Pulmonary Function
Tests
Classification
 Obstructive

lung disease(pattern):
COPD,Asthma,Bronchiolitis ,Bronchiectasis
Restrictive lung disease(pattern)
ILD,NMD,…
Pulmonary Function Tests
Spirometry
 Body Plethysmography (Body Box)
 Body Box + Dlco
 Metacholine Challenge text(MCT)
 Cardiopulmonary Exercise Test
(Ergospirometry)

Spirometry
Spirometry
Flow Loop- Normal
Flow Volume Loop
What information does a spirometer yield?

A spirometer can be used to measure the
following:
 FVC
and its derivatives (such as FEV1, FEF 25-75%)
 Peak expiratory flow rate
 Maximum voluntary ventilation (MVV)
 Slow VC
 IC, IRV, and ERV
 Pre and post bronchodilator studies
Information Provided by the Spirometer
The ratio of FEV1/FVC is normally between 0.7
and 0.8. Values below 0.7 are a marker of
airway obstruction, except in older adults
where values 0.65–0.7 may be normal.
In people over 70 years old, the FEV1/FVC
ratio may need to be lowered to 0.65 as a
lower limit of normal. conversely, in people
under 45, using a ratio of 0.7 may result in
under-diagnosis of airway obstruction.
INTERPRETATION
Interpretation of spirometry involves looking at
the absolute values of FEV1, FVC, and
FEV1/FVC,
comparing them with predicted values, and
examining the shape of the spirograms.
Patients should complete three blows that are
consistent and within 5% of each other—
many electronic spirometers automatically
provide this information.
Spirometry Quality
Upper Airway Obstruction
Bronchodilator Reversibility Testing
Bronchodilator reversibility testing is best done as a
planned procedure, as it is time consuming. If the
patient is undiagnosed and on no therapy, acute
reversibility can be assessed on the first visit.
Short-acting bronchodilators need to be withheld for at
least 4 hours prior to testing, and long-acting
bronchodilators for 12 hours. Recent treatment with
inhaled glucocorticosteroids can also reduce
bronchodilator reversibility because the prebronchodilator FEV1 may improve significantly with
Inhaled glucocorticoid therapy.
Reversibility testing
Spirometry should be undertaken when the patient is
clinically stable and free from a respiratory tract infection.
Short-acting bronchodilators should be withheld for the
previous 6 hours, long-acting bronchodilators for 12
hours, and sustained release theophylline for 24 hours.
FEV1/FVC should be measured before and 15-20
minutes after bronchodilator is given.
The bronchodilator should be given by metered dose
inhaler, ideally through a spacer. A nebulizer may be
used but generally larger doses are delivered by this
route.
The dose administered should be high on the doseresponse curve.
Possible dose protocols include 400  g salbutamol, up to
160  g ipratropium, or the two combined.
Pre-Post Bronchodilator
ATS recommends a positive response is > 12% improvement
in FEV1
Patterns of Spirometric Curves
NORMAL: FEV1 and FVC above 80% predicted
FEV1/FVC ratio above 0.7
OBSTRUCTIVE: FEV1 below 80% predicted
FVC can be normal or reduced – usually to a lesser degree
than FEV1
FEV1/FVC ratio below 0.7
RESTRICTIVE: FEV1 below 80% predicted
FVC below 80% predicted
FEV1/FVC ratio normal - above 0.7.
Spirometry (Indication)
1- Evaluate dyspnea
2- Detect Pulmonary Diseases
3- Monitoring of Treatment
4- Evaluate Preoperative Risk
5- Evaluate respiratory impairment
6- Surveillance for occupational lung diseases
Spirometry (Contraindaction)
1- Hemoptysis
2- Pneumothorax
3- Recent MI (UA)
4- Aortic Aneurysm
5- Cerebral Aneurysm
6- Recent eye surgery
7- Recent thoracic & abdominal surgery
Body plethysmography
Body plethysmography
 The most accurate way
 The patient sits inside a fully
enclosed rigid box and breath
through mouthpiece connected
through a shutter to the internal
volume of the box
 while breathing in and out again
into a mouthpiece. The volume
of all gas within the thorax can
be measured by Changes in
pressure inside the box and
allow determination of the lung
volume( Boyles Law)
These parameters will be evaluated by Body Box:








Residual volume (RV)
Tidal volume (TV)
Total Lung Capacity (TLC)
Expiratory reserve volume (ERV)
Inspiratory Reserve Volume (IRV)
Inspiratory capacity (IC)
Functional residual capacity (FRC)
Vital Capacity (VC)
Diffusing Capacity(Dlco)

Diffusing capacity of lungs for CO

Measures ability of lungs to transport inhaled gas
from alveoli to pulmonary capillaries

Depends on:
- alveolar—capillary membrane
- hemoglobin concentration
- cardiac output
Diffusing Capacity

Decreased DLCO

Increased DLCO
(>120-140% predicted)
(<80% predicted)

Obstructive lung disease

Asthma (or normal)

Parenchymal disease

Pulmonary hemorrhage

Pulmonary vascular
disease

Polycythemia

Left to right shunt

Anemia
DLCO — Indications

Emphysema

Evaluation and severity of restrictive lung
disease

Early stages of pulmonary hypertension
Methacholine Challenge Test
Bronchoprovocation testing
INDICATIONS:
 accurate diagnosis of bronchial asthma
 assessment of the response to asthma
therapy
 identification of triggers for environmental
or occupational asthma.
Methacholine challenge

A series of methacholine chloride solutions are prepared,
ranging from approximately 0.05 mg/mL to 25 mg/mL
being administered by nebulizer.

After inhalation of the aerosol, the FEV1 is measured at
1, 3, 5, and 10 minutes, and the concentration is
increased one step until a 20 percent decrease in FEV1
or a 35 or 40 percent decrease in specific airways
conductance (SGaw) is observed

The dose that provokes a 20 percent drop in FEV1 is
referred to as the PC20. Generally, a PC20 of 8 mg/ml
methacholine or less is considered a positive test
CPET(Ergospirometry)
Indications for Exercise Testing
Diseases that affect the heart, lungs, circulation, or blood
shortness of breath that otherwise cannot be determined at
rest or through conventional lung function testing
exercise capacity and anaerobic threshold of the individual
abnormal blood pressure response to
exercise
Follow responses to therapy in patients with
cardiopulmonary
disease
poor circulation
COPD
ILD
PVD
Obesity
Decondit Heart
ioned
failure
V’O2,peak
Reduced
Reduced
Reduced
Reduced
Normal
Reduced
Reduced
LT
Indeter.
Nor. Low
Normal
Low
Low
Low
Normal
Low
Low
VE,reserve Reduced
or none
Reduced Normal
or Normal
Normal
Normal
Normal
HRR
normal
increased
normal
increased
normal
normal
normal
Reduced
or Normal
O2 pul .pa
Reduced
Reduced
Reduced
normal
Reduced
Reduced
Fall in
SaO2
Present
Absent
Present
Present
Absent
Absent
Absent