Pulmonary Mechanics Flashcards
are used to assess function of the pulrnonary/thoracic system mder dynamic conditions
Tests for pulmonary mechanics
may be used in conjunction with lung
volume tests to confirm suspected pulmonary disorders
Dynamic testing
are used to evaluate a variety of breathing maneuvers and dynamic ventilatory parameters
Pulmonary mechanics tests
Pulmonary mechanics tests are used to evaluate a variety of breathing maneuvers and dynamic ventilatory parameters. They include :
Forced vital capacity maneuvers (FEEV1, FEVt%f, FEF200-1200, FEF 25%-75%, FEF 75-85%, PEFR)
-Volume of isoflow.
-Maximum voluntary ventilation.
-Airway resistance/conductance.
-Maximum inspiratory/expiratory pressures.
-Elastic recoil pressure/compliance.
is the most frequently used method for assessing dynamic pulmonary function
forced vital capacity (FVC) maneuver
It is evaluated on the basis of both volumes and flow rates measured from the maneuver.
FVC
are used for pulmonary function screening as well as for in-laboratory testing
FVC maneuvers
Equipment required for FVC
spirometer and recording system
FVC spirometer required
primary flow measuring (PFM) or primary volume measuring (PVM) system
linked to the spirometer for the purpose of graphic tracing
recording system
recording system for graphic tracing is recommended unless _____ are being performed
large-group pulmonary function screenings
if used, should have accurate speed regulation
real-time chart recorders
The volume of an expiratory vital
capacity maneuver exhaled as
rapidly and forcefully as
possible
Forced vital capacity (FVC)
The volume of air exhaled within a
specified time from the start of
a FVC maneuver-specifically,
within the first 0.5, 1, 2, and 3
second(s1.
timed forced expiratory volume (FEVt, FEV 0.5, FEV 1, FEV 2, FEV 3)
the percent of total fvc volume that was exhaled within a specified time from the start of the maneuver—specifically within the first 0.5, 1, 2, and 3 seconds.
Forced expiratory volume percent (FEV t%, FEV .5%, FEV 1%, FEV 2%, FEV 3%)
The average expiratory flow rate
between the first 0.2 and 1.2
liters of the FVC volume.
Maximum Expiratory Flow Rate FEF 200-1200, MEFR 200-1200)
The average expiratory flow rate
over the middle 50% of the
FVC volume.
Maximal Mid-Expiratory Flow Rate (FEF 25-75%, MMFR)
The average expiratory flow rate
between 75% and 85% of the FVC volume.
Maximum End-Expiratory Flow Rate (FEF 75-85%)
VOLUME TIME CURVE Forced Expiratory Volumes (FEV)
Forced Vital Capacity
Timed Forced Expiratory Volume
Forced Expiratory Volume Percent
VOLUME TIME CURVE Forced Expiratory Flow Rates (FEF)
Maximum Expiratory Flow Rate
Maximal Mid-Expiratoryy Flow
Maximum End-Expiratory Flow Rate
Volume/Time Curve Component
Forced Expiratory Volumes (FEv)
Forced expiratory flow rates (fef)
FLOW VOLUME LOOP Forced Expiratory Flow rates (FEF)
Peak Expiratory Flow Rate (FEF max, PEFR)
Instantaneous Forced Expiratory Flow Rate (FEF x% etc)
Instantaneous Forced Expiratory Flow Rate (Vmax x etc)
The maximum expiratory flow rate achieved at any point during
the FVC maneuver.
Peak Expiratory Flow Rate (FEF max, PEFR)
The expiratory flow rate at a specified point in the FVC and FEF75%) maneuver-specifically, when 25%, 50%, or 75% of the FVC volume has been exhaled.
Instantaneous Forced Expiratory Flow Rate (FEF x%, FEF 25%, FEF 50%, FEF 75%)
The expiratory flow rate at a
specified point in the FVC
maneuver-specifically, when
there is 75%, 50%, or 25% of
the FVC volume remaining to
be exhaled.
Instantaneous Forced Expiratory Flow Rate (Vmax x, Vmax 75, Vmax 50, Vmax 25)
The volume of an inspiratory vital
capacity maneuver inhaled as
rapidly and forcefully as
possible.
Forced INspiratory Vital Capacity (FIVC)
The maximum inspiratory flow
rate achieved at any point
during the FlVC maneuver.
Peak Inspiratory Flow Rate (FIFmax and PIFR)
The average inspiratory flow rate
over the middle 50% of the
FlVC volume.
Maximal Mid-Inspiratory Flow Rate (FIF 25-75%)
The inspiratory flow rate at a
specified point in the FlVC
maneuver-specifically, at
75%, 50%, and 25% of the
FVC volume.
Instantaneous Forced Inspiratory Flow Rate (FIF x%, FIF 75%, FIF 50%, FIF 25%)
FLOW VOLUME LOOP Forced Inspiratory Flow Rates
Peak Inspiratory Flow Rate
Maximal Mid-Inspiratory FLow Rate
Instantaneous Forced Flow Rate
The usefulness of a dynamic measurement such as FVC depends primarily on the
subject’s understanding, cooperation, and effort
are crucial for maximizing subject effort.
The instruction and coaching provided by the technologist
An _____ of the breathing maneuver by the technologist is recommended
active demonstration
are generally not necessary when open-circuit spirometer is used.
nose clips
nose clips are not necessary when an ______ is used.
open-circuit spirometer
Nose clips are helpful when a slow vital capacity is to be performed and are required when a _______ is used.
close-circuit spirometer
During the FVC procedure, __________ is needed.
appropriate and directive coaching
The subject must be encouraged strongly to perform a maximal inspiration and to continue the inspiratory effort at the
full total lung capacity (TLC) level for one to two seconds.
The forced expiration should be continued for a mnimum of_____ unless there is an obvious volume plateau demonstrated on the volume / time curve display.
six seconds
Generally in fvc , however, an effort of at
_____ is expected for the test to be acceptable
least six seconds
Once the forced expiration is started and has lasted at least six seconds, the effort may be ended when one of the following criteria is met:
—There is a volume plateau in the volume/time curve display with no detectable
change in volume for at least one second. The minimum detectable volume for the spirometer must be 0.030 liter or less.
—-The forced expiratory effort has been continued for a reasonable period of time. Some subjects with obstructive disorders may require expirations of 15 or more seconds. It is recommended that expirations greater than 25 seconds not be encouraged. They do not generally produce data useful for test evaluation. Such prolonged efforts, however, may be excessively stressful to the subject.
—-The subject demonstrates clinically significant reasons for not continuing the maneuver. These may include dizziness, light-headedness, or syncopal episodes
At least ____ acceptable FVC maneuvers must be performed by the subject.
three
Up to _____ maneuvers may be performed by the subject to produce the three acceptable tests. this is considered the maximum for most subjects to avoid problems with fatigue or effort-induced bronchospasm
8
Up to eight maneuvers may be performed by the subject to produce the three acceptable tests. Eight is considered the maximum for most subjects to avoid problems with
fatigue or effort-induced bronchospasm
Test maneuvers must be repeated and acceptable results collected until test ____ is demostrated
reproducibility
The largest FVC and FEV1 do not have to be from the same maneuver. The second largest FVC and FEV1 also do not.
true
It should be noted that ______ are meant only to indicate whether additional testing is needed. They should not be used to eliminate data from being reported
from the testing.
reproducibility criteria
A test for FVC can be considered acceptable if there is:
—-relating to the start of the expiratory effort-
No excessive subject hesitation or false start by the subject,
Not a back-extrapolated volume exceeding 5% of the FVC volume or 0.15
liter, whichever is greater.
—-Relating to the presence of artifacts during the maneuver
No cough during the first second of the maneuver (affecting FEV?) or that, in the technologist’s opinion, interferes with the accuracy of the test results.
no valsalva maneuver performed before or during forced expiration
no variable effort demonstrated by the subject during the maneuver.
No volume loss because of a leak in the system.
No obstruction of the spirometer mouthpiece. This can be caused by the subject’s tongue or by falling of the subject’s dentures.
No premature termination of the forced expiration.
—Relating to the end of the expiratory effort
No expiratory test maneuver performed for less than six seconds unless a
volume plateau is present on the volume/time curve display.
Traditionally, assessment of FVC and its components is based on evaluation of both
graphic tracings of the maneuver and numerical test results.
Two types of spirometer tracing, or graphs, are used in assessing the volume and flow results of an FVC maneuver
volume/time curve
flow/volume loop
This curve may be made directly by use of a volume-displacement spirometer and mechanical recorder
volume/time curve
Graphing of a_____ requires use of a spirometer system
that can measure and record flow rates directly
flow/volume loop
are generally capable of producing; both types of tracings.
modern electronic spirometers
The volume/time curve resulting from an FVC maneuver is traced or plotted with _______ indicated on the _____ and _____ on the ______.
volume, vertical axis. time, horizontal axis.
is based on the slope of the line between two points
on the curve.
Flow-rate determination
Steeper or more vertical lines produce a larger value for slope and indicate
faster rates
forced expiratory flow (FEF) and forced inspiratory flow (FIF)
The FVC of a normal subject should be ____ to the vital capacity (VC) measured with an unforced maneuver.
approximately equal
by having the subject inhaling forcefully and maximally from the RV level. This i
referred to as
forced inspiratory vital capacity (fivc)
during the maneuver are important in making accurate volume determinations
Direct observation and evaluation of subject effort
The results determined for the _______ provide an indication of the average flow rate over a time interval.
FEVt
The FEV1 has many applications for assessment and is used in a number of clinical circumstances. These include
rapid test evaluation during screening procedures, evaluating subject response to bronchodilator therapy or to inhalation challenges for extrinsic
asthma, and assessing the existence of exercise-induced bronchospasm
In order to make accurate determinations of the FEVt, it is important to establish the
start of the maneuver (time-zero) correctly.
is performed by drawing a
line tangent to the steep, initial portion of the curve.
Back-extrapolation
On a volume/time spirometer tracing, this is possible by back-extrapolating the curve. Back-extrapolation is performed by drawing a line tangent to the steep, initial portion of the curve. The line should extend back to intersect with a line indicating the maximal inspiratory volume. The point at which these
two lines intersect is
the time-zero point.
The difference in volume between the maximum inspiratory volume and the volume at the level of the time-zero point is the
extrapolated volume.
The FVC values may cause serious overestimation of the FEVt% in situations where patient performed the FVC maneuvers with poor effort. For
this reason, ________ is used by some technologists in making FEVt% determinations.
the largest value for a slow VC maneuver
The FEF200-1200 measures flow early in the expiratory maneuver. It intentionally disregards the first 200 ml of the expiratory maneuver. This is because
inertia, in both the subject and the spirometer system at the start of the maneuver, may cause the initial volume to be exhaled at a slower rate
Because the FEF25-75% is measured at a _____ in the maneuver
than for FEV200-1200, its normal value is _____
later point, less.
The ______measures expiratory flow rates toward the end of the maneuver.
FEF 75-85%
Because it is measured so late in the maneuver, FEF75-85% values will be the ______ the FEF values.
smallest of all
The_____ can be determined from a volume/time tracing.
peak expiratory flow rate (PEFR)
It is based on a line drawn tangent to the steepest part of the curve.
PEFR
is plotted with flow indicated on the vertical axis and volume on the horizontal axis.
The flow/volume loop
It is possible to plot both a maximum/expiratory flow/volume (MEFV)
curve and a maximum inspiratory flow/volume (MIFV) curve.
flow/volume loop
Flow/volume loops are beneficial for a number of reasons. They allow for
inspiratory and expiratory peak flow rates to be read directly from the graph.
The PEFR is more easily read from a ______ than it is from a _____
flow/volume loop, volume/time curve.
Pulmonary function studies are interpreted by comparing a _____ with what
are predicted to be _____
subject’s test values, normal values for that subject
Pulmonary function studies should be evaluated in conjunction with
data from the
subject’s history, physical examination, and other types of clinical assessment.
Interpretation of the test results from a FVC maneuver is based on analysis of a number of factors. Included is ____
evaluation of the volume and the flow-rate components.
Relates directly to changes in VC
from volume spirometry.
Evaluation of the flow-rate
parameters below aids in disorder
differentiation.
FVc
Relates to flow rates and disorders in
the large, upper airways. Very
effort-dependent. Also used to
monitor asthma and bronchodilator
therapy.
PEFR
Relate to flow rates and disorders in
the large, upper airways. Still may
be relatively effort-dependent.
FEV 0.5, FEV 1, FEF 200-1200
Relate to flow rates and disorders in
smaller bronchi and larger
bronchioles. Some degree of
effort-dependence remains.
FEF 2, FEF 25-75%
Relate to flow rates and disorders in
smaller bronchioles. Little or no
effort-dependence.
FEV 3, FEF 75-85%
Relates to changes in both flow rates
and lung volumes. Generally,
opposite results are demonstrated
between restrictive and
obstructive disorders.
FEV t%
Relates most significantly to flow
rates and disorders in the large
upper airways.
FEV x%
pulmonary restrictive disorders
insterstitial fibrosis
vascular congestion
pneumoconioses
sarcoidosis
extrapulmonary restrictive disorder
thoracic
-kyphoscoliosis
-rheumatoid spondylitis
abdominal
-ascites
-peritonitis
-severe obesity
neuromuscular defects
-poliomyelitis
-myasthenia gravis
large airway obstruction
fixed
-tracheostenosis
-large substernal goiter
variable intrathoracic
-tracheal carcinoma
variable extrathoracic
-laryngeal carcinoma
small airway obstruction
-bronchial asthma
-emphysema
-chronic bronchitis
-bronchiectasis
-cystic fibrosis
Most significant for making restrictive/obstructive differentiations are values for the
FEVt%
values provide an additional resource for differentiating between restrictive and obstructive disorders.
RV, TLC, and RV/TLC%
The effects of air trapping are more pronounced during a
forced expiratory maneuver
flow rates that are measured early in the maneuver are most affected by
large airway obstruction.
On the other hand, in subjects with small airway
obstruction, flow rates later in the FVC maneuver are
most affected.
Reductions in ________ may serve as an early indicator of small airway obstruction
FEF25-75%, FEF 75-85%, FEF75% (Vmax 25)
It provides a simple graphic representation of the parameters measured with forced expiratory and inspiratory VC maneuvers
flow/volume loop
it also demonstrates a ver characteristic shape in certain disorders
flow/volume loops
quantifies the degree of concavity that
the middle portion of the MEPV curve may have toward the volume axis.
angle beta
In ___ the latter portion of the expiratory loop begins to take on a concave appearance,
small airway obstruction
In sao the latter portion of the expiratory loop begins to take on a concave appearance, This concavity is most pronounced in subjects with ____ because of their greater sensitivity to dynamic airway compression
emphysema