lecture 3: measuring the lung capacity for both inhalation and exhalation because many lung disease will affect the normal capacity of lung volume

1. Pulmonary or
(Lung Function
Tests)
30-9-2019

2. • Useful in assessing the functional status of the
respiratory system both in physiological and
pathological conditions.
• Lung function tests are based on the 1)
measurement of volume of air breathed in and
out in quiet breathing and 2) forced breathing.

3. 1- TIDAL VOLUME:
• is the volume of air breathed in and
out of lungs in a single normal quiet
respiration.
• Tidal volume signifies the normal depth
of breathing.
• This is about 500 ml in adults.
• The 500ml of tidal volume will divide
into:
• 150 ml containing in (dead space).
• 350 ml containing in (alveolar
ventilation).

4. 2- INSPIRATORY RESERVE
VOLUME:
• is an additional volume of air that can be
inspired forcefully after the end of normal
inspiration.
• The normal IRV is 3.3 liters in men and 1.9
liters in women.
• a maximal inspiratory effort.

5. 3- EXPIRATORY RESERVE
VOLUME:
• is the additional volume of air that can be
expired out forcefully, after normal
expiration.
• The normal ERV is 1.2 liter in men and 0.7
liter in women.
• a maximum expiratory effort.

6. 4- RESIDUAL VOLUME:
• is the volume of air remaining in lungs even
after forced expiration.
• Normally, lungs cannot be emptied completely
even by forceful expiration.
• Some quantity of air always remains in the
lungs even after the forced expiration.
• The normal value of RV in men is 1.2 liter and
in women is 1.1 liter.

7. Example of
RESIDUAL VOLUME:

8. Spirometry.
• is a common office test used to assess how well your lungs
work by measuring how much air you inhale, how much
you exhale and how quickly you exhale.
• Pulmonary ventilation can be studied by recording the
volume movement of air into and out of the lungs.
• Spirometry is used to diagnose asthma, chronic
obstructive pulmonary disease (COPD) and other
conditions that affect breathing.
• Spirometry may also be used periodically to monitor your
lung condition and check whether a treatment for a
chronic lung condition is helping you breathe better.
• Spirometry is generally a safe test. You may feel short of
breath or dizzy for a moment after you perform the test.

12. lung capacities:
• lung capacities are the combination of two or
more lung volumes.
IC = TV + IRV
FRC = ERV + RV
VC = IRV + TV + ERV
TLC = IRV + TV + ERV + RV

14. COMPUTERIZED SPIROMETER
PLETHYSMOGRAPHY
RESPIROMETER

15. VITAL CAPACITY:
is the maximum volume of air that can be expelled
out of lungs forcefully after a maximal or deep
inspiration.

16. RESPIRATORY MINUTE VOLUME:
• Also called; Pulmonary ventilation or minute
ventilation.
• is the volume of air breathed in and out of
lungs every minute.
• It is the product of tidal volume (TV) and
respiratory rate (RR).
OR

17. • When the Respiratory rate increases 40/min for
example, the tidal volume will equal to that of
vital capacity = 4600ml.
So the RMV = tidal volume X RR
RMV = 4600ml X 40/min.
RMV = 184000ml or 184 L.
• When the respiratory rate decreases 4/min for
ex, the tidal volume will not changed to it’s
normal =500ml.
So the RMV = tidal volume X RR
RMV = 500ml X 4/min.
RMV = 2000ml or 2 L.

18. ALVEOLAR VENTILATION:
• is the amount of air utilized for gaseous
exchange every minute.
• Alveolar ventilation is different from pulmonary
ventilation.
• Is the areas that include the alveoli, alveolar
sacs, alveolar ducts, and respiratory bronchioles.
• The rate at which new air reaches these areas
called alveolar ventilation and can be calculated
as this:

19. DEAD SPACE:
• Some of the air a person breathes never reaches the gas
exchange areas but simply fills respiratory passages
where gas exchange does not occur, such as the nose,
pharynx, and trachea.
• This air is called dead space air because it is not useful
for gas exchange.
• Volume of normal dead space is 150 mL

21. TYPES OF DEAD SPACE :
1- Anatomical Dead Space:
• Anatomical dead space extends from nose up to terminal
bronchiole.
• It includes nose, pharynx, trachea, bronchi and branches of
bronchi up to terminal bronchioles.
• These structures serve only as the passage for air movement.
• Gaseous exchange does not take place in these structures.
2- Physiological Dead Space:
• Air in the alveoli, which are non-functioning.
• In some respiratory diseases, alveoli do not function because
of dysfunction or destruction of alveolar membrane.
• Air in the alveoli, which do not receive adequate
blood flow.