Lung volumes and lung capacities refer to the volume of air in the lungs at different phases of the respiratory cycle. The average total lung capacity of an adult human male is about 6 litres of air.[1] Tidal breathing is normal, resting breathing; the tidal volume is the volume of air that is inhaled or exhaled in only a single such breath. The average human respiratory rate is 30–60 breaths per minute at birth,[2] decreasing to 12–20 breaths per minute in adults.[3

1. LUNG VOLUMES
&CAPACITIES
BEDSIDE PULMONARY
FUNCTION TESTS

2. • Lung volumes and lung capacities refer to volume of
air associated with different phases of the respiratory
cycle.
• Lung volumes are directly measured.
• Lung capacities are inferred from lung volumes.
• John Hutchinson invented spirometer.
• Cant Measure –FRC,RV,TLC
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3. LUNG VOLUMES
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• 1.Tidal volume
• 2.Inspiratory reserve volume
• 3.Expiratory reserve volume
• 4.Residual volume

4. • TIDAL VOLUME
• Normal volume of air inspired or expired during quiet
breathing
• Normal volume:500ml
• RESIDUAL VOLUME:
• Volume remaining in the lung after a maximal expiratory
effort
• Normal value:1200ml
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5. • INSPIRATORY RESERVE VOLUME:
• Volume of air that can be inspired with maximal effort
above the normal resting end expiratory position of a tidal
volume.
• Normal value:3000ml in adult male
• EXPIRATORY RESERVE VOLUME:
• Volume of air that can be forcibly exhaled between resting
end expiratory volume and RV.
• Normal value:1100ml

6. CAPACITIES
• VITAL CAPACITY:
• amount of air that can be exhaled from the point of
maximal inspiration to the point of maximal
expiration (IRV+TV+ERV).
• FORCED VITAL CAPACITY:
• Volume of air that can be exhaled with maximal
effort from total lung capacity
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7. • TOTAL LUNG CAPACITY(TLC):
• Total volume of air in the lungs after a maximal
inspiration
• IRV+TV+ERV+RV
• FRC-FUNCTIONAL RESIDUAL CAPACITY
• Amount of air in the lung at the end of quiet
exhalation.
• ERV+RV

8. FUNCTIONAL RESIDUAL
CAPACITY
INCREASED DECREASED
1)Height 1) upright to supine(1 L)
2)Age
2)Inductionanaesthesia0.5L
20%
3)Fibrotic lung diseases
4)women
5)obesity

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11. • Closing Capacity:
 CC is the sum of closing volume (CV) and
RV.
 Measurement is by wash in technique with a
small bolus of insoluble tracer gas xenon or by
nitrogen washout after inspiration of a breath of
oxygen from RV.
 Normal value-15% to 20% of VC
 Increases with age due to loss of structural
parenchymal support tissue in the lung and
increase in RV.

12. Closing volume:
 CV is the lung volume below which small airways
begin to close (or at least cease to contribute
expiratory gas) during expiration.
 Closure of small airways in the basal portions of the
lung during deep expiration is a normal phenomenon
due to the gravity-dependent increase in pleural
pressure at the bases and due to lack of
parenchymal support in distal airways.

13. SPIROMETRYPREREQUISITES
Do not smoke for at
least1hourbefore the
test.
Do not drink alcohol for at
least 4 hours before the test.
Do not exercise heavily for at
least 30 minutes before the
test.
Do not wear tight clothing
that makes it difficult for you
to take a deep breath.
Do not eat a large meal
within 2 hours before the test.

14. ACCEPTABILITY CRITERIA
Good start of test- without any hesitation
No Artifact (coughing / glottis closure)
 No variable flow
 No early termination(> 6 sec)
 No air leak
REPEATABILITY CRITERIA
Two largest FVC within 150 ml of each
other
Upto 8 manoeuver can be repeated
till criteria are met

15. MEASURING FRC ANDRV
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16. 1) N2 WashoutTechnique:
patient breathes 100%
oxygen
all the nitrogen in the lungs is washed
out
exhaled volume and the
nitrogen concentration are
measured.
nitrogen volume at
the initial concentration
final exhaled FRC
concentration

17. 2)HeliumDilutiontechnique:
Pt breathes in and out from a reservoir
with known volume of gas containing
trace of helium.
Helium gets diluted by gas previously
present in lungs.

18. 3)BodyPlethysmography
Plethysmography (derived from greek
word meaning enlargement). Based on
principle of BOYLE’S LAW(PV=k)
A patient is placed in a sitting position
in a closed body box with a known
volume
The patient pants with an open glottis
against a closed shutter to produce
changes in the box pressure
proportionate to the volume of air in the
chest.
As measurements done at
end of expiration, it yields FRC

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20. Forced expiratory volume in 1 sec (FEV1): Volume of air
that can be forcefully exhaled in 1 sec. Values between 80%
and 120% of the predicted value are considered normal.
Forced vital capacity (FVC): The volume of air that can be
exhaled with maximum effort after a deep inhalation. Normal
values are 3.7 L in females and 4.8 L in males. Ratio of
FEV1 to FVC: This ratio in healthy adults is 75%–80%.
Forced expiratory flow at 25%–75% of vital capacity
(FEF25%– 75%): A measurement of airflow through the
midpoint of a forced exhalation.

21. Maximum voluntary ventilation (MVV): The maximum
amount of air that can be inhaled and exhaled within 1
min.
• The volume is measured over a 15-sec time period
and results are extrapolated to obtain a value for 1
min expressed as liters per minute.
• Average values for males and females are 140–180
and 80–120 L/min, respectively

22. . Diffusing capacity (Dlco):
• The volume of a substance [CO] transferred
across the alveoli into blood per minute per unit
of alveolar partial pressure.
• CO is rapidly taken up by hemoglobin and Its
transfer is therefore limited mainly by diffusion.
• A single breath of 0.3% CO and 10% helium is
held for 20 sec. Expired partial pressure of CO
is measured.
• Normal value is 17–25 mL/min/mm Hg.

23. OBSTRUCTIVE PATTERN
Common obstructive lung diseases;
 Asthma
 COPD (chronic bronchitis, emphysema)

24. RESTRICTIVE PATTERN
 Characterized by reduced lung
volumes/decreased lung compliance
Examples:
Interstitial Fibrosis
Scoliosis
Obesity
Lung Resection
Neuromuscular diseases

26. FEV1 FVC FEV1/FVC
OBSTRUCTIVE DECREASED
(<80%)
DECREASED DECREASED(< 0.7)
RESTRICTIVE DECREASED DECREASED NORMAL OR INCREASED

27. 1) FORCED VITAL CAPACITY
Maximum volume of air that can be breathed out
as forcefully and rapidly as possible following a
maximum inspiration.
The expiration should be at least 4 seconds and
should not be interrupted by coughing, glottis
closure or mechanical obstruction.
Normal healthy subjects have VC = FVC.
Indirectly reflects flow resistance property of
airways.
Interpretation of % predicted:
>80-120% Normal
70-79% Mild reduction
50%-69% Moderate reduction
<50% Severe reduction

28. 2) FORCED EXPIRATORY VOLUME in 1 SEC.
(FEV1)
Forced expired volume in 1 sec during
FVC maneuver.
Expressed as an absolute value or % of
FVC
Normal - FEV1 (1 SEC)- 75-85% OF FVC
FEV2 (2 SEC)- 94% OF FVC
FEV3 (3 SEC)- 97% OF FVC
FEV1 – Decreased in both obstructive &
restrictive lung disorders

30.  FEV1%=FEV1/VC X100.
• FEV1/FVC – Reduced in obstructive
disorders.
Interpretation of FEV1 % predicted:
>80% Normal
50%-80% Mild obstruction
30%-50% Moderate
<30% Severe
A FEV1% that is too high is suggestive for a
restriction of the pulmonary volume.

31. PULMONARY
FUNCTION TESTS
Indicate group of studies or maneuvers
performed using standardized equipment
to measure lung function
 Evaluate one or more aspects of the
respiratory system
Respiratory mechanics
Lung parenchymal function/ Gas
exchange
Cardiopulmonary interaction
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32. INDICATIONS
Investigation of patients with symptoms/signs/
investigations that suggest pulmonary disease
e.g.(Cough/Wheeze/Breathlessness/Crackles)
Monitoring patients with known pulmonary
disease for progression and response to
treatment e.g.
• Interstitial fibrosis
• COPD & Asthma
• Pulmonary vascular disease

33. Investigationof patients with disease that may
have a respiratory complications e.g.
• Connective tissue disorders
• Neuromuscular diseases
Preoperative evaluation prior to
• Lung resection
• Abdominal surgery
• Cardiothoracic surgery

34. • Evaluation of patients at risk of lungdiseases
• Exposure to pulmonary toxins such as
radiation,medication,environmental,occupational,
exposure
• Surveillance following lung transplantation to
assess for
• 1)Acute rejection
• 2)Infection
• 3)Obliterative bronchiolitis

35. CONTRAINDICATIONS
• Myocardial infarction with in last month
• Unstable angina
• Recent thoracoabdominal surgery
• Recent ophthalmic surgery
• Thoracic or abdominal aneurysm
• H/o syncope with forced exhalation
• Current pneumothorax/hemoptysis

36. INDICATIONS OF PFT IN PAC
TISI GUIDELINES FOR PREOPERATIVE
SPIROMETRY
Age > 70 yrs.
Morbid obesity
Thoracic surgery
Upper abdominal surgery
Smoking history and cough
Any pulmonary disease

37. American College Of Physicians
(ACP) Guidelines For
Preoperative Spirometry
Lung resection
H/o smoking, dyspnoea
Cardiac surgery
Upper abdominal surgery
Lower abdominal surgery
Uncharacterized pulmonary
disease (defined as history of
pulmonary Disease or symptoms
and no PFT in last 60 days)

38. Bed sidepulmonary
function tests

39. 1) SABRASEZ BREATHHOLDING
TEST:
Ask the patient to take a full but not too deep breath &
hold it as long as possible.
Assessment of cardio pulmonary reserve
>25 SEC - NORMAL Cardiopulmonary Reserve
(CPR)
15-25 SEC - LIMITED CPR
<15 SEC - VERY POOR CPR (Contraindication for
elective surgery)

40. 2) SCHNEIDER’S MATCH BLOWING
TEST:Ability of patient to cough &bring out secretions in post
operative period or reduction in post op atelectasis
Measures Maximum Breathing Capacity
Ask to blow a match stick from a distance of 6” (15
cms) with-
 Mouth wide open
 Chin rested/supported
 No purse lipping
 No head movement
 No air movement in the room
 Mouth and match at the samelevel

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42. Can’t blow
out
Able to
blow
MBC < 60 L/min
FEV1 < 1.6L
Modified match test:
DISTANCE
9”
6”
3”
MBC > 60L/min
FEV1>1.6L
MBC
>150 L/MIN.
>60 L/MIN.
>40 L/MIN

43. 3.COUGH TEST
Deep breath inadequate cough if:
Followed by cough FVC<20 ml/kg
• Ability to cough FEV1<15 ml/kg
• Strength PEFR<200L/min
• Effectiveness VC-3 Times TV for
effective cough

44. 4) FORCED EXPIRATORYTIME:
After deep breath, exhale maximally and
forcefully & keep stethoscope over
trachea& listen.
Normal FET – 3-5 SECS.
OBS.LUNG DIS. - > 6 SEC
RES. LUNG DIS.- < 3 SEC
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5)SINGLE BREATHCOUNT:
After deep breath, hold it and start
counting till the nextbreath.
N- 30-40 COUNT
Indicates vital capacity

46. 6) WRIGHT PEAK FLOW METER:
Measures Peak Expiratory Flow Rate
(PEFR)
• Normal – males- 450-700
l/min.
females- 350-500 l/min.

47. 7) DE-BONO WHISTLE BLOWING
TEST:
Measures PEFR.
Patient blows down a wide
bore tube
whistle blows
leak hole is gradually increased till the
till the intensityof whistle disappears.
The last position at which the whistle can be blown
the PEFR can be read off the scale.
,

48. 8) WRIGHT RESPIROMETER:
measures TV, MV
 Instrument- compact, light and portable.
Can be connected to endotracheal tube or face
mask
MV- instrument record for 1
min. and read directly
TV-calculated by dividing
MV by counting Respiratory
Rate.
Disadvantage: It under-
reads at low flow rates and
over- reads
at high flow rates.

49. 9)SPHYGMOMANOMETER BLOW
TEST (endurancetest):
-Ask to blow and raise column of Hg
upto 40- 50 mmHg and duration is
noted.
-50 seconds is normal.
10)MICROSPIROMETERS;Measure
VC
11) BED SIDE PULSE OXIMETRY
12) ABG.

50. REFERENCES;
1).MILLERS ANAESTHESIA
2).STOELTINGS PHYSIOLOGY AND
PHARMACOLOGY
3).STOELTINGS CO-EXISTING DISEASES
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