Static & Dynamic Lung Volumes
Lab 6
Spirometer

Classic instrument for measuring air volumes
–
Wet- Consists of an air collecting bell inverted in a
vessel of water
Amount of water displaced
gives you estimate of the air
required to displaces it
Spirometer

Useful for static volume measurement
–
–

Vital capacity
Peak airflow
Limited usefulness when measuring rapid
volume changes- speech
–
–
–
Inertia of the bell
Sluggish response
Total volume is not obscured but breath group
data is!
Chest Wall Measurement
Lung volume can be determined from
changes in rib cage and abdominal size
 Devices for transducing size changes:

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–
–
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Magnetometers
Mercury strain gauges
Inductance plethysmography
Respitrace
Chest Wall Measurement

Chest wall’s 2 parts (rib cage & abdomen), Contribute to
the total lung volume change
–
Rib cage and abdomen movement are not 1:1 so calibration of
abdomen & rib cage are completed
Normal Adult- 20 year old Male
Vtl
Red= LV
Green= RC
Blue = AB
Yellow= Audio
Normal Adult- 20 year old Male
Vtl
LV
RC
AB
Audio
Multihandicapped
MultihandicappedAdultAdult-3636year
yearold
oldMale
Male
Lt. Blue =
Orange = Pt
Red= LV
Green= RC
Blue = AB
Yellow= Audio
Multihandicapped Adult- 36 year old Male
Pt
Vtl
LV
RC
AB
Audio
Articulatory & Phonatory Volumes

Specific articulatory events & phonatory
tasks can be measured by:
–
Spirometer- Although not accurate enough
 Poor
–
Respitrace- Also not accurate enough
 Poor
–
resolution & frequency response
time resolution
Pneumotachograph
 Integration
of the flow signal to get volume
 Shows very small volume changes in a fraction of a
second
Pneumotachograph vs. Spirometer
•Greater squareness of
the corners indicate better
frequency response
Air Volume Measurements

Volume is calculated by multiplying mean
flow by the event’s duration
–
.123 (flow) x 20 (duration)= 2.46 L (volume)
–
Not always the most accurate method for
measuring articulatory volumes
Laboratory

Purpose:
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–
–
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Measure a patient's forced vital capacity (FVC)
Evaluate maximum phonation volume
Derive estimates of mean airflow from a
volume record
Estimate lung volume used for each breath
group during reading of a standard passage (in
absolute terms and as a %age of FVC)
Laboratory

Part I–
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FVC= maximum amount of air that can be
expired after a maximal inspiration- represents
the total amount of air that is available for use.
Measure height of patient
Measure FVC with spirometer or aerophone



Max. inhalation at REL, then max exhalation
3 trials
Determine patient’s expected FVC (norms or formula in
Appendix G
Laboratory

Part II:
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–
Phonation volume (PV)= the maximum amount
of air that is available for a maximally sustained
phonation
Use sample (figure A) of sustained /a/ for the
lab questions
 Is
PV normal (Use norms in text)
 Abnormal PV might occur in which pathological
conditions?
–
For the patient exercise do a sustained /a/ on
the aerophone, mark it and calculate volume.
Laboratory

Part III:
– Assessment of lung volume change during a
speaking task (how a patient manages air for
speech purposes)
Duration & relative volume of each breath group
(amount of air expressed as a %age of VC)
– Mark speaking record
 Use Figure B
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Laboratory
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Analysis questions for part III:
 Find
REL- draw line across bottom of cycle
 Divide into 10 equal segments (10% each)
 Mark each breath group
 The FVC for this sample will be ?
 To calculate %age of VC:
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Volume (in Liters) x 100 / VC in L
ex. .64 x 100/ 4.4= 14.5%
Laboratory

Mean airflow data
–
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Used to assess more general characteristics of
ventilatory, laryngeal and/or articulatory
function
Mean speech airflow= volume of air the
speaker uses divided by the duration of the
utterance
Laboratory

Part IV:
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Use Figs. 3 & 4 of the running speech samples and
highlight the mean flow rate from your calculations
 baseline volume= where speech begins
 Finishing volume= where speech ends
 Total volume= baseline volume-finishing volume
 Speech volume of each breath group & expiration
duration
 Mean airflow rate= mean speech volume/mean
duration