and inferior values of FEV1 and FVC is ≤0.150 L [4, 5, 7]. (2) Selection of curves and data: Select the curve with the largest sum of FEV1 and FVC among the curves that meet acceptability and repeatability as the best curve, FEV1 and FVC take the maximum value, and select in the best curve in the other parameters [5, 6, 7].
(IV) Quality control of bronchodilation test
Quality control of force pulmonary dysfunction examination is shown in the "II and 3" chapters of this article. For the quality control related to bronchodilator, the type, dosage, administration method and interval time after the medication, please refer to the corresponding guidelines [6, 7] .
3. The expected value formula and algorithm of portable lung function instrument
The normal expected value of lung function is generated by the expected value simulation equation based on factors such as gender, age, height, and weight. Choosing the appropriate expected value equation is a prerequisite for correctly interpreting the report on lung function. In 2012, the Global Working Group on Pulmonary Function (GLI) launched the equation for predicted pulmonary ventilation function aged 3 to 95 years old for multiple regions and races. Data from two major domestic sample research shows that the estimated value of the GLI2012 Southeast Asian population equation underestimates the Chinese FEV1 and FVC [9, 10]. In 2017, my country updated the normal expected value equation of lung ventilation function in the six major administrative regions of the country, and provided the lower limit of normal, LLN value, which is more suitable for the interpretation of lung function results in my country [11].
4. Report format and results of portable lung function instrument
(I) Report standardized format of portable lung function instrument
portable lung function instrument report [11, 12], which should include at least the following aspects.
1. Basic information of the lung function report: The report should include: the name of the medical institution and the name of the lung function test report issued; the basic information of the subject, name, examination number, gender, age, height or bilateral arm span length, weight; as well as the estimated value system used for the instrument, environmental parameters and specific date and time.
2. Lung function data and graphics: (1) The data in the lung function report should be displayed in a table form, and the list of lung ventilation function reports is: index name and unit, estimated value, measured optimal value and its percentage of the estimated value. The report of the bronchodilation test should also include the actual best value after medication and the change amount and percentage after medication compared with before medication. (2) Portable lung function instrument, currently there are three most practical measurement indicators. The first part is the volumetric indicators of spirometry: VT, respiratory rate (BF), VC, IC and ERV. The second part is the ventilation indicators determined by force pulmonary dysfunction: FVC, FEV1, FEV1/FVC, FEV1/VCmax, PEF, exhaled 25% of the lung capacity (FEF25%), exhaled 50% of the lung capacity (FEF50%), exhaled 75% of the lung capacity (FEF75%), and maximum exhaled mid-term dysfunction (FEF25%-75%) [11, 12]. The third part is the relevant indicators for evaluating quality control: FIVC, FET, EBV and EBV account for the percentage of FVC [5]. The above three parts should be fully included in the report on pulmonary ventilation function. The report of the bronchodilation test can be compared with the indicators in the second part. (3) The force-exercise graphic measured by the portable lung function instrument needs to be displayed in the flow-volume curve and the capacity-time curve respectively; the lung capacity graph only needs to be displayed in the capacity-time curve. Bronchodilation test requires flow-volume curve and volume-time curve for the flow-volume curve before and after medication [11].
3. Conclusions in the report of portable pulmonary function: (1) Evaluation of lung ventilation function: A preliminary qualitative and quantitative evaluation of lung ventilation function can be carried out in combination with data and graphics. Qualitative evaluations include basic normal pulmonary ventilation function, small airway dysfunction , restrictive ventilation dysfunction, obstructive ventilation dysfunction and mixed ventilation dysfunction, etc.; quantitative evaluations mainly classify the degree of ventilation dysfunction [4, 11]. The bronchodilation test report should include the name, dosage and method of administration, FEV1 and (or) FVC change amount, improvement rate and result judgment, etc. (2) The degree of cooperation of the subject's examination: The degree of cooperation is mainly divided into three levels: good cooperation, better cooperation or poor cooperation [11]. (3) Quality control rating of lung function data and graphics: Considering the initial screening effect of portable lung function instruments in community respiratory chronic diseases prevention and management, clinically, the measurement of FEV1 and FVC can be subject to quality assessment and graded [4, 5, 11] , mainly divided into 7 levels, the standards are shown in Table 3, but there is no requirement in the report on simple lung ventilation function [13] .
(II) Results of portable lung function instrument
Portable lung function instrument Common lung function parameters ≥LLN is normal. If the lung function index does not have LLN, the main indicators VC, FEV1≥80% are used to predict the value of normal, and FEV1/FVC≥92% are normal [7, 14, 15]. The volume parameters of each lung ventilation are within the normal range or only some of the flow indicators are slightly lower than the expected value of 80%, which can be judged that the lung ventilation function is normal or basically normal.
1. Types of pulmonary ventilation dysfunction: divided into obstructive ventilation dysfunction, restrictive ventilation dysfunction and mixed ventilation dysfunction. Small airway dysfunction is a type that involves basic normal pulmonary ventilation and obstructive ventilation dysfunction. For the preliminary diagnosis process, see Figure 2 for details. (1) Obstructive ventilation dysfunction: refers to ventilation dysfunction caused by restricted airflow inhalation and/or exhalation. Its characteristic is that FEV1/FVC is reduced. If the measured value is 92% expected and VC≥LLN or 80% expected value, it can be diagnosed as obstructive ventilation dysfunction. (2) Restricted ventilation dysfunction: refers to ventilation dysfunction caused by restricted lung dilation and (or) retraction. Given that portable lung function instruments cannot measure TLC and RV indirect indicators that determine lung volume reduction, restrictive ventilation dysfunction can be initially diagnosed when VCLLN or 80% expected value and FEV1/FVC is normal or elevated. (3) Hybrid ventilation dysfunction: refers to the presence of obstructive and restrictive ventilation dysfunction at the same time. (4) Small airway dysfunction: When the lung ventilation function is basically normal, PEF and FEF25% are normal or basically normal, it is only manifested as low-capacity segment flow indicators FEF50%, FEF75%, and FEF25%-75%. If 2 of these three indicators are below the expected value of 65%, it can be judged as small airway dysfunction [7, 14], and there is no need to judge the severity of it [11].
Considering that these traffic indicators are volume-dependent, it is recommended that when the rate of one second is slightly reduced, VC is basically normal but approaching LLN, in addition to FEF50%, FEF75% and FEF50%-75%, in addition to the two items below the expected 65% of the estimated values, FEF50% and FEF75% also showed that the reduction degree of FEF50% and FEF75% was significantly lower than that of PEF and FEF25%, and combined with the low volume segment depression of the curve, it was diagnosed as small airway dysfunction [15].
2. Classification of ventilation dysfunction: Whether obstructive, restrictive or mixed ventilation dysfunction, the classification is judged according to the percentage of FEV1 as the expected value. Chinese Medical Association Respiratory Diseases Branch Pulmonary Function Professional Group Recommend five-grade method [4, 7, 11, 12, 14] , see Table 4 for details.
3. Results of bronchodilation test: If FEV1 or FVC increases by ≥12% after taking the drug, and the absolute value increases by ≥200 ml, the bronchodilation test is positive, otherwise it is negative [5, 6, 7].
5. Similarities and differences between laboratory lung function instruments and portable lung function instruments
portable lung function instruments are simplified on the basis of traditional laboratory lung function instruments, retaining their core functions, and simplifying the complexity, realizing the miniaturization and portability of the equipment, and are cheap and easy to use. In order to correctly use the portable lung function instrument and obtain high-quality data with good accuracy/accuracy and high repeatability, it is necessary to emphasize the similarities and differences between laboratory lung function instruments and portable lung function instruments.
1. Definition and equipment composition: Traditional laboratory pulmonary function instruments consist of spirometer, gas analyzer, pressure gauge , etc. Through their combination, most indicators of lung function can be measured, such as lung capacity , ventilation, diffusion, respiratory resistance, respiratory muscle strength, oxygen consumption, carbon dioxide production, etc. It is generally used in the lung function rooms of hospitals of secondary and above levels. The equipment is mainly in the form of a trolley, including lung function instruments, computers and printers. Portable pulmonary function instruments are generally composed of spirometers and computer systems. They can be used alone. They can also connect to tablets, computers, and TVs through data cables, WIFI, Bluetooth , etc., and perform real-time operations. Portable lung function instruments can be subdivided into desktop lung function instruments and handheld lung function instruments. Desktop lung function instruments can be used in primary hospitals, community outpatient clinics, physical examination centers, epidemiological investigation sites, or large hospitals as backup instruments for laboratory lung function instrument failures; while handheld lung function instruments are mainly aimed at home and individual users. (1) Similarities and differences in core components: The core component of the lung function instrument is the flow sensor. With the changes of the times, sensors have experienced a development model from reed type, turbine type, to thermal-sensitive type (hot wire type), ultrasonic type, and then to pressure differential type. At present, laboratory pulmonary function instruments usually use differential pressure flow sensors with high accuracy, good linearity, fast response and high sensitivity. The core components of the portable lung function instrument vary depending on the manufacturer's technical level, target users and cost budget. Sensor modes such as turbine, thermal, ultrasonic, differential pressure type, etc. No matter what kind of flow sensor is used, it is based on the laws of physics. Assume that the fluid flow at a certain moment is q and the volume of the fluid flowing in a certain time t is V, then q=dV/dt, and it can be seen that the flow, time and volume can be converted accordingly. By measuring the flow rate of inhaled and exhaled gas and the time of inhaled and exhaled gas, the volume of inhaled and exhaled gas can be calculated; vice versa. Therefore, from a macro perspective, the working principle of a small portable lung function instrument is basically the same as that of a large laboratory lung function instrument [2]. (2) Testing items and parameters comparison: There are many items that can be detected by laboratory pulmonary function instruments, including conventional ventilation function (pulmonary capacity, forced lung capacity, maximum ventilation per minute), diastolic test, excitation test, body-scanning lung volume measurement/airway resistance; diffusion function, residual air measurement, etc. The portable pulmonary function instrument only retains the core functions of the laboratory pulmonary function instrument, namely, conventional ventilation function (pulmonary capacity, forceful lung capacity, maximum ventilation per minute), diastolic tests, and cannot perform volume, diffusion and residual gas measurements. Some portable lung function instrument brands have also developed additional functions different from traditional laboratory lung function instruments, such as respiratory muscle strength determination, big data cloud platform, etc., see Table 5 for details.
2. Similarities and differences between equipment quality control and process quality control of laboratory lung function instruments and portable lung function instruments: In order to ensure the accuracy and reliability of lung function instrument detection data, it is necessary to perform quality control of the lung function instrument, including equipment quality control and process quality control. Equipment quality control includes testing environment calibration: that is, the calibration is normal body temperature (37 ℃), standard atmospheric pressure [760 mmHg (1 mmHg=0.133 kPa)] and saturated water vapor state (BTPS). If the instrument has built-in thermometer, hygrometer and pressure gauge, it is necessary to confirm its reliability [16, 17]. Capacity calibration, three-flow rate calibration and calibration verification are carried out in different time periods (such as daily, weekly, etc.). Process quality control refers to the determination of the acceptability of FVC force exhalation ring and inspiration ring according to the quality assessment criteria of the ATS/ERS2005 guidelines and the 2014 guidelines of the Pulmonary Function Group of the Chinese Medical Association.Repeatability means that in 3 acceptable tests, the difference between the optimal value of FVC and FEV and the second best value should be ≤0.150 L [6]. These basic quality control standards are extremely important and indispensable for laboratory pulmonary function instruments and portable pulmonary function instruments. Some portable lung function instruments do not indicate detailed quality control parameters when they leave the factory, and some claim to be no calibration during use, which is all wrong.
For any disease with limited respiratory flow, portable lung function can be used to assist in the diagnosis of the disease. Common types of diseases include diseases that cause airflow obstruction, such as chronic obstructive pulmonary disease , bronchial asthma , bronchial dilation , etc.; diseases with limited ventilation function, such as interstitial pulmonary disease, after partial pulmonary resection, etc. The portable lung function instrument has the advantages of strong portability, low cost, simple operation, and convenient quality control. Its application scenarios are more suitable for specialized clinics, communities and grassroots health institutions. It can serve as an ideal screening device for early disease screening, large-scale epidemiological investigations and health examinations.
1. Early screening of chronic respiratory diseases: Research data from 2018 to 2019 showed that the prevalence of COPD in my country was 13.7%, with the total number of patients as high as 99.9 million [18] ; the prevalence of upper bronchial asthma in my country was 4.2%, with the total number of patients being 45.7 million [19] . my country's primary doctors lack understanding of the definition and risk factors, clinical manifestations and group treatment of COPD. Many studies have shown that the proportion of patients with COPD in my country undergoing pulmonary function examinations before diagnosis is low, and the use of pulmonary function instruments accounts for 30% [20]. Portable pulmonary function instruments are important auxiliary examination instruments for chronic respiratory diseases. With the promotion of portable pulmonary function instruments, the premature screening of chronic airway diseases will be greatly promoted.
2. Epidemiological Investigation: In recent years, portable pulmonary function instruments have been used in epidemiological investigations and have achieved credible results. For example, Chinese pulmonary health (CPH) is an epidemiological survey of chronic respiratory diseases conducted nationwide from 2012 to 2015. The study mobilized doctors, technicians and community workers from more than 10 provinces and cities across the country to survey the sampling areas, and completed a total of 57,779 adults questionnaires and pulmonary function examinations. Portable lung function instrument is the main instrument that ensures the smooth completion of this work [18, 19, 21].
3. Physical examination and occupational disease screening: Portable pulmonary function instruments can be used to conduct mass physical examinations and screen for early lung injury caused by occupational diseases. The physical examination center inquires about people over 40 years old, such as smoking, kitchen smoke, chronic cough, previous respiratory diseases, etc., which can quickly detect high-risk COPD people. If they can be equipped with a portable pulmonary function device, they will accurately screen patients with early COPD. Occupational lung diseases such as silicosis , coal workers' lungs, asbestos lungs, etc. are extremely harmful to the health of people in this industry. Portable lung function instruments can be widely used to high-risk dust areas due to their convenient portability and low price. Regular and regular health examinations for high-risk personnel to assist in early diagnosis of occupational diseases.
4. Scientific research and clinical trials: Smoking cessation clinics conducted rapid lung function screening, and it was found that the success rate of smoking cessation for those who quit smoking with decreased lung function was 38.5%, while those who quit smoking with normal lung function had only 9.1%. This shows that reports of abnormal lung function can improve people's motivation for quitting smoking [22]. In addition, there are a large number of clinical studies of new drugs, such as COPD, asthma, pulmonary fibrosis, , etc., have used the reports of portable lung function examinations as important indicators for patient screening, disease diagnosis, process monitoring and efficacy judgment. Portable lung function has the advantages of reliable data, convenient transmission, cloud database, and data query and traceability, which is very suitable for clinical research with strict requirements on data.
5. Assess the therapeutic effect of inhaled drugs and chronic disease follow-up management: The newly revised "Guidelines for Diagnosis and Treatment of Chronic Obstructive Pulmonary Diseases" by the Chinese Medical Association in 2021 pointed out that for all confirmed patients with stable COPD, one or more bronchodilators are recommended for inhalation treatment, and a management process of "evaluation-review-adjustment" long-term follow-up should be established. Because of its lightweight and portable advantages, portable pulmonary function instruments can be promoted and used in patients who use antispasmodic antiasthma drugs or hormone drugs for a long time, which is conducive to timely adjustment of treatment plans and long-term management of patients.
6. Use at home or on the bedside: Small portable lung function instruments (handheld phones) are available for patients to use at home. A study has reported 16 handheld portable lung function instruments for self-management of asthma abroad, and their detection indicators can meet clinical needs. [23, 24]. In addition, using portable pulmonary function instruments at home can reduce the inconvenience of patients' repeated visits to the hospital and the risk of cross-infection. For example, the regular (weekly/monthly) monitoring of FEV1 is very important for early identification of whether patients with occlusion bronchioles 5 after lung transplantation or neuromuscular disease are involved in respiratory system. Portable pulmonary function instruments can also be used for elderly, weak and mobility-free patients in the internal medicine ward, postoperative pulmonary function detection in surgical wards, and bedside respiratory muscle strength measurement in intensive care unit patients.
1. Basic contents of portable lung function instrument operation technology training: refer to the relevant guidelines of the Pulmonary Function Group of the Respiratory Disease Branch of the Chinese Medical Association [3, 4, 6, 7, 8, 11], the training of portable lung function instrument operation technology includes at least five aspects: ① Quality control before inspection of portable lung function instruments; ② Quality control of the lung ventilation function determination process; ③ Sensor control management of portable lung function instruments; ④ Lung function data storage and backup; ⑤ Interpretation of lung function report.
2. Training strategies, models and popularization of portable lung function instrument operation technology: (1) Characteristics and strategies of training objects: The operation technology of portable lung function instruments is mainly promoted among medical staff in the grassroots community. In view of the common characteristics of grassroots medical staff, training strategies also focus on. It is recommended that the training methods be flexible and diverse, combining online theory with offline practical training, and combining centralized training with periodic training; it is emphasized that practical training should ensure the total class hours, but can be completed in stages within a certain period. (2) Training model: It is recommended to divide the training into three stages: the first stage is at least 20 hours of online theoretical learning, introducing basic theoretical knowledge; the second stage is concentrated training, at least half a day of practical training; the third stage is at least 40 hours of practical training, which can be completed in batches within a certain period. Only by passing the training at each stage can you pass the assessment. After the training, you can also use online uploads or on-site random spot checks to regularly quality control and guide students' operations. The entire training adheres to the overall policy of theoretical first, practical operation, targeted training, cycle assessment, and quality control tracking, and gradually promotes the improvement of portable lung function detection technology in stages and focuses. (3) The core, support and development direction of popularization and promotion: The popularization and promotion of portable lung function instrument operation technology, with tertiary hospitals as the core of quality control and secondary hospitals as the technical support, and regional development with the help of the medical alliance model, help grassroots medical personnel master the operation technology of portable lung function instruments, and gradually play their important role in early screening of airway diseases and management of chronic respiratory diseases.
. Future development trends of portable lung function instrumentsportable lung function instruments were born in the Internet era. Compared with traditional laboratory lung function instruments, it organically integrates many high-tech technologies, such as intelligent data transmission, cloud database, data computing and processing, and software development. It also integrates various biosensing detection technologies to make the instruments more intelligent and diversified.
1. Respiratory Big Data, AI Intelligent Analysis: Portable Pulmonary Functional Device can upload data to cloud databases in real time. This information can be used as an important reference for patient condition tracking and updating treatment plans.Through data analysis of patient files, data mining technology can be used to improve drug research and development efficiency and create a new model in the medical service industry. The future management of chronic respiratory diseases will focus on "people", and use the Internet, artificial intelligence and other technologies to build a large database of medical service resources and an Internet medical service ecosystem [25, 26, 27]. AI intelligent analysis allows doctors to predict changes in patients' condition as early as possible so as to protect themselves and adjust treatment plans; it can also make patients more vigilant and prevent them early; it can predict whether the disease breaks out, hospitalization costs and hospitalization days for hospital management, etc.
2. Internet of Things: The organic combination of portable lung function instruments and Internet of Things technology helps to dynamically monitor patients' respiratory functions. Using big data, cloud computing and other technologies, real-time monitoring and remote management of chronic respiratory diseases can be achieved. Its fused biosensing technology, such as the use of inhalation devices for patients, automatic environmental parameter detection, etc., can be transmitted to mobile phones and computers in real time through Internet of Things technology, real-time sharing of data between hospitals of different levels [28, 29]. Internet of Things lung function products help effectively improve the respiratory diagnosis and treatment capabilities of grassroots level, and better support the implementation and implementation of "graded diagnosis and treatment".
3. Multifunctionalization: The portable lung function instrument gradually develops some additional functions, such as airway pressure detection, quantitative evaluation of inhalation medication, respiratory questionnaire, pulmonary rehabilitation, etc. These corresponding functions help to achieve the implementation of one-stop solutions for disease assessment, diagnosis and treatment, and rehabilitation based on lung function. Taking respiratory rehabilitation as an example, the late stage of chronic respiratory disease can lead to chronic respiratory failure. At this time, the efficacy of the drug is limited. Early respiratory rehabilitation can reduce the symptoms of dyspnea, improve activity endurance, improve physical and mental state, improve quality of life, reduce disability rate, medical expenses and resource occupation, and extend patient life. At present, some commonly used portable pulmonary function instrument brands in China have built the respiratory muscle strength measurement and respiratory training functions into the pulmonary function instrument. The improvement of these functions will help primary medical institutions achieve the treatment and management goals of rehabilitated patients.
List of expert group writing
Advisor: Sun Tieying, Niu Shanfu, Huang Shaoguang, Liu Jinming, Sun Xingguo, Wang Huiwu
General responsible: Song Yuanlin, Zheng Jinping
Writer: Chen Zhihong, Li Li, Guo Jian, Gao Yi
Member of consultation expert group (arranged by Chinese pinyin order):
Cao Jie (General Hospital of Tianjin Medical University), Chen Fang (Zhejiang Provincial Hospital of Traditional Chinese Medicine), Chen Yahong (Third Hospital of Peking University), Chen Zhihong (Zhongshan Hospital of Fudan University), Cheng Kebin (Shanghai Pulmonary Hospital), Dai Yuan Rong (Second Affiliated Hospital of Wenzhou Medical University), Gai Xiaoyan (Third Hospital of Peking University), Gao Yi (First Affiliated Hospital of Guangzhou Medical University), Guo Jian (Shanghai Pulmonary Hospital), Guo Yi (Ruijin Hospital Affiliated to Shanghai Jiaotong University Medical College), Gu Yutong (Zhongshan Hospital Affiliated to Fudan University), Hang Jingqing (Shanghai Putuo District People's Hospital), Heping (Second Affiliated Hospital of Xi'an Jiaotong University), Jia Huiying (People's Hospital of Xinjiang Uygur Autonomous Region), Jie Zhijun (Shanghai Fifth People's Hospital of Fudan University), Jiang Depeng (Second Affiliated Hospital of Chongqing Medical University), Jiang Sunfang (Zhongshan Hospital of Fudan University), Jiang Handong (Renji Hospital of Shanghai Jiaotong University Medical College), Jin Meiling (Zhongshan Hospital of Fudan University), Li Li (Zhongshan Hospital of Fudan University), Li Li (Haihe Hospital of Tianjin University), Li Meihua (First Affiliated Hospital of Guangxi Medical University) , Li Yanming (Beijing Hospital), Liang Binmiao (West China Hospital of Sichuan University), Liu Chuanhe (Capital Pediatrics Institute), Liu Jinming (Shanghai Pulmonary Hospital), Lu Yong (Beijing Chaoyang Hospital Affiliated to Capital Medical University), Ma Qianli (Chongqing Northern Kuanren Hospital), Miao Lijun (First Affiliated to Zhengzhou University), Pang Min (First Hospital of Shanxi Medical University), Pan Zhigang (Zhongshan Hospital Affiliated to Fudan University), Qinling (Xiangya Hospital of Central South University), Que Chengli (Peking University First Hospital), Song Yuanlin (Zhongshan Hospital Affiliated to Fudan University), Sun Peili (Jiangsu Provincial People's Hospital), Sun Tieying (Beijing Hospital), Sun Xingguo (Fuwai Hospital of Chinese Academy of Medical Sciences), Su Hong (Inner Mongolia Medical University Affiliated to Inner Mongolia Medical University), Wang Lu (Zhabei Central Hospital, Jing'an District, Shanghai), Xiong Weining (Ninth People's Hospital Affiliated to Shanghai Jiaotong University Medical University), Yang Danlei (Affiliated to Tongji Medical College of Huazhong University of Science and Technology Tongji Hospital), Yang Ting (Sino-Japan Friendship Hospital), Yang Weijiang (Traditional Medicine Hospital Affiliated to Xinjiang Medical University), Yang Yimeng (Beijing Hospital), Yao Yinan (First Affiliated to Zhejiang University Medical College), Yu Li (Tongji Hospital Affiliated to Tongji University), Zhang Cheng (Guizhou Provincial People's Hospital), Zhang Xuhua (Ningxia Medical University General Hospital), Zhang Yunhui (Yunnan Provincial People's Hospital), Zhao Guihua (Henan Provincial People's Hospital), Zhao Haijin (Southern Medical University Southern Hospital), Zhao Haitao (Shenyang Military Region General Hospital), Zheng Jinping (First Affiliated to Guangzhou Medical University General Hospital), Zhou Ning (Tianjin Medical University General Hospital), Zhou Mingjuan (Guangdong Provincial Traditional Chinese Medicine Hospital), Zou Yimin (Second Hospital of Zhejiang University Medical College)
References (omitted)
3. Conclusions in the report of portable pulmonary function: (1) Evaluation of lung ventilation function: A preliminary qualitative and quantitative evaluation of lung ventilation function can be carried out in combination with data and graphics. Qualitative evaluations include basic normal pulmonary ventilation function, small airway dysfunction , restrictive ventilation dysfunction, obstructive ventilation dysfunction and mixed ventilation dysfunction, etc.; quantitative evaluations mainly classify the degree of ventilation dysfunction [4, 11]. The bronchodilation test report should include the name, dosage and method of administration, FEV1 and (or) FVC change amount, improvement rate and result judgment, etc. (2) The degree of cooperation of the subject's examination: The degree of cooperation is mainly divided into three levels: good cooperation, better cooperation or poor cooperation [11]. (3) Quality control rating of lung function data and graphics: Considering the initial screening effect of portable lung function instruments in community respiratory chronic diseases prevention and management, clinically, the measurement of FEV1 and FVC can be subject to quality assessment and graded [4, 5, 11] , mainly divided into 7 levels, the standards are shown in Table 3, but there is no requirement in the report on simple lung ventilation function [13] .
(II) Results of portable lung function instrument
Portable lung function instrument Common lung function parameters ≥LLN is normal. If the lung function index does not have LLN, the main indicators VC, FEV1≥80% are used to predict the value of normal, and FEV1/FVC≥92% are normal [7, 14, 15]. The volume parameters of each lung ventilation are within the normal range or only some of the flow indicators are slightly lower than the expected value of 80%, which can be judged that the lung ventilation function is normal or basically normal.
1. Types of pulmonary ventilation dysfunction: divided into obstructive ventilation dysfunction, restrictive ventilation dysfunction and mixed ventilation dysfunction. Small airway dysfunction is a type that involves basic normal pulmonary ventilation and obstructive ventilation dysfunction. For the preliminary diagnosis process, see Figure 2 for details. (1) Obstructive ventilation dysfunction: refers to ventilation dysfunction caused by restricted airflow inhalation and/or exhalation. Its characteristic is that FEV1/FVC is reduced. If the measured value is 92% expected and VC≥LLN or 80% expected value, it can be diagnosed as obstructive ventilation dysfunction. (2) Restricted ventilation dysfunction: refers to ventilation dysfunction caused by restricted lung dilation and (or) retraction. Given that portable lung function instruments cannot measure TLC and RV indirect indicators that determine lung volume reduction, restrictive ventilation dysfunction can be initially diagnosed when VCLLN or 80% expected value and FEV1/FVC is normal or elevated. (3) Hybrid ventilation dysfunction: refers to the presence of obstructive and restrictive ventilation dysfunction at the same time. (4) Small airway dysfunction: When the lung ventilation function is basically normal, PEF and FEF25% are normal or basically normal, it is only manifested as low-capacity segment flow indicators FEF50%, FEF75%, and FEF25%-75%. If 2 of these three indicators are below the expected value of 65%, it can be judged as small airway dysfunction [7, 14], and there is no need to judge the severity of it [11].
Considering that these traffic indicators are volume-dependent, it is recommended that when the rate of one second is slightly reduced, VC is basically normal but approaching LLN, in addition to FEF50%, FEF75% and FEF50%-75%, in addition to the two items below the expected 65% of the estimated values, FEF50% and FEF75% also showed that the reduction degree of FEF50% and FEF75% was significantly lower than that of PEF and FEF25%, and combined with the low volume segment depression of the curve, it was diagnosed as small airway dysfunction [15].
2. Classification of ventilation dysfunction: Whether obstructive, restrictive or mixed ventilation dysfunction, the classification is judged according to the percentage of FEV1 as the expected value. Chinese Medical Association Respiratory Diseases Branch Pulmonary Function Professional Group Recommend five-grade method [4, 7, 11, 12, 14] , see Table 4 for details.
3. Results of bronchodilation test: If FEV1 or FVC increases by ≥12% after taking the drug, and the absolute value increases by ≥200 ml, the bronchodilation test is positive, otherwise it is negative [5, 6, 7].
5. Similarities and differences between laboratory lung function instruments and portable lung function instruments
portable lung function instruments are simplified on the basis of traditional laboratory lung function instruments, retaining their core functions, and simplifying the complexity, realizing the miniaturization and portability of the equipment, and are cheap and easy to use. In order to correctly use the portable lung function instrument and obtain high-quality data with good accuracy/accuracy and high repeatability, it is necessary to emphasize the similarities and differences between laboratory lung function instruments and portable lung function instruments.
1. Definition and equipment composition: Traditional laboratory pulmonary function instruments consist of spirometer, gas analyzer, pressure gauge , etc. Through their combination, most indicators of lung function can be measured, such as lung capacity , ventilation, diffusion, respiratory resistance, respiratory muscle strength, oxygen consumption, carbon dioxide production, etc. It is generally used in the lung function rooms of hospitals of secondary and above levels. The equipment is mainly in the form of a trolley, including lung function instruments, computers and printers. Portable pulmonary function instruments are generally composed of spirometers and computer systems. They can be used alone. They can also connect to tablets, computers, and TVs through data cables, WIFI, Bluetooth , etc., and perform real-time operations. Portable lung function instruments can be subdivided into desktop lung function instruments and handheld lung function instruments. Desktop lung function instruments can be used in primary hospitals, community outpatient clinics, physical examination centers, epidemiological investigation sites, or large hospitals as backup instruments for laboratory lung function instrument failures; while handheld lung function instruments are mainly aimed at home and individual users. (1) Similarities and differences in core components: The core component of the lung function instrument is the flow sensor. With the changes of the times, sensors have experienced a development model from reed type, turbine type, to thermal-sensitive type (hot wire type), ultrasonic type, and then to pressure differential type. At present, laboratory pulmonary function instruments usually use differential pressure flow sensors with high accuracy, good linearity, fast response and high sensitivity. The core components of the portable lung function instrument vary depending on the manufacturer's technical level, target users and cost budget. Sensor modes such as turbine, thermal, ultrasonic, differential pressure type, etc. No matter what kind of flow sensor is used, it is based on the laws of physics. Assume that the fluid flow at a certain moment is q and the volume of the fluid flowing in a certain time t is V, then q=dV/dt, and it can be seen that the flow, time and volume can be converted accordingly. By measuring the flow rate of inhaled and exhaled gas and the time of inhaled and exhaled gas, the volume of inhaled and exhaled gas can be calculated; vice versa. Therefore, from a macro perspective, the working principle of a small portable lung function instrument is basically the same as that of a large laboratory lung function instrument [2]. (2) Testing items and parameters comparison: There are many items that can be detected by laboratory pulmonary function instruments, including conventional ventilation function (pulmonary capacity, forced lung capacity, maximum ventilation per minute), diastolic test, excitation test, body-scanning lung volume measurement/airway resistance; diffusion function, residual air measurement, etc. The portable pulmonary function instrument only retains the core functions of the laboratory pulmonary function instrument, namely, conventional ventilation function (pulmonary capacity, forceful lung capacity, maximum ventilation per minute), diastolic tests, and cannot perform volume, diffusion and residual gas measurements. Some portable lung function instrument brands have also developed additional functions different from traditional laboratory lung function instruments, such as respiratory muscle strength determination, big data cloud platform, etc., see Table 5 for details.
2. Similarities and differences between equipment quality control and process quality control of laboratory lung function instruments and portable lung function instruments: In order to ensure the accuracy and reliability of lung function instrument detection data, it is necessary to perform quality control of the lung function instrument, including equipment quality control and process quality control. Equipment quality control includes testing environment calibration: that is, the calibration is normal body temperature (37 ℃), standard atmospheric pressure [760 mmHg (1 mmHg=0.133 kPa)] and saturated water vapor state (BTPS). If the instrument has built-in thermometer, hygrometer and pressure gauge, it is necessary to confirm its reliability [16, 17]. Capacity calibration, three-flow rate calibration and calibration verification are carried out in different time periods (such as daily, weekly, etc.). Process quality control refers to the determination of the acceptability of FVC force exhalation ring and inspiration ring according to the quality assessment criteria of the ATS/ERS2005 guidelines and the 2014 guidelines of the Pulmonary Function Group of the Chinese Medical Association.Repeatability means that in 3 acceptable tests, the difference between the optimal value of FVC and FEV and the second best value should be ≤0.150 L [6]. These basic quality control standards are extremely important and indispensable for laboratory pulmonary function instruments and portable pulmonary function instruments. Some portable lung function instruments do not indicate detailed quality control parameters when they leave the factory, and some claim to be no calibration during use, which is all wrong.
. Application scope and scenarios of portable lung function instruments For any disease with limited respiratory flow, portable lung function can be used to assist in the diagnosis of the disease. Common types of diseases include diseases that cause airflow obstruction, such as chronic obstructive pulmonary disease , bronchial asthma , bronchial dilation , etc.; diseases with limited ventilation function, such as interstitial pulmonary disease, after partial pulmonary resection, etc. The portable lung function instrument has the advantages of strong portability, low cost, simple operation, and convenient quality control. Its application scenarios are more suitable for specialized clinics, communities and grassroots health institutions. It can serve as an ideal screening device for early disease screening, large-scale epidemiological investigations and health examinations.
1. Early screening of chronic respiratory diseases: Research data from 2018 to 2019 showed that the prevalence of COPD in my country was 13.7%, with the total number of patients as high as 99.9 million [18] ; the prevalence of upper bronchial asthma in my country was 4.2%, with the total number of patients being 45.7 million [19] . my country's primary doctors lack understanding of the definition and risk factors, clinical manifestations and group treatment of COPD. Many studies have shown that the proportion of patients with COPD in my country undergoing pulmonary function examinations before diagnosis is low, and the use of pulmonary function instruments accounts for 30% [20]. Portable pulmonary function instruments are important auxiliary examination instruments for chronic respiratory diseases. With the promotion of portable pulmonary function instruments, the premature screening of chronic airway diseases will be greatly promoted.
2. Epidemiological Investigation: In recent years, portable pulmonary function instruments have been used in epidemiological investigations and have achieved credible results. For example, Chinese pulmonary health (CPH) is an epidemiological survey of chronic respiratory diseases conducted nationwide from 2012 to 2015. The study mobilized doctors, technicians and community workers from more than 10 provinces and cities across the country to survey the sampling areas, and completed a total of 57,779 adults questionnaires and pulmonary function examinations. Portable lung function instrument is the main instrument that ensures the smooth completion of this work [18, 19, 21].
3. Physical examination and occupational disease screening: Portable pulmonary function instruments can be used to conduct mass physical examinations and screen for early lung injury caused by occupational diseases. The physical examination center inquires about people over 40 years old, such as smoking, kitchen smoke, chronic cough, previous respiratory diseases, etc., which can quickly detect high-risk COPD people. If they can be equipped with a portable pulmonary function device, they will accurately screen patients with early COPD. Occupational lung diseases such as silicosis , coal workers' lungs, asbestos lungs, etc. are extremely harmful to the health of people in this industry. Portable lung function instruments can be widely used to high-risk dust areas due to their convenient portability and low price. Regular and regular health examinations for high-risk personnel to assist in early diagnosis of occupational diseases.
4. Scientific research and clinical trials: Smoking cessation clinics conducted rapid lung function screening, and it was found that the success rate of smoking cessation for those who quit smoking with decreased lung function was 38.5%, while those who quit smoking with normal lung function had only 9.1%. This shows that reports of abnormal lung function can improve people's motivation for quitting smoking [22]. In addition, there are a large number of clinical studies of new drugs, such as COPD, asthma, pulmonary fibrosis, , etc., have used the reports of portable lung function examinations as important indicators for patient screening, disease diagnosis, process monitoring and efficacy judgment. Portable lung function has the advantages of reliable data, convenient transmission, cloud database, and data query and traceability, which is very suitable for clinical research with strict requirements on data.
5. Assess the therapeutic effect of inhaled drugs and chronic disease follow-up management: The newly revised "Guidelines for Diagnosis and Treatment of Chronic Obstructive Pulmonary Diseases" by the Chinese Medical Association in 2021 pointed out that for all confirmed patients with stable COPD, one or more bronchodilators are recommended for inhalation treatment, and a management process of "evaluation-review-adjustment" long-term follow-up should be established. Because of its lightweight and portable advantages, portable pulmonary function instruments can be promoted and used in patients who use antispasmodic antiasthma drugs or hormone drugs for a long time, which is conducive to timely adjustment of treatment plans and long-term management of patients.
6. Use at home or on the bedside: Small portable lung function instruments (handheld phones) are available for patients to use at home. A study has reported 16 handheld portable lung function instruments for self-management of asthma abroad, and their detection indicators can meet clinical needs. [23, 24]. In addition, using portable pulmonary function instruments at home can reduce the inconvenience of patients' repeated visits to the hospital and the risk of cross-infection. For example, the regular (weekly/monthly) monitoring of FEV1 is very important for early identification of whether patients with occlusion bronchioles 5 after lung transplantation or neuromuscular disease are involved in respiratory system. Portable pulmonary function instruments can also be used for elderly, weak and mobility-free patients in the internal medicine ward, postoperative pulmonary function detection in surgical wards, and bedside respiratory muscle strength measurement in intensive care unit patients.
. Training and popularization of portable lung function instrument operation technology 1. Basic contents of portable lung function instrument operation technology training: refer to the relevant guidelines of the Pulmonary Function Group of the Respiratory Disease Branch of the Chinese Medical Association [3, 4, 6, 7, 8, 11], the training of portable lung function instrument operation technology includes at least five aspects: ① Quality control before inspection of portable lung function instruments; ② Quality control of the lung ventilation function determination process; ③ Sensor control management of portable lung function instruments; ④ Lung function data storage and backup; ⑤ Interpretation of lung function report.
2. Training strategies, models and popularization of portable lung function instrument operation technology: (1) Characteristics and strategies of training objects: The operation technology of portable lung function instruments is mainly promoted among medical staff in the grassroots community. In view of the common characteristics of grassroots medical staff, training strategies also focus on. It is recommended that the training methods be flexible and diverse, combining online theory with offline practical training, and combining centralized training with periodic training; it is emphasized that practical training should ensure the total class hours, but can be completed in stages within a certain period. (2) Training model: It is recommended to divide the training into three stages: the first stage is at least 20 hours of online theoretical learning, introducing basic theoretical knowledge; the second stage is concentrated training, at least half a day of practical training; the third stage is at least 40 hours of practical training, which can be completed in batches within a certain period. Only by passing the training at each stage can you pass the assessment. After the training, you can also use online uploads or on-site random spot checks to regularly quality control and guide students' operations. The entire training adheres to the overall policy of theoretical first, practical operation, targeted training, cycle assessment, and quality control tracking, and gradually promotes the improvement of portable lung function detection technology in stages and focuses. (3) The core, support and development direction of popularization and promotion: The popularization and promotion of portable lung function instrument operation technology, with tertiary hospitals as the core of quality control and secondary hospitals as the technical support, and regional development with the help of the medical alliance model, help grassroots medical personnel master the operation technology of portable lung function instruments, and gradually play their important role in early screening of airway diseases and management of chronic respiratory diseases.
. Future development trends of portable lung function instrumentsportable lung function instruments were born in the Internet era. Compared with traditional laboratory lung function instruments, it organically integrates many high-tech technologies, such as intelligent data transmission, cloud database, data computing and processing, and software development. It also integrates various biosensing detection technologies to make the instruments more intelligent and diversified.
1. Respiratory Big Data, AI Intelligent Analysis: Portable Pulmonary Functional Device can upload data to cloud databases in real time. This information can be used as an important reference for patient condition tracking and updating treatment plans.Through data analysis of patient files, data mining technology can be used to improve drug research and development efficiency and create a new model in the medical service industry. The future management of chronic respiratory diseases will focus on "people", and use the Internet, artificial intelligence and other technologies to build a large database of medical service resources and an Internet medical service ecosystem [25, 26, 27]. AI intelligent analysis allows doctors to predict changes in patients' condition as early as possible so as to protect themselves and adjust treatment plans; it can also make patients more vigilant and prevent them early; it can predict whether the disease breaks out, hospitalization costs and hospitalization days for hospital management, etc.
2. Internet of Things: The organic combination of portable lung function instruments and Internet of Things technology helps to dynamically monitor patients' respiratory functions. Using big data, cloud computing and other technologies, real-time monitoring and remote management of chronic respiratory diseases can be achieved. Its fused biosensing technology, such as the use of inhalation devices for patients, automatic environmental parameter detection, etc., can be transmitted to mobile phones and computers in real time through Internet of Things technology, real-time sharing of data between hospitals of different levels [28, 29]. Internet of Things lung function products help effectively improve the respiratory diagnosis and treatment capabilities of grassroots level, and better support the implementation and implementation of "graded diagnosis and treatment".
3. Multifunctionalization: The portable lung function instrument gradually develops some additional functions, such as airway pressure detection, quantitative evaluation of inhalation medication, respiratory questionnaire, pulmonary rehabilitation, etc. These corresponding functions help to achieve the implementation of one-stop solutions for disease assessment, diagnosis and treatment, and rehabilitation based on lung function. Taking respiratory rehabilitation as an example, the late stage of chronic respiratory disease can lead to chronic respiratory failure. At this time, the efficacy of the drug is limited. Early respiratory rehabilitation can reduce the symptoms of dyspnea, improve activity endurance, improve physical and mental state, improve quality of life, reduce disability rate, medical expenses and resource occupation, and extend patient life. At present, some commonly used portable pulmonary function instrument brands in China have built the respiratory muscle strength measurement and respiratory training functions into the pulmonary function instrument. The improvement of these functions will help primary medical institutions achieve the treatment and management goals of rehabilitated patients.
List of expert group writing
Advisor: Sun Tieying, Niu Shanfu, Huang Shaoguang, Liu Jinming, Sun Xingguo, Wang Huiwu
General responsible: Song Yuanlin, Zheng Jinping
Writer: Chen Zhihong, Li Li, Guo Jian, Gao Yi
Member of consultation expert group (arranged by Chinese pinyin order):
Cao Jie (General Hospital of Tianjin Medical University), Chen Fang (Zhejiang Provincial Hospital of Traditional Chinese Medicine), Chen Yahong (Third Hospital of Peking University), Chen Zhihong (Zhongshan Hospital of Fudan University), Cheng Kebin (Shanghai Pulmonary Hospital), Dai Yuan Rong (Second Affiliated Hospital of Wenzhou Medical University), Gai Xiaoyan (Third Hospital of Peking University), Gao Yi (First Affiliated Hospital of Guangzhou Medical University), Guo Jian (Shanghai Pulmonary Hospital), Guo Yi (Ruijin Hospital Affiliated to Shanghai Jiaotong University Medical College), Gu Yutong (Zhongshan Hospital Affiliated to Fudan University), Hang Jingqing (Shanghai Putuo District People's Hospital), Heping (Second Affiliated Hospital of Xi'an Jiaotong University), Jia Huiying (People's Hospital of Xinjiang Uygur Autonomous Region), Jie Zhijun (Shanghai Fifth People's Hospital of Fudan University), Jiang Depeng (Second Affiliated Hospital of Chongqing Medical University), Jiang Sunfang (Zhongshan Hospital of Fudan University), Jiang Handong (Renji Hospital of Shanghai Jiaotong University Medical College), Jin Meiling (Zhongshan Hospital of Fudan University), Li Li (Zhongshan Hospital of Fudan University), Li Li (Haihe Hospital of Tianjin University), Li Meihua (First Affiliated Hospital of Guangxi Medical University) , Li Yanming (Beijing Hospital), Liang Binmiao (West China Hospital of Sichuan University), Liu Chuanhe (Capital Pediatrics Institute), Liu Jinming (Shanghai Pulmonary Hospital), Lu Yong (Beijing Chaoyang Hospital Affiliated to Capital Medical University), Ma Qianli (Chongqing Northern Kuanren Hospital), Miao Lijun (First Affiliated to Zhengzhou University), Pang Min (First Hospital of Shanxi Medical University), Pan Zhigang (Zhongshan Hospital Affiliated to Fudan University), Qinling (Xiangya Hospital of Central South University), Que Chengli (Peking University First Hospital), Song Yuanlin (Zhongshan Hospital Affiliated to Fudan University), Sun Peili (Jiangsu Provincial People's Hospital), Sun Tieying (Beijing Hospital), Sun Xingguo (Fuwai Hospital of Chinese Academy of Medical Sciences), Su Hong (Inner Mongolia Medical University Affiliated to Inner Mongolia Medical University), Wang Lu (Zhabei Central Hospital, Jing'an District, Shanghai), Xiong Weining (Ninth People's Hospital Affiliated to Shanghai Jiaotong University Medical University), Yang Danlei (Affiliated to Tongji Medical College of Huazhong University of Science and Technology Tongji Hospital), Yang Ting (Sino-Japan Friendship Hospital), Yang Weijiang (Traditional Medicine Hospital Affiliated to Xinjiang Medical University), Yang Yimeng (Beijing Hospital), Yao Yinan (First Affiliated to Zhejiang University Medical College), Yu Li (Tongji Hospital Affiliated to Tongji University), Zhang Cheng (Guizhou Provincial People's Hospital), Zhang Xuhua (Ningxia Medical University General Hospital), Zhang Yunhui (Yunnan Provincial People's Hospital), Zhao Guihua (Henan Provincial People's Hospital), Zhao Haijin (Southern Medical University Southern Hospital), Zhao Haitao (Shenyang Military Region General Hospital), Zheng Jinping (First Affiliated to Guangzhou Medical University General Hospital), Zhou Ning (Tianjin Medical University General Hospital), Zhou Mingjuan (Guangdong Provincial Traditional Chinese Medicine Hospital), Zou Yimin (Second Hospital of Zhejiang University Medical College)
References (omitted)
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