Pulmonary Function Tests.ppt

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Dr. Nisreen Mansour Dr. Nisreen Mansour Pulmonary Function Pulmonary Function Tests Tests

Transcript of Pulmonary Function Tests.ppt

  • Pulmonary Function Tests

  • I- Static TestsDescribe change in volume of the lungs during 1 breathe

  • I- Static Tests1- Minute Respiratory Volume (MRV)Volume of air that enters into the lung in 1 min. = Tidal volume x Resp. rate = 500 ml x 16 = 8 L/min

  • 2- Effective Pulmonary Ventilation (E.P.V)The volume of air that actually undergoes gas exchange in the alveoli with the pulmonary capillaries = 350 ml of 500 ml that represent Tidal volumeThus, E.P.V or Alveolar ventilation = 350 ml x 16/min =5.6 L/min

  • The difference in volume between MRV & EPV that = 500-350= 150 mlWhy calculating the alveolar ventilation is important? Because some diseases can affect EPV but not the MRV

  • 3- Dead Space

    The space that contains the volume of air that dose not undergo gas exchangeDead space is filled with inhaled air at the end of inspiration & with alveolar air at the end of expirationTypes of Dead space: Anatomical; conducting zone of resp.tract Physiological; non-functioning or partly functioning alveoli Physiological DS = anatomical D.S + non-functioning alveoli

  • 4- Lung Volumes & CapacitiesSpirometry is measuring lung volumes & capacities (except RV, FRC).The device is spirometerSpirometry - gives a preliminary idea about lung functions - Assessment of bronchodilator treatment

  • Lung Volumes 1- Tidal volume = 500 ml2- Inspiratory Reserve volume = 3000 ml3- Expiratory Reserve volume = 1000 ml4- **Residual Volume (what is its significance?) = 1200 ml5- Minimal Air (1st breath air; of medicolegal importance)

  • Spirogram; record of Lung Volumes & Capacities

  • Lung Capacities1- Inspiratory Capacity =TV+IRV=500+3000= 3500 ml2- Expiratory Capacity = TV+ERV= 500+1000 = 1500 ml3- Functional Residual Capacity = volume remaining in lungs after normal expiration = RV+ERV = 1200+1000 = 2200 ml4- Vital capacity = TV+IRV+ERV=500+3000+1000 = 4500 ml5- Total lung capacity = VC+RV= 4500+1200 = 5700 ml

  • Vital CapacityDef. Factors affecting VC:PostureAbdominal contentRespiratory musclesThoracic wallResistance to airflowLung elasticity Pulmonary blood volume

    Lung Chest

  • II- Dynamic Lung Functions Tests1- Maximal Voluntary Ventilation (MVV) or MBCBreathing as rapid & as deep as possible for 15 sec= 80-160 L/min in = 60-120 L/min in Breathing Reserve = MVV-MPV =100 - 8 = 92 L/minDyspnoea Index = Breathing Reserve/MBC Normally = 90% Dyspnoea < 60%

  • 2- Timed Vital Capacity (FVC) & Forced Expiratory Volume (FEV) Useful & common screening test Forced expiratory volume (FEV) used for measuring volume of air expired/unit timeNormally, one expires 80% of VC in 1st second, so ratio FEV1/FVC = 8o% or more- By 2 sec. ratio FEV2/FVC = 93%- By 3 sec. FEV3/FVC = 97%

  • FEV/FVCFEV1/FVC < 80% : Obstructive lung dis.FEV1/FVC 80%: restrictive lung dis.

  • 3- Peak Expiratory Flow Rate (PEFR)Measuring maximal velocity of expired air after forceful inspiration using peak flow meterValues for age, sex, heightAlternative for FEV/FVCReduced in Obstructive lung dis.Of special importance in asthma for rapid follow up of treatment efficacyPEFR (L/min) = [Height (cm) - 80] x 5

  • Obstructive Spirogram vs. Normal0231

  • A key of Ventilation Disorders

  • THANK U