spirometry by: dr saraei by: dr saraei. content indicationindication indications in occupational...

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


Mixed

Case 3

43 year old woman with progressive dyspnea on exertion. Chest x-ray shows bilateral reticular infiltrates, especially in the lung bases


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


FVC = 4.77 (115%)

FEV1 = 3.50 (101%)

FEV1/FVC = 73.40%

FEF25-75 = 2.74 (66%)

Normal

Case 7


FVC = 3.81 (81%)

FEV1 = 2.38 (63%)

FEV1/FVC = 62.5%

FEF25-75 = 1.72 (41%)

Moderate obx

Case 8


FVC = 5.82 (111%)

FEV1 = 4.98 (116%)

FEV1/FVC = 85.6%

FEF25-75 = 5.25 (114%)

Normal

Case 9


FVC = 3.93 (76%)

FEV1 = 2.75 (66%)

FEV1/FVC = 70%

FEF25-75 = 1.91 (43%)

Mixed or pure obx

Case 10


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


FVC = 3.8 (115%)

FEV1 = 2.3 (81%)

FEV1/FVC = 69 %

FEF25-75 = 3.9 (68%)

Borderline obx

Case 14


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



Obstruction

Case 18



Obstruction (border line)

Case 19



Obstruction

Case 20



Mixed / severe obstruction

spirometry by: dr saraei by: dr saraei. content indicationindication indications in occupational...

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