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Spirometry
By: Dr Saraei
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
Definition of spirometry
A physiological test for measuring volumes inhaled or exhaled by an individual as a
function of time
Indication
• Not a screening test for general population
• Diagnostic • Monitoring• Impairment evaluation• Public health
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
Indication (monitoring)
• Assess therapeutic intervention• Monitor people exposed to injurious agents
Indications in occupational medicine
• Primary prevention (Pre-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 self-contained breathing apparatus, or prolonged use of certain negative-pressure masks under conditions of heavy physical exertion and/or heat stress
• Research (Respiratory hazards)
• 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 changes
• Tertiary prevention• Follow-up spirometry• Workers’ compensation setting
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
Confounding factors
• Common cold (3 days ago)• Severe respiratory infection (3w)• Smoking( 1hr)• Heavy food (1hr)• Bronchodilator use
Complications
• Chest pain• Syncope, dizziness• Increased ICP• Paroxysmal coughing• Nosocomial infection• Bronchospasm
Spirometry standards
• ATS (American Thoracic Society)
• ERS (European Respiratory Society)
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
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
Lung Volumes
• 4 Volumes
• 4 Capacities– Sum of 2 or
more lung volumes
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
15
Tidal Volume (TV)
• Volume of air inspired and expired during normal quiet breathing
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
16
Inspiratory Reserve Volume (IRV)
• The maximum amount of air that can be inhaled after a normal tidal volume inspiration
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
17
Expiratory Reserve Volume (ERV)
• Maximum amount of air that can be exhaled from the resting expiratory level
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
18
Functional Residual Capacity (FRC)
• Volume of air remaining in the lungs at the end of a TV expiration
• The elastic force of the chest wall is exactly balanced by the elastic force of the lungs
• FRC = ERV + RV
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
19
Total Lung Capacity (TLC)
• Volume of air in the lungs after a maximum inspiration
• TLC = IRV + TV + ERV + RV
IRV
TV
ERV
RV
IC
FRC
VC
TLC
RV
20
Spirometric values
• FVC (forced vital capacity)• FEV1 (forced expiratory volume in 1 s)
• FEV1/FVC• FEF25-75 (maximum midexpiratory flow)• PEF (peak expiratory flow)• VT curve• FV curve
Normal values depends on:
• Age• Height
Kyphoscoliosis → arm span (H=arm span/1.06)• Gender• Race
CaucasianATS recommended scaling factor of 0.88 to the
Caucasian predicted FEV1 and FVC for African-American, Chinese, and Japanese subjects
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
Subject maneuvers
FVC maneuver• Closed circuit • Open circuit
• Well-fitting false teeth → yes or no• Sitting or standing• Nose clip• Procedure 1. Inhale compete & rapid 2. Exhale:
with minimal hesitation “blast” not just “blow” “keep going”
maneuver evaluation
• Start of test criteria
- Extrapolation volume (EV < 5% of FVCor 150 ml)
-Time-to-PEF < 0.120 s
• End of test criteria- 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 (<0.025 lit) for at least 1s
In obstruction or older subjects more than 6s exhalation (till 15s)
b
c
a
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 At the most eight tests should be performed
Acceptable spirogram
“rainbow”
G
Reproducibility
• At least three acceptable maneuvers
Maximum difference between the largest and next largest FVC and FEV1 = 150ml or 5% (If FVC <1lit, this value is 100ml)
Reproducibility
Flow chart of criteria
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
LLN
• FEV1 and FVC = 80%
• FEV1/FVC = 70-75%
• FEF25-75 = 50-60%
Interpretation
A. Normal: both the FVC and the FEV1/VC ratio are normal.
“Knee”
• B.Obstructive : FEV1/FVC , FEV1 TLC & RV or NL
The severity of the abnormality is graded:
- % Pred FEV1 > 100 = May be a physiological variant
- % Pred FEV1 < 80 and > 70 = Mild
- % Pred FEV1 < 70 and > 60 = Moderate
- % Pred FEV1 < 60 and > 50 = Moderately severe
- % Pred FEV1 < 50 and > 35 Severe
- % Pred FEV1 < 34 = Very severe
C. Restrictive: FEV1/FVC or NL FVC & FEV1 , TLC & RV
The severity of the abnormality might be graded as follows:
- % Pred FVC < LLN and > 70 = mild- % Pred FVC < 70 and > 60 = Moderate- % Pred FVC < 60 and > 50 =
Moderately severe- % Pred FVC < 50 and > 34 = Severe- % Pred FVC < 34 = Very severe
D.Mixed pattern:
FEV1, FVC, FEV1/FVC< LLN
ORFEV1,FVC <LLN,FEV1/FVC:NL
VC
RV
Obstructive
VC
RV
Normal
VC
RV
Restrictive
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
Probably normal spirogram
• Only FEF 25-75• No small airway disease (ATS)• If FEV1/FVC is borderline → airway obx
• Only FEV1/FVC
FEV1> 100% Normal
FVC>100%
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
Significant changes %
Time FVC FEV1
Within a day
Normal subjects
≥ 5 ≥ 5
COPD patients
≥ 5 ≥ 13
Week to week
Normal subjects
≥ 11 ≥ 12
COPD patients
≥ 20 ≥ 20
Year to year ≥ 15 ≥ 15
Significant changes
Gender FEV1 FVC
Male 30ml / yr 25 ml / yr
Female 25 ml / yr 25 ml / yr
Case 1
A 60 year old man with a 60 pack/year smoking history and dyspnea on exertion
FVC = 73% FEV1 = 23% FEV1/FVC = 25% FEF25-75 = 6% TLC = 150%
obstruction
Case 2
50 year old man with a 65 pack/year smoking history and a cough. His chest x-ray shows a diffuse reticulonodular pattern
FVC = 62% FEV1 = 42% FEV1/FVC = 56% FEF25-75 = 11% TLC = 64%
Mixed
Case 3
43 year old woman with progressive dyspnea on exertion. Chest x-ray shows bilateral reticular infiltrates, especially in the lung bases
FVC = 51% FEV1 = 49% FEV1/FVC = 78% FEF25-75 = 35% TLC = 52%
Restriction
Case 4
A 38 year-old male
Height: 171, weight: 82
FVC = 4.53 (100%)
FEV1 = 3.35 (89%)
FEV1/FVC = 74%
FEF25-75 = 2.85 (65%)
Normal
Case 5
A 53 year-old male Height: 180, weight: 73
FVC = 4.51 (97%)
FEV1 = 3.18 (86%)
FEV1/FVC = 70.50%
FEF25-75 = 2.26 (58%)
Borderline obx
Case 6
A 41 year-old male Height: 171, weight: 65
FVC = 4.77 (115%)
FEV1 = 3.50 (101%)
FEV1/FVC = 73.40%
FEF25-75 = 2.74 (66%)
Normal
Case 7
A 52 year-old male Height: 181, weight: 95
FVC = 3.81 (81%)
FEV1 = 2.38 (63%)
FEV1/FVC = 62.5%
FEF25-75 = 1.72 (41%)
Moderate obx
Case 8
A 39 year-old male Height: 184, weight: 83
FVC = 5.82 (111%)
FEV1 = 4.98 (116%)
FEV1/FVC = 85.6%
FEF25-75 = 5.25 (114%)
Normal
Case 9
A 44 year-old male Height: 185, weight: 92
FVC = 3.93 (76%)
FEV1 = 2.75 (66%)
FEV1/FVC = 70%
FEF25-75 = 1.91 (43%)
Mixed or pure obx
Case 10
A 54 year-old male Height: 178, weight: 80
FVC = 4.56 (121%)
FEV1 = 3.10 (102%)
FEV1/FVC = 68%
FEF25-75 = 1.83 (51%)
Normal
Case 11
41 year-old Female Height: 168, weight:72
FVC = 2.43 (68%) FEV1 =2.2(76%) FEV1/FVC = 91% FEF25-75 = 3.3 (123%) TLC = 79% Restriction
Case 12
A 68 year-old male
FVC = 2.63(56%)
FEV1 = 2.64 (52%)
FEV1/FVC = 66%
FEF25-75 = .7 (26%) TLC = 63%
Mixed
Case 13
A 54 year-old male Height: 178, weight: 80
FVC = 3.8 (115%)
FEV1 = 2.3 (81%)
FEV1/FVC = 69 %
FEF25-75 = 3.9 (68%)
Borderline obx
Case 14
A 44 year-old male Height: 185, weight: 92
FVC = 1.73(42%)
FEV1 = .5 (15%)
FEV1/FVC = 30%
FEF25-75 = 1.91 (43%) TLC = 119%
Obstruction
Case 15
A 30 yrs male Height :173 ,weight : 70
FVC:74% FEV1: 66% FEV1/ FVC :75.4% FEF25-75 :45%
Restriction
Case 16
A 24 yrs male Height :170 ,weight :82
FVC:85% FEV1: 78% FEV1/ FVC :69% FEF25-75 :55%
Obstruction
Case 17
A 33 yrs male Height :170 ,weight :85
FVC:83% FEV1: 68% FEV1/ FVC :66% FEF25-75 :43%
Obstruction
Case 18
A 29 yrs male Height :168 ,weight :76
FVC:96% FEV1: 81% FEV1/ FVC :71.1% FEF25-75 :51%
Obstruction (border line)
Case 19
A 33 yrs male Height :170 ,weight :75
FVC:85% FEV1: 55% FEV1/ FVC :53% FEF25-75 :28%
Obstruction
Case 20
A 38 yrs male Height :180 ,weight :67
FVC:64% FEV1: 51% FEV1/ FVC :67.7% FEF25-75 :31%
Mixed / severe obstruction