Content Indica c tion Lung v olumes e & Lung Indica c tions i n c paci c ties

Transcription

1 Spirometry

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5 Content Indication Indications in occupational medicine Contraindications Confounding factors Complications Type of spirometer Lung volumes & Lung capacities Spirometric values Hygiene & infection control Spirometry steps Reference values Interpretation

6 Pulmonary function tests Spirometry Post bronchodilator spirometry Bronchial challenge test Diffusing capacity of lung (DLCO) Arterial blood gas (ABG) Static lung volumes (TLC, RV ) Resistance & compliance of lung

7 Definition of spirometry A physiological test for measuring volumes inhaled or exhaled by an individual as a function of time

8 Indication Not a screening test for general population Diagnostic Monitoring Impairment evaluation

9 Indication (diagnostic) Evaluation of symptoms and signs Measuring the effect of dis. on pulmonary function Screening individuals at risk for pulmonary dis. Assess preoperative risk

10 Indication (monitoring) Assess therapeutic intervention Monitor people exposed to injurious agents

11 Indications in occupational medicine Primary prevention (Pre-employment) employment) physical demands of a job require a certain level of cardiopulmonary fitness, eg, heavy manual labor or firefighting Respirator use can impose a significant burden on the cardiopulmonary systems, eg, use of a selfcontained breathing apparatus, or prolonged use of certain negative-pressure masks under conditions of heavy physical exertion and/or heat stress

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13 Secondary prevention Medical surveillance programs & periodic evaluation OSHA : asbestos, cadmium, coke oven emissions, or cotton dust respirator-wearers exposed to benzene, formaldehyde methylene chloride Silicosis Spirometry detect large changes over a short time or smaller changes cumulated over a longer observation period, it is not sensitive to small, short-term term changes Tertiary prevention Follow-up spirometry Workers compensation setting

14 Contraindications Active hemoptysis Pneumothorax Unstable Cardiovascular status (6 w) Cerebral/Thoracic/Abdominal aneurysm Recent eye surgery Acute disorder that may interfere with performance (e.g, vomiting) Thoracic or abdominal surgery( 3 w) Recent CVA or pulmonary emboli Respiratory distress

15 Confounding factors Common cold (3 days ego) Severe respiratory infection (3w) Smoking( 1hr) Heavy food (1hr) Bronchodilator use

16 Complications Chest pain Syncope, dizziness Increased ICP Paroxysmal coughing Nosocomial infection Bronchospasm

17 Type of spirometer Volumetric spirometer Flow-type spirometer

18 Spirometry standards ATS (American Thoracic Society) ERS (European Respiratory Society)

19 Lung volumes TV :The: volume of air inhaled & exhaled at each breath during normal quiet breathing IRV: The maximum amount of air that can be inhaled after a normal inhalation ERV: The volume of air that can be forcefully expired following a normal quiet expiration RV: The volume of air remaining in the lungs after a forceful expiration

20 Lung capacities TLC: The total volume of the lungs VC:The maximum amount of air that can be exhaled after the fullest inspiration possible IC :The : maximum of air that can be inhale after end tidal position FRC: The amount of air remaining in the lungs after a normal quiet expiration

21 Lung volumes VC IC TLC ERV RV RV

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24 Spirometric values FVC FEV 1 FEV 1 /FVC FEV t FEF PEF FVC (forced vital capacity) (forced expiratory volume in 1 s) (forced expiratory volume in t s) (maximum midexpiratory flow) PEF (peak expiratory flow) VT curve FV curve

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26 Normal values depends on: Age Height Kyphoscoliosis arm span (H=arm span/1.06) Gender Race Caucasian

27 Hygiene & infection control Hand washing Gloves Disposable mouth piece & nose clip Disinfection or sterilization of reusable mouth piece Extra precautions for patient with known transmissible infection

28 Spirometry steps Equipment performance criteria Equipment validation Quality control Subject maneuvers Measurements procedures Acceptability Repeatability interpretation

29 Equipment validation Calibration: daily if for screening every 4hr

30 calibratio n

31 Subject maneuvers FVC maneuver Closed circuit Open circuit Well-fitting Sitting or standing Nose clip Procedure 1. Inhale 2. Exhale

32 maneuver evaluation Start of test criteria - Extrapolation volume (EV < -Time-to-PEF < s End of test criteria (EV < 5% of FVCor 150 ml) - the subject cannot or should not continue - exhalation at least 6s (in children <10 yrs: at least 3s) - volume-time curve show no change in volume (< lit) for at least 1s In obstruction or older subjects more than 6s exhalation (till 15s)

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34 a b c

35 Acceptability Start of test criteria End of test criteria Cough especially during first second Valsalva maneuver (glottis closure) Leak from the mouth Obstruction of the mouthpiece Extra breath during the maneuver

36 Acceptable spirogram

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38 G rainbow

39 Reproducibility At least three acceptable maneuvers Maximum difference between the largest and next largest FVC and FEV 1 = 150ml or 5% (If FVC <1lit, this value is 100ml)

40 Reproducibility

41 Flow chart of criteria Perform FVC Acceptability criteria 3 acceptable maneuvers Repeatability criteria Largest FVC and largest FEV1 Maneuver with largest FVC + FEV1 for other indices

42 Reference values Knudson (male/ female) NHANES III (race difference) ACOEM recommends that the NHANES III equations be considered for general use in the occupational setting ERS ATS

43 Predicted value & lower limit of normal (LLN) LLN : fifth percentile, the point below which 5% of normal subjects fall. LLN calculated in this way affect by age sex, height & race

44 LLN FEV 1 and FVC = 80% FEV 1 /FVC = 70-75% FEF = 50-60%

45 Interpretation

46 A. Normal: both the FVC and the FEV 1 /VC ratio are normal. K nee

47 B.Obstructive : FEV1/FVC, FEV1 TLC & RV or NL

48 The severity of the abnormality is graded: - % Pred FEV 1 > 100 = May be a physiological variant - % Pred FEV 1 < 80 and > 70 = Mild - % Pred FEV 1 < 70 and > 60 = Moderate - % Pred FEV 1 < 60 and > 50 = Moderately severe - % Pred FEV 1 < 50 and > 35 Severe - % Pred FEV 1 < 34 = Very severe

49 C. Restrictive: FEV1/FVC or NL FVC & FEV1, TLC & RV

50 The severity of the abnormality might be graded as follows: - % Pred FVC < LLN and > 70 = mild - % Pred FVC < 70 and > 60 - % Pred FVC < 60 and > 50 Moderately severe - % Pred FVC < 50 and > 34 = Moderate = = Severe - % Pred FVC < 34 = Very severe

51 D.Mixed pattern: FEV1, FVC, FEV1/FVC< LLN

52 VC VC VC RV Obstructive RV Normal RV Restrictive

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56 Upper airway obx

57 Early small airway obx FV curve :upward concavity FVC, FEV1, FEV1/FVC :NL FEF 25-75??? ATS states that FEF25-75% should not be used to diagnose small airway disease or to assess respiratory impairment

58 Probably normal spirogram Only FEF No small airway disease (ATS) If FEV1/FVC is borderline airway obx Only FEV1/FVC FEV1> 100% Normal FVC>100%

59 Non-specific ventilatory pattern FEV1/FVC NL FEV1 < LLN FVC< LLN TLC, RV, DLCO NL Obesity Normal variant Occult asthma Early stage of parenchymal disease

60 Spirogram with restrictive pattern Spirogram with mixed pattern Spirogram with obstructive pattern

61 Case 1 A 71 yrs male Height :175,weight :88 FVC:45% FEV1: 31% FEV1/ FVC :53 53% FEF25-75 :15%

62 Case 2 A 36 yrs female Height :162,weight :83 FVC:89% FEV1: 94% FEV1/ FVC :89 89% FEF25-75 :131% TLC :92%

63 Case 3 A 29 yrs female Height :165,weight :109 FVC:78% FEV1: 79% FEV1/ FVC :86 86% FEF25-75 :85% TLC :82%

64 Case 4 A 43 yrs female Height :167,weight :61 FVC:33% FEV1: 17% FEV1/ FVC :42 42% TLC :114% RV/TLC :103%

65 Case 5 A 30 yrs male Height :186,weight :68 FVC:19% FEV1: 21% FEV1/ FVC :93 93% FEF25-75% :48% TLC :28%

66 Case 6 A 30 yrs male Height :175,weight :70 FVC: 88% FEV1: 69% FEV1/ FVC :66 66% FEF25-75 :38% VEXT : 90

67 Case 7 A 29 yrs male Height :179,weight :83 FVC: 104% FEV1: 84% FEV1/ FVC :67 67% FEF25-75 :51% VEXT : 120

68 Case 8 A 26 yrs male Height :177,weight :67 FVC: 97% FEV1: 77% FEV1/ FVC :66 66% FEF25-75 :48% VEXT : 60

69 Post bronchodilator spirometry (reversibility testing) Short-acting inhaled drugs should not be used within 4h of testing Long-acting should be stopped for 12h prior test Smoking should be avoided for 1h Salbutamol 400 µg (4 puffs) at min and up to 15 min 30s s intervals Ipratropium bromide 160 µg (4 puffs) 30 min later

70 Positive reversibility testing Percent change from baseline & absolute change in FEV1 and/or FVC : >12% AND 200 CC

71 A 24 yrs male Height :170,weight :82 FVC:80% FEV1: 70% FEV1/ FVC :69 69% FEF25-75 :50%

72 pre post %change FVC FEV FEV1/ FVC FEF

73 Case 7 A 70 yrs male Height :172,weight :65 pre %pred post %chg FVC FEV FEV1/ FVC 64.5

74 Case 26 A 28 yrs male Height :192,weight :92 pre %pred post %chg FVC FEV FEV1/ FVC 68.2

75 Change in spirometric indices over time In occupational setting, changes over time in pulmonary function should be examined for two reasons: (1) to evaluate a worker's response to treatment in the clinical setting (2) to screen healthy workers for excessive loss of function over time.

76 Change in spirometric indices over time NIOSH :(0.85.baseline value) (expected decline over time) FEV1 FVC male female male female 30 ml/yr 25 ml/yr 25 ml/yr 25 ml/yr

77 Significant change in periodic spirometry (ATS) > 15% of FEV1 or FVC over one year > 5% of FEV1 or FVC over one working shift (8 am- 4 pm) > 25-30% of PEF over one working shift

78 Bronchial provocation test Specific: emergency hospital available Nonspecific : out patient Purpose : detection hyper reactive airways

79 Methacholine challenge test (MCT) Most agent for BCT: methacholine Immediate response More useful in excluding a dx of asthma Excellent sensitivity

80 MCT is also positive in: Allergic rhinitis Sarcoidosis (50 50%) COPD CF

81 Data presentation PC20 provocative concentration causing a 20% fall in FEV1

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