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1. LUNG VOLUMES AND
CAPACITIES
BED SIDE PFT
Dr. Harith

2. Lung volumes and lung capacities refer to
the volume of air associated with different phases
of the respiratory cycle.
 Lung volumes are directly measured; Lung
capacities are inferred from lung volumes.
Instrument is spirometry

3. LUNG VOLUMES
Four types
1. Tidal volume
2. Inspiratory reserve volume
3. Expiratory persevere volume
4. Residual volume

6. 1) TIDAL VOLUME (TV):
 VOLUME OF AIR INHALED/EXHALED
IN EACH BREATH DURING QUIET
RESPIRATION.
 N – 6-8 ml/kg.
 TV FALLS WITH DECREASE IN
COMPLIANCE, DECREASED
VENTILATORY MUSCLE STRENGTH.

7. 2) INSPIRATORY RESERVE VOLUME (IRV):
 MAX. VOL. OF AIR WHICH CAN BE
INSPIRED AFTER A NORMAL TIDAL
INSPIRATION
 i.e. FROM END INSPIRATION
 N- 1900 ml- 3300 ml.

8. 3) EXPIRATORY RESERVE VOLUME (ERV):
MAX. VOLUME OF AIR WHICH CAN BE
EXPIRED AFTER A NORMAL TIDAL
EXPIRATION
i.e. FROM END EXPIRATION PT.
N- 700 ml – 1000 ml
700-1000ml

9. Residual Volume (RV):
Volume of air remaining in lungs
after maximium exhalation (20-25
ml/kg) (1700-2100ml)
Indirectly measured (FRC-ERV)

10. CAPACITIES
Two or more Volumes combined together
Functional Residual Capacity (FRC):
Volume of air remaining in the lungs at
passive end expiration.
N- 2.3 -3.3 L OR 30-35 ml/kg
FRC = RV + ERV

11. FRC INCREASES WITH
 Increased height
 Erect position (30% more than in supine)
 Decreased lung recoil (e.g. emphysema)
FRC DECREASES WITH
 Obesity
 Muscle paralysis (especially in supine)
 Supine position
 Restrictive lung disease (e.g. fibrosis, Pregnancy)
 FRC does NOT change with age.

12. Total Lung Capacity (TLC):
 Maximum volume of air
attained in lungs after maximal
inspiration.
N- 4-6 l or 80-100 ml/kg
TLC= VC + RV

13. Inspiratory Capacity (IC):
MAX. VOL. OF AIR WHICH CAN BE
INSPIRED AFTER A NORMAL TIDAL
EXPIRATION.
IC = IRV + TV
N-2400 ml – 3800 ml.

14. Expiratory Capacity (EC):
TV+ ERV
N 1200-1700 ml

15. Vital Capacity (VC):
MAX. VOL. OF AIR EXPIRED AFTER A
MAX. INSPIRATION .
VC= TV+ERV+IRV
N- 3.1-4.8L. OR 60-70 ml/kg

16.  Alteration in muscle power- d/t drugs, n-m dis., cerebral tumours.
 Pulmonary diseases – pneumonia, chronic bronchitis, asthma, fibrosis,
emphysema, pulmonary edema,.
 Space occupying lesions in chest- tumours, pleural/pericardial effusion,
kyphoscoliosis
 Abdominal tumours, ascites.
 Depression of respiration : opioids/ volatile agents
 Abdominal splinting – abdominal binders, tight bandages, hip spica.
 Abdominal pain – decreases by 50% & 75% in lower & upper
abdominal Surgeries respectively.
 Posture – by altering pulmonary Blood volume.

21. HELIUM DILUTION METHOD

22. • Patient breathes in and out of a spirometer filled with 10%
helium and 90% o2, till conc. In spirometer and lung
becomes same (equilibirium).
As no helium is lost; (as he is insoluble in blood)
C1 X V1 = C2 ( V1 + V2)
V2 = V1 ( C1 – C2)
C2
• V1= VOL. OF SPIROMETER
• V2= FRC
• C1= Conc.of He in the spirometer before equilibrium
• C2 = Conc, of He in the spirometer after equilibrium
2(10-5)
5

23.  Volume above residual
where airway closure begins
 Total volume in the lung
where airway closure begins
CLOSING VOLUME AND CAPACITY

24. BED SIDE PFT
Sabrasez breath holding test:
• Ask the patient to take a full but not too deep breath &
hold it as long as possible.
>25 SEC.-NORMAL Cardiopulmonary Reserve
(CPR)
15-25 SEC- LIMITED CPR
<15 SEC- VERY POOR CPR (Contraindication for
elective surgery)
25 - 30 SEC - 3500 ml VC
20 - 25 SEC - 3000 ml VC
15 - 20 SEC - 2500 ml VC
10 - 15 SEC - 2000 ml VC
5 - 10 SEC - 1500 ml VC

25. Single breath count:
After deep breath, hold it and start counting till the next breath.
 N- 30-40 COUNT
Indicates vital capacity
SCHNEIDER’S MATCH BLOWING TEST: 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 same level

26. Can not blow out a match
 MBC < 60 L/min
 FEV1 < 1.6L
Able to blow out a match
 MBC > 60 L/min
 FEV1 > 1.6L
MODIFIED MATCH TEST:
DISTANCE MBC
9” >150 L/MIN.
6” >60 L/MIN.
3” > 40 L/MIN.

27. COUGH TEST: DEEP BREATH F/BY COUGH
 ABILITY TO COUGH
 STRENGTH
 EFFECTIVENESS
INADEQUATE COUGH IF: FVC<20 ML/KG
FEV1 < 15 ML/KG
PEFR < 200 L/MIN.
VC ~ 3 TIMES TV FOR EFFECTIVE COUGH.
A wet productive cough / self propagated
paraoxysms of coughing – patient susceptible for
pulmonary Complication.

28. DEBONO WHISTLE BLOWING TEST
MEASURES PEFR.
Patient blows down a wide bore tube at
the end of which is a whistle, on the
side is a hole with adjustable knob.
 As subject blows → whistle blows,
leak hole is gradually increased till the
intensity of whistle disappears.
 At the last position at which the
whistle can be blown , the PEFR can
be read off the scale.

29. FORCED EXPIRATORY TIME:
After deep breath, exhale maximally and forcefully & keep
stethoscope over trachea & listen.
Normal FET – 3-5 SECS.
Obstructive Lung Disease - > 6 SEC
Restrictive Lung Disease - < 3 SEC
MICROSPIROMETERS – MEASURE VC.

30. THANK YOU