英文版肺功能检查

Pulmonary Function Testing,Respiratory Department of the Second Affiliated Hospital of Guangzhou Medical University Huaxing Huang,History of pulmonary function testing,More than 300 years, water sealed spirometer wedged-typed spirometer drum-typed spirometer digitalized spirometerIn 1679,BORELLI measured lung volume firstly.In 1846,HUTCHINSON put forward the concept of vital capacity.In 1919,NIANSTROHL put forward the concept of forced vital capacity.In 1967,DOLLFUSS put forward the concept of disease of small airway.In 1979,ATS setup the work standards of pulmonary function testing.,Clinical Pratice of Pulmonary Function Testing,DiagnosticObjective AssessmentMonitoringEvaluations for Disability / Impairment,Lung volume and capacityVentilation functionDiffusion functionMechanics of breathing,Main Programs of Pulmonary Function Testing,Lung volume,Lung volume means the maximal volume of gas contained by a lung.Lung volume = tidal volume(VT) + inspiratory reserve volume(IRV) + expiratory reserve volume(ERV) + residual volume(RV)Lung capacity: inspiratory capacity(IC), vital capacity(VC), functional residual capacity(FRV), total lung capacity(TLC),Curve of lung capacity,Vital capacity,Themaximumvolumeofairthatcanbe inspiredbyforcefulexpiration.,Residual volume,Inspiratory reserve volume,Expiratory reserve capacity,Total lung capacity,Tidal volume,Functional reserve volume,Tidal volume (VT),Thevolumeofairinspiredorexpiredwitheachnormalbreath.8-15ML/KG,Inspiratory capacity（IC）Inspiratory reserve volume（IRV）,IC, themaximumvolumeofairthatcanbe inspiredbyforcefulexpiration. It is equal to VT plus IRV.IRV, themaximumextravolumeofairthatbe inspiredoverandabovethenormaltidalvolume.These reveal the maximam expansion of lung and chest at static state.,Expiratory reserve volume (ERV）,Themaximumextravolumeofairthat beinspiredoverandabovethenormal tidalvolume.It reflects the power of expiratory muscle and abdominal muscle.,Vital capacity （VC）,Thelargestamountofairthatcanbeexpiredafteramaximalinspiratoryeffortfrequently.VC varies among normal bodies, so ratios of measured VC to predicted VC are used for judgment.Grading standard： ratio of measured VC to predicted VC 80%normal 60-79%mildly reduced 40-59%moderately reduced FRC%Pred 120% increased FRC10L hyperventilationMV3L hypoventilation,Alveolar ventilation (VA),The amount of air reaching the alveoli per minute at rest.Anatomic dead space: thespaceintheconducingzoneoftheairwaysoccupiedbygas thatdoesnotexchangewithbloodinthepulmonaryvessels, such as the space in nose and pharynx.Alveolar dead space: some of the alveoli themselves are nonfunctional or only partially functional because of absent or poor blood flow through adjacent pulmonary capillaries.Physiological dead space（VD）= Anatomic dead space + Alveolar dead space . VA=（MVVD）RR,VA varies in bodies and ranges from 3 to 5.5L. VA reflects the effective ventilation. Reduction of MVV and increased dead space will result in alveolar hypo-ventilation.Dead space that results from deep and slow breathing is less than that of shallow and rapid breathing. So less respiratory rate and more VT will be better for VA.,Alveolar ventilation (VA),Maximal volumtary ventilation （MVV）,The total amount of new air moved into the respiratory passages by deepest and faster breathing in each minute. It depends on lung volume, compliance of lung and thorax, airway resistance and respiratory muscle. MVV%Pred 80% normal Damage grading： MVV%Pred 60-79% mildly reduced 40-59% moderately reduced 40% severely reduced,Increased airway resistance: asthma Thoracic deformity or neuromuscular diseases: kyphoscoliosis, Guillian-Barre syndrome Diseases of lung tissue：pulmonary edema,Main causes of reduced MVV,Timed Vital Capacity (TVC),FVCFEV1FEV1 /FVC%MMEFPEF,Timed Vital Capacity (TVC),FVC(forced vital capacity):This is the amount of air expelled from the lungs after first filling the lungs to maximum extent and then expiring rapidly and forcefully.FEV1(forced expiratory volume in one second)is the amount that can be got in the first second when FVC is measured.FEV1/FVC%：ratio of FEV1 to FVC,Timed Vital Capacity (TVC),MMEF (maximal mid-expiratory)：After FVC divided into four average parts, divide the amount of the two middle parts by the corresponding expiratory time, MMEF will be got.,Timed Vital Capacity (TVC),FVC%Pred 80% FEV1%Pred 80% FEV1/FVC 70%-80% FEV1%Pred can be used to evaluate the damage degree of ventilation and differentiate obstructive ventilation dysfunction from restrictive ventilation dysfunction.,TimeVolume curve,restrictive,obstructive,Clinical SignificanceIn normal body, FVC is closed to VC. Increased intrapleuralpressure makes small airway close in earlier stage of expiration. At this situation, FVC is less than VC. It happens to patients with COPD.Evaluate ventilation dysfunction： obstructive diseases: FEV1 /FVC% reduced, flat curve restrictive diseases:FEV1/FVC% normal or increased, gradient curve,Grading Classification of Ventilation Function in COPD (bronchial dilator used),PEF (peak expiratory flow),The maximal flow during a forceful expiration. PEF should be measured in the morning, afternoon and before sleeping. PEFR= （PEFmaximum-PEFminimum) 2 PEFmaximum+PEFminimumPEF help to evaluate the chage of airway resistance.,100%,Classification of ventilation dysfunction,Obstructive ventilation dysfunctionRestrictive ventilation dysfunctionMixed ventilation dysfunction,Characteristics of ventilation dysfunction,Characteristics of ventilation dysfunction,Diffusion function,Gas exchange function means the course of gas exchange, including the exchange of O2 and CO2 between alveolus and blood, blood and histocyte. It involves lung ventilation, blood perfusion, ventilation-perfusion ratio and diffusion function.Diffusion function can be measured to evaluate gas exchange function to some extent.,Diffusion function,The gas exchange between alveolus and blood capillary from the high partial pressure side to the low side.Relative factors: molecular weight, solubility, gas partial pressure gradient, diffusion area, diffusion distance.,Gas Exchange,PO2104 mm HgPCO240 mm Hg,PO2104 mm HgPCO240 mm Hg,PO240 mm HgPCO245 mm Hg,Clinical significance Factors that can reduce the capacity of diffusion:Reduced effective diffusion area: atelectasis, airway obstruction, pulmonary embolism Increased diffusion distance: PIF, pulmonary edema, sarcoidosis, alveolar cell carcinomaThe capacity of diffusion also depends on gas partial pressure.,FlowVolume curve (F-V loop),Its a record about the course that take a rapid expiration to the extent of RV after a maximal inspiration to the extent of TLC. The flow rises rapidly at the beginning of forceful expiration and reaches the point of PEF soon. With the reduction of VC, the flow goes down perpendicularly almost.,PEF and Vmax75 reflect the main airway resistance and respiratory muscle strength. Vmax50 and Vmax25 reflect small airway resistance. Descending branch sinks to the volume axis in obstructive diseases, but VC may not reduce.In restrictive diseases, the curves rise sharply and the descending branches sink nearly perpendicularly. They have reduced VC.,FlowVolume curve (F-V loop),flow,volume,Types of FlowVolume curves of Different Ventilation Dysfunction,normal,obstructive,restrictive,mixed,changeable External chest typedupper airway obstruction,flow,volume,expiration,inspira