DR QAZI IMTIAZ RASOOL
1.
Describe normal spirogram, labeling, defining and mentioning
the normal values of lung volumes and capacities.
2.
Discuss and identify volume and capacities that cannot be
measured by spirometry and discuss their significance and
factors affecting them.
3.
Define dead space, identify its different types and mention its
significance.
4.
Describe the changes in these volumes and capacities in
obstructive and restrictive pulmonary diseases.
The term means a wide variety of objective methods to
assess lung function
Examples include:
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Spirometry
Lung volumes by helium dilution or body plethysmography
Blood gases
Exercise tests
Diffusing capacity
Bronchial challenge testing
Pulse oximetry
Angiography
Ct scan
MRI
Basic tools to know respiratory status.
1.
2.
3.
4.
5.
6.
7.
In patients with suspected pulmonary disease,
As a first diagnostic test employed In pre-operative
evaluation,
In managing patients with pulmonary disease,
In quantifying pulmonary disability.
In evaluation of allergic status for drug therapy
As epidemiological survey to know normal values
To assess impact of an occupational exposure
“ is a medical test that measures the volume of air an
individual inhales or exhales as a function of time. (ATS,
1994)”
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Simple, office-based
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Measures flow, volumes
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Volume vs. Time
.
Spirogram is the recorded graph on paper
Spirometer is the apparatus
Volumes
1. Tidal Volume
(Minute)T.V
2. Residual Volume R.V
Capacities
1. Vital Capacity V.C
2. Total Lung Capacity
T.L.C
3. Inspiratory Reserve
3. Function Residual
4. Expiratory Reserve
4. Inspiratory Capacity
Volume I.R.V
Volume E.R.V
Capacity F.R.C
I.C
provides :
1)
2)
3)
4)
5)
FVC and its derivatives (such as FEV1, FEF 25-75%)
Forced inspiratory vital capacity (FIVC)
Peak expiratory flow rate(PEFR)
Maximum voluntary ventilation (MVV)
Pre and post bronchodilator studies
-Lung
volume can be measured by;-
the changes of the lung volume during one breathing at
static conditions, called static/ Primary lung volume
Or
Same / unit time called dynamic/ secondary lung volume
1. Tidal volume
- the volume of air inspired or expired with each normal
breath ( amount of air within the lungs )
during ordinary ,quiet breathing. (500 ml)
extra amount of air, maximum vol one can inspire
above normal inspiration
(3 liters)
3. Expiratory Reserve Volume
Extra amount of air, below tidal volume, that can be exhaled
during forced expiration.
(1.1 liter)
4. Residual Volume
The amount of air that remains in the lungs after the most
forceful expiration.
(1.2 liters)
Static Lung Capacities
1. Functional residual capacity
vol. of air left in the lungs after a normal expir.,
balance point of lung recoil & chest wall forces
FRC = ERV + RV 2.2 l
2. Inspiratory capacity
max. vol. one can inspire during an insp effort
IC =TV + IRV (IC): 3.5 liters
3. Vital capacity
max. vol. one can exchange in a resp. cycle
VC = IRV + TV + ERV
4.5 liters
4. Total lung capacity
the air in the lungs at full inflation TLC = VC + RV Lung and chest wall
properties
◦ Inspiratory muscle strength
5.7 liters
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Gas dilution techniques
 All operate on a principle SIMILAR to Boyle’s Law (P1 V1 = P2
V2),
C1 V1 = C2 V2
NOTE;- 1. Can only measure lung volumes in communication with
conducting airways
2. Obstruction or bullous disease can have trapped,
noncommunicating air within the lungs (FRC may be measured is
less than its actual volume)
Static lung volumes & capacities,
RV, FRC, & TLC cannot be determined with
direct spirometry.
i.e, Closed-Circuit Helium dilution method for RV, FRC,
TLC
Usually first FRC is calculated
1. FRC= ([He]i/[He]f-1)Vi
 [He]i=initial concentration of helium in spirometer
 [He]f=final concentration of helium in spirometer
 Vi=initial volume of air in bell of spirometer
2. RV = FRC- ERV
3. TLC= RV + VC
Vital Capacity
amount of air that can be exchanged in the lungs after
the most forceful inspiration and expiration
FVC;-Total volume of air that can be exhaled forcefully
from TLC(The majority of FVC can be exhaled in <3 seconds in normal
people, )
Two ways to record results of FVC maneuver:
1.Flow-volume curve---flow meter measures flow rate in L/s upon
exhalation; flow plotted as function of volume
2. Classic spirogram---volume as a function of time
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Performance of FVC maneuver
Check spirometer calibration.
Explain test.
Prepare patient.
Ask about smoking, recent illness, medication use, etc.
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Normal standards depend upon:
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Height
Gender
Age
Race
Posture
Reproducibility criteria (3 trials examined)
Rate of decline: normal fall in FEV1 with
age = 20-30cc/year; in COPD = 5080cc/year
1. Maximum flow rate
achieved during an FVC
2. Used in asthmatics to
identify the severity of
airway obstruction and
guide therapy
3. Dependent on patient
effort
4. Normal value is 10L/sec
(600L/min), decreases
with age and obstruction
1.Anatomical dead space
(= 150 ml)
Not all of the inspired
air reached the alveoli.
2.As fresh air is inhaled it is
mixed with anatomical dead space
1.
2.Physiological dead space
= anatomical + non functional alveoli
FRC (2300 ml) - dead space (150 ml) = 2150 ml (alveolar vol.)
1.
Narrowing of the airways due to bronchial smooth muscle
contraction i.e. Asthma
2.
Narrowing of the airways due to inflammation and swelling of
bronchial mucosa and the hypertrophy and hyperplasia of
bronchial glands i.e, bronchitis
3.
Material inside the bronchial passageways physically obstructing
the flow of air i.e excessive mucus plugging, inhalation of foreign
objects or the presence of pushing and invasive tumors
4.
Destruction of lung tissue with the loss of elasticity and hence the
loss of the external support of the airways i.e. Emphysema
5.
External compression of the airways i.e.Tumors, trauma
A. Intrinsic Restrictive Lung Disorders
1. Sarcoidosis 2. Tuberculosis 3. Pnuemonectomy (loss of lung) 4.
Pneumonia
B. Extrinsic Restrictive Lung Disorders
1. Scoliosis, Kyphosis 2. Ankylosing Spondylitis 3. Pleural Effusion 4.
Pregnancy 5. Gross Obesity 6. Tumors 7. Ascites 8. Pain on
inspiration - pleurisy, rib fractures
C. Neuromuscular Restrictive Lung Disorders
1. Generalized Weakness – malnutrition 2. Paralysis of the diaphragm
3. Myasthenia Gravis - in which the nerve impulses fail to induce
muscular contraction. 4. Muscular Dystrophy 5. Poliomyelitis 6.
Amyotrophic Lateral Sclerosis
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concave, scooped appearing
VC is normal.FEV1 is reduced.
General rule:
↓ VC, normal shape reduced.
FVC is normal.
when flow is ↓→ lesion is obstructive
When volume is↓→it is restrictive
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Helpful in evaluation of air flow limitation on inspiration
and expiration
In addition to obstructive and restrictive patterns, flowvolume loops can show provide information on upper
airway obstruction:
◦ Fixed obstruction: constant airflow limitation on inspiration
and expiration—such as in tumor, tracheal stenosis
◦ Variable extrathoracic obstruction: limitation of inspiratory
flow, flattened inspiratory loop—such as in vocal cord
dysfunction
◦ Variable intrathoracic obstruction: flattening of expiratory
limb; as in malignancy or tracheomalacia
FEV1
FVC
>75%
80-120%
Normal
60%-75%
70-79%
reduction
Mild
50-59%
<49%
50%-69%
<50%
Moderate
Severe
Predicted
Values
Measured
Values
% Predicted
FVC
6.00 liters
4.00 liters
67 %
FEV1
5.00 liters
2.00 liters
40 %
FEV1/FVC
38 %
50 %
60 %
Decision : This person is obstructed
Predicted
Values
Measured
Values
%
Predicted
FVC
5.68 liters
4.43 liters
78 %
FEV1
4.90 liters
3.52 liters
72 %
FEV1/FVC
84 %
79 %
94 %
Decision : This person is restricted
FEV1/FVC
obstruction
MVV
VC
restriction
N or
or N
N or
RV
uncertain
TLC
N or
uncertain
N or
mix
1.
VC and MVV ↓
1.
RV and DS
2.
3.
↑
Ability to remove mucus from respiratory
passageways ↓
Gas exchange across respiratory
membrane ↓