Pulmonary function testing is the process of having the patient perform specific inspiratory and expiratory maneuvers while breathing in and out of tubing attached to the equipment that measure a variety of variables
3. Pulmonary function testing is the process of
having the patient perform specific inspiratory
and expiratory maneuvers while breathing in and
out of tubing attached to the equipment that
measure a variety of variables
4. To determine the functional status of the
lungs
How much gas can be moved in and out of the lungs
How fast gas can be moved
The stiffness of the lung and chest wall
The diffusion characteristics of the alveolar-capillary
membrane
How well lung responds to the therapy
5.
6. • To evaluate symptoms, signs or abnormal
laboratory tests
• To measure the effect of disease on pulmonary
function
• To differentiate between obstructive and
restrictive disease
• To screen individuals at risk of having pulmonary
disease
• To assess pre-operative risk
• To assess prognosis, response to therapy
7. • Hemoptysis of unknown origin
• Pneumothorax
• Unstable cardiovascular status or recent MI or
pulmonary embolus
• Thoracic, abdominal or cerebral aneurysms
• Presence of an acute disease process that might
interfere with test performance
• Recent surgery of thorax and abdomen
9. Height and weight:
Taller person, larger lung size, and larger predicted
lung volume
Muscular person-increase in lung size
Obese person-reduction in lung size
Gender: Males>females
Age:
Vital capacity increases in person until mid 20s
Average predicted VC for 20yrs is slightly over 5lt
By age 70, approx 4lt
Race
Environmental factors
Personal Factors
10.
11. Volume of air exhaled and inhaled during quiet
breathing
350-600ml
Decrease Vt can occur both in restrictive an
obstructive defects
12. The inspiratory reserve volume is the extra volume
of air that can be inspired over and above the normal
tidal volume when the person inspires forcefully.
It is usually equal to about 3000 ml
13. The expiratory reserve volume is the maximum
extra volume of air that can be expired by forceful
expiration after the end of a normal tidal expiration
It normally amounts to about 1100 ml
14. The residual volume is the volume of air remaining in
the lungs after the most forceful expiration
This volume averages about 1200 Ml
Is reduced in restrictive defects
Increased in obstructive defects
Expressed as ratio to TLC and VC
15.
16.
17. The inspiratory capacity equals the tidal volume
plus the inspiratory reserve volume.
It’s the amount of air a person can breathe in,
beginning at the normal expiratory level and
distending the lungs to the maximum amount.
about 3500 milliliters
18. The vital capacity equals the inspiratory reserve
volume plus the tidal volume plus the expiratory
reserve volume.
This is the maximum amount of air a person can
expel from the lungs after first filling the lungs to
their maximum extent and then expiring to the
maximum extent
About 4600 ml
If the person forcefully exhales the volume, it is
called Forced vital capacity(FVC)
19. Three phases of FVC maneuver:
Maximal inspiratory effort
Initial expiratory blast
Forceful emptying of the lungs
Both restrictive and obstructive defects can cause
decrease in VC
Important preoperative assessment factor useful in
evaluating the patient’s need for mechanical
ventilation
20. FRC = ERV+RV
Resting volume of the lungs after exhalation of Vt
breath
This is the amount of air that remains in the lungs at
the end of normal expiration
About 2300 ml
Represents balance between the expanding chest
wall forces and the contractile rebound forces of
lung tissue
21. Sum of VC and RV
Is increased with most obstructive lung defects and
decreased with restrictive lung defects
To measure TLC, RV must be determined
22. The lung volumes that can be directly measured
using a spirometer include- Tidal Volume, Inspiratory
Reserve Volume, Expiratory Reserve Volume and
thus Vital Capacity
Total Lung Capacity can be measured if RV and
FRC are known.
RV and FRC is obtained in one of indirect methods:
Body plethysmograph (body box)
Open-circuit nitrogen washout
Closed-circuit helium dilution
23. Generated by integrating
flow with volume on graph
Volume is plotted on the
horizontal axis
Flow on the vertical axis
Expiratory loop is shown
above the line
24. Generated by
integrating volume
with time on graph
Volume is plotted on
the vertical axis
Time on the
horizontal axis
Volume – Liters
Time- secs
25. The expiratory side of the FVC curve provides data
regarding the contractile state of the airways
This part of the curve evaluates the amount of the
obstruction present in the patient’s airways
Routinely identified flows are:
FEV1 --FEV25%-75%
FEV3 --PEF
26. Measures the maximal volume of air exhaled during
the first second of expiration
Reflects the flow characteristics in the larger airways
Best indicator of obstructive diseases
Expressed as percentage of the observed FVC
(FEV1/FVC)
Normal: 75% of VC in 1 second
Decreased: acute and chronic obstructive pulmonary
disease
Normal in restrictive disorders
27. Look at the 3-second point of the expired curve
Indication of the flow in smaller airways
Decrease normally with age
Normal: approx 95%
28. FEV25%-75%
Expressed in liters/second
Indicator of flow
First 25% is disregarded because of the lung’s initial
inertia
Last 25% is disregarded because of effort
dependency
Middle 50% reflects the degree of airway patency
Early indicator of obstructive disease
Can also be reduced in restrictive dysfunction
29. Is the maximum flow rate achieved by the patient
during the FVC maneuver
PEF < 100L/min : severe obstructive disease
PEF= 100 to 200L/min : moderate obstructive
disease
PEF > 200L/min : mild obstructive disease
30. Indicates the respiratory muscle endurance
Requires the patient to inhale and exhale as quickly
as possible for a period of 12 secs
Normal: 170L/min for healthy young adult
32. Obstructive defects:
• Can occur in upper and larger airways or in smaller
airways(less than 2mm)
• Upper airways obstruction will reduce flow rates in the
initial 25% of a FVC maneuver
• Smaller airway obstruction will reduce flow rates in the
later portion of the exhaled volume
Restrictive defects:
• Present when the lung volume are reduced to less
than 80% of the predicted levels
• Includes chest wall dysfunction, neurologic disorders,
scarring of lung, obesity
33.
34.
35.
36. Measurement Obstructive Restrictive
FVC N or decrease Decrease
FEV1 Decrease Decrease
FEV1/FVC N or decrease N or increase
FEF25%-75% Decrease N or decrease
PEF Decrease N or decrease
FEF50 Decrease N or decrease
Slope of FV curve Decrease Increase
MVV Decrease N or decrease
37.
38. Based on the initial results of a baseline spirometry,
additional testing of pulmonary mechanics is often
desirable.
If the baseline test indicates airway obstruction,
determining the reversibility of obstruction is
indicated.
In the laboratory , FVC maneuver is often repeated
after the patient has received a bronchodilator
Reversibility is defined as 15% or greater
improvement in FEV1