Brief guide for the use and interpretation of spirometry.

1. Spirometry
in Practice
• A technique used to measure air flow in and out of the
lungs.
• A recording of lung volumes and capacities defined by
the respiratory process. These recordings may be static
(untimed) or dynamic (timed).
• Assesses the integrated mechanical functions of lungs,
chest wall and respiratory muscles.
•The gold standard for diagnosis, assessment and
monitoring of COPD.
• Better than PEFR (which is effort dependent) for
demonstrating airway obstruction in BA.
• The most commonly used PFT.

2. Indications
• Measure airflow obstruction to help make a definitive
diagnosis of COPD
• Detect airflow obstruction in smokers who may have few
or no symptoms
• Assess one aspect of response to therapy
• Perform pre-operative assessment
• Distinguish between obstruction and restriction as
causes of breathlessness
• Perform pre-employment screening in certain
professions

3. Flow
Sensitive
Spirometer
• Utilizes a sensor that measures air flow as the
primary signal and calculates volume by integration.
• Automatically calculates a wide range of ventilatory
indices and draw curves, which provide an immediate
feedback on quality.

4. How to DO?
Before the Test
1) Exclude contraindications:
• Haemoptysis of unknown origin.
• Current chest infection or within in last 6 weeks.
• Pneumothorax.
• Recent myocardial infarction or PE (< 3 m).
• Unstable angina in last 24 hours.
• Recent surgery (eye, chest, abdomen) (< 3m).
• Recent CVA (< 3m).
• Aneurysm (cerebral, thoracic, abdominal).

5. How to DO?
Before the Test
2) Stop Asthma Medications:
• SABA 6h
• LABA 12h
• Ipratropium 6h
• Tiotropium 24h
Medications may be continued if the test aims to
assess the patient condition on treatment.

6. How to DO?
Before the Test
3) Other Precautions:
• Physical and mental rest.
• No coffee or smoking for 30 mins.
• Empty the bladder in females or those with
history of urinary incontinence.

7. How to DO?
• Patient is sitting comfortably, not leaning
forwards, legs not crossed, feet firm on floor.
• No tight clothes or collars.
• Explain the procedure to the patient.
• Nasal clip is optional.
During the Test

8. How to DO?
• Ask the patient to do a
Forced Expiratory Maneuver (FEM):
- Take a maximal inspiration.
- Hold the breath and seal your lips tightly around the mouth piece.
- Blow as fast as possible (blast expiration) until the lungs feel
completely empty (at least 6 sec., up to 12 sec in obstructive disease)
During the Test
• Repeat the test 3 times and record the highest reading
• Continue watching, explanation and encouragement
throughout the procedure.

9. • Submaximal effort
o Submaximal effort
o Air leak around the mouthpiece (lips not tight enough)
o Air leak through nose
o Incomplete inspiration before the forced expiratory
maneuver (not at TLC)
o Incomplete or weak expiration (lack of blast effort)
o Slow start of expiration
o Cough (particularly within the first second of expiration)
o Glottic closure
o Obstruction of the mouthpiece by the tongue
o Vocalisation during the forced manoeuvre
o Poor posture (leaning forwards).
o Extra- breath during the blow
Causes of Poor Record

10. Spirometry includes:
• Lung volumes (most simple).
• Lung capacities (composite of > 2 volumes)
• Volume per time: as FEV1,2,3,4,5,6
• Volume / Time Curve.
• Flow / Volume Loop.

11. Total
Lung
Capacity
Tidal Volume
Inspiratory Reserve
Volume
Expiratory Reserve
Volume
Residual Volume
Inspiratory
Capacity
Vital
Capacity
End Normal Exp
End Normal Insp
End Maximal Insp
End Maximal Exp
Functional
Residual
Capacity

13. Predicted Normal Values
 Age
 Height
 Sex
 Ethnic Origin
Affected by
biodemographic
variables:

14. Obstructive Pattern Restrictive Pattern
•↓ VC
•↓ FEV1
/ FVC
•↑ RV
•↑ RV / TLC
•↓ PEF
• Normal FEV1
/ FVC
•↓ Other lung volumes,
capacities

16. Normal
Obstructive
Restrictive

17. Volume Time Curve

18. Flow Volume Loop
Expiratory
flow rate
L/sec
Volume (L)
FVC
Peak expiratory flow (PEF)
Inspiratory
flow rate
L/sec
RVTLC
Peak Inspiratory flow (PIF)

20. (> 0.7)
(< 80%)
(< 0.7)
(< 80%)(< 80%) (< 80%)
(< 80%)

21. Bronchodilator Reversibility Testing
•FEV1 should be measured (minimum twice, within
5% or 150mls) before a bronchodilator is given
Bronchodilator* Dose FEV1 before
and after
Salbutamol 400µg 15minutes
Terbutaline 500µg 15minutes
Ipratropium 160µg 45minutes

22. Bronchodilator Reversibility Testing
• An increase in FEV1 that is both greater than 200 ml and
12% above the pre-bronchodilator FEV1 (baseline value)
is considered significant (Up to 8% increase may occur in
normal persons).
• It is usually helpful to report the absolute change (in
mL) as well as the % change from baseline to set the
improvement in a clinical context .
• The absence of reversibility does not exclude asthma
because an asthmatic person’s response can vary from
time to time and at times airway calibre is clearly normal
and incapable of dramatic improvement.

23. 6
4 8
3
7
2
1
9
Inspiratory
Capacity
(IC)
5

24. Look at FEV1/FVC and FVC
FEV1/FVC > 0.7
FVC > 80%P
FEV1/FVC< 0.7
FVC > 80%P
FEV1/FVC > 0.7
FVC < 80%P
FEV1/FVC < 0.7
FVC < 80%P
NORMAL OBSTRUCTIVE RESTRICTIVE MIXED or
OBSTRUCTIVE + AT
Provocation
Test
BD Reversibility
Test
?Parenchymal
or ExtraParenchymal
BD Reversibility
Test
If asthma suspected
Reversible Not Reversible Reversible Not Reversible
BA COPD OBSTRUCTIVE + AT RV, TLC
Mixed
High Low

26. Parenchymal RLD Extraparenchymal RLD
FVC Decreased Decreased
MVV Normal Decreased
DLCO Decreased Normal
FVC: Forced Vital Capacity
MVV: Maximum Voluntary Ventilation
DLCO: Carbon Monoxide Diffusion

27. %
Predicted
FEV1 FVC
)or TLC(
Obstruction Restriction
65> -80 Mild
50> -65 Moderate
>50 Severe
Degree of Ventilatory Impairment

28. FVC = 50%P )< 80%P(
FEV1/FVC = 0.41)< 0.7(
∴Mixed or Obstructive + AT
BD Reversibility: -6% )NO(
RV, TLC not provided
There are 2
possibilities:
1( Mixed
Ventilatory
Defect
2( Obstructive +
AT

29. Measured FEV1
Predicted FEV1
Measured FVC
Predicted FVC
FEV1/FVC
FEV1 after Bronchodilator
Is there obstructive hypoventilation?
What evidence?
Is there restrictive hypoventilation?
What evidence?
What is the degree of ventilatory impairment?
Is there significant reversibility after bronchodilator?
What evidence?
Matching condition:
BA/Interstitial Pulmonary Fibrosis/Emphysema/Acute rhinitis
How to Present Your Analysis of Spirometry Results?