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Lung Function Tests. Sema Umut. Lung Factors Affecting Function. Mechanical properties Resistive elements. Mechanical Properties. Compliance Describes the stiffness of the lungs Change in volume over the change in pressure Elastic recoil
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LungFunctionTests Sema Umut
Lung Factors AffectingFunction • Mechanical properties • Resistive elements
Mechanical Properties Compliance • Describes the stiffness of the lungs • Change in volume over the change in pressure Elastic recoil • The tendency of the lung to return to it’s resting state
Resistive Properties • Determined by airway caliber • Affected by • Lung volume • Bronchial smooth muscles • Airway collapsibility
A TEST SHOULD BE • Acceptabile,easy • Noninvasive • Cost effective • Informative • Reproducible
Spirometry Acceptabile,easy Noninvasive Costeffective Inexpensive Informative Reproducible
Spirometry • It is the most commonly used lung function screening study • It should be the clinician's first option
When can spirometry help us? • - Diagnosing disease • - Monitoring disease • - Prognosis • Directing therapy
Indications for Spirometry Diagnostic • To evaluate symptoms, signs, or abnormal laboratory tests • Dyspnea • Wheezing • Cough • Abnormal breath sounds • Overinflation • Expiratory slowing • Cyanosis
Abnormallaboratorytests • Hypoxemia • Hypercapnia • Polycythemia • Abnormal chest radiographs
To screen individuals at risk of having pulmonary diseases • Smokers • Individuals in occupations with exposures to injurious substances
Indications for Spirometry • To assess preoperative risk • To assess health status before physical activity programs • To evaluate therapy
Disability/ImpairmentEvaluations • To assess individuals for legal reasons
Prognosis Survival predictor of general population Copenhagen City Heart Study 13,900 subjects for 25 yrs Lange P. J Clin Epidemiol 1990; 43: 867-873. Cox proportional hazards FEV1/ht2 best index Framingham study
Spirometry Requirements 1. Good equipment 2. Good technicians (efor dependent) 3. Good clinicians - correct indication - correct use / presentation of the data - correct decision making
Pulmonary Function Testing relates • Age : Smaller lung volumes as we age • Gender : The lung volumes of males are larger than females • Height • Race
Perform manoeuvre • Attach nose clip, place mouthpiece in mouth • Inhale completely and rapidly • Exhale maximally until no more air can be expelled • Repeat for a minimum of 3 manoeuvres
ForcedVitalCapacity FVC • Total volume of airexpiredforcefullyafter a fullinspiration • Patientswithrestrictivelungdiseasehave a decreasedvitalcapacity
Slow Vital Capacity (SVC) • This is the total volume of air expired slowly after a full inspiration • If the SVC is greater than FVC,it indicates the presence of obstructive disease
Forced Expiratory Volume in 1 Second FEV1 Volume of air expired in the first second during maximal expiratory effort
FEV1/FVC • Percentage of the forced vital capacity which is expired in the first second of maximal expiration to forced vital capacity • In health the FEV1/FVC is usually around 80% • Decrease in FEV1/FVC means obstruction
Tidal volume TV The volume of air moved during normal quiet breathing (about 0.5 L)
RESIDUEL VOLUME (RV) The volume of air remaining in the lungs after a forceful expiration (about 1.0 L).
FUNCTIONAL RESIDUEL CAPACITY(FRC) The amount of air remaining in the lungs after a normal quiet expiration
TOTAL LUNG CAPACITY (TLC) It is the volume of air in the lungs when the person has taken a full inspiration TLC = RV + VC
TLC,RV,FRC Can not be measured by spirometry • Helium dilution • Nitrogenmetry • Body plethysmography
INTERPRETATION OF SPIROMETRY • Compare the measured values of the patient with normal values derived from population studies • The percent predicted normalis used to define normal and abnormal and to grade the severity of the abnormality
Categories of Disease • Obstructive • Restrictive • Mixed
Spirogrammeasurestwocomponents - airflowandvolume Ifflow is reduced, thedefect is obstructive Ifvolume is reducedthedefect is restrictive
Interpretation FVC and FEV1 are normal – NORMAL FVC is low but FEV1/FVC is >80 RESTRICTIVE FEV1/FVC < 70% OBSTRUCTIVE
Spirometry • Obstruction (FEVı /FVC) < %70
Obstructive Lung Diseases • Asthma • Chronicobstructivepulmonarydisease
COPD -COPDis characterized by airflow limitation that is not fully reversible -The airflow limitation is usually progressive and associated with an abnormal inflammatory response of the lung to noxious particles or gases
Diagnosis of COPD EXPOSURE TO RISK FACTORS SYMPTOMS cough tobacco sputum occupation shortness of breath indoor/outdoor pollution è è è SPIROMETRY
Asthma • Asthma is a chronic inflammatory disease of the airways • Inflammation causes the airways to narrow periodically • Thisproduces wheezing and breathlessness • Obstruction to air flow is reversible
Bronchodilator Test • Evaluates how responsive the patient is to a bronchodilator medication • Spirometry is repeated about 15 minutes after giving a bronchodilator (400 mg salbutamol)
WHY TEST FOR REVERSIBILITY? • To determine best function • To follow rate of change in PFTs over time • To exclude asthma • To determine response to therapy
REVERSIBILITY Increase of 200 ml or 12-15% of the baseline FEV1 shows REVERSIBLE OBSTRUCTION 40 Both drugs combined 30 20 10 0 0 2 4 6 8
Restriction • Restriction means a decrease in lung volumes
Extrinsic Restrictive Lung Disorders . Neuromuscular Disorders . Scoliosis, Kyphosis . Rib fractures . Pleural Effusion . Pregnancy . Gross Obesity . Tumors . Ascites
Intrinsic Restrictive Lung Disorders • Pnuemonectomy • Pneumonia • Lung tumors • Interstitial lung diseases • Sarcoidosis • Lung oedema
Flow – Volume Loop is a measure of how much air can be inspired and expired from the lungs It is a flow rate measurement
Restrictive Lung Disease • Characterized by diminished lung volume • Decreased TLC, FVC • Normal FEV1/FVC ratio
Large Airway Obstruction can be detected by Flow – Volume Loop • Characterized by a truncated inspiratory or expiratory loop