pulmonary function test

1. PULMONARY FUNCTION TEST
KRISHNA GOHIL
MPT 1ST YEAR CARDIO

2. CONTENT
• Introduction
• Physiology
• Pathophysiology
• PFT
• Types
• Purpose
• Indication & Contraindication
• Procedure
• Interpretation of Flow-Volume loop and Time-Volume graph
• Interpretation of PFT values for diagnosis

3. Pulmonary Function Test
• Pulmonary function tests (PFTs) provide the clinician with information
about the integrity of the airways, the function of the respiratory
musculature, and the condition of the lung tissues themselves.
• A thorough evaluation of pulmonary function involves several tests
that measure lung volumes and capacities, gas flow rates, gas
diffusion, and gas distribution.

4. Introduction
 The most important function of
the lungs is gas exchange.
 Venous blood passes through the
pulmonary circulation, the lungs
add oxygen and remove carbon
dioxide.

5. There are various measurements available to aid in
the diagnosis and assessment of pulmonary disease.
 That includes a patient’s history, physical
examination, radiographic imaging, arterial blood gas
analysis, and pulmonary function test (PFT).

6. Mechanism of respiration
• Atmospheric pressure: it is sum of all the partial pressure of gases in the
air.
• 780 mmHg at sea level
• 598mmHg (nitrogen) + 159mmHg (oxygen)
• air flows from high pressure to low pressure.
• Pressure increase => Volume decrease
• Pressure decrease => Volume increase

7. • Intrapulmonary pressure (Ppul) or intra alveolar pressure is falls
with inspiration and rise with expiration.
• Ppul always eventually equalizes with atmospheric pressure.
• Intrapleural pressure (Pip) decrease on inspiration and increase on
expiration.
• Intrapleural pressure in the pleural space becomes more negative
during chest wall expansion and return to baseline values as the chest
wall recoils.

8. Physiology
The ability of the lungs to perform gas exchange depends on:
 The diaphragm and thoracic muscles expand the thorax and lungs.
 The airway size (radius) is suitable to allow gas to flow into the
lungs and reach the alveoli.
 O2 and CO2 diffuse through the alveolar capillary membrane.
 The cardiovascular system circulates blood through the lungs and
ventilated alveoli.

9. LUNG VOLUMES AND CAPACITIES
• Albert J. Heuer, Craig L. Scanlan; Wilkin's clinical assessment in respiratory care; Ch:9; page:181;7th edition
Measures Abbreviation Functional Definition
Tidal volume VT Volume of air inhaled or exhaled during each normal breath
Inspiratory reserve volume IRV
Maximal volume of air that can be inhaled over and above the
inspired tidal volume
Expiratory reserve volume ERV
Maximal volume of air that can be exhaled after exhaling a normal
tidal breath
Residual volume RV Volume of air remaining in the lungs after a maximal exhalation
Total lung capacity TLC
Maximal volume of air in the lungs at the end of a maximal inhalation
(RV + Vt + ERV + IRV)
Functional residual capacity FRC
Volume of air present in the lung at end expiration during tidal
breathing (RV + ERV)
Inspiratory capacity IC
Maximal volume of air that can be inhaled from the resting end
expiratory level (IRV + Vt)
Vital capacity VC
Maximal volume of air that can be exhaled after a maximal inhalation
(IC + ERV)

10. LUNG VOLUMES AND CAPACITIES

11. Pathophysiology
• PFT provides the basis for classifying pulmonary disease into two
major categories,
• Obstructive pulmonary disease
• Restrictive pulmonary disease

12. • Robert M. Kacmarek, James K. Stouer, Albert J. Heuer; Egan’s fundamentals of respiratory care; Ch: 20;
page: 397; 12th edition
characteristic Obstructive disease Restrictive disease
Anatomy affected airways
Lung parenchyma, thoracic
pump
Breathing phase
difficulty
expiration inspiration
pathophysiology Increased airway resistance
Decreased lung or thoracic
compliance
Useful measurement Flow rates Volumes or capacities
COMPARISON OF OBSTRUCTIVE AND RESTRICTIVE
TYPES OF PULMONARY DISEASE

13. Obstructive Lung Disease
• The primary problem in obstructive pulmonary disease
is an increased airway resistance (Raw).
• Raw is the difference in pressure between the ends of
the airways divided by the flow rate of gas moving
through the airway
Raw = ∆P
V
• according to Poiseuille’s law, the major determinant
of airway resistance is its radius.

14. • Airway radius can be reduced by
• Excessive contraction of the bronchial and bronchiolar
muscles (bronchospasm)
• Excessive secretions in the airways
• Swelling of the airway mucosa
• Airway tumors
• Collapse of the bronchioles
• By the measuring flow rates, PFTs indirectly measure
Raw estimate the size of the airways and indicate the
presence of obstructive disease.

15. Restrictive Lung Disease
• In restrictive lung disease is reduced lung compliance,
thoracic compliance, or both.
• Compliance is the volume of gas inspired per the amount of
inspiratory effort.
• Effort is measured as the amount of pressure created in the
lung or in the pleural space when the inspiratory muscles
contract.
C = ∆𝑉
∆𝑃
• If the pressure difference is constant, a reduced inspiratory
volume indicates a reduction in compliance.

16. •Reduced lung compliance is usually the result of
•alveolar inflammation (pneumonia)
•Swelling (pulmonary oedema)
•Scarring (pulmonary fibrosis)
•Reduced thoracic compliance is usually the result of
•Thoracic wall abnormalities: kyphosis
•External pressure exerted on the thoracic cavity:
ascites, severe obesity, or pregnancy.

17. • Neuromuscular disease such as amyotrophic lateral
sclerosis (ALS) or muscular dystrophy also can result in
reduced lung volumes and restrictive type pulmonary
impairment muscles.
• In this case lung compliance and thoracic compliance may
be normal, but the patient is unable to generate enough sub-
atmospheric pressure to take a full, deep breath.

19. PFT
Pulmonary function test can provide valuable
information about these important individual processes
that support gas exchange.
PFT measuring:
Dynamic flow rates of gases through the airways.
Lung volumes and capacities.
The ability of gases to diffuse through lungs.

20. Types
• closed circuit helium dilution method
• open circuit nitrogen washout
• whole body plethysmography

21. CLOSED CIRCUIT HELIUM DILUTION

22. • A spirometer is filled with known volume and concentration of helium
gas.
• Before breathing from the spirometer, the person exhales normally.
• In normal subjects, equilibrium takes about 7 minutes,
• At the end of equilibrium FRC is calculated
FRC=
𝑖𝑛𝑖𝑡𝑖𝑎𝑙 𝐻𝑒% −𝑓𝑖𝑛𝑎𝑙 𝐻𝑒% ×𝑉𝑎𝑝𝑝
𝑓𝑖𝑛𝑎𝑙 𝐻𝑒%
- VDmech
Vapp = apparatus volume
VDmech = dead space of the mouthpiece/breathing valve

23. OPEN CIRCUIT NITROGEN WASHOUT

24. • The patient breaths 100% O2 with the expired N2 concentration
continuously monitored.
• The test continues for at least 7 mins or until all the N2 is washout.
• Washout is judged complete when the N2 concentration is less than
1.5% for at least three consecutive breaths.
• The air originally in person’s lungs contained 78% N2
FRC =
𝑣𝑜𝑙 𝑁2 𝑤𝑎𝑠ℎ𝑜𝑢𝑡 −𝑣𝑜𝑙 𝑁2 𝑓𝑟𝑜𝑚 𝑡𝑖𝑠𝑠𝑢𝑒
𝑠𝑡𝑎𝑟𝑡𝑖𝑛𝑔 𝑁2% −ending 𝑁2%

25. Whole body plethysmography

26. • V is the change in gas volume in the lungs, as sensed by the chamber
pressure manometer. P is the change in pressure produced by the
respiratory efforts of breathing against the shutter, as sensed by the
airway pressure manometer.
• V(FRC) = PB atmospheric ×
∆𝑉
∆𝑃
• PB is the barometric pressure in cm H2O

27. • Measures the volume of gas in thorax, gas trapped in airway
obstruction, pleural space, and abdominal.
Pt sits in sealed chamber
pressure transducer measure pressure in mouth and chamber
electrically controlled shutter near the mouthpiece that measures
airway pressure while there is no airflow.
Pressure changes measured at the mouth and alveoli
That’s create change in pressure in thorax and chamber
When that measurements are done, pts starts breathing through
mouthpiece with normal tidal volume.
When it near to FRC, the shutter is closed at the end of expiration for
2 to 3 seconds. And pts starts genteelly panting at one pant per sec.

28. Traditional equipments
• Water sealed spirometer
• Dry rolling seal spirometer
• Bellows Spirometer

29. PNEUMOTACHOMETER

30. PURPOSE
• The primary purposes of PFT are to identify pulmonary impairment
and quantify the severity of pulmonary impairment if present.
• Assess the ability of the lungs to move large volumes of air quickly
through the airways to identify airway obstruction.
• PFT has diagnostic and therapeutic roles and helps clinicians to
answer some general questions about patients with lung disease.

31. Robert M. Kacmarek, James K. Stouer, Albert J. Heuer; Egan’s fundamentals of respiratory care; Ch: 20; page: 396; 12th edition
Basic Diagnostic And Therapeutic Questions For
Clinical Pulmonary Function Testing
Diagnostic
• Is lung disease present?
• What type of lung impairment is present?
• What is the degree of lung impairment?
• Is more than one type of lung impairment present?
• Can multiple lung disease be separated?
Therapeutic
• Is therapy indicated?
• What treatment are most effective?
• To what degree is the disease reversible?
• Can treatment be evaluated?
• Is rehabilitation feasible?

32. Parameters

33. Indications
• Confirm a suspected restrictive disease pattern (low FVC, normal or
highFEV1/FVC)
• Assess the impact of or response to medical or surgical interventions such as lung-
volume reduction, lobectomy, lung transplantation, and radiation or chemotherapy
• Provide an index of gas trapping (requires comparison of FRC by gas dilution to
plethysmography thoracic gas volume)
• To identify and quantify changes in pulmonary function.
• To evaluate the need for and quantify therapeutic effectiveness.
• To perform epidemiologic surveillance for pulmonary disease.
• To assess patients for postoperative pulmonary complications.

34. Contraindications
• Haemoptysis
• Pneumothorax
• Acute myocardial infarction or ischemia
• Acute pulmonary embolism
• Acute chest or abdominal pain
• Recent cataract surgery
• Inability to follow instructions
• Patient who have nausea and recently vomited should not be tested because there is
a risk of aspiration.
• In person who have recently smoked a cigarette, the test validity of measuring the
forced vital capacity may be hindered.

35. Preparation Of Subject
• For baseline testing, patient should temporarily abstain from bronchodilator
medications.
• Short acting bronchodilators should not be used for 4 hours before
spirometry test.
• β agonist
• Albuterol
• Anticholinergic agent
• Ipratropium bromide
• Whereas long action β agonist bronchodilators and oral therapy with
aminophylline should be stopped for 12 hours.
• when baseline result shows airway obstruction, performing FVC after
treatment given of albuterol bronchodilator aerosol or metered dose inhaler
can help to determine if the treatment is effective.

36. Acceptability And Repeatability Criteria
• To ensure validity, each patient must perform a minimum of three
acceptable FVC maneuvers.
• To ensure reliability, the largest FVC and second largest FVC from the
acceptable trials should not vary by more than 0.15 L.
• An acceptable FVC trial should be smooth, continuous, and complete.
• A cough, an inspiration, a Valsalva maneuver, a leak, or an obstructed
mouthpiece while performing FVC maneuver then disqualifies the
trial.

37. • An exhalation time of at least 6 seconds (adult an children older than 10
years).
• 15 seconds exhalation time may be needed for airway obstructive
patients.
• 3 seconds exhalation time acceptable for younger children less than 10
years.
• The largest acceptable FVC measured from the set of three acceptable
trials should be recorded as the patient’s FVC.
• Robert M. Kacmarek, James K. Stouer, Albert J. Heuer; Egan’s fundamentals of respiratory care; Ch: 20; page: 402; 12th edition

38. PRECAUTIONS
• Infective microorganisms may transmit by direct or indirect contact so
standard precautions should be applied because of the potential
exposure to saliva, mucus, or blood .
• Practitioners should wear gloves and personal respirator or close
fitting surgical mask when handling potentially contaminated
mouthpiece, valves, tubing, and equipment surfaces.
• Wash their hands and sterilized the hands and equipments between
testing patients.
• Try to use the disposable instrumental parts: mouthpiece, nose clips,
tubing.

39. Procedure
• Turn device on, insert mouthpiece/sensor, input sensor data, perform start-up test.
• Accurately input all required patient information (height, age, gender race).
• Have the patient remove candy, gum, and dentures from the mouth.
• Have the patient sit upright or stand with good posture and head slightly elevated
(be consistent and record position) (standing usually produces a larger FVC
compared with sitting)
• Demonstrate the procedure using your own mouthpiece/ sensor, being sure to
show:
• How to hold the sensor steady and avoid jerky motions.
• How deeply to inhale (completely).
• How to correctly place the mouthpiece on top of the tongue.
• How to blast out the breath for as long as possible.

40. • Use nose clips to prevent patient leaks.
• Have the patient inhale completely and rapidly with a pause of >1 second at
TLC.
• Have the patient place mouthpiece/sensor in mouth and obtain tight seal
with lips.
• Have the patient perform the FVC maneuver while you observe.
• Have the patient BLAST the breath out, as fast and long as possible.
• Loudly prompt MORE, MORE, MORE, until the subject has exhaled for at
least 6 seconds.
• Carefully observe the patient for poor technique and correct as needed.
• Repeat instructions as necessary, coaching vigorously.
• Repeat the procedure until you have three acceptable maneuvers.
• Document the quality of the results, including any validity issues.

41. Volume Vs Time Graph
• In spirometry test,
FVC and FEV1
parameters are
measured and
demonstrated on
volume-time
spirogram.

42. • the forced expiratory volume in 1, 3, and 6 seconds (FEV1, FEV3, and
FEV6) are all volumes measured at specific times during the forced
exhalation.
• Note also that a normal individual is able to exhale more than 75% of
the FVC in 1 second and generally 95% or more in 3 seconds.
• However, the minimal time needed to assure a valid FVC
measurement is 6 seconds, with some patients requiring more than 10
seconds to fully empty their lungs.

43. • The obstructive pattern is
characterized by a decrease
in the slope of the curve
(indicating reduction in
expiratory flow) and a
longer time to empty the
lungs.
In the restrictive pattern,
the lung empties as fast or
faster than normal but to a
smaller volume

44. Flow Volume Loop
• The flow volume loop record flow and volume during
forced inspiration and expiration.
• Its represent graphically the events on X-Y recorder
that occur during forced inspiration and expiration.
• Initial portion of the expiratory loop is effort
dependent.
• after first one third of the expiratory curve, is effort
independent and reproducible.
• Highest point denotes to PEFR.
• Above the horizontal line plotted curve is maximal
expiratory flow volume curve (MEFV), and below
zero flow line is maximal inspiratory flow volume
curve (MIFV).

45. Increasing severity of obstructive lung disease (asthma and COPD) is reflected by increasing
concavity of the effort-independent portion of the expiratory curve.

46. • In obstructive lung
disease
• Look essentially normal
except for a slight
“scooped out” appearance
at the end of expiration.
• In restrictive lung
disease
• Processes will show near
normal peak expiratory
flow volume (FEVt) when
compared with the
percentage of FVC
(%FEVt/FVC).

47. large airway obstruction
• intrathoracic obstruction loop reveals a
markedly reduced peak flow on
expiration despite near-normal
inspiratory flows.
• This typically is the result of expiratory
flow obstruction in the large airways, as
may occur with tracheomalacia or
tumors of the trachea or bronchi.

48. • An equal reduction in inspiratory and
expiratory flows suggests a fixed large
airway obstruction.
• Causes of fixed large airway obstruction
include tracheal stenosis, tracheal
tumors, and foreign body aspiration.

49. • extra thoracic obstruction, that is, reduced
inspiratory flow and relatively normal
expiratory flow.
• Vocal cord dysfunction and laryngeal
edema are common causes of variable extra
thoracic obstruction.

50. Peak Expiratory Flow
• PEF is the maximum flow that occurs at any point in time during the
FVC.
• Normal peak flows average 9 to 10 L/sec.
• The reliability of PEF as a clinical tool for evaluation of lung
mechanics is limited because of the initial high flow that can occur
even in obstructive disorder.
• Decreased peck flows reflect non specific mechanical problem of the
lung, patient cooperation and effort.

51. PEF cont.
• PEF is a highly effort-dependent measure and is not particularly useful
in diagnosing pulmonary dysfunction. However, it is commonly used
by patients with asthma to monitor the severity of bronchospasm and
its response to treatment.
• 80% to 100% of the patient’s personal best peak flow as the green
zone, or normal (no special action required)
• 50% to 80% of the patient’s personal best as the yellow zone
(requiring self-administration of bronchodilator plus possibly oral
steroids)
• below 50% of the patient’s personal best as the red zone (requiring
self-administration of bronchodilator, contacting the doctor)

52. Maximal Voluntary Ventilation
• Volume of air inhaled and exhaled with maximum effort over 12 or15
seconds. (then multiplied 5 or 4 to convert in 1 min.)
• MVV is affected by the strength of the respiratory muscles,
compliance of the lung and thorax, inspiratory and expiratory airway
resistance, and patient motivation and effort.
• 160 to 180 L/min is normal value.
• MVV is typically described as being about 40 × FEV1.

53. Validity of MVV depends on
the duration of the maneuver,
which should be at least 12
sec; the breathing frequency
should be 90 breaths/mins;
and the average volume which
should be at least 50% of
FVC.

54. LLN & ULN
• Determination of upper and
lower limits of normal.
• Ninety-five percent of all
values in a normal distribution
fall within ±2 standard
deviations (SD) of the mean.
• The boundaries of this range are
the lower limit of normal (LLN)
and the upper limit of normal
(ULN).

55. Compare FVC, FEV1,
FEV1/FVC to Normals (N)
FVC ↓
FEV1 N
FEV1/FVC
≥ LLN
FVC N or ↓
FEV1 ↓
FEV1/FVC
< LLN
FVC N
FEV1 N
FEV1/FVC
≥ LLN
Likely
Restrictive
Ventilatory
Impairment
Obstructive
Ventilatory
Impairment
Normal
Pulmonary
Function
Consider
Static Lung
Volumes
and DLCO
Assess
Response to
Bronchodilator
> 12%↑in
FEV1 &
FVC?
Reversible
Airway
Obstruction
Obstructive
Ventilatory
Impairment
Confirm
Test
Validity
YES NO

56. Typical effect of obstructive and restrictive disease on
Spirometric and airflow volume measurements
MEASUREMENT OBSTRUCTIVE RESTRICTIVE NORMAL VALUE
Tidal Volume (TV) N or ↑ N or ↓ 500 ml
Inspiratory Capacity (IC) N or ↓ N or ↓ 3.60 L
Expiratory Reserve Volume (ERV) N or ↓ N or ↓ 1.20 L
Vital Capacity (VC) N or ↓ ↓ 4.80 L
Forced Vital Capacity (FVC) N or ↓ ↓ 4.80 L
Residual Volume (RV) N or ↑ N or ↓ 1.20 L
Functional Residual Capacity (FRC) N or ↑ N or ↓ 2.40 L
Total Lung capacity (TLC) N or ↑ ↓ 6 L
Forced Expiratory Volume in 1 sec. (FEV1) ↓ N 4.20 L
Peak Expiratory Flow (PEF) N or ↓ N or ↓ 9.5 L/s
Maximum Voluntary Ventilation (MVV) ↓ N or ↓ 160 L/min

57. DLCO
• Diffusing Capacity Of Lung
• The diffusing capacity (also called the
transfer factor) is a measure of the
lung’s ability to exchange oxygen with
the mixed venous blood.
• The most commonly used standardized
method is the single-breath DLCO, or
DLCOsb.

58. • In the single-breath technique, the patient first fully exhales to RV, then
quickly inhales the test gas to TLC (an inspiratory VC).
• Then the patient performs a relaxed breath-hold with the breathing valve
closed.
• After 10 seconds, the breathing valve opens, allowing the patient to exhale.
• The initial 0.5 to 0.75 L of the patient’s expired gas (dead space) is
discarded, with the remainder diverted by the valve to the sampling system
for He and CO analysis.
• The most commonly cited normal range for Dlco is 25 to 30 mL/min/mm
Hg.

59. Report

60. References
• Robert M. Kacmarek, James K. Stoller, Albert J. Heuer, Egan’s
fundamentals of respiratory care, 12th edition.
• Ellen Hillegass, essential of cardiopulmonary physical therapy, 3rd edition.
• Albert J. Heuer, Craig L. Scanlan, Wilkins' clinical assessment in
respiratory care, 7th edition.
• Alexandra Hough, physiotherapy in respiratory care, An evidence-based
approach to respiratory and cardiac management, 3rd edition.
• Ellen A. Hillegass, H. Steven Sadowsky, essentials of cardiopulmonary
physical therapy, 2nd edition.
• Patricia A. Downie, Cash’s textbook of chest, heart and vascular disorders
for physiotherapists, 4th edition.