PULMONARY FUNCTION TEST.pdf

ALL ABOUT TH BASIC IDEA OF PFT

1. PULMONARY FUNCTION TEST
ShilpasreeSaha,
BPT (TIPS, Agartala), MPT-Cardio-Thoracic Disorders (MMIPR, MM(DU, Mullana)
Assistant Professor, NIHS

2. INTRODUCTION
•Pulmonaryfunctiontests
(PFTs)helpintheevaluationof
themechanicalfunctionofthe
lungs.
•PFTsareusefulinassessingthe
functionalstatusofthe
respiratorysystembothin
physiologicalandpathological
condition.
•Itiscarriedoutbyusinga
spirometer.
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3. BASICS OF PFT
•Theyarebasedonresearchednormstakinginto
accountgender,height,andagetoseeifhefallswithin
the"normal"range,orhasarestrictiveorobstructive
componentbasedonthetests.
•Whenthepatientperformsthetestactualresults
(observed)willbecomparedwiththepredictedvalue.
•Ifthepatientisnotwithinthenormalrange,a
bronchodilatorisgiven,andthetestwillberepeatedto
seeifthereissignificantimprovementwithmedication.
•Basically,thepulmonaryfunctiontestsarecategorized
asvolume,flow,ordiffusionstudies.
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4. LUNG VOLUME AND CAPACITIES
Lung Volume
TV is the normal breath.
IRV is the maximal amount of air that can be
inhaled from the end of a normal inspiration.
ERV is the maximal amount of air that can be
expired after a normal exhalation.
RV is the volume of gas that remains in the lungs
at the end of a maximum expiration.
Lung capacities
TLCistheamountofgasthelungcontainsatthe
endofamaximuminspiration.Itismadeupofall
fourlungvolumes.
VCisthemaximumamountofgasthatcanbe
expelledfromthelungsbyforcefuleffortfollowing
amaximuminspiration.ItcontainstheIRV,TV,ERV.
ICisthemaximalamountofairthatcanbe
inspiredfromtherestingexpiratorylevel.It
containstheIRVandtheTV.
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5. A SPIROGRAM (PULMONARY FUNCTION TESTING)
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6. DEAD SPACE
•Thereisaseriesofconductingairwaysinthelungs
fromthetracheadowntotheterminalbronchi,
whichdonotparticipateinrespirationbutonly
movethegasestothealveoli.Thisisthevolume
knownasanatomicdeadspace.
•Generally,theanatomicdeadspaceisappropriately
equaltotheadultbodyweight.Forexample,ina
150-lb.person,thereisanapproximately150mL
anatomicdeadspace.
•Thephysiologicaldeadspaceisdefinedasincluding
anatomicaldeadspaceandalveolardeadspace
components.
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7. Normal tidal volume (TV), the breath normally taken, needs to be large enough to reach the alveoli well past the
anatomic dead space. In a normal adult, the TV is generally 450 to 600 mL.
The anatomic dead space would thus represent about one third TV volume.
The rest of the breath would reach the alveoli and be considered "alveolar ventilation."
With many neurologically impaired patients who have a limited TV, it is important to note that little alveolar
ventilation may be taking place when the patient is breathing in a rapid and shallow pattern.
For example, if a patient's TV was 200 mL, 150 mL would be anatomic dead space and only 50 mL of each breath
would be alveolar ventilation.
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8. INDICATION
Investigationof patients with
symptoms/signs/investigationsthatsuggest
pulmonarydiseasee.g.Cough,Wheeze,
Breathlessness,Crackles,Abnormalchestx-ray.
Monitoringpatientswithknownpulmonary
diseaseforprogressionandresponsetotreatment
e.g.Interstitialfibrosis,COPD,Asthma,Pulmonary
vasculardisease.
Investigationofpatientswithdiseasethatmayhave
arespiratorycomplicationse.g.Connectivetissue
disorders,Neuromusculardiseases.

9. Preoperative evaluation prior to e.g. Lung resection, Abdominal surgery, Cardiothoracic surgery.
Evaluation patients a risk of lung diseases e.g. Exposure to pulmonary toxins such a radiation, medication, or
environmental or occupational exposure
Surveillance following lung transplantation to assess for Infection.
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10. CONTRA-INDICATION
Myocardial infarction within the last month
Unstable angina
Recent thoraco-abdominal surgery
Recent ophthalmic surgery
Thoracic or abdominal aneurysm
Current pneumothorax
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11. PROCEDURE
Spirometryisthemostfrequentlyusedmeasure
oflungfunctionandisameasureofvolumeagainst
time.
Itisasimpleandquickproceduretoperform:
patientsareaskedtotakeamaximalinspiration
andthentoforcefullyexpelairthroughmouth
intothemouthpieceforaslongandasquicklyas
possibleagainstclosednostril.
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12. Measurements that are made include:
Forced expiratory volume in one second (FEV1)
Forced vital capacity (FVC)
The ratio of the two volumes (FEV1/FVC)
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13. AIR FLOW MEASUREMENTS
When patients perform a VC maneuver, it can either be slow or fast.
During exhalation, the amount of air exhaled over time can be measured. In a slow VC a patient with emphysema
can take a great deal of time to empty his lungs.
In a forced VC a normal individual can exhale 75% of the VC in the first second of exhalation (FEV I).
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14. FLOW VOLUME CURVE
The flow volume curve is helpful in diagnosing lung
disease.
The curve demonstrates that flow rises to a high
value and then declines over most of expiration
In restrictive lung disease, the maximum flow rate
is reduced.
In obstructive lung disease, the flow rate is low in
relation to lung volume, and a scooped-out
appearance is often seen.
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15. FLOW VOLUME LOOP
Another diagnostic test that uses forced
expiration is the flow volume loop.
It is a graphical analysis of the flow generated
during a forced expiratory volume maneuver
followed by a forced inspiratory volume maneuver.
This graph offers a pictorial representation of data
(e.g., peak inspiratory and expiratory flow rates
FVC, and FEV1).
The shape of the graph may also be helpful in
diagnosing disease, again seeing a more scooped-
out appearance with obstructive disease.
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17. CLOSING VOLUME AND AIRWAY CLOSURE
The assessment of closing volume is used to help diagnose small airway disease.
A test called the single breath nitrogen (N2) washout is used for assessing closing volume and closing capacity of
the small airways.
In this test, the patient takes a single VC breath of 100% oxygen.
During complete exhalation, the N2 concentration can be measured.
The characteristic tracing of N2 concentration can be measured. The characteristic tracing of N2 concentration
vs. lung volume reflects sequential emptying of differentially ventilated lung units, resulting in different expiratory
N2 concentrations.
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18. FOUR PHASES CAN BE IDENTIFIED:
Phase I contains pure dead space and virtually none of
the potential N2 from the RV.
Phase Il is associated with an increasing N2
concentration of a mixture of gas from the dead space
and alveoli.
The plateau in N2 concentration observed in Phase III
reflects pure alveolar gas emanating from the bases and
middle lung zones.
Phase IV occurs toward the end of expiration and is
characterized by an abrupt increase in N2 concentration.
This high N2 concentration reflects closure of airways at
the base of the lungs and expiration of gas from the
upper lung zones, because in the single breath of 100%
oxygen, less oxygen was initially directed to this area.
Closing volume is the lung volume at which the inflection
of Phase IV, the marked increase in N2 concentration
after the plateau, is observed.
Closing capacity refers to closing volume and RV.
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19. The closing volume is 10% of the vital capacity in young, healthy individuals. It increases with age and is 40% of the
vital capacity at age 65.
Closing volume is used as an aid in the diagnosis of small airway disease and as a means of evaluating treatment or
drug response.
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20. MAXIMAL VOLUNTARY VENTILATION
Maximal voluntary ventilation measures the maximal breathing capacity of the patient. It reflects strengths and
endurance of the respiratory muscles.
The patient is asked to pant for 15 seconds into the spirometer tubing.
This is often examined preoperatively with the other results to determine a patient's prognosis for success after
surgery, such as his or her ability to cough, to take deep breaths, and to enhance airway clearance.
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21. REFERENCES
RanuH, Wilde M, Madden B. Pulmonary function tests. Ulster Med J. 2011 May;80(2):84-90. PMID: 22347750;
PMCID: PMC3229853.
Principles And Practice Of Cardiopulmonary Physical Therapy, Donna Frownfelter, Third Edition.
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22. THANK YOU
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