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Pulmonary Function Testing,Pulmonary Function Testing,How much air volume can be moved in and out of the lungsHow fast the air in the lungs can be moved in and outHow stiff are the lungs and chest wall - a question about complianceThe diffusion characteristics of the membrane through which the gas moves (determined by special tests)How the lungs respond to chest physical therapy procedures,Evaluating the patient prior to surgery,2,Used for the following reasons,vital capacity,A vital capacity is an important preoperative assessment tool.Significant reductions in vital capacity (less than 20 cc/Kg of ideal body weight) indicates that the patient is at a higher risk for postoperative respiratory complications.This is because vital capacity reflects the patients ability to take a deep breath, to cough, and to clear the airways of excess secretions.,Contents,Documenting the progression of pulmonary disease - restrictive or obstructive,4,Documenting the effectiveness of therapeutic intervention,Used for the following reasons,Bronchial classification,pulmonary alveoli,RB 呼吸性细支气管,AD 肺泡管A 肺泡,impact factors,gender and body size which have an impact on the lung function of one individual compared to another.Race environmental factors and altitude,Static lung parameter,IRV,ERV,VT,VC,Spirometry,FRC,RV,Terminology and Definitions,FVC - Forced Vital Capacity FEV1 - Forced Expiratory Volume in One Second FEV1/FVC - FEV1 Percent (FEV1%) - T FEV1/FVC ratio. FEV3 - Forced Expiratory Volume in Three Seconds FEV3/FVC - FEV3% - This number is the ratio of FEV3 to the FVC -,PEFR - Peak Expiratory Flow Rate FEF - Forced Expiratory Flow - Forced expiratory Flow is a measure of how much air can be expired from the lungs. FEF25%, FEF50%, and FEF75% of FVC.FEF25%-75% - MVV - Maximal Voluntary Ventilation,What Can A PFT Be Used For,Pulmonary function abnormalities can be grouped into two main categories : obstructive defects. restrictive defects.,Obstructed Airflow,be reduced for a number of reasons ：narrowing of the airways due to bronchial smooth muscle contraction as is the case in asthmanarrowing of the airways due to inflammation and swelling of bronchial mucosa and the hypertrophy and hyperplasia of bronchial glands as is the case in bronchitismaterial inside the bronchial passageways physically obstructing the flow of air as is the case in excessive mucus plugging, inhalation of foreign objects or the presence of pushing and invasive tumors,destruction of lung tissue with the loss of elasticity and hence the loss of the external support of the airways as is the case in emphysemaexternal compression of the airways by tumors and trauma,Obstructed Airflow,Restricted Airflow,Extrinsic Restrictive Lung Disorders 1.Scoliosis, Kyphosis2. Ankylosing Spondylitis3.Pleural Effusion (fluid in the pleural cavity)4.Pregnancy5. Gross Obesity6. Tumors7.Ascites8. Pain on inspiration - pleurisy, rib fractures,Neuromuscular Restrictive Lung Disorders1.Generalized Weakness malnutritio2. Paralysis of the diaphragm3.Myasthenia Gravis 4. Muscular Dystrophy5. Poliomyelitis6. Amyotrophic Lateral Sclerosis - Lou Gerigs Disease,Restricted Airflow,Restricted Airflow,Intrinsic Restrictive Lung Disorders 1.Sarcoidosis（结节病）2. Tuberculosis（结核）3.Pnuemonectomy (loss of lung)4. Pneumonia（肺炎）,Criterion for Obstructive and Restrictive Disease,FVC （用力肺活量）In obstructive diseases, the lungs air volume will be more slowly expelled and will be a smaller volume over the time course of the FVC test than would be expected in a normal, healthy individual. In patients with restrictive lung disease, the FVC will be smaller because the amount of air that can be forcefully inhaled or exhaled from the lungs is smaller to start with because of disease.,Criterion for Obstructive and Restrictive Disease,Since FVC will be smaller in obstructive disorders and in restrictive disorders (usually no one worries about the FVC unless it is 80% - 85% of predicted volumes), FVC alone cannot be used to diagnose obstructive and restrictive disorders all by itself,Criterion for Obstructive and Restrictive Disease,The patient may repeat the test after inhaling a bronchodilator. an improved FVC - often times a 10% - 15% improvement.This simple clinical test strongly suggests that the FVC was low due to obstructive phenomenon. If the FVC did not change, it suggests the FVC was possibly low due to restrictive pathologies.,Another strategy that can help you decide if the low FVC is due to obstructive or restrictive processes is to have the patient perform a Slow Vital Capacity (SVC) Test. This test is performed by having the patient slowly and completely blow out all of the air from their lungs.,Criterion for Obstructive and Restrictive Disease,F V C,If the vital capacity improves after a SVC test, then it can be assumed that the original small FVC was caused by airway collapse and does not indicate the presence of restrictive disease.If the vital capacity does not improve either with the inhalation of a bronchodilator or does not improve with the administration of a SVC test, then restrictive pathologies must be considered as a possible cause for the small vital capacity results.,FEV1 FEV1%,FEV1Healthy individuals to be able to expell 75% - 80 % highly diagnostic of obstructive diseasFEV1% a low FEV1 and the FEV1% is low -obstructive pathologies a low FEV1 and so will the FVC the %FEV1 may well be calculated to be between 85% - 100% of normal. -restrictive disease,通气功能的临床意义,临床上常用第1秒用力呼出气量(FEV1)应1.2升,若80%).,FEV1%=FEV1/FVC100,FEF25%- 75%,the presence of obstructive airway disease. the first quarter of the FVC test is in part effected by the patients effort in overcoming the inertial forces which resist thoracic wall expansion. last quarter of a FVC test is polluted by the patients diminishing physical effort, the instigation of bronchospasm during forced expiration most representative of true expiratory patency and is therefore a very sensitive test for the presence of obstructive disease.,2018/5/8,28,Dynamic lung parameter,通气功能的临床意义,最大呼气中期流量(MMEF): 将FVC曲线起始至终止两点平均分为四等分， 取其中间2/4段(MEF75 MEF25)的肺容量与其所用的呼气时间之比所得之值, 見下图 MMEF=AB/CD 单位: L/sec。 MMEF反映的是呼气的非用力 部分,至一定程度用力时流量恒 定不变,流量的大小取决小气 道的直径,反映了小气道气流阻 塞.比FEVF1,FEV1%能灵敏地 反映小气道阻塞情况.,How Do You Tell If The Patient Is Normal or Has Mild, Moderate or Severe Pulmonary Disease?,There are a number of systems which physicians use to determine the severity of disease.Here is just one way that is very commonly used :Normal PFT Outcomes - 85 % of predicted valuesMild Disease - 65 % but 50 % but 65 % of predicted valuesSevere Disease - 50 % of predicted values,The PFT Before and After Aerosol Bronchodilators,Beta-2 selective sympathomimetic （沙丁胺醇）This assesses the degree of reversibility of the airway obstruction.FVC, FEV1 and FEF25% - 75% improve, then it can be said that the patient has a reversible airway obstruction FVC : an increase of 10% or moreFEV1 : an increase of 200 ml or 15% of the baseline FEV1FEF25%-75% : an increase of 20% or more,a systematic way to read the PFT,Step 1. Look at the forced vital capacity (FVC) to see if it is within normal limits.Step 2. Look at the forced expiratory volume in one second (FEV1) and determine if it is within normal limits.Step 3. If both FVC and FEV1 are normal, then you do not have to go any further - the patient has a normal PFT test.,a systematic way to read the PFT,Step 4. If FVC and/or FEV1 are low, then the presence of disease is highly likely.Step 5. If Step 4 indicates that there is disese then you need to go to the %predicted for FEV1/FVC.If the %predicted for FEV1/FVC is 88%-90% or higher, then the patient has a restricted lung disease.If the %predicted for FEV1/FVC is 69% or lower, then the patient has an obstructed lung disease.,Decision : This person is obstructed,Decision : This person is obstructed,Decision : This person is obstructed,Decision : This person is obstructed,实 例,男，59岁。身高151cm。体重46kg。,谢 谢！,
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