What is Spirometry? V

Spirometry is a method of assessing lung function by measuring the total volume of air the patient can expel from the lungs after a maximal inhalation. 

Indications: Diagnostic

•To evaluate  respiratory symptoms, signs, or abnormal laboratory tests

•To measure the effect of disease on pulmonary function

•To screen individuals at risk of having pulmonary diseases

•Smokers

•Individuals in occupations with exposures to injurious substances

•To assess preoperative risk

•To assess prognosis (lung transplant, etc.)

•To assess health status before enrollment in strenuous physical activity programs

•Spirometry is a method of assessing lung function by measuring the total volume of air the patient can expel from the lungs after a maximal inhalation. 

Indications: Monitoring

•To assess therapeutic interventions

•bronchodilator therapy for COPD and asthma

•Other (antibiotics in cystic fibrosis, etc.)

•To describe the course of diseases affecting lung function

•Pulmonary diseases

•Obstructive airways diseases

•Interstitial lung diseases

•Cardiac diseases

•Congestive heart failure

•Neuromuscular diseases

•Guillain-Barre Syndrome

 

Indications: 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

•Social Security or other government compensation programs

•Personal injury lawsuits

•Others

 

Indications: Public Health

•Epidemiologic surveys

•Comparison of health status of populations living in different environments

 

Contraindications

•Very ill or dyspnoeic patient

•Hemoptysis of unknown origin

•Pneumothorax

•Unstable cardiovascular status

•Thoracic/abdominal/cerebral aneurysms

•Chest wall trauma, pain

•Recent eye surgery

•Presence of acute disease process that may interfere with performance (e.g., vomiting)

•Recent surgery of thorax or abdomen

Loading…

Spirometry

•Best objective tool; to evaluate & compare efficacy of bronchodilators in Asthma & COPD

•Parameters – FEV1, FVC, FEV1/FVC, PEFR, FEF 25-75%

•Effort  dependent test

•Obtaining good quality report is important for reliable & meaningful result

 

Spirometry – Basics

Right equipment

•Accurate: follow ATS/ERS standards for accuracy

•Show both flow-volume and volume-time graphs

•Should be caliberated

•Measure FEV1, FVC, FEV1/FVC, PEFR, FEF 25-75%

 

Spirometry – Basics

Right technique

•Operator : patient and skilled 

•Full patient co-operation

•Effort dependent test

•Best blow by patient 

•Reproducible 

Calibrate regularly

1 liter syringe

3 liter syringe

IDEAL

Reliability

Measure room temperature accurately

 

Decrease in temperature 

Decrease in air volume

Measure age accurately

 

Age Vs FEV 1

Age Vs FEV1

Patient 

Age yrs

Height cm

Weight kgs

Predicted FEV1

Predicted FVC

XX

30

160

55

2.67

3.08

YY

35

160

55

2.44

2.82

Difference of 5 yrs changes predicted value by about 200-400 ml

Measure height accurately

Patient 

Age yrs

Height cm

Weight kgs

Predicted FEV1

Predicted FVC

XX

35

160

62

3.04

3.45

YY

35

165

62

3.39

3.83

Difference of 5 cms changes predicted value by about 200-400 ml

Height Vs FEV1

Other important parameters are

•Sex

•race

Patient Preparation

Patient should avoid

•Smoking for 24 hours;

•Drinking alcohol for at least four hours;

•Vigorous exercise for at least 30 minutes;

•Wearing any tight clothing;

•Eating a large meal for at least two hours;

•Taking short-acting bronchodilators for four hours;

•Taking long-acting beta-2-agonist inhalers for 12 hours;

•Taking slow-release medicines that affect respiratory function, and theophylline-based drugs for 24 hours

Doing the Test

•Explain test; Let him watch the previous patient or demonstrate the procedure by using simple mouth piece

•Prepare patient    

•Ask about smoking, recent illness, medication use, etc. 

 

Position: Sitting preferably; loosen collar

Phase I – Deep Inspiration

•FVC

•FEV1

•PEFR

•FEF 25-75%

Fill your chest as much as you can

Phase II – Blast

•FEV1

•PEFR

•FEF 25-75%

Blow as fast as you can

Blast maximum

Phase III – Continue to exhale

•FVC

•FEV1/FVC

•FEF 25-75%

Blow as long as you can

Keep Blowing…….

Phase IV – Deep Inspiration

 

Inhale as much air as was blown out

Is deep inhalation taken?

Good quality report

•Subjective evaluation—has the patient done it right

•Objective evaluation– acceptability and repeatability

Lung volumes and capacities

CURVES

Two types 

•Flow volume curve 

•Time volume curve 

Loading…

Normal Spirogram

•All parameters are normal

•Normal shape in VT and FV loop

Flow Volume Curve

 

Expiratory flow rate

L/sec 

Volume (L) 

FVC

Maximum expiratory flow (PEF)

Inspiratory flow rate

L/sec

 

RV

TLC

Time volume curve
Normal Trace Showing FEV1and FVC

1

2

3

4

5

6

1

2

3

4

 

 

Volume, liters

Time, sec

FVC

5

1

FEV1 = 4L

FVC  = 5L

FEV1/FVC = 0.8

 

Acceptability criteria

•With-in maneuver criteria

•Between maneuver criteria

With in maneuver criteria

•Start of forced expiration

 

•EOFE

With in maneuver criteria

•Start of forced expiration

•BEV (150 ml/ 5% of FVC)

•Hesitation time (2 sec)

•Time to PEF (150 ms)

 

Good Start

 

With in maneuver criteria

•EOFE

•Plateau (less than 25 ml change for at least 1 sec)

OR

•Exhalation for 15 sec

OR

•FVC is within repeatability tolerance

Cough

FET < 15 sec

•False reduced FVC

 

•False high FEV1/FVC

1s

15 s

2s

TIME

VOLUME

FEV1

False FVC

True FVC

FEV1/FVC = 78%

FEV1/FVC = 62%

Variable Effort

 

Between maneuver criteria

•3 acceptable FEV1 and FVC maneuvers (150 ml )

 

Reasons for unacceptable FEV1

•Cough in the first second of expiration

•Glottic closure in 1st second of expiration

•Obstructed mouthpiece or spirometer

•Leak

•FIVC-FVC > 100 ml or 5%of FVC whichever is greater

Reasons for Unacceptable FVC

•Glottic closure in 1st sec of expiration and after 1st second of expiration

•EOFE criteria not achieved- no plateau/ FET <15 sec/ FVC is not within repeatability tolerance

•Obstructed mouthpiece

•

INTERPRETATION

FEV1/FVC

FVC%

    

Reduced (OAD)

FVC%

Reduced

NORMAL

(>80%)

FEV1/FVC

Normal    (>70%)

 

FVC%

Normal

RLD

Normal

OAD

Mild or Moderate

Reduced

OAD + RLD or Severe Obstruction

(>80%)

Spirometry Interpretation 

Obstructive 

•Obstructive Disorders

•FVC nl or  ↓

•FEV1 ↓

•FEF25-75% ↓ 

•FEV1/FVC  ↓

•TLC nl or ↑

 

Restrictive Defect

•Restrictive Disorders

•FVC   ↓

•FEV1  ↓ 

•FEF 25-75% nl to ↓

• FEV1/FVC nl to ↑

• TLC ↓

 

Vs

Mixed Obstructive/Restrictive

•FEV1 /FVC: < 0.7

•FEV1: < 80% predicted

•FVC: < 80% predicted

Exampl- cystic fibrosis

      Obstructive

Restrictive

Mixed

       Time

     Time

 

    Time

  Volume

  Volume

  Volume

Spirometry:  Abnormal Patterns

 

Slow rise, reduced volume expired; prolonged time to full expiration

Fast rise to plateau at reduced maximum volume 

Slow rise to reduced maximum volume; measure static lung volumes and full PFT’s to confirm  

Flow Volume Curve Patterns Obstructive and Restrictive

 

 

  Obstructive

Severe obstructive

Restrictive

       Volume (L)

  Expiratory flow rate

Expiratory flow rate

 Expiratory flow rate

       Volume (L)

       Volume (L)

Steeple pattern, reduced peak flow, rapid fall off 

 

Normal shape, normal peak flow, reduced volume

Reduced peak flow, scooped out mid-curve

Flow-Volume  Loops

Upper airway obstruction

 

54 year – old man

With dyspnea &cough

Non-smoker,with no occupational exposures.

His flow volume loop is as follows:

 

Case 1

 

Pre-Bronchodilator (BD)

Post- BD

Test

Actual

Predicted

% Predicted

Actual

% Change

FVC (L)

3.19

4.22

76

4.00

25

FEV1 (L)

2.18

3.39

64

2.83

30

FEV1/FVC (%)

68

80

 

71

4

 

Flow volume loop:        PEFR

                                    Scooped out appearance

 

 

Decreased  FEV1 ,FVC & FEV1/FVC          moderate airflow obstruction

 

BD response

 

Dx: obstructive disease

Case 1 interpretation

 

30 year-old woman 

Dyspnea on exertion from 2 month ago

Non-smoker 

She has a cat and parrot at home.

 

 

Case 2

Her flow volume loop is as follows:

 

Pre-Bronchodilator (BD)

Post- BD

Test

Actual

Predicted

% Predicted

Actual

% Change

FVC (L)

1.73

4.37

40

1.79

4

FEV1 (L)

1.57

3.65

43

1.58

0

FEV1/FVC (%)

91

84

 

88

-3

RV (L)

1.01

1.98

51

 

 

TLC (L)

2.68

6.12

44

 

 

RV/TLC (%)

38

30

 

 

 

DLCO corr

5.13

32.19

16

 

 

 

Decreased FEV1 ,FVC + NL FEV1/FVC               Restrictive pattern

Decreased  TLC            severe restriction 

 

Case 2 interpretation

60 year-old man

With progressive  dyspnea on exertion

40 pack-year smoker

Retired following as a building contractor

His flow volume loop is as follows:

Case 3

 

Pre-Bronchodilator (BD)

Post- BD

Test

Actual

Predicted

% Predicted

Actual

% Change

FVC (L)

1.89

4.58

41

3.69

96

FEV1 (L)

0.89

3.60

25

1.89

112

FEV1/FVC (%)

47

79

 

 

 

RV (L)

5.72

2.31

248

 

 

TLC (L)

7.51

6.41

117

 

 

RV/TLC (%)

76

37

 

 

 

Case 3 interpretation

Reduced   FEV1,FVC&FEV1/FVC          very  severe obstruction

Significant BD response

 

25 year-old man

With dyspnea and wheezing

Non smoker

History of motor vehicle accident , hospitalization and  tracheostomy 2 years ago

Case 4

His flow volume loops is as follows:

 

 

Pre-Bronchodilator (BD)

Test

Actual

Predicted

% Predicted

FVC (L)

4.73

4.35

109

FEV1(L)

2.56

3.69

69

FEV1/FVC (%)

54

85

 

 

Case 4 interpretation

Flow volume loop:   Flattened  inspiratory &expiratory limb

Decreased FEV1 , FEV1/FVC          moderate obstruction

Dx: Fixed UAWO

Reference