学习临诊肺功能respiratory function test

1、Respiratory Function TestRespiratory Function Test Lung volumesVentilation functionGas exchangeBlood flowRespiratory motive forceLung Volume and SubdivisionsVTIRVERVRVICFRCVCRVTLCBasal Lung VolumeVT (tidal volume): 500mlIRV (inspiratory reserve volume)ERV (expiratory reserve volume)RV (residual volu

2、me)Basal Lung Capacity IC (inspiratory capacity): VT+ IRVFRC (functional residual capacity): ERV + RVVC (vital capacity) : IC + ERV normal men: 4217ml women: 3105ml TLC (total lung capacity): VC + RV Some Explanatory PointsLung volume is to describe the changes of the lung volume during one breathin

3、g at static conditions, also called static lung volume.VT, VC, TLC are used at clinical. VT and VC are determined by Spirometric trace , but FRC and RV by indirect method: Helium or Nitrogen analyses method.Clinical SignificanceVC depends on sex, age and height.VC% 80% is abnormal.VC : restrictive v

4、entilation disorder severe obstructive ventilation disorder Clinical SignificanceRV/TLC% (residual air rate) normal : 40 % old person can be 50%.FRC : emphysemaFRC : interstitial pulmonary fibrosisVentilation Function TestIt is called as dynamic lung volumes.Fast spirometric trace to illustrate time

5、d ventilation tests (air volume and air flow during breathing). Ventilation Function TestLung ventilation volume VE and MVVForced vital capacity (FVC)Maximal mid-expiratory flow (MMEF. MMF)Alveolar ventilation (VA) VE ( minute ventilation): = VTRR/min normal : 46 liter 10L: hyperventilationMVV ( max

6、imal voluntary ventilation): ventilative volume at the most rate and most breathing deep during a minute Normal : 80100L abnormal: 95% ventilation storage : 80% 80 70Mild reduce 80-71 70-61Mediate reduce 70-51 60-41Severe reduce 50-21 =40Respiratory failure =20Classification of Ventilative Function

7、Disorder obstruction restriction mixFEV1/FVC N or MVV or N VC N or Rate index 1.0 =1.0RV N or uncertainTLC N or uncertainDegrees of Obstructive Emphysema RV/TLC (%)Normal =56Bronchial Dilation TestMethod: to determine FEV1 and FEV1/FVC% before and after 2-agonist inhalationResult: improved rate= Pos

8、itive: 15%Reversible limitation: asthma 15% and improved volume200mlAfter-before before100%PEF Variable RatePEF (peak expiratory flow): the most flow during forced expiration. It indicates the force of respiratory muscle and airway obstruction.PEF variability=PEF variability20% : asthmaPEFmax-PEFmin

9、1/2 (PEFmax+PEFmin)100%Bronchial Provocation TestMethod : to inhale histamine from low to high concentration till the FEV1 decrease 20%. Calculate drug volume (PD20FEV1).Positive: PD20FEV17.8umol indicate airway hyperresponsiveness asthmaGas Exchange TestGas distribution: Nitrogen concentration method normal 2.5%Ventilation/perfusion ratio (V/Q) : 0.4 P(A-a)O2: 5-15mmHgDiffusion capacity (DL): CO methodSmall Airway Function TestSmall