Lung Volumes Flashcards
The volume of air that normally moves into and out of
the lungs in one “quiet” breath.
tidal volume
volume of tidal volume
500 ml
The volume of air that can be
exhaled after a normal tidal volume.
Expiratory Reserve Volume (ERV):
expiratory reserve volume
Normal: 1,200 mL
The maximum volume of air that can be inhaled after a
normal tidal volume.
inspiratory reserve volume
inspiratory reserve volume
normal: 3100 ml
The amount of air remaining in the
lung after a maximal exhalation.
residual volume
residual volume
1200 ml
Cannot be measured with simple spirometry
residual volume
Breathe normally in and out.
Tidal Volume (Vt):
• Inhale as much as you can from a normal inhalation.
Inspiratory Reserve Volume (IRV):
Exhale as much as you can from a normal exhalation..
Expiratory Reserve Volume (ERV):
Take a deep breath in, as deep as you can, and then
blow it out slowly until you can’t blow out any more.
Slow Vital Capacity (SVC):
Result of tidal breathing over a period of one minute
ventilation
Ve
liters of ventilation/ 1 minute
2 factors that determine how much ventilation occurs:
Frequency of breathing (f), Size of the tidal volume (VT)
• Used to measure all volumes and capacities except RV,
TLC, FRC
Direct Spirometry
• Involves the use of a spirometer to measure the
volumes of air moving into and out of a subject’s lungs
during breathing
Direct Spirometry
The end-expiratory volume of the three tidal breaths
that precede the VC maneuver varies by less than
0.1 liter
__ occurs during the maneuver that, in the
technologist’s opinion, interferes with the accuracy of the
test results
No coughing
Acceptability Criteria for vital capacity
• The end-expiratory volume of the three tidal breaths
that precede the VC maneuver varies by less than 0.1 liter
• No coughing occurs during the maneuver that, in the
technologist’s opinion, interferes with the accuracy of the
test results
• No variable effort is demonstrated by the subject during
the maneuver
• No volume loss from a leak in the system is
demonstrated
• No obstruction of the spirometer mouthpiece occurs.
(Tongue and dentures)
• Maximal expiratory and inspiratory efforts and
demonstrated
The largest and second largest VC values are within_____ of each other
0.2
liters
- VC Testing must continue until:
•
A total of four tests have been performed
• The patient cannot continue
• Criterium is met with the performance of
additional acceptable test maneuver
• Required for the determination of RV, TLC, FRC
- Indirect Spirometry
Most often, performed to measure FRC
Indirect Spirometry
is the most reproducible lung volume and provides
a consistent baseline for measurement
FRC
2 approaches of indirect spirometry
A. Gas Dilution Techniques
B. Body Plethysmograph
Gas Dilution Techniques
•
Open-Circuit Method
• Closed- Circuit Method
Operate on Boyle’s law except that the fractional
concentration of a known gas is used instead of its partial
pressure
Gas Dilution Techniques
Gas Dilution Techniques Operate on Boyle’s law except that the______ is used instead of its partial
pressure
fractional concentration of a known gas
• C1V1 = C2V2;
gas dilution tech, boyle’s law
produces erroneous measurements
System air leaks
Can only measure lung volumes in communication with
conducting airways
gas dilution
MUSTS in Gas Dilution Techniques
- Tight system connections
- Flanged mouthpiece with a good subjects seal
- Use of nose clip
- Used to determine the anatomical deadspace in the
lungs
Open- Circuit (NITROGEN WASHOUT) Method
This technique can only measure gas that is in
communication with the mouth.
Open- Circuit (NITROGEN WASHOUT) Method
- Any trapped gas distal to airway obstruction will not be
measured
open circuit nitrogen washout
- Patient’s lungs is diluted with 100% oxygen from the FRC
baseline
ocnw
- As the subject breathes the oxygen, all of his or her
exhaled gas is collected in a ______ which
measures its volume.
TISSOT Spirometer
A _______ in the breathing circuit is used to
monitor nitrogen concentrations.
nitrogen analyzer
______ should be discontinued for a few minutes
prior to testing to avoid erroneous measurements
02 therapy/supplemental oxygen
_____ automatically measures the final nitrogen concentration
and exhaled volume, calculating the FRC, RV, and TLC
Computer-based pulmonary function system
Approximately ________ of breathing 100% 02 to
wash out N2 from the lungs
3-7 minutes
- Test is successfully completed when the N2 levels
decrease to become
less than 1.5% for at least 3
successive breaths (subjects without obstructive
disorders)
a different method of FRC determination is needed if
oxygen-induced hypoventilation is a documented
problem (as in COPD),
Open- Circuit (NITROGEN WASHOUT) Method
- Hypercapnia stimulates breathing
- Prolonged breathing of 100% oxygen may
increase the blood oxygen level - Stimulus to breath is lost
- Hypoventilation and acidosis
may result from washout of nitrogen from
poorly ventilated lung zones (obstructed areas)
atelectasis
Problems with Nitrogen Washout
Atelectasis may result from washout of nitrogen from
poorly ventilated lung zones (obstructed areas)
• Elimination of hypoxic drive in CO2 retainers
is possible
• Underestimates FRC due to underventilation of areas
with trapped gas
Criteria for ending a Nitrogen Washout Test
(Table 4-4 pg. 89, Madama)
- Exhaled nitrogen levels decrease to become <1.0% for
subjects without obstructive disorders - Prematurely discontinue: System leak, Pt. is unable to
continue, If Tissot Spirometer used, becomes full
Nitrogen Washout Criteria for Acceptability
- The washout tracing/display should indicate a
continually falling concentration of alveolar N2 - The test should be continued until the N2
concentration falls to <1.5% for 3 consecutive breaths - Washout times should be appropriate for the subject
tested. Health subjects should washout N2 completely in
3-4 minutes. - The washout time should be reported. Failure to wash
out N2 within 7 minutes should be noted. - Multiple measurements should agree within 10% 6.
Average FRC from acceptable trials should be used to
calculate lung volumes. - At least 15 minutes of room air breathing should elapse
between repeated trials, >1 hr for patients with severe
obstructive or bullous disease
A technique for measuring functional residual capacity
and residual volume and total lung capacity.
Closed- Circuit (HELIUM DILUTION) Method
It is based on the principle that if a known volume and
concentration of helium are added to a patient’s
respiratory system, the helium will be diluted in
proportion to the lung volume to which it is added.
Closed- Circuit (HELIUM DILUTION) Method
Since Helium is _____, as patients breaths the helium, it’s
volume does not decrease since it is not absorbed by the
blood
inert
- Patient is connected to a ________ and a
known volume and concentration of helium is added to
the system
“rebreathing system”
- is defined as Helium
concentration changes of less than 0.02% over a 30
second interval
- A state of equilibrium
- A state of equilibrium is defined as Helium
concentration changes of less than
0.02% over a 30
second interval
During He dilution measurement of lung volumes,
patients breathe from a known volume and concentration
of Helium gas for a period of typically
4 to 7 minutes.
The oxygen concentration in the starting mixture is set
at _____ to ensure patients with COPD can remain
comfortable during the test
30%
-___ is situated in line with expired
breath to keep the closed-circuit CO2 level below 0.5%
and avoid discomfort and hyperventilation.
A carbon dioxide absorber
A carbon dioxide absorber is situated in line with expired
breath to keep the closed-circuit CO2 level below _____
and avoid discomfort and hyperventilation.
0.5%
is added to the system to maintain the starting
volume in the spirometer.
Oxygen
A Volume of ____ is sometimes subtracted from
the FRC to correct loss of He to the blood
100 ml
should be subtracted from the FRC
The dead space volume of the breathing valve and
filter
- Spirometer is filled with
a known volume of air with added
oxygen of 25-30%
- A volume of He is added so that a concentration of
approximately ____ is achieved
10%
helium dilution Criteria for Acceptability
- Spirometer tracing should indicate no leaks (detected
by a sudden decrease in He), which would cause an
overestimation of FRC - Test is successfully completed when He readings
change by less than 0.02% in 30 seconds or until 10
minutes has elapsed - Multiple measurements of FRC should agree within
10% - The average of acceptable multiple measurements
should be reported
Criteria for ending a helium dilution test Table 4-5 p. 92
The amount of CHANGE in air pressure and CHANGE in
volume during breathing is measured and used in the
equation
body plethysmography
The amount of _______ is measured and used in the body pleth
equation
CHANGE in air pressure and CHANGE in
volume during breathing
- Also measures air trapped within noncommunicating
thoracic compartments
body pleth
- To calibrate the box pressure signal, a ____ is used with the cabin door closed and the box sealed.
30 ml sinusoidal pump
The _____ in and out of the sealed box
causes a change in the box pressure signal. Thus, the
pressure change can be calibrated against a known
volume
30 ml stroke of volume
can be measured simultaneously
during open-shutter panting (1.5-2.5 Hz)
Airway Resistance (Raw) and Specific Airway
Conductance (SGaw)
- Airway Resistance (Raw) and Specific Airway
Conductance (SGaw) can be measured simultaneously
during
open-shutter panting (1.5-2.5 Hz)
Most plethysmographs have___ and allow VC maneuvers to be
performed during the same testing session
built-in
pneumotachometers
- This method of measuring FRC actually measures all the
________; the actual
measurement made is VTG (Volume of Thoracic gas)
conducting pathways including abdominal gas
- This method of measuring FRC actually measures all the
conducting pathways including abdominal gas; the actual
measurement made is
VTG (Volume of Thoracic gas)
- The most significant volumes for evaluating the effects
of pulmonary disorders are
VC, FRC, RV, and TLC
Patient is required to support cheeks with both hands
and pant with an open glottis at a rate of
0.5 - 1 Hz (30 -
60 breaths/min)
Body pleth Criteria for Acceptability
- Panting maneuver shows a closed loop without drift
- Tracing does not go off the screen
- Panting is 0.5 - 1 Hz
- Tangents should be within 10%
- At least 3 FRC pleth values should agree within 5% and
the mean reported
• Increase FRC is considered
pathologic
FRC values >120% of predicted represent
air trapping (Emphysematous
FRC values _____ of predicted represent air trapping
> 120%
• FRC, RV and TLC typically decreased
restrictive pattern
• Usually lung volumes are decreased equally
restrictive pattern
When TLC is <80% a_____ process is present
restrictive
RV/ TLC is relatively normal
restrictive pattern
RV/ TLC% >35% + Normal TLC
air trapping
RV/ TLC% >35% + >Normal TLC
hyperinflation
acute or chronic? hyperinflation
acute
acute or chronic? air trapping
chronic
IC volum
3600
frc volume
2400
vc volume
4800
tlc volume
6000
The total volume of the lungs can be subdivided into smaller units of volume. These units are based on
total lung capacity (TLC), the resting end-expiratory lung volume, and a series of specific breathing maneuvers
A capacity is a larger unit which includes
two or more of the
defined lung volumes.
The expressions _____ and _______ are both traditionally used to describe ventilation.
“exhaled minute ventilation”
“rninute volume”
A consistent point of reference is needed for accurate lung volume measurement. ______ lung volume provides a reliable, stable reference level.
The resting end-expiratory or FRC
a deep inspiration can trigger _______ and affect the measurement
bronchospasm
to avoid the effects of bronchospasm, the maneuver should be performed as a
maximal expiration followed by a
maximal inspiration.
The subject should breathe on the spirometer using a
mouthpiece and with noseclips on
The subject must be observed to ensure that
the lips are sealed, nothing obskucts the mouth, and that there are no leaks in the system.
Three key points for VC test are
- The breathing by the subject during the maneuver should be relaxed and controlled, not forceful.
- The inspirations and expirations should be at a relatively constant flow rate.
- The subject should maintain a brief volume plateau at both the maximal expiratory level and inspiratory level.
The most significant factor affecting test performance is
subject effort.
Acceptable maneuvers
should be repeated until _______ is demonstrated
reproducibility
Measureinents of VC should be made before ______ are
performed. This is recommended to help avoid possible _______
on VC measurement.
FVC tests
muscle-fatigue and volume-history effects
is the volume of air that was exhaled during the VC maneuver from the FRC baseline down to the RV level
ERV
. volume of air inhaled from the FRC level up to
the TLC level.
Inspiratory capacity (IC) is the
Accurate measurement of _____ as a separate volume is not possible. This is because the tidal end-inspiratory level does not provide a stable baseline from which to initiate and complete the maneuver.
IRV
117 the past, volume measureincnts for direct spirometry had to be made by hand from a
spirometry tracing
Most often, indirect spirometry is performed to measure_____. Once it has been determined, the subject’s RV and TLC can be calculated.
FRC volume
Air trapped within the lung and not in communication with conducting airways cannot experience the
required gas dilution.
Subjects with ____ can have trapped, noncommunicating air within
their lungs that is not detectable by gas dilution techniques
obstructive or bullous disease
t. Another potential source of a “system” leak that can affect measurement results is the subject having a
perforated eardrum.
the natural volume of nitrogen
in the subject’s lungs is washed out and diluted with
100% oxygen
The washout procedure must be carefully initiated with the subject breathing in 100% oxygen from the
FRC baseline level.
Because prolonged breathing of 100% oxygen may have negative effects on some subjects, tests should generally not extend beyond
7 minutes
. In some people with COPD, ____ can blunt the normal
blood carbon dioxide stimulus that maintains regular breathing.
chronic hypercapnia
known concentration of nitrogen (CalvN2) in the lungs is considered to be approximately
0.75.
CalvN2
known concentration of nitrogen
If for some reason a nitrogen washout test is not acceptably completed, the test can be repeated after a delay of_______ The delay may have to be longer for
subjects who have an obstructive pulmonary disorder.
at least 15 minutes.
If the test must be repeated for some reason, it should be delayed for at least _______, this allows time for any residual helium to wash
out of the lungs before the next test.
four minutes
During the test, a_____ in the system helps to circulate and effectively distribute the air,
blower
is used to prevent carbon dioxide retention by the subject.
A soda lime canister
With this method, a large bolus of
oxygen is added to the spirometer before the start of the test.
oxygen-bolus method
With this method, oxygen is added to the system continuously during the test. The rate of oxygen addition is titrated to match the rate of consumption by the subject during the test.
volume-stabilized method.
for the rebreathed helium-containing volume.
Douglas bag-like reservoir
has the disadvantage of requiring a correction for tissue
nitrogen contribution.
The open-circuit method
also provides a generally accepted method
for assessing the distribution of ventilation
the nitrogen washout test
During BP test administration, the subject is required to perform
an open-glottis panting maneuver at a rate of approximately one to two breaths per second.
is closed suddenly at end-expiration just prior to an inspiration
The BP shutter
Therefore, airway pressure changes at
the mouth may be assumed to reflect
alveolar pressure changes
is used to create a graph of the pressure and volume changes during panting
An oscilloscope or video display
A minimum of three acceptable test maneuvers must be performed because the calculation for VTG requires a____ for angle tangent from several test tracings
mean value
may be estimated by using measureinents made from chest radiographs
Total lung capacity
Two methods have been developed. In each, the measurements are based on
____________ that are taken at maximum subject inspiration.
posterior-anterior and lateral chest X rays
assumes that the lungs, in a cross sectiOn through the chest,
are basically elliptical in shape. Measurements are made on the X rays that divide the thorax into a series of five vertical segments
ellipsoid volume method
The _______ is a second radiographic technique for estimating TLC. It uses to correlate the lung surface areas measured on chest X rays to TLC
measurements made by body plethysmography.
planimetry method, regression equations
The planimetry surface areas can be determined by
use of a device called a
planimeter
Normal values for lung volumes are related most directly differences between subjects
to height, age, and gender
A useful tool in evaluating lung volume studies is the
residual volume/total lung capacity ratio (RV/TLC%)
In normal, young, healthy adults,
the RV/TLCO%, ranges between
20% and 35%
A value greater than 35% indicates
air trapping in the lungs
is demonstrated when, in addition to the
RV/TLCU/, being greater than normal, the TLC of the subject is also significantly greater
than normal.
Hyperinflation of the lungs
tend to demonstrate reductions in all lung volumes.
restrictive
on the other hand, tend to demonstrate increases in only some volumes
Obstructive patterns,
Space-occuppying abnormalities within the thorax
(c.g., pleural effusion, pneumonia, tumor)
, loss of lung volume
(e.g., atelectasis, surgical excisions),
increased lung elastic recoil
(e.g., interstitial fibrosis-sarcoidosis, asbestosis, and complicated silicosis)
deformities of the chest wall
(e.g., severe kyphosco1iosis)
all can produce general restrictive patterns.
Space-occuppying abnormalities within the thorax (c.g., pleural effusion, pneumonia, tumor), loss of lung volume (e.g., atelectasis, surgical excisions), increased lung elastic recoil (e.g., interstitial fibrosis-sarcoidosis, asbestosis, and complicated silicosis), and deformities of the chest wall (e.g., severe kyphosco1iosis)-
, can demonstrate a greater reduction in VC than in other lung volumes.
weakness of the ventilatory muscles, neuromuscular disorders, and
CNS depression
are the result of obstructive airway disorders
obstructive patterns
Diseases such as chronic bronchitis and emphysema are common types of disorders producing this
pattern.
obstructive pattern
Inflammatory diseases such as _____ can result in airway obstruction during
acute exacerbations but may be fully reversible.
asthma
One is where increases in RV result in a proportional reduction
of VC while the TLC remains relatively constant
air trapping
In the second pattern, RV increases with little or no change in VC. This causes an increase in TLC in direct proportion to the increase in RV.
Hyperinflation
Ventilation must be evaluated within the context of
arterial blood gas (ABC) values.
Hypoventilation, for example,
will produce
hypercapnia and acidosis
will cause a subject to increase ventilation significantly
Diabetic ketoacidosis
Increases in ventilation are caused by disorders or changes from
homeostasis
A normal pattern of tidal breathing.
eupnea
Tidal breathing at a more rapid rate than normal.
tachypnea
Tidal breathing at a slower rate than normal.
bradypnea
tidal breathing larger volumes than normal, faster rate of breathing
hyperpnea
tidal breathing smaller volumes than normal, slower rate of breathing
hypopnea
Ventilation insufficient for physiologic needs,
results in a relative hypercapnia and respiratory acidosis.
hypoventilation
Ventilation in excess for physiologic needs,
results in a relative hypocapnia and respiratory alkalosis.
hyperventilation
In severe thoracic/pulmonary restrictive disorders, the
work of breathing (WOB) is _____ when the subject breathes with smaller tidal volumes. As a result, in order to maintain adequate ventilation, the respiratory rate must be______ than normal.
less, greater
Subjects with flow resistance caused by obstructive disorders experience ______ WOB at_____ respiratory rates. As a result of the_____ breathing rate, the tidal volume will be _____to maintain adequate overall ventilation.
less, slower, slower, increased
It must be noted that increases in tidal volume and or respiratory rate can be exhibited by subjects solely as a .
result of breathing on the pulmonary function apparatus, eg anxiety or effects of nose clips
