Transcript spirometer - Amirkabir University of Technology

Kaveh Roshanbin far
8533046
 Spirometry is the measurement of the flow and
volume of air entering and leaving the lungs
 Test of pulmonary function (PFT)
• Indicator of health status or disease
• Exercise fitness
 Respiratory system is functions include gas exchange ,
pH regulation, vocalization , and protection from
foreign substances.
 Respiration:
 Cellular
is the cellular mechanism of energy conversion
 External
is the exchange of gases between atmosphere and
cells, Includes ventilation, gas
exchange at lungs and cells, and transport of gases in
the blood.
The process of exchange of air between the lungs
and the ambient air
 Airflow in respiratory system is directly proportional
to the pressure gradient and inversely related to
the resistance of the airways.
 A single respiratory cycle = inspiration + expiration
 Lung air pressure < Atmosphere air pressure
 Diaphragm & inspiratory muscles contract →
 Thoracic cavity expands → negative pressure →
 air flows into lungs
 Passive process resulting from natural elastic
recoil of the expanded lung walls.
 During rapid breathing, internal intercostal and
abdominal muscles contract to help force air out at
a more forceful, rapid rate
Tidal volume
TV
The volume of air inhaled & exhaled at each breath
during normal quiet breathing
Inspiratory reserve
volume
IRV The volume of air that can be forcefully inspired
following a normal quiet inspiration
Expiratory reserve
volume
ER
V
The volume of air that can be forcefully expired
after a
normal or resting expiration
Vital capacity
VC
The maximum amount of air that can be exhaled
after the fullest inspiration possible
(TV + ERV + IRV)
Inspiratory capacity IC
The maximum amount of air that can be inhaled
after a normal exhalation (TV + IRV)
Residual volume
RV
The volume of air remaining in the lungs after a
forceful expiration
Total lung capacity
TL
C
The total volume of the lungs (VC + RV)
Functional residual
capacity
FR
C
The amount of air remaining in the lungs after a
normal quiet expiration (ERV + RV)
 Age
 Body size (height & weight)
 Gender
 Pulmonary health
 Altitude(height)
 Irritants
Forced vital
capacity
FVC
The total volume expired by a forced maximal
Expiraion from a position of maximal inhalation
Forced
expiratory
volume in 1 sec
FEV1.0 The volume of air expired in the first second of
maximal forced expiration from a position of full
inspiration
Forced
expiratory flow
from 25-75% of
exhalation
FEF25
-75
The average flow rate during the middle 50% of the
forced vital capacity maneuver
Or Maximum Mid-Expiratory Flow
(MMEF)
Apparatus used to measure static & dynamic lung
volumes/capacities using a closed system
• Registers the amount and rate of air moved into
or out of the lungs
• 2 main types;
1. Volume: records the amount of air exhaled or
inhaled within a certain time*
2. Flow: measures how fast the air flows in or out
as the volume of air inhaled or exhaled
increases
 Key features:
 Real time tracings record volume in relation to time
 Some are portable versions
 Leak tests and calibrations are easy to perform
 Many can produce flow/volume curves and loops
with the addition of special electronic or
digital circuitry.
 Volume spirometers hold their calibration months to
years better than flow spirometers
 Not practical by hand to determine peak expiratory
flow or instantaneous volumes,
 Coughs and submaximal efforts are not as obvious
 Some are heavy, cumbersome and may be prone to
fostering mold or bacterial growth if not cleaned
properly
Key features
 Measure how quickly air flows past a detector and
then derives the volume by electronic means.
 Records flow rate at brief intervals (30-300x/sec)
and use data to reconstruct the flow rate at each
point in time and volume (digitization).
 Tracings measure flow in relation to volume
 Computer can produce volume-time
tracings
 Tend to be lighter and more portable
 Disposable, single-use flow sensors, available on
some floe spirometers eliminate the risk (low)
of cross-contamination.
 No real-time or hard copy tracings
 Reliance on electronic equipment
 FEV1.0 cannot be calculated by hand unless the
time is indicated in seconds on a flow-volume
tracing
 Some flow spirometers are more difficult to
calibrate and may lose their calibration over time
if not well maintained
 Test results are not disease specific
 May not be sensitive enough to show
abnormalities before extensive and in some
cases irreversible damage has been done
(mostly for restrictive diseases)
∴ Should not be used as the sole screening tool of
a respiratory surveillance program.
 Obstructive deficits
 Restrictive deficits
 Mixed deficits
 A reduction of FEV1
 In relation to the forced vital capacity will result in a
low FEV1/FVC%
 The lower limit of normal for FEV1/FVC is around 7075%
 The exact limit is dependent on age.
 Normal or high FEV1/FVC% ratio
 Reduction in both FEV1 and FVC
 Interstitial lung disease
 Respiratory muscle weakness
 Thoracic cage deformities such as kypho-scoliosis
 A combination of both obstruction and restriction
resulting in gas trapping, rather than as a result of
small lungs.
 A reduced FVC together with a
 low FEV1/FVC% ratio
 It is necessary to measure the patient's total lung
capacity to distinguish between these two possibilities.
Severity of Airway Obstruction
FEV1 (% of Predicted)
Mild
>70
Moderate
> 60 and < 70
Moderately severe
> 50 and < 60
Severe
> 34 and < 50
Very severe
< 34
Severity of Chest Restriction*
FVC (% of Predicted)
Mild
>70 but < LLN
Moderate
> 60 and <70
Moderately severe
> 50 and < 60
Severe
> 34 and < 50
Very severe
< 34
Type of response
FEV1
FVC
FEV1/FVC %
Normal
> 80 %
> 80 %
> 75 %
Obstructive
< 80 %
> 80 %
< 75 %
Restrictive
> 80 %
< 80 %
>75 %
Mixed
< 80 %
< 80 %
< 75 %