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
A_____ causes relatively equal decreases in both expiratory and inspiratory flow rates
fixed large airway obstruction
cause a flattening of the expiratory portion of a flow/volume loop caused by the limitations of expiratory Row.
intrathoracic variable large airway obstructions
cause a flow limitation on inspiration, with a characteristic flattening of the flow/volume loop’s inspiratory portion
extrathoracic variable large airway obstructions
This flattening occurs because obstructions of this type are exposed to the same dynamic forces as the lungs themselves. These are airway-inflating forces during inspiration and airway-collapsing forces (dynamic compression) during expiration. The forced expiration compresses the airway and limits expiratory flow during the effort.
intrathoracic variable large airway
The sub-ambient airway pressure that draws air into the lungs during inspiration tends to promote an inward collapse of the large airway structures that precede the airways within the thorax. On expiration, these forces are reversed. Airway collapse is therefore not added as a flow limitation and flow rates are less affected
extrathoracic variable large airway obstruction
A variable intrathoracic obstruction will produce a greater decrease in the ____. A variable extrathoracic obstruction will produce a greater decrease in the ______ value.
FEF 50%, FIF 50%
involves measuring an FVC maneuver after the subject has breathed a helium/oxygen (80% He/20% 02) mixture.
Low-density spirometry
The comparison can serve as a sensitive method for detecting the early stages of small airway disease. it may also help to differentiate the site of an obstruction-between larger versus smafler airways.
low-density gas spirometry
low-density gas spirometry test is based on the relationship between
turbulent flow, laminar flow, and gas density.
Resistance to turbulent flow changes as
gas density changes.
In airways where turbulent flow is exhibited, gases with less density than air (He/O2 mixtures) show
less resistance to flow.
Laminar flow
is independent of
gas density.
large central airways, early in maneuver
turbulent flow
small, peripheral airways, late in the maneuver
laminar flow
it indicates the maximum or earliest flow rate that is controlled by density-independent flow through the small, peripheral airways
volume of isoflow (V isoV)
are generally unsuitable for the direct measurement of
the He/O2) mixture maneuver.
pneumotachometers
Breathing the mixture in low-density gas spirometry for
10 minutes.
Breathing the mixture in ldgs for ______ breaths.
three to four VC
The standard and He/02 loops selected for comparison must demonstrate FVC volumes within
2.5%-5% of being the same
Generally, two points of comparison on the superimposed fIow/volume loops are evaluated. These are the
volume of isoflow (V isov) and the change in flowrate at 50% of vital capacity
is the volume measured between the point where the two superimposed loops begin to match and the point where
the loops share the same RV value.
volume of isoflow (V isov)
generally consists of using a portable, handheld peak flow meter to evaluate periodically a subject’s peak flow capabilities.
peak expiratory flow rate (PEFR) monitoring
is often used for monitoring asthma patients and their management with bronchodilators
PEFR
The test is done by having the subject perform a maximal inspiration followed by a short, maximally forceful expiration through the PEFR monitong device
pefr
The expiratory effort in pefr needs to last
only one to two seconds.
PEFR monitoring requires an instrument that can measure with ___ accuracy or within ___ of the actual flow rate, whichever is greater.
+-10%, +-20 l/min
Pediatric PEFR meter measurements typically range from
60 l/min to 100 l/min
adult PEFR meter measurements typically range from
100 l/min to 850 l/min
Since these pefr devices are often used in the home,_____must be provided.
data on the instrument’s life expectancy and durability
A package insert should be included with the device
that includes the following information:
- Clear instructions on use, with ilustration.
- Instructions on cleaning and maintenance of the instrument and methods to recognize its malfunction
- Appropriate actions to be taken when PEFR readings change significantly (whom to contact).
satifactory informance of PEFR monitoring by the subject is both
volume- and effort-dependent
The forced expiratory effort must be started from a ____, and it must be performed____
maximal inspiratory position, sharply and vigorously
A peak expiratory flow value is generally achieved within the _____of expiratory effort.
first one tenth of a second
should be reported, because it best
indicates the subject’s current condition.
The largest value for PEFR
The results should be recorded in the order of their
performance. This information can be useful in determining whether _____ has occurred
test-induced bronchospasm
Adult subjects can generally produce peak expiratory flow rates of
400-600 l/min (6.7-10 l/sec)
Young adults may generate PEFRs that exceed
600 l/min.
Clinically, decreases in PEFR values are most specifically related to
obstruction of the
large upper airways
Subjects wih relatively mild to moderate small airway obstruction often demonstrate ____________. This is because they are able to generate a normal PEFR in the fraction of a second of effort before small airway closure occurs and later expiratory flow rates are abnormally slowed.
normal or near normal PEFR values
Subjects with severe small airway obstruction will probably demonstrate ____ in PEFRs. However, their reductions in such measurements as _____ will be much more significant than the reductions shown in PEFR.
definite reductions
FEF 25-75%, and FEF 75-85%
are small and relatively inexpensive.
PEFR monitoring devices
Clinically significant worsening of small airway obstruction can cause____ in PEFRs.
reductions
The key to PEFR monitoring is
serial measurement of PEFR values and a comparison
of those values to the subject’s past measured values.
is the largest volume that a subject can breathe in
and out of the lungs in one minute with maximum voluntary eifort.
Maximum voluntary ventilation (mvv)
It provides a nonspecific overall test of ventilatory function.
mvv
In the past, the mvv test was referred to as the
maximum breathing capacity (mbc)
The MVV maneuver volume is generally measured for a
period of
10-15 seconds
The minimum time period for mvv measurement is
five seconds
The subject should be coached to breathe as ____ as possible during the mvv test.
rapidly and as deeply
Breathing rates in mvv may be between____ breaths per minute.
70 and 120
Individual mvv volumes should be ____ than the subject’s tidal volume but ____ a vital capacity effort.
greater, less than
A test for MVV may be considered acceptable if:
- A volume/time tracing demonstrates the breathing pattern to be regular in volume or breathing rate.
- The end-expiratory baseline on a volume/time tracing remains fairly constant.
The only exception to this is if the subject‘s baseline changes because of air
trapping. Air trapping is demonstrated by a baseline that shifts gradually from
the FRC level upward toward the TLC level during the time of the maneuver.
*A value for MVV is measured for the subject that is at least as large as the volume determined by multiplying the measured value for FEV1 by 35.
mvv criteria for reproducibility
–reproducibility is achieved when the largest and second largest values measured for MVV are within 10 % of each other
–The best test for MVV is the one that demonstrates the largest MVV value.
If the measured value for MVV is significantly less than the estimated value, it is likely that subject effort was
submaximal.
MVV should be determined from a series of at least ___acceptable maneuvers.
two
Some subjects who have hyper-reactive airways (asthma) may experience ___ from performing an MVV test
maneuver
bronchospasm
Normal values for MVV are directly related to __ and are indirectly related to ___
height, age.
normal mvv value for male
160 l/min
normal mvv value for female
120 l/min
is useful in interpreting a subject’s ventilatory response to exercise during stress testing
The MVV test
It tests the ability to sustain an elevated level of ventilation
mvv
. It is possible for subjects with restrictive pulmonary disorders to have values for MVV that are within ___. This is because they are
able to compensate for the lack of volume increase with significant increases in ___
normal tolerances, breathing rate
Moderate to severe obstructive disorders, however, may produce abnormal values for MVV, These abnormal values are Largely due to the ______ that occur with this type of forced breathing pattern.
exaggerated air trapping and ventilatory muscle fatigue
is the result of friction between the
gas molecules and also between gas molecules and the airway walls
Resistance to air flow (Ra) in the pulmonary system
is a measure of the Rfl in the pulmonary system. I
Airway resistance
(Raw)
It is the drive pressure required to
create a flow of air through a subject’s airways.
airway resistance
The drive pressure is the difference between ______ during ventilation.
atmospheric pressure (P Atm) and alveolar pressure (P a)
Airway passages in the subject that affect Raw with mouth breathing include the
mouth; pharynx; larynx; larger, central airways; and smaller, peripheral airways.
on inspiration, intrathoracic airways are dilated by the more
negative intrapleural pressures.
Raw is ___during inspiration and is ____ during expiration
less, more
Raw is ____ at large lung volumes and is _____ at small lung volumes.
less, more
is the reciprocal of Raw.
Airway conductance (Gaw)
is a measure of the flow that is generated from the available drive pressure.
Airway conductance (Gaw)
As values for Raw increase, the values far Gaw in
the same subject will ____
decrease.
raw measurement is generally performed at the
FRC level,
is used for the measurement of Raw.
body plethysmograph system
Raw is measured with the subject performing a
panting-type breathing maneuver.
The subject in body pleth should be observed during test administration in order to prevent ____ during the panting maneuver
grunting
could artificially increase the measured Raw value.
Grunting
in body pleth, ____ is measured while the subject is panting and the plethysmograph shutter is ___
V, open
in body pleth, ____ is measured
while the subject is panting and the shutter is ____
Pa, closed
normal value for raw
0.6-2.8 cm H2O/l/sec
normal SRaw value
0.190-0.667 cm H2O/l/sec/l
normal Gaw value
0.36-1.70 l/sec/cm H2O
normal SGaw value
0.114-0.404 l/sec/cm H2O/l
_____ of the normal WOB is due to _____ to ventilation, also referred to as ______
65%, elastic resistance, pulmonary/thoracic compliance
_____ of the normal WOB is due to _____ to ventilation.
35%, nonelastic resistance
35% of the normal WOB is due to nonelastic resistance to ventilation. These nonelastic resistances to ventilation include:
flow resistance
tissue resistance
also referred to as Raw which accounts for 80% of all nonelastic resistance and 28% of the overall resistance to ventilation
Flow resistance
which is the least significant source of resistance to ventilation.
It accounts for only 20% of all nonelastic resistance and 7% of the overall resistance to ventilation.
tissue resistance
The majority of normal Raw (approximately ___) is the result of air flow through airways greater than _____ in diameter.
90%, 2.0 mm
The airways themselves may be larger in diameter, but their total Cross-sectional area at any given level in the tracheobronchial tree is
limited.
The smaller, peripheral airways (less than ____ in diameter) normally contribute
____ to RAW because their combined cross-sectional area is so large. This is the reason why a significant amount of small airway disease must occurbefore the subject’s Raw and WOB will be noticeably affected
2.0 mm, very little
Raw will increase in disorders where the cross-sectional area of the airways has become
smaller
Raw will increase in disorders where the cross-sectional area of the airways has become smaller. These areas can occur in either the
larger upper or smaller peripheral airways.
Assignment of severity for Raw disorders
2.8-4.5_______Mild
4.5-8.0_______Moderate
>8.0_________Severe
The elastic resistance of the lungs can be evaluated by measurements of
elastic recoil pressure, compliance, and dynamic compliance.
is an indication of the elastic force that is generated by the thoracic/lung system when the lungs are expanded.
Elastic recoil pressure
It is generally measured at the TLC level after a maximal inspiration and is referred to as the
maximum elastic recoil pressure
is an indication of the elastic resistance (R el) to ventilation
Compliance
It is the amount of transpulmonary pressure (PL) change required to produce a certain change in lung volume
compliance
is a measure of the combined effect of both the Rel and Rfl that must be overcome during ventilation
dynamic compliance (Cdyn)
generally provides the most convenient arrangement for measuring elastic recoil pressures and compliance
A plethysmograph system
The subject’s lung volume history must be____ just prior to administration of
tests for maximum recoil pressure and compliance
standardized
The lung volume history standardization
is done by having the subject perform a
maximum inspiration followed by a passive expiration back to FRC level
is based on measuring the transpulmonary pressure (PL) required to generate a maximum inspiratory volume.
Elastic recoil pressure
is the difference between alveolar pressure
(PA} and intrapleural pressure (Ppl)
PL
It may be assumed that PA is equal to atmospheric pressure ______ during periods of no air flow into or out of the Lung.
(0 mm Hg)
During the procedure, Ppl changes are measured through changes in
esophageal pressure.
During the procedure, Ppl changes are measured through changes in esophageal pressure. This is done by having the subject swallow a
10 cm long esophageal balloon.
The balloon’s length minimizes the effects of esophageal _____ on ballon pressure.
peristalsis
A catheter, with the balloon at its distal end, is passed through one nostril, the nasopharynx, and into the esophagus. When the balloon is positioned in the _____, esophageal pressure (Peso) changes approximate changes in Ppl.
lower third of the esophagus
The initial higher pressure is used because the Ppl
value ____ as inspiration is maintained
decays (decreases)
The initial higher pressure is used because the Ppl
value decays (decreases) as inspiration is maintained. This pressure decrease is thought to be due to _____ of the lung
“stress relaxation”
is determined by relating PL changes during breathing to changes in lung volume.
CL- lung compliance
Measurements made during ____ are the most useful in clinical applications.
lung deflation
provides components useful for measuring CL
body pleth
During CL test expiration, the shutter in
the pneumotachometer circuit is used to intermittently occlude the subject’s airway for
one to two seconds.
is based on the change in transthoracic/pulmonary pressure (PTL) required to produce a change in VL,
CLT or total lung/thoracic compliance
is the difference between atmospheric pressure (PAtm) and PA when there is no air
flow in the lungs
PTL, or transthoracic/pulmonary pressure
The difficulty in determining a value for CLT is that the Ptl, measurements must be made with the subjecf ‘s
muscles completely relaxed
provides a method based on correlating a subject’s CLT value to the value of the subject’s FRC
Specific compliance (SCLT
As stated previously, which compliance cannot be measured directly.
CT, thoracic complince
As stated previously, CT cannot be measured directly. However, once ___ have
been determined, CT can then be calculated
CL and CLT
can be measured during quiet tidal breathing.
CDyn
can be evaluated by measuring values far CDyn at
different subject respiratory rates.
frequency of dependence of compliance
normal elastic recoil pressure
34 cm H2O
normal CL
0.2 l/cm H2O
normal CT
o.2 l/cm H2O
normal CLT
0.1 l/cm H2O
normal SCLT
0.05-0.06 l/cm H2O/l
normal CDyn
0.09-0.07 l/cm H2O (at a flow of 0.5 l/sec)
measure a subject’s ventilatory muscle strength.
Tests for maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP)
Both tests are administered with the subject
performing maximum ventilatory maneuvers against an occluded airway.
MIP, MEP
is a measure of the most negative (subatmospheric) pressure that can be generated with an inspiratory effort.
MIP
This maneuver provides a strength test for the diaphragm, intercostals, and inspiratory accessory muscles.
MIP
It relates to a subject’s ability to breathe sufficiently deeply to maintain ventilation and a ventilatory reserve.
MIP
is the greatest positive supra-atmospheric pressure that a subject can generate.
MEP
It provides a test of strength for the abdominal muscles and other accessory muscles fur expiration.
MEP
The ability of a subject to _____ relates directly to the capacity to generate a sufficient MEP.
cough effectively
use of mip evaluation
—Assessment of neuromuscular disorders or injury of the inspiratory muscles
—Assessment of reduced inspiratory muscle strength resulting from
Chronic lung hyperinflation (emphysema)
Severe chest wall deformities
Effects of drugs
—Assessment of inspiratory muscle strength for monitoring
Weaning from continuous mechanical ventilatiori
Beathing-retaining exercises
use of mep evaluation
Assessment of neuromuscular disorders or injury of the expiratory muscles,
Assessment of impaired cough function retained secretions
Assessment of weaning from continuous mechanical ventilation
is required to provide intermittent airway occlusion
A three-way directional breathing valve or a shutter mechanism
an apparatus for measuring airway pressure changes is
also needed. Either a _______ may be used.
direct-reading dial-type manometer or an electronic pressure transducer and recorder
mepmip ____ are required to maintain an airtight seal during
the procedure.
Nose clips and a flanged mouthpiece
A controlled leak between the occlusion apparatus and the subject is needed
to minimize the possible influence of the subject’s cheek muscles. The leak may be produced by use of a _____ or similar size
tube 15 mm long with an inner diameter of 1 mm
normal mip values
> -60cm H2O
normal mep value
> +80 to 100 cm H2O
A subject’s MW is more greatly affected by reductions in ____ than by
reductions in ____
MIP, MEP.
Tt is generally accepted that an MIP value of _____ indicates a need
for mechanical ventifatory support
-20 cm H2O or smaller
Subjects with an MEP value of less than ____
may have difficulty in coughing effectively and clearing secretions.
+40 cm H2O
It has been found that subjects with _______ may demonstrate reductions in both MIP and MEP
generalized neuromuscular disorders
Quadriplegic subjects, however, demonstrate a greater loss of ____ than
of ____
MEP, MIP.
