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Pulmonary function testing (spirometry )

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Pulmonary function testing (spirometry )

  1. 1. Pulmonary Function testing (Spirometry ) Dr. Emad Efat Shebin El kom Chest hospital July 2016
  2. 2. PFTs - Significance 1. Pulmonary Function tests (PFTs) Help in diagnosis and differentiation of many respiratory diseases (restrictive and obstructive lung disorders, diagnose exercise induced asthma, differentiate chronic bronchitis from Bronchial asthma (BA) ) 2. Explain the cause of symptoms in patients who are diseased and clinically normal (as early detection of small air way disease) 3. Assessing the course of the disease and effect of therapy (as steroids with Bronchial asthma and radiotherapy with cancer) 4. Objective quantitative measurements of lung damage due to occupational injury 5. Pre-operative assessment
  3. 3. PFTs - Classification 1. Tests of ventilatory function: Evaluate lung volumes and capacities: • Spirometry (FVC, FEV1, FEF25-75, MVV) • Body plethysmography • Gas dilution method (functional residual capacity (FRC) and residual volume (RV) detection) Evaluate hypersensitivity: broncho-provocative test 2. Tests for gas exchange: tests of diffusion (DLCo, ABGs) Oximetry for O2 saturation and Capnography for trans-cutaneous CO2
  4. 4. PFTs - Classification 3. Other Tests:  Tests for lung compliance  Tests for resistance and impedance: impulse oscillometry  Assessment of regional lung functions  Cardio-pulmonary stress tests (CPX) and assessment of respiratory muscle strength  Breath condensate
  5. 5. Spirometry • Spirometry with flow volume loops assesses the mechanical properties of the respiratory system by measuring expiratory volumes and flow rates. • Maximal inspiratory and expiratory effort. • At least 3 tests of acceptable effort are performed to ensure reproducibility.
  6. 6. ways of representing the spirometry test Spirometry
  7. 7. Acceptability and Reproducibility Criteria: 1. Acceptability criteria (within maneuver criteria): Individual spirograms are "acceptable" if: Lack of artifact induced by coughing, glottic closure, or equipment problems (primarily leak). Satisfactory start to the test without hesitation or coughing for the 1st second. Satisfactory exhalation with 6 seconds of smooth continuous exhalation, or a reasonable duration of exhalation with a plateau of at least 1 second. Spirometry - Acceptability criteria
  8. 8. Cough Variable Effort Spirometry - Acceptability criteria
  9. 9. Sub maximal effort  Trace does not curve upwards smoothly Abnormal Forced vital capacity (FVC):
  10. 10. Early stoppage • Trace does not curve smoothly up to a plateau • Affects the volume of the Forced vital capacity Abnormal Forced vital capacity
  11. 11. Coughing Trace is irregular  Extra inhalation during coughing will affect volume of FVC  Coughing is a common problem with bronchial hyper reactivity. Abnormal Forced vital capacity
  12. 12. Extra breath• Trace is not smooth and upward • Extra breath has affected the volume of the FVC • Affect FEV1 FVC giving a falsely low ratio. Abnormal Forced vital capacity
  13. 13. Slow start Patient has not made a maximum effort from the start of the blow Affects the volume FEV1 and FEV1 to FVC Abnormal Forced vital capacity
  14. 14. acceptable & unacceptable spirometric curves
  15. 15. Again, acceptable & unacceptable spirometric curves
  16. 16. 2. Reproducibility criteria (Between maneuver criteria) After 3 acceptable spirograms have been obtained, apply the following tests:  Are the two largest FVC within 0.2 L of each other?  Are the two largest FEV1 within 0.2 L of each other?  PEF values may be variable (within 15%). If these criteria are met, the test session may be concluded. Best two blows within 5% or 200ml of each other. Spirometry - Reproducibility criteria
  17. 17. If these criteria are not met, continue testing until:  The criteria are met with analysis of additional acceptable spirograms; OR  A total of 8 tests have been performed; OR  The patient cannot or should not continue Save at a minimum the three best maneuvers Spirometry - Reproducibility criteria
  18. 18. Spirometry - Reproducibility criteria
  19. 19. Spirometry - Indications • Indications: 1. Diagnostic A. To evaluate symptoms, signs or abnormal laboratory tests Symptoms: dyspnea, wheezing, orthopnea, cough, phlegm production, chest pain Signs: diminished breath sounds, overinflation, expiratory slowing, cyanosis, chest deformity, unexplained crackles Abnormal laboratory tests: hypoxemia, hypercapnia, polycythemia, abnormal chest radiographs B. To measure the effect of disease on pulmonary function
  20. 20. Spirometry - Indications C. To screen individuals at risk of having pulmonary disease: Smokers Individuals in occupations with exposures to injurious substances Some routine physical examinations D. To assess pre-operative risk E. To assess prognosis (lung transplant ...etc.) F. To assess health status before beginning strenuous physical activity programs
  21. 21. Spirometry - Indications 2. Monitoring To assess therapeutic intervention  Bronchodilator therapy  Steroid treatment for asthma, interstitial lung disease (ILD), etc.  Management of congestive heart failure  Other (antibiotics in cystic fibrosis, etc.) To describe the course of diseases that affect lung function • Pulmonary diseases (Obstructive airway diseases, ILD) • Cardiac diseases (Congestive heart failure) • Neuromuscular diseases (Guillian-Barre Syndrome)
  22. 22. Spirometry - Indications To monitor people exposed to injurious agents To monitor for adverse reactions to drugs with known pulmonary toxicity 3. To identify flow-volume loop patterns 4. Disability/impairment evaluations To assess patients as part of a rehabilitation program (medical, industrial, vocational) To assess risks as part of an insurance evaluation To assess individuals for legal reasons 5. Public health Epidemiological surveys and Derivation of reference equations Clinical research
  23. 23. Spirometry • Contraindications to Use of Spirometry Uncooperative patient and Severe dyspnoea Infectious diseases (TB) and Hemoptysis of unknown origin Pneumothorax Recent myocardial infarction or unstable angina Acute disorders (e.g., vomiting, nausea, vertigo) .  Recent abdominal or thoracic surgery Recent eye surgery (increases in intraocular pressure during spirometry) Thoracic aneurysms (risk of rupture because of increased thoracic pressure) N.B Spirometry should be avoided after recent heart attack or stroke
  24. 24. Spirometry • Performing Spirometry How to do it ?? 1. Withholding Medications Before performing spirometry, withhold:  Short acting β2-agonists for 6 hours  Ipratropium for 6 hours  Long acting β2-agonists for 12 hours  Tiotropium for 24 hours
  25. 25. Spirometry - Preparation 2. Preparation  Explain the purpose of the test and demonstrate the procedure  Record the patient’s age, height and gender  Note when bronchodilator was last used  The patient sits comfortably  Loosen any tight clothing  Empty the bladder  Breath in until the lungs are full
  26. 26. Spirometry - Preparation  Hold the breath and seal the lips tightly around a clean mouthpiece  Blast the air out as forcibly and fast as possible. Provide lots of encouragement!  Continue blowing until the lungs feel empty  Watch the patient during the blow to assure the lips are sealed around the mouthpiece  Check to determine if an adequate trace has been achieved  Repeat the procedure at least twice more until ideally 3 readings within 5% of each other are obtained.
  27. 27. Spirometry - Quality Control • Most common cause of inconsistent readings is poor patient technique • Sub-optimal inspiration • Sub-maximal expiratory effort • Delay in forced expiration • Shortened expiratory time • Air leak around the mouthpiece • Subjects must be observed and encouraged throughout the procedure
  28. 28.  Inadequate or incomplete blow & Lack of blast effort during exhalation  Slow start to maximal effort  Lips not sealed around mouthpiece  Coughing during the blow & Extra breath during the blow  Glottic closure or obstruction of mouth piece by tongue or teeth  Poor posture – leaning forwards Spirometry - Common Problems
  29. 29. Spirometry - Lung volumes Lung volumes that can be measured by spirometer: 1. Static Lung Volumes: Lung volumes that are not affected by the rate of air movement in and out of the lungs (VT, IRV, ERV, IC and VC). CAN’T MEASURE – FRC, RV, TLC. It can be measured by:  nitrogen washout technique  Helium dilution method  Body plethysmography 2. Dynamic Lung Volumes: Lung volumes that depend upon the rate at which air flows out of the lungs (FVC, MVV, FEF 25–75, MRV and FEV1)
  30. 30. Lung Volumes and Capacities - Static
  31. 31. Respiratory Volumes - Static • Static Lung Volumes and Capacities:  4 Volumes  4 Capacities: Sum of 2 or more lung volumes 1. Tidal volume (Vt), about 500 mL, is the amount of air inspired during normal, relaxed breathing. 2. Inspiratory reserve volume (IRV), about 3,100 mL, is the additional air that can be forcibly inhaled after the inspiration of a normal tidal volume. 3. Expiratory reserve volume (ERV), about 1,200 mL, is the additional air that can be forcibly exhaled after the expiration of a normal tidal volume. 4. Residual volume (RV), about 1,200 mL, is the volume of air still remaining in the lungs after the expiratory reserve volume is exhaled.
  32. 32. 1. Slow vital capacity (SVC): maximum amount of air that can be expired after deep inspiration by slow expiration 2. Forced (Timed) vital capacity(FVC): maximum amount of air that can be expired after deep inspiration by forced expiration 1. Vital capacity (VC), about 4,800 mL, is the total amount of air that can be expired after fully inhaling. Vt IRV ERV VC Respiratory Capacities - Static
  33. 33. Normal Slow vital capacity • The curve is 1. Smooth 2. Has no irregularities 3. Curves upwards 4. Reaches a plateau • FVC is read at the top of the curve, where it reaches a plateau
  34. 34. SVC FVC SVC FVC SVC FVC X
  35. 35. 2. Function residual capacity (FRC), about 2,400 mL, is the amount of air remaining in the lungs after a normal expiration. Respiratory Capacities - Static ERV RV FRC
  36. 36. 3. inspiratory capacity (IC), about 3,600 mL, is the maximum amount of air that can be inspired (IC = TV + IRV).
  37. 37. 4. Total lung capacity (TLC), about 6,000 mL, is the maximum amount of air that can fill the lungs (Vt +IRV+ ERV+ RV) { VC+RV} TLC < 80% of predicted value = restriction. TLC > 120% of predicted value = hyperinflation. VC RV TLC Vt IRV ERV RV TLC Respiratory Capacities - Static
  38. 38. Relationship between VC, RV, and TLC VC VC VC RV RV RV Normal RV TLC 20-35% Restrictive RV TLC ≤20-35% Obstructive RV TLC >35%
  39. 39.  Dynamic Lung Volumes: Lung volumes that depend upon the rate at which air flows out of the lungs (FVC, FEV1, FEF 25–75, MVV, and MRV)  Minute Respiratory Volume (MRV) : quantity of air moved into and out of the lungs in one minute (TVx Respiratory rate). Respiratory Volumes - dynamic
  40. 40. Forced vital capacity (FVC) • Total volume of air that can be exhaled forcefully from TLC • The majority of FVC can be exhaled in <3 seconds in normal people, but often is much more prolonged in obstructive diseases • Measured in liters (L)
  41. 41. Forced vital capacity (FVC) • Interpretation of % predicted:  80-120% Normal  70-79% Mild reduction  50%-69% Moderate reduction  <50% Severe reduction
  42. 42. Forced expiratory volume in 1 second (FEV1) • Volume of air forcefully expired from full inflation (TLC) in the first second • Measured in liters (L) • Normal people can exhale more than 75-80% of their FVC in the first second; thus the FEV1/FVC can be utilized to characterize lung disease
  43. 43. • Interpretation of % predicted:  Normal >75%  Mild 70-75%  Moderate 50-69 %  Severe 35-49%  Very severe < 35% Forced expiratory volume in 1 second (FEV1)
  44. 44. • Mean forced expiratory flow during middle half of FVC • Measured in L/sec • May reflect effort independent expiration and the status of the small airways • Highly variable • Depends heavily on FVC Forced expiratory flow 25-75% (FEF25-75)
  45. 45. • Interpretation of % predicted:  >60% Normal  40-60% Mild obstruction  20-40% Moderate obstruction  <20% Severe obstruction Forced expiratory flow 25-75% (FEF25-75)
  46. 46. • FEV1/FVC ratio: It indicates what percentage of the total FVC was expelled from the lungs during the first second of forced exhalation • A ratio of <70% implies obstructive disease • If the patient has a restrictive ventilatory defect, the FEV1 and FVC are both reduced, but in proportion, so the FEV1/FVC ratio remains normal (greater than 75%). FEV1/FVC ratio
  47. 47. • It is also called the maximal breathing capacity (MBC). • It's the maximum volume of air which can be respired in 1minute by deepest and fastest breathing (test of entire respiratory system). • Normal value: male: 80-200 L/min, female: 60-160 L/min. • Measured by: breathing deeply and rapidly for 15 sec. • Significance:  Index for respiratory efficiency and physical fitness  Respiratory muscle assessment.  Pre-operative assessment. • MVV= FEV1 X35 Maximum voluntary ventilation (MVV)
  48. 48. Maximum voluntary ventilation (MVV)
  49. 49. • It's the maximum flow rate over the first 10 milliseconds of forced expiration (first part of FEV1). • Normal value: 10 L/s (600 L/min) in healthy adult. • Measured by peak flow meters • Significance:  Diagnosis of Bronchial asthma ( BA ) variability >15-20 % in PEFR in a single day or from day to day is diagnostic.  Response to treatment in BA  Diagnosis of occupational asthma , and exercise induced asthma (fall of FEV1 >15%) Peak expiratory flow (PEF)
  50. 50. Peak Flow Meter Spirometry Tests of Ventilation
  51. 51. Peak flow meters
  52. 52. 1. Normal 2. Obstructive 3. Restrictive 4. Mixed Obstructive and Restrictive Spirogram Patterns Criteria for Normal Post-bronchodilator Spirometry  FEV1: % predicted > 80%  FVC: % predicted > 80%  FEV1/FVC: > 0.7
  53. 53. Spirogram Patterns Obstruction caused by: Restrictions caused by:  COPD  BA  Bronchiolitis  Pneumonia  Bronchiectasis  Cystic fibrosis  Acute bronchitis  Alpha1 anti-trypsin deficiency  Obesity  Pregnancy  Ascitis  Interstitial lung disease  Kyphoscoliosis  Pleural effusion  Pleural tumors  Neuromuscular disease  Diaphragmatic abnormality  Lung resection  Congestive heart failure  Inability to breathe (pain)  Severe obstructive disorders  Cardiomegally
  54. 54. • Criteria: Obstructive Disease  FEV1: % predicted < 80% ( used to grade the severity )  FVC: Can be normal or reduced – usually to a lesser degree than FEV1  FEV1/FVC: < 0.7 SPIROMETRY OBSRUCTIVE DISEASE
  55. 55. • Criteria: Restrictive Disease  FEV1: % predicted < 80%  FVC: % predicted < 80%  FEV1/FVC: > 0.7 SPIROMETRY RESTRICTIVE DISEASE
  56. 56. • Criteria: Mixed Obstructive/Restrictive  FEV1: % predicted < 80%  FVC: % predicted < 80%  FEV1 /FVC: < 0.7 SPIROMETRY Mixed Obstructive/Restrictive
  57. 57. Measures of Assessment and Monitoring of Asthma • Asthma diagnosis criteria:  Repeated variability in well-performed spirometic values (increase in FEV1 or FVC).  Positive bronchodilator (BD) responses (increase in FEV1 or FVC ⩾12% and 200 mL from baseline).  Positive methacholine challenge (20% fall in FEV1 at a dose ⩽8 μg/mL).  Objective lung function measurements in Asthma:  Spirometry: Forced Expiratory Maneuvers.  Exhaled Nitric Oxide.  Peak Flows.
  58. 58. FEV1 Results for Asthma
  59. 59. Positive bronchodilator responses in asthma
  60. 60. GOLD 2013: Diagnosis of COPD
  61. 61. At Risk for COPD Spirometric classification of airflow limitation • Adapted from GOLD 2013 in patients with FEV1/FVC < 0.70 GOLD 1 Mild FEV1 ≥80% predicted GOLD 2 Moderate 50% ≤FEV1 <80% predicted GOLD 3 Severe 30% ≤FEV1 <50% predicted GOLD 4 Very severe FEV1 <30% predicted
  62. 62. Changes in Lung Volumes in Various Disease States • Total lung capacity ( TLC ) < 80% of predicted value = restriction. • TLC > 120% of predicted value = hyperinflation.
  63. 63. Volume Restrictive Air trapping Hyperinflation TLC ↓ N ↑ VC ↓ ↓ N FRC ↓ ↑ ↑ RV ↓ ↑ ↑ RV/TLC% N ↑ ↑ Changes in Lung Volumes in Various Disease States
  64. 64. Bronchodilator Reversibility Testing  Provides the best achievable FEV1 (and FVC)  Helps to differentiate COPD from asthma  Must be interpreted with clinical history - neither asthma nor COPD are diagnosed on spirometry alone  bronchodilating agents: Bronchodilator Dose FEV1 before and after Salbutamol 200 – 400 µg via large volume spacer 15 minutes Terbutaline 500 µg via Turbohaler® 15 minutes Ipratropium 160 µg via spacer 45 minutes
  65. 65. Bronchodilator Reversibility Testing • Preparation • Tests should be performed when patients are clinically stable and free from respiratory infection • Patients should not have taken: Withholding Medications:
  66. 66. Bronchodilator Reversibility Testing - Spirometry 1. FEV1 should be measured (minimum twice, within 5%) before a bronchodilator is given. The bronchodilator should be given by metered dose inhaler through a spacer device or by nebulizer to be certain it has been inhaled 2. FEV1 should be measured again:  10-15 minutes after a short-acting b2-agonist  30-45 minutes after the combination  The test is considered significant if there is  > 12% increase in the FEV1 and 200 ml improvement in FEV1 OR  > 12% increase in the FVC and 200 ml improvement in FVC.
  67. 67. • To express the degree of improvement: • Calculate the absolute changes in FEV1 • Calculate the absolute changes in FEV1 from base line • % improvement in FEV1= FEV1 (post BD)- FEV1 (base line) X100 FEV1 (base line) Measuring degree of reversibility
  68. 68. Bronchodilator Reversibility Testing - Spirometry
  69. 69. Normal flow volume loop has a rapid peak expiratory flow rate with a gradual decline in flow back to zero. Flow Volume Loop
  70. 70. • As with a normal curve, there is a rapid peak expiratory flow, but the curve descends more quickly than normal and takes on a concave shape Flow Volume Loop in Obstructive lung disease Obstruction
  71. 71. ObstructionNormal
  72. 72. Restriction The shape of the flow volume loop: 1. Relatively unaffected in restrictive disease 2. Overall size of the curve will appear smaller when compared to normal on the same scale. Flow Volume Loop in restrictive lung disease
  73. 73. Flow Volume Loop
  74. 74. Spirometry interpretation 1. Assess validity 2. Determine ventilatory pattern 3. Grade severity 4. Grade response to BD challenge
  75. 75. Interpreation of results Take the best of the 3 consistent readings of FEV1 and of FVC
  76. 76. Predicted Normals = Predicted Value Depends on: 1. Age 2. Sex 3. Height 4. Race
  77. 77. Results classification 1. Normal 2. Obstructive 3. Restrictive 4. Combined
  78. 78. 1. Obstructive Pattern 2. Restrictive Pattern 3. Mixed Pattern Abnormalities of lung function are categorized as:
  79. 79. Value (95 % function test confidence interval) BMI 21- 25 kg/m2 FEV1 80-120% FVC 80-120% FEV1 /FVC > 80% FEF 25-75% 65 TLC 80-120% FRC 75-120% RV 75- 120% RV/TLC 20-35% FRC/TLC 50% Normal Values of Pulmonary Function Tests
  80. 80. Objective Measures: Spirometry Is airflow obstruction present and is it at least partially reversible? Use Spirometry to establish airflow obstruction 1. FEV1/FVC <70% 2. FEV1 < 80% Use Spirometry to establish reversibility 1. FEV1 increases >12% and at least 200 ml. after using inhaled SABA 2. A 2- to 3-week trial of oral corticosteroid therapy may be required to demonstrate reversibility
  81. 81. 1. Patients data (age, sex, body weight, height) BMI 2. Expiratory Time 3. Static lung volume 4. Dynamic lung volume (FEV1 FVC, FEV1, FVC, PEFR, PIFR, FEF25-75) 5. MVV Interpretation of Spirometry
  82. 82. 1). BMI= weight kg (Height m)2 Interpretation of Spirometry 21-25 Normal BMI No effect on PFT < 21 Under weight Nutrition suppleme ntation > 25 >25 < 30 >30 < 40 >40 Morbid obesity Obese Over weight Restrictive pattern on PFT
  83. 83. 2). Expiratory Time Interpretation of Spirometry Expiratory Time < 4 sec. Poor initial effort Restrictive Pattern Respiratory muscle weakness > 6 sec. Obstructive Pattern Normal 4-6 sec.
  84. 84. • imp NB: - Marked prolongation of exp. Time denote either:- Incorrect test …..or Resp. center depression → drug overdose, brain stem infarction, head trauma, bilat. diaphragmatic paralysis→ all of these causes mean marked noncompliance & incorrect test Interpretation of Spirometry
  85. 85. 3). SVC Interpretation of Spirometry SVC < 80 Restrictive pattern Severe obstructive pattern Combined pattern 80 - 120 Normal
  86. 86. • imp NB:- – From TV we can calculate minute ventilation – MV= TV X RR (from Exp. T) – FVC slightly less than SVC , but if there is marked disparity → one of 2 tests is incorrect Interpretation of Spirometry
  87. 87. SVC FVC SVC FVC SVC FVC X
  88. 88. 4). Dynamic lung volume: • FEV1 FVC Interpretation of Spirometry FEV1 FVC 80-120 % Nor. Or ↑ Normal Restrictive 70 -80% Combined < 70 % Obstructive
  89. 89. Interpretation of Spirometry FVC < 80% Restrictive pattern Severe obstructive pattern Combined pattern 80 – 120% Normal 4). Dynamic lung volume: • FVC
  90. 90. 4). Dynamic lung volume: • FEV1: 75 -85% Interpretation of Spirometry ↓FEV1 Marked↓↓ Obstructive slight↓ Restrictive Combined
  91. 91. 4). Dynamic lung volume: • FEF 25 -75 % : 65 % (4-5 L S) • Denote small airway diseases • The only ventilatory parameters effort independent Interpretation of Spirometry
  92. 92. 4). Dynamic lung volume: • maximal voluntary ventilation (MVV) MVV Decrease Obstructive Restrictive Resp. muscle weakness Neuro muscular Normal or↑↑ Restrictive Normal Interpretation of Spirometry
  93. 93. 4). Dynamic lung volume: All parameters of obstructive lung defects are similar to that of combined defects and differentiated only by TLC Interpretation of Spirometry Normal or increase TLC Obstructive pattern Decrease TLC Combined Pattern
  94. 94. Interpreation of results of Spirometry • Step 1. Look at the Flow-Volume loop to determine acceptability of the test, and look for upper airway obstruction pattern. • Step 2. Look at the FEV1 to determine if it is normal (≥ 80% predicted). • Step 3. Look at FVC to determine if it is within normal limits (≥ 80%). • Step 4. Look at the FEV1/FVC ratio to determine if it is within normal limits (≥ 70%). • Step 5. Look at FEF25-75% (Normal (≥ 60%)
  95. 95. Interpreation of results of Spirometry • If FEV1, FEV1/FVC ratio, and FEF25-75% all are normal, the patient has a normal PFT. • If both FEV1 and FEV1/FVC are normal, but FEF25- 75% is ≤ 60% ,then think about early obstruction or small airways obstruction. • If FEV1 ≤ 80% and FEV1/FVC ≤ 70%, there is obstructive defect, if FVC is normal, it is pure obstruction. If FVC ≤ 80% , possibility of additional restriction is there. • If FEV1 ≤ 80% , FVC ≤ 80% and FEV1/FVC ≥ 70% , there is restrictive defect, get lung volumes to confirm.
  96. 96. Interpreation of results of Spirometry • Different patterns: Mixed A reduced FVC together with a low FEV1/FVC% ratio is a feature of a mixed ventilatory defect, or air trapping.  It is necessary to measure the patient's total lung capacity to distinguish between these two possibilities.
  97. 97. FEV1FVC > 70% Normal or restrictive < 70 % Obstructive FVC or TLC Decrease Normal Normal Spirometry Restrictive DLCO Normal chest wall ↓ Lung diseases FEV1 (severity) FVC ↓↓ Normal or ↓ TLC ↓ combined ↑↑ Pseudo- restriction Pure Obstruction
  98. 98. Again , more simple
  99. 99. Parameter Obstructive Combined Restrictive Expiratory time > 6 sec. <4-4 sc. < 4 sec. FEV1 FVC ↓70% 70-79% Normal or ↑ FVC Normal or ↓ ↓ ↓↓ FEV1 Marked ↓↓ ↓ Normal or slightly ↓ PEFR ↓↓ ↓ Normal or ↑with linear ↓in flow vs. lung volume PEF 25-75% ↓↓ (COPD) ↓ Normal or ↓↓ MVV ↓↓ ↓↓ ↓ TLC Normal or ↑ ↓ ↓↓ Classification of Ventilatory Abnormalities by Spirometry
  100. 100. • Normal • SVC=FVC ≥ 80% • FEV1 ≥ 80% • FEV1FVC (IVC) ≥ 80% • FEF 25-75 ≥ 65% • FEF50 FIF50≤ 1 • ET= 4-6 sec • MVV (male 80-200 L, female 60-160 L) • Obstruction • SVC=FVC = 80% N • FEV1 • FEV1FVC (IVC) • FEF 25-75 < 65% • FEF50 FIF50 ≤ 0.3 • ET= ≥ 6 sec • MVV • Restrictive • SVC=FVC • FEV1 N • FEV1FVC (IVC) N • FEF 25-75 ≥ 65% • FEF50 FIF50≤ 1 • ET= 4 • MVV (male 80-200 L, female 60-160 L)
  101. 101. FVC NORMALFVC < 80% Pred. 80% Normal Lungs FEV1÷FCV is N Obstructive Disease FEV1÷FCV is Low Restrictive Disease FEV1÷FCV is High Combined Obs+Res FEV1÷FCV is N or L The Four Square GameFEV1NORMALFEV1<80%ofPd. 80%
  102. 102.  In normal subject: FIF 50% or MIF50% is usually greater than FEF50%  SO, FEF50% / FIF50% → <1 Upper airway obstruction
  103. 103. Upper airway obstruction FEF50 % FIF50% (MEF 50 MIF 50%) 1 or near 1 MEF 50= MIF 50% Fixed large airway obstruction High (> 1) FIF50% Variable extra- thoracic airway obstruction Very low (0.3) FEF50% Variable intra – thoracic air way obstruction
  104. 104. 1. If FEF50% / MIF50% → Less than 1→ normal 2. If FEF50% = MIF50% or FEF50% / MIF50% → 1 or near 1→ fixed large airway obstruction DD:- goiters, Neoplasm, foreign body, or stricture from previous intubation NB:- Observe FEV1 & FIV1 are nearly equal. 3. If FEF50% / MIF50% → High (usually greater than 2) →variable extra thoracic airway obstruction e.g.: vocal cord paralysis, thyromegaly, tracheomalacia, or neoplasm NB:- Observe FEV1 is greater than FIV1 . 4. If FEF50% / MIF50% → Very low (may reach 0.3) →variable intra thoracic airway obstruction e.g.: tracheomalacia or neoplasm NB:- Observe FEV1 is lower than FIV1 Upper airway obstruction
  105. 105. Upper Airway Obstruction • Truncation of flow loop: Expiratory – Intra Thoracic Inspiratory –Extra Thoracic Both – Fixed Obstruction
  106. 106. Patterns of Abnormality
  107. 107. Patterns of Abnormality
  108. 108. Patterns of Abnormality
  109. 109. Thank you
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