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Comparison of evacuation and compression for cough assist
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Comparison of evacuation and compression for cough assist
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Content
COMPARISON OF EVACUATION AND COMPRESSION FOR
COUGH ASSIST
by
M arlene Sue Young
A Thesis Presented to the
FACULTY OF THE GRADUATE SCHOOL
UNIVERSITY OF SOUTHERN CALIFORNIA
In Partial Fulfillm ent of the
Requirements for the Degree
MASTER OF SCIENCE
(Biomedical Engineering)
May 1996
Copyright 1995 Marlene Sue Young
This thesis, written by
Mad.en£..Sjue...Y.ounfl...................................................
under the guidance of Faculty Committee
and approved by all its members, has been
presented to and accepted by the School of
Engineering in partial fulfillment of the re
quirements for the degree of
Master o f Sc 1 ence In B1 omed 1 caT Engl neer 1 ng
D ate .......................................................
Faculty Com m ittee
J1 hair man
Dedication
This body of work is dedicated to Mr. and Mrs. Louis Young.
W ithout the strength, knowledge, and love of my parents, this work
would not have been possible.
iii
Acknowledgments
I would like to thank my Committee Chairm an Dr. Stanley
Yamashiro, and other committee members, Dr. David DArgenio and
Dr. Jean-M ichel M aarek, for having patience with me and my work
while this thesis was put together.
I would also like to thank the staff of the Cardio Thoracic
Surgery research group at Children's Hospital of Los Angeles for their
help w ith all the experiments.
Table of Contents
iv
Page Num ber
Dedication ii
Acknowledgm ents iii
List of Tables v
List of Figures vii
C hapter
I. Introduction 1
II. Background Inform ation 2
a. Development of Cough 4
b. Mechanical Assisted Cough 7
c. Hypothesis 9
III. Methods and M aterials 10
IV. Results 14
V. Discussion 43
V I. Conclusions 46
Notes
Works Cited
47
49
V
L ist o f T ables
Title Pace Number
Table 1: D ata for Animal 1 28
Table 2: D ata for Animal 2 29
Table 3: D ata for Animal 3 30
Table 4: Data for Animal 4 31
Table 5: Data for Animal 5 32
Table 6: D ata for Animal 6 33
Table 7: D ata for Animal 7 34
Table 8: D ata for Animal 8 35
Table 9: Data for Animal 9 36
Table 10: Paired Comparison Probabilities
Animal 1 38
Table 11: Paired Comparison Probabilities
Animal 2 38
Table 12: Paired Comparison Probabilities
Animal 3 39
Table 13: Paired Comparison Probabilities
Animal 4 39
Table 14: Paired Comparison Probabilities
Animal 5 40
Table 15: Paired Comparison Probabilities
Animal 6 40
Table 16: Paired Comparison Probabilities
Animal 7 41
Table 17: Paired Comparison Probabilities
Animal 8 41
L ist o f T ables (con tin u ed )
vi
Title
Table 18: Paired Comparison Probabilities
Animal 9
Page Number
42
l i s t o f F ig u r e s
1. Flow vs. Time Curve for Animal 6
Compression of +40 cm HjO Trial 1
2. Volume vs. Time Curve for Animal 6
Compression of +40 cm H2O Trial 1
3. Flow vs. Volume Curve for Animal 6
Compression of +40 cm H2O Trial 1
4. Flow vs. Time Curve for Animal 6
Compression of +40 cm H2O Trial 2
5. Volume vs. Time Curve for Animal 6
Compression of +40 cm H2O Trial 2
6. Flow vs. Volume Curve for Animal 6
Compression of +40 cm H2O Trial 2
7. Flow vs. Time Curve for Animal 6
Compression of +40 cm H2O Trial 3
8. Volume vs. Time Curve for Animal 6
Compression of +40 cm H2O Trial 3
9. Flow vs. Volume Curve for Animal 6
Compression of +40 cm H2O Trial 3
10. Flow vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 4
11. Volume vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 4
12. Flow vs. Volume Curve for Animal 6
Compression of +30 cm H2O Trial 4
13. Flow vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 5
List of Figures (continued)
Title
14. Volume vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 5
15. Flow vs. Volume Curve for Animal 6
Compression of +30 cm H2O Trial 5
16. Flow vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 6
17. Volume vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 6
18. Flow vs. Volume Curve for Animal 6
Compression of +30 cm H2O Trial 6
19. Flow vs. Time Curve for Animal 6
Evacuation of -40 cm H2O Trial 1
20. Volume vs. Time Curve for Animal 6
Evacuation of -40 cm H2O Trial 1
21. Flow vs. Volume Curve for Animal 6
Evacuation of -40 cm H2O Trial 1
22. Flow vs. Time Curve for Animal 6
Evacuation of -40 cm HjjO Trial 2
23. Volume vs. Time Curve for Animal 6
Evacuation of -40 cm H2O Trial 2
24. Flow vs. Volume Curve for Animal 6
Evacuation of -40 cm H2O Trial 2
25. Flow vs. Time Curve for Animal 6
Evacuation of -40 cm H2O Trial 3
26. Volume vs. Time Curve for Animal 6
Evacuation of -40 cm H2O Trial 3
List of Figures (continued)
Title
27. Flow vs. Volume Curve for Animal 6
Evacuation of -40 cm H20 Trial 3
28. Flow vs. Time Curve for Animal 6
Evacuation of -30 cm HjjO Trial 4
29. Volume vs. Time Curve for Animal 6
Evacuation of -30 cm H2O Trial 4
30. Flow vs. Volume Curve for Animal 6
Evacuation of -30 cm HgO Trial 4
31. Flow vs. Time Curve for Animal 6
Evacuation of -30 cm H2O Trial 5
32. Volume vs. Time Curve foT Animal 6
Evacuation of -30 cm H2O Trial 5
33. Flow vs. Volume Curve for Animal 6
Evacuation of -30 cm H2O Trial 5
34. Flow vs. Time Curve for Animal 6
Evacuation of -30 cm HjjO Trial 6
35. Volume vs. Time Curve for Animal 6
Evacuation of -30 cm H2O Trial 6
36. Flow vs. Volume Curve for Animal 6
Evacuation of -30 cm H2O Trial 6
1
I. Introduction
Cough is an im portant biological function for all hum ans th at
involves a num ber of different muscles and neural pathways. Cough
provides two im portant physiological functions. The most common role
coughing has is as a clearance mechanism for the body.* As well as th at
function, it is also a part of a system th at keeps foreign m aterials from
entering the human airway. This role is equally important as expelling
foreign m aterials and secretions from the central airways.
Without this process, hum ans can become susceptible to various
types of respiratory tract infections or other respiratory illnesses. The
build up of bronchial secretions or foreign m aterials can lead to serious
health problems, such as bronchopneumonia. Bronchopneumonia can
lead to death in acute situations. Cough can also be used as an
indicator for other health ailments. Chronic cough is one the most
common indicators of lung disease.
There are a variety of health problems which are associated with
deficient cough. For example, subjects with tetraplegia and
quadriplegia often have a defective cough.2 This is also true for patients
with different types of neuromuscular disease such as Muscular
Dystrophy. There have been several investigations to develop a means
for mechanical assisted cough th at can be used on patients such as
these, as well as other types of patients with a compromised cough.3
Paraplegia, quadriplegia and tetraplegia are caused by
transection of the spinal cord .4 Quadriplegia is often caused by spinal
transection at the cervical level. Transection of the upper segments of
2
the cervical cord produces complete paralysis of all the muscles of
expiration. However, tetraplegics with transection of the lower cervical
cord have been shown to retain some expiratory muscle function. This is
im portant due to the fact th a t cough is primarily a forced expiratory act,
and it differs from a forced expiration only in its ferocity. This means
th a t a percentage of these compromised patients may not lose the ability
to cough completely.
Obviously, if a process can be developed to help these types of
patients to cough a sizable number of people from a health stand point
could benefit. Before this can be done, it is im portant to investigate to
w hat extent a maximal expiratory flow can be generated, and its
relation to cough. It is also necessary to see how maximal expiratory
flow and cough are related.
II. Background Information
Before any type of mechanical assisted cough can be developed, it
is im portant to determine what type of muscle function is needed for a
normal cough.. With a normal cough, both the inspiratory and
expiratory respiratory muscles are active. The inspiratory muscles are
active during the inspiratory phase of a cough, and the expiratory
muscles are active during the compressive and expulsive phases.^ It is
mainly the expiratory muscles which contribute during the entire cough
process.
The main inspiratory muscle during respiration is the
diaphragm.^ When the diaphragm contracts, the domed portion of the
3
muscle descends in to the abdomen. H ie muscle flattens out across the
bottom of the thoracic cavity, and the abdominal contents are forced
downward. The movement of the diaphragm downward lowers the air
pressure in the chest.
This movement also enlarges the vertical dimensions of the chest,
and as a result, the chest vo’ume increases. The scalenes and the
external intercostals are im portant in working with the diaphragm
during inspiration. The scalene, muscles are attached to the first two
ribs and to the sternum . The scalenes aid inspiration by pulling up on
the rib cage. The internal intercostal muscles run over, under, and
between the ribs. The internal intercostals act to move the rib cage
upwards and outwards. During forced exhalations, the internal
intercostals cause the ribs to be depressed further than normal, and this
decreases thoracic volume.
The main expiratory muscles are in the antero-lateral wall of the
abdomen.? When the expiratoiy muscles contract, the intra-abdominal
pressure rises, and the diaphragm is pushed upward into the chest.
This reduces the chest volume. The internal intercostals are expiratory
muscles th at rotate the ribs downward when they contract. The
scalenes are im portant, because they contract during all strong
expiratoiy efforts. The paralysis of these different muscles in
quadriplegics or tetraplegics varies depending on the type of iryury.
In addition to the vaiying degrees of muscle activity, chest wall
stiffness and compliance of the abdominal com partment become
important. It has been seen th at after traum atic transection of the
4
cervical cord, the rib cage becomes abnormally stiff over time, as does
the abdomen & There is a reduction in lung compliance also. The
decrease in total chest displacement contributes to the reduction in
thoracic gas volume. This reduction in gas volume in the chest affects
the peak flows th a t can be achieved during a maximal expiratoiy flow or
cough.
Traditionally, cough in tetraplegic subjects has been considered a
passive process rather than an active one.9 But there is evidence th at a
small expiratory reserve volume is present which refutes the idea that
cough is a passive process. The presence of an expiratoiy reserve
volume also supports the idea th a t expiratoiy muscle function is still
present. Expiratoiy muscle function may be incomplete, b ut the
muscles can still cause emptying of the lungs when contracted. 10 Active
expiration by tetraplegics involves a muscle or a group of muscles to
deflate the upper rib cage. It has also been shown in a few studies th at
tetraplegics also contract the clavicular portion of the pectoralis major
during cough. This also supports the claim th at cough is still an active
process.
a. Development of Cough
Cough utilizes maximum expiratoiy flow rates th at the lung is
capable of achieving. An im portant feature of the cough mechanism is
th at the maximum flows are reached with a relatively small expiratoiy
effort.
5
H ie cough reflex is activated by the mechanical or chemical
stimulation of receptors in the hypopharynx and aditus laryngis.H
Once the receptors are stimulated, the actual cough event occurs in
several phases. H ie inspiratory phase requires the inhalation of a
variable volume of a i r . 12 This volume facilitates the production of
greater expiratoiy flows. During this inspiratory phase, the glottis
actively dilates. H iis is normal during regular inspiration.
When the compressive phase occurs, the glottis closes, and the
contraction of the expiratoiy muscles begins. H ie glottis is normally
closed for approximately 0.2 seconds. 13 It is during this period th at the
pressure in the abdominal, pleural, and alveolar spaces is raised.
During this phase the pleural pressure and the esophageal pressure
begin to rise.
Next, is the expiratory phase. H i is phase begins with the rise of
expiratory flow to high levels as the glottis opens. Once the glottis
opens, the trachea] pressure falls to atmospheric pressure. At this time,
alveolar pressure exceeds th at at the airway opening, and the pleural
pressure also exceeds the pressure within the central airways. Hence,
these airways relax and decrease their volume. H i is causes the airways
to collapse abruptly, and there is an acceleration of gas and, perhaps
secretions, th at are to be forced out of the lungs. H ie actual volume
decrease of the expiratory phase is not great, but it occurs so quickly
th a t the instantaneous flow is great.
Once the expiratory phase is carried out, the removal of any
undesired m aterial from the respiratory tract will occur. Plow is finally
6
stopped when the glottis closes. This is followed fay relaxation of the
expiratory muscles and a fall in pleural and alveolar pressures.
Repetitive coughing can occur a t this point without the need for another
inspiration or uptake of air. With repetitive coughing one does not see a
sequence of high to low lung volumes.
It is during the expiratory phase th at tetraplegics and paraplegics
are a t a severe disadvantage. The expiratory muscles are im portant in
m aintaining high intrathoracic pressures, because the high pressures
lead to a high cough flow.15 Since the compromised patient may not be
able to use the expiratory muscleB to m aintain the intrathoracic
pressures necessary to generate a high peak flow, it may not be possible
for the patient to successfully move any secretions from the airway. If
the high intrathoracic pressure cannot be achieved, a reduced cough
flow is often the result.
One of the interesting aspects of expiratory flow during cough
deals with the supra maximal flow th at can be achieved during the
cough. If flow-volume curves are taken during a cough, a spike can be
seen th at represents a peak flow th at is greater than any voluntary
maximum expiratory flow. This spike is due to the rapid collapse of the
intrathoracic airways once the glottis opens. Hence, the glottis plays an
im portant in role in the achievement of these peak expiratory flows.
However, the glottis is not essential for effective c o u g h .15 Expiratory
muscles are able to produce high intrathoracic pressures with an open
glottis. A normal maximal forced expiration is normally set by a flow-
limiting mechanism operation in the lung and intrathoracic airways.
7
Muscle strength does not set the upper limits to low, but it is believed to
influence cough effectiveness.
Flow through the airways during cough is characterized by two-
phase cocurrent flow. Two phase cocurrent flow refers to flow of gas and
liquid together in the same direction w ithin a conduit.^ Four different
types of two phase cocurrent flow exist. They are bubble, slug, annular,
and misty. Each flow has a different superficial velocity, which is the
average speed of the gas through a tube in a clinical setting. Bubble
flow has the slowest superficial velocity, and misty flow has the highest.
Clearance of large plugs of sputum from central airways appears to be
most effective by slug flow. However, m ist flow is usually assumed to be
the most im print clearance mechanism in coughing.
h. Mechanical Assisted Cough
There are several different ways to have an assisted cough. One
way to achieve an assisted cough is to have direct muscle stimulation of
the respiratoiy muscles, as well as a sort of training regimen for the
respiratory muscles. If specific muscles can be identified it is thought
th at specific training programs could be used to increase the strength
and endurance of these m u s c l e s . 18
It has been shown th a t the diaphragm of tetraplegics can be
trained, as well as the pectoral is mqjor muscle, an expiratoiy muscle.
Weak expiratory muscles tend to diminish cough. Training of
inspiratory muscles may also be effective. Stronger inspiratory muscles
may allow cough to sta rt a t higher lung volumes where it is thought to
8
be more effective. With any type of muscle training however, fatigue is
also a significant concern.
Another method which can be used is called exsufflation with
negative pressure.!® With this procedure, the respiratory system is
inflated to a static pressure, and then a valve is opened th a t exposes the
airway to a negative pressure for a few seconds. This pressure at the
mouth will create the needed pressure difference between the alveolar
and pleural pressures to cause the closing of the glottis and the
instantaneous flow needed for cough. Once the exposure to the negative
pressure is turned off, the generated flow can be used for a cough.
The most interesting method which seems to show the most
promise is to use a type of corset to apply pressure to the chest and
abdominal area. In several studies, it has been shown th at mechanical
compression of the trunk by a corset or by m anual pressure applied by
people's hands, has increased expiratory flow and lung v o l u m e .20 This
method works much like the exsufflation with negative pressure. The
respiratory system is raised to a certain static pressure, and then
positive pressure is applied to the rib cage to force the air out of the
lungs.
When compressing the trunk however, it is also im portant to bind
the abdomen. Binding the abdomen proves to be more convenient to
allow the rib cage to lift and widen during assisted cough. By applying
direct pressure to the chest, it is im portant th at the pressure not be too
high. If the pressure is too great, other problems may result, such as rib
fractures.
9
c. Hypothesis
It ia necessary to see which maneuvers produce the highest
maximal expiratory flows and lung volume. By comparing the lung
volumes and flows with two different maneuvers it will be possible to
see which maneuver would be best to utilize on possible patients. I
would expect the maximal peak flow during an actual cough to be
slightly higher than an artificially induced maximal expiration peak
flow.
A cough, whether it is voluntary or involuntary, is used to
disengage secretions trapped in the airways. To generate enough force
to get rid of the secretions, the body m ust generate a greater flow. This
flow th at is generated during a cough cannot be too great, due to the
natural physiological constraints of the hum an body. It is necessary to
observe the lung volumes as well, since the flow th at can be achieved is
directly related to the actual lung volume.
Once the kinds of peak flows th a t can be artificially achieved are
known, it will be necessary to analyze the actual maneuvers. The
accuracy of the results and the ability to do repetitive maneuvers are
im portant factors to deal with. If these peak flows can be generated, it
will be im portant to see w hat kinds of steps will be necessary to repeat
the process on hum ans th a t need the process.
It has previously been shown th a t exsufflation with positive and
negative pressure is successful. I would expect negative pressure
10
exsufflation to be more successful in compressing the thoracic cavity to
produce the highest flows and larger vital capacities.
III. Methods and Matarlala
In order to measure expiratory flow, a spirometry device was
developed. The apparatus th at was used in the experiments consisted of
a flow meter, a solenoid, a pressure transducer, a pump th at provides
positive and negative pressure, and a 486/66 MHz PC computer was
used for data collection and data storage.
The spirometry device set-up is standard. The
pneumotachograph, or flow meter, is the device th at the expiratoiy flow
from the anim al travels through. H ie flow meter will only work in one
certain direction, therefore, it is necessary for the pressure entering the
"in" side be greater than the pressure on the "out" side. H ie pressure
transducer is coupled to the "out" side of the flow meter.
H ie actual data is collected at the site of the Validyne, model
DP45-S, pressure transducer. The flow through the flow meter is
matched with a voltage reading by the pressure transducer. The voltage
data then passes through a 12 bit analog-to-digital converter, and the
data is then filtered through a computer sampling program. H ie
sampling period is approximately ten seconds, and the sampling
interval is 0.02 seconds.
H ie flow data from the sampling program is stored in a data file.
H ie data is written in to a MATLAB file and saved for data analysis.^!
By using MATLAB or a comparable software program, for each flow
11
data point, a volume data point can be calculated. It is then possible to
plot flow vs. volume curves.
Before any actual data is collected, the flow m eter and pressure
transducer m ust first be calibrated. H ie flow m eter is calibrated with
the use of a calibration plunger. H ie plunger is calibrated to supply a
known volume. With the known volume, it is possible to read the
voltage reading of the pressure transducer. H ie calibration trial is also
im portant in determining the calibration factor which is needed during
the data manipulation phase.
H ie animals used in these trials were rats. H ie rats were
weighed at the time of the tests, and then were sedated with a dosage of
60 milligrams per kilogram of Pentobarbital sodium solution. Once
sedated, an endotracheal tube was inserted in to the animal. H ie
anim al was then connected to a model 683, Harvard rodent ventilator.
H ie ventilator setting is 67 strokes per minute.
During data collection, it is ideal for the anim al to breath solely
through the ventilator. If the anim al is still breathing on its own, the
flow points th at are collected during the trial may be artificially
elevated, and hence, inaccurate. To ensure animal paralysis, the animal
was treated with a dosage of 0.1 milligram of Pancuronium Bromide.
Finally, the anim al is placed on its back on a tray. With the
animal continuing to lay on its back, the entire tray is then placed into
the test chamber. The test chamber was a clear plastic, air tight
container th at was large enough for the animal to fit in. H ie lid of the
test chamber has two ports on it. Port one will be the point of
12
connection between the anim al's endotracheal tube and the external
testing apparatus. Port two will connect the test chamber to the
positive or negative pressure pump. It is imperative th at the tubing
connected to the ports in the lid of the test chamber be as air tight as
possible to ensure th at air leaks are not a problem.
The tubing leading from port one of the test chamber lid, leads to
a three way stopcock. One side of the stopcock is connected to the
rodent ventilator, while the other side of the connector leads to the flow
m eter and pressure transducer. When the animal is not being used for a
trial, the stopcock is turned so th at the pathway to the rodent ventilator
is open, and the pathway to the flow m eter is closed. This keeps the
anim al breathing.
Prior to data collection, the anim al is manually given three
breaths. This is done by inflating the animal's lungs to +30 cm H2O and
then deflating. Once the animal is deflated for the third time, the
animal is then once again inflated to +30 cm H2O . The anim al is now
ready for data collection. For all the trials, the animal's lungs were
inflated to +30 cm H2O .
The solenoid is connected in line with the positive or negative
pressure pump. The opening and closing of the solenoid is manually
controlled by a switch. Therefore, it is possible to control the air flow
from the pump to the test chamber. When the solenoid is open, the air
coming from the pump passes though port two and enters the test
chamber. Therefore, the solenoid m ust be open during data collection.
It is best to have a large reservoir of air to fill the testing chamber
13
instantaneously when the solenoid opens. Therefore, it is advisable to
have the pump connected to a tank of some volume greater than the test
chamber to provide the reservoir of air. The tank is then connected to
the solenoid.
Almost instantaneously, the stopcock is turned to close the
pathway to the ventilator and open the pathway to the flow meter, the
sampling program is initiated from the computer key board, and then
the solenoid is opened. Depending on which maneuver is being done,
the test chamber fills with either positive or negative pressure. The
lungs of the animal are deflated from the pressure in the chamber.
Once the sampling program is finished, the pathway to the ventilator is
re-opened for the animal
For data collection, two different maneuvers were done on each
animal. Positive pressure was applied to the test chamber for the
decompression maneuver, and negative pressure was applied to the test
chamber for the evacuation maneuver. For each animal, the maneuver
th a t data collection would sta rt with was randomized. However, for
whichever maneuver was being done, the pressure a t 40 cm H2O was
always done first. If the evacuation maneuver is to be done, evacuation
a t -40 cm H2O is done before -30 cm H2O . If the compression maneuver
is to be done, +40 cm H2O is done before +30 cm H2O .
The concept for the two maneuvers is basically the same. With
the compression maneuver, once the animal's lungs are inflated, the
positive pressure introduced in to the testing chamber literally
compresses the thoracic cavity and forces the air from the animal's
14
lungs. With the evacuation maneuver, the negative pressure sucks the
air from the animal's lungs like a vacuum. When switching from the
compression maneuver to the evacuation maneuver, it was necessary to
reverse the flow meter. Since the pressure coming from the anim al will
always be larger than the negative pressure in the test chamber.
Once the data has been stored, the calibration factor is removed
from all the points. The volume data points are calculated by
multiplying the sampling interval and the cumulative sum of the flow
points. Once the volume points are calculated the flow vs. time curves,
volume vs. time curves, and flow vs. volume curves can be plotted.
Other param eters such as maximal expiratory flow and vital capacity
can also be calculated. D ata manipulation can take place within the
sampling program, or it can take place outside the sampling program.
IV. Results
For each trial completed, flow vs. time, volume vs. time, and flow
vs. volume curves are generated. Examples of Animal 6 are shown in
Figures 1 to 36. From the flow vs. time curves for all nine animals, it is
possible to see w hat the peak flow for each m aneuver is. Peak flows in
excess of 100 ml/sec were achieved in six of the nine animals with the
evacuation maneuver. None of the anim als th a t achieved peak flows
over 100 ml/sec with the evacuation maneuver, reached peak flows of
100 ml/sec with the compression maneuver.
In eight out of nine animals, the peak flows associated with
evacuation at -40 cm H20 are significantly higher than compression at
Figure 1: Flow vs. Time Curve for Animal 6.
Compression of +40 cm H jjO Trial 1
Rat 6: Oomp M ion +40 cm H20 Trial 1
100
g 00
g, 40
1 20
-20
0.5 2.5
Figure 2: Volume vs. Time Curve for Animal 6
Compression of +40 cm H20 Trial 1
Rat 6: Coniprc* « ion +40 an H20 THal 1
a
time (aecoods)
Figure 3: Flow vs. Volume Curve for Animal 6
Compression of +40 cm HjjO Trial 1
Rat:6: Comptewioo +40 cm H20 Trial 1
100
80
•20
vohxne(ml)
f l o w (m l/K c) v o lu m e ( m l) f l o w (ml/bec)
Figure 4: Flow vs. Time Curve for Animal 6.
Compression of +40 cm H20 Trial 2
Ret 6: Cbpv*— +40 cm wm TrielZ
100
00
-20
1.5
time (seconds)
0.5 2.5
Figure 5: Volume vs. Time Curve for Animal 6
Compression of +40 cm H20 Trial 2
Ret 6: Compression +40 an H20 Trial 2
Figure 6: Flow vs. Volume Curve for Animal 6
Comoression of +40 cm HaO Trial 2
Ret 6: Compwrioo +40 cm H20 Trial 2
100
60
-20
volume (ml)
Figure 7: Flow vs. Time Curve for Animal 6.
Compression of +40 cm H20 Trial 3
R* 6: Comprenioo +40 cm H 2Q Trial 3
I
1 1.5 2
time (seconds')
Figure 8: Volume vs. Time Curve for Animal 6
Compression of +40 cm H2O Trial 3
Rat 6: Comprc«iion +40 cm H20 Trill 3
time (second*)
Figure 9: Flow vs. Volume Curve for Animal 6
Compression of +40 cm H2O Trial 3
R*t6: Comprcasioo -M O cm H20 Trial 3
100
80
IT 60
40
20
-20
volume (ml)
f l a w (mlfec) v o lu m e ( m l) f l o w (ml/sec)
Figure 10: Flow vs. Time Curve for Animal 6.
Compression of +30 cm H20 Trial 4
Rat6: CompreMlon+30cmH20Trial4
100
80
20
-20
0.5 1.5
time ('second*'*
2.5
Figure 11: Volume vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 4
R j i 6: Compreaiion - > - 3 0 cm H20 Trial 4
10
5
0
-5
8 2 6 10 4 0
time (seconds)
Figure 12: Flow vs. Volume Curve for Animal 6
Compression of +30 cm H2O Trial 4
Ret 6: Comprcieioc +30 cm H20 Trial 4
100
80
60
-20
volume (ml)
Figure 13: Flow vs. Time Curve for Animal 6.
Compression of + 30 cm H2O Trial 5
Rat 6; Compreailon +30 cm H30 Trial 5
100
I 20
-20
0.5 2.5
Figure 14: Volume vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 5
Rat 6: Compreaaloo +30 cm H20 Trial 5
100
80
| 60
40
I 20
-20
volume (ml)
Figure 15: Flow vs. Volume Curve for Animal 6
Compression of +20 cm H2Q Trial 5
Rat 6: Compreaaion +30 an H20 Trial 5
time (secoods)
f l o w (m lA ec) v o lu m e ( m l) f l o w (ml/sec)
Figure 16: Flow vs. Time Curve for Animal 6.
Compression of +30 cm H20 Trial 6
Rat 6; Conuvmrioo+30 cm H20 Trill 6
100
80
60
20
-20
2.5 0.5 1.5
time (seconds')
Figure 17: Volume vs. Time Curve for Animal 6
Compression of +30 cm H2O Trial 6
Rat 6: Comprewioo +30 cm H20 Trial 6
0 2 4 6 8 10
time (leconds)
Figure 18: Flow vs. Volume Curve for Animal 6
Compression of +30 cm H2 O Trial 6
Rat 6: Comproifam +30 on H20 Trial 6
100
80
60
40
20
-20
volume (ml)
Figure 19: Flow vs. Time Curve for Animal 6.
Evacuation of -40 cm HgO Trial 1
Rat 6: Bvacnatioo -40 cm H20 Trial 1
100
1
I
•20
0 0.5 1 1.5 2 2.5 3
time (secoods)
Figure 20: Volume vs. Time Curve for Animal 6
Evacuation of -40 cm HaO Trial 1
Rat 6: Evacuation -40 cm H20 Trial 2
Figure 21: Flow vs. Volume Curve for Animal 6
Evacuation of -40 cm H2O Trial 1
Rat 6: Evacuation -40 cm H20 Trial 2
100
1
0 2 4 6 8 10
volume (ml)
f l o w (m tocc) v o lu m e (ml)
Figure 22: Flow vs. Time Curve for A n im a l 6.
Evacuation of -40 cm HgO Trial 2
Rat 6: Evacuation -40 cm H20 Trial 2
100
£ 40
I 20
-20
0.5 2.5
Figure 23: Volume vs. Time Curve for Animal 6
Evacuation of -40 cm H 2O Trial 2
Rat 6: Evacuation -40 cm H20 Trial 1
time (aecooda)
Figure 24: Flow vs. Volume Curve for Animal 6
Evacuation of -40 cm H2O Trial 2
Rat 6: Evacuation -40 cm H20 Trial 1
100
-20
f l o w (m l/aec) v o lu m e ( m l) f l o w (mlAec)
23
Figure 25: Flow vs. Time Curve for Animal 6.
Evacuation of -40 cm H20 Trial 3
Ratfc Evacuation-40 cm H20Ttial 3
100
-20
0.5 2.5
Figure 26: Volume vs. Time Curve for Animal 6
Evacuation of -40 cm H2O Trial 3
Rat 6: Evacuation -40 an H20 Trial 3
Figure 27: Flow vs. Volume Curve for Animal 6
Evacuation of -40 cm H2O Trial 3
Rat 6: Evacuation -40 cm H20 Trial 3
100
80
-20
f l o w (m l/sec) v o lu m e ( m l) f l o w (ml/see)
Figure 28: Flow vs. Time Curve for Animal 6.
Evacuation of -30 cm H2O Trial 4
R a ft Evacuation-30cm H20Thai4
100
20
2.5 0.5
Figure 29: Volume vs. Time Curve for Animal 6
Evacuation of -30 cm H2P Trial 4
Rat 6: Evacuation -30 cm H20 Trial 4
Figure 30: Flow vs. Volume Curve for Animal 6
Evacuation of -30 cm H2 O Trial 4
Rat & . Evacuation -30 cm F T 2 Q Trial a
100
80
-20
volume (ml)
f l o w (m l/sec) v o lu m e ( m l) f l o w (ml/sec)
Figure 31: Flow vs. Time Curve for Animal 6.
Evacuation of -30 cm HsP Trial 5
R ife Evacuation-30cmH20Trial5
100
80
20
-20
0 0.5 1.5 1 2 2.5 3
time (seconds)
Figure 32: Volume vs. Time Curve for Animal 6
Evacuation of -30 cm H2O Trial 5
R ife Evacuation-30cmH20Trial5
Figure 33: Flow vs. Volume Curve for Animal 6
Evacuation of -30 cm H2O Trial 5
Rat 6: Bvaniatioo -30 cm H 7Q Triil S
100
80
20
-20
vohxne (ml)
26
Figure 34: Flow vs. Time Curve for Animal 6.
Evacuation of -30 cm H2O Trial 6
Rat 6: Evacuation -30 an H20 Trtal 6
100
-20
0 0.5 1 1.5 2 2.5 3
time fsecoDdst
Figure 35: Volume vs. Time Curve for Animal 6
Evacuation of -30 cm H2O Trial 6
Hitfe Evacuation -30 cm H2Q Trial 6
Figure 36: Flow vs. Volume Curve for Animal 6
Evacuation of -30 cm H2O Trial 6
Rat 6: Evacuation -30 cm H20 Trial 6
100
-20
27
either pressure, as well as evacuation a t -30 cm H2O . This is also an
indicator th at the evacuation maneuver is better suited for assisted
cough than compression.
The evacuation m aneuver appears to be most effective with a
pressure of -40 cm H20 than -30 cm H2O . Of the six anim als th at had a
peak flow over 1 00 ml/sec, none of them had a peak flow over 1 0 0 ml/sec
with a negative pressure of -30 cm H5 5 O . This may imply th at the
evacuation maneuver with -40 cm H2O is better suited to generate
higher flows.
Vital capacity, VC, maximal expiratoiy flow a t 25% of vital
capacity, MEF 25, maximal expiratory flow at 50% of vital capacity,
MEF 50, maximal expiratoiy flow at 75% of vital capacity, MEF 75, and
the difference of maximal expiratory flow at 25% and 75% of vital
capacity, MEF25-75, are calculated for each trial. This data is shown in
Tables 1 to 9. The mean and standard deviation for each param eter
measured is also calculated.
For all nine animals, the vital capacities produced with the
evacuation maneuver at both -30 and -40 cm H2O are larger than the
vital capacities using the compression maneuver. H ie vital capacities
produced with evacuation at -40 cm H2O are slightly higher than the
ones produced with evacuation a t -30 cm H2O . However, the difference
is not significant. With seven out of nine animals, the compression
maneuver produced slightly higher vital capacities a t +30 cm H2O than
+40 cm H20, but again the difference is not significant.
2 8
TABLE 1: DATA FOR ANIMAL 1
Rat weight: 266 Grama
VC MEF26-76 MEF 26 MEF 60 MEF 76
(ML) (ML/SEC) (MIVSEC) (ML^SEC) (ML/SEC)
COMPRESSION
Pressure +40 cm H20
TRIAL 1 11.45823 48.26260 25.091 66.666 61.690
TRIAL 2 11.21666 38.66486 16.041 56.256 60.739
TRIAL 3 11.72833 42.26887 15.767 66.489 64.980
MEAN 11.46737 43.06540 18.966 56.803 65.803
STD. DEV. 0.26661 4.84816 6.306 0.628 4.680
COMPRESSION
Pressure +30 cm H20
TRIAL 4 11.88063 46.06876 28.244 48.262 60.063
TRIAL 6 11.64672 43.44082 23.171 66.392 69.514
TRIALS 11.83263 43.30371 19.068 56.077 64.578
MEAN 11.76393 44.27109 23.491 53.244 64.715
STD. DEV. 0.17933 1.66833 4.601 4.328 4.732
EVACUATION
Pressure -40 cm H20
TRIAL 1 12.76940 31.66369 18.372 17.138 91.451
TRIAL 2 12.57979 36.46848 16.727 47.028 64.678
TRIAL 3 12.20648 36.83697 17.412 27.833 63.883
MEAN 12.61489 34.32306 17.604 30.666 69.971
STD. DEV. 0.28281 2.31042 0.826 15.146 19.366
EVACUATION
Pressure -30 cm H20
TRIAL 4 12.92266 44.28633 22.760 52.238 63.070
TRIAL 6 12.76899 62.86709 36.100 56.392 53.609
TRIAL 6 12.60036 47.69121 36.608 48.126 68.646
MEAN 12.76397 48.28164 31.489 51.918 68.408
STD. DEV. 0.16116 4.32073 7.697 3.644 4.732
29
TABLE 2: DATA FOR ANIMAL 2
Rat weight: 266 gram s
VC MEF 25-75 MEF 26 MEF 60 MEF 76
EVACUATION
Pressure -40 cm H20
TRIAL 1 12.04096 32.29783 18.235 48.262 63.892
TRIAL 2 11.53601 27.29848 17.275 27.421 62.294
TRIAL 3 11.86173 31.02957 20.017 27.696 84.596
MEAN 11.80923 30.20862 18.609 34.460 66.927
STD. DEV. 0.26663 2.59881 1.391 11.964 16.364
EVACUATION
Pressure -30 cm H20
TRIAL 4 11.80374 34.18920 17.961 40.996 80.620
TRIAL 5 11.97787 36.38279 17.824 36.786 46.205
TRIALS 11.71187 38.02214 16.041 46.342 43.062
MEAN 11.83116 36.86471 17.275 41.041 66.626
STD. DEV. 0.13610 1.96139 1.071 6.279 20.839
COMPRESSION
Pressure +40 cm H20
TRIAL 1 11.08266 30.10313 16.178 30.164 68.828
TRIAL 2 10.68759 26.42402 14.633 25.913 56.603
TRIAL 3 11.13877 28.86914 16.727 30.849 68.967
MEAN 10.93630 28.46643 16.813 28.976 61.196
STD. DEV. 0.30330 1.87248 1.142 2.674 6.796
COMPRESSION
Pressure +30 cm H20
TRIAL 4 11.26805 33.26860 18.646 32.494 62.668
TRIALS 11.62413 32.41780 17.412 33.866 63.344
TRIAL 6 11.33767 33.74848 20.429 37.430 61.562
MEAN 11.40668 32.84320 18.829 34.697 62.521
STD. DEV. 0.19266 0.67390 1.617 2.648 0.899
30
TABLE 3: DATA FOR ANIMAL 3
Rat weight: 270 Grains
VC MEF 26-76 MEF 26 MEF 60 MEF 76
(ML) (ML/SEC) CMIVSEC) (MIVSEC) (ML/SEC
Compression
Pressure +40 cm H20
TRIAL 1 11.36910 40.11692 26.776 41.407 66.401
TRIAL 2 11.63921 42.27866 20.703 38.527 64.441
TRIAL 3 11.22103 41.19167 20.017 63.682 64.441
MEAN 11.40978 41.19539 22.166 47.939 64.761
STD. DEV. 0.21204 1.08137 3.146 13.882 0.564
Compression
Pressure +30 cm H20
TRIAL 4 11.09900 40.73291 13.299 60.044 61.426
TRIALS 10.89334 40.79004 17.138 43.463 60.182
TRIAL 6 11.23063 46.66459 22.760 47.861 61.141
MEAN 11.07432 42.36918 17.732 47.119 64.249
STD. DEV. 0.16999 2.76746 4.768 3.361 6.233
Evacuation
Pressure -40 cm H20
TRIAL 1 12.847IS 64.23818 27.696 47.028 81.660
TRIAL 2 12.09441 40.08164 14.633 47.988 77.606
TRIAL 3 12.38646 41.42988 23.171 48.948 64.304
MEAN 12.44267 46.24990 21.800 47.988 74.496
STD. DEV. 0.37961 7.81321 6.686 0.960 9.048
Evacuation
Pressure -30 cm H20
TRIAL 4 11.66978 42.67629 17.687 67.037 68.006
TRIALS 11.77495 46.17168 23.171 43.189 51.827
TRIALS 11.26764 40.08164 14.807 43.463 79.249
MEAN 11.66746 42.97617 18.665 47.896 66.361
STD. DEV. 0.26696 3.06610 4.249 7.917 13.785
31
TABLE 4: DATA FOR ANIMAL 4
Rat weight: 260 Grama
VC MEF 26-76 MEF 26 MEF 60 MEF 76
(ML) (ML/SEC) (ML/SEC) (MIVSEC) (MIVSEC
COMPRESSION
Preoaure +40 cm H20
TRIAL 1
10.69866 27.660 14.944 29.615 44.286
TRIAL 2 10.36460 31.064 16.590 32.367 51.827
TRIAL 3 10.95230 28.879 18.646 30.712 54.295
MEAN 10.83612 29.198 16.727 30.896 60.136
STD, DEV. 0.30057 1.729 1.856 1.380 5.214
COMPRESSION
Pressure +30 cm H20
TRIAL 4 10.97972 32.867 19.469 40.868 60.466
TRIALS 11.14973 34.320 15.767 37.430 53.198
TRIALS 10.63283 31.349 17.276 38.664 66.361
MEAN 10.92076 32.842 17.604 38.984 66.671
STD. DEV. 0.26346 1.486 1.862 1.736 3.644
EVACUATION
Pressure -40 cm H20
TRIAL 1 12.93216 34.766 17.275 41.644 56.763
TRIAL 2 12.80190 34.826 19.068 34.003 61.562
TRIALS 11.78692 30.696 18.609 40.868 76.644
MEAN 12.60666 33.429 18.281 38.802 64.990
STD. DEV. 0.62757 2.367 0.913 4.170 10.374
EVACUATION
Pressure -30 cm H20
TRIAL 4 12.08482 38.571 18.236 46.206 62.101
TRIAL 6 12.17806 38.263 20.017 50.319 76.096
TRIALS 12.34807 40.163 19.880 37.706 66.255
MEAN 12.20366 38.996 19.377 44.743 61.160
STD. DEV. 0.13348 1.014 0.992 6.433 13.038
32
TABLE 5: DATA FOR ANIMAL 5
Rat weight: 282 Grama
VC MEF25-76 MEF 26 MEF 60 MEF 76
(ML) (ML/SEC) (ML/SEC) (ML/SEC) (ML/SEC
EVACUATION
Pressure -40 cm H20
TRIAL 1 13.87273 38.06309 19.469 37.706 92.000
TRIAL 2 13.84804 37.09666 22.348 37.979 87.476
TRIAL 3 13.23928 40.94429 21.389 29.752 61.160
MEAN 13.65335 38.70134 21.069 36.146 80.208
STD. DEV. 0.36881 2.00166 1.466 4.673 16.669
EVACUATION
Pressure -30 cm H20
TRIAL 4 13.73699 42.22969 16.041 56.803 64.158
TRIALS 13.46413 41.88692 20.017 53.061 71.433
TRIAL 6 13.04733 40.30169 17.001 64.980 78.837
MEAN 13.41616 41.47273 17.686 54.615 68.143
STD. DEV. 0.34732 1.02862 2.075 1.407 12.664
COMPRESSION
Pressure +40 cm H20
COMPR1 12.89239 41.68126 21.114 38.939 66.636
COMPR 2 13.02960 38.66690 12.476 61.416 74.176
COMPR3 13.08161 38.99906 16.316 37.979 66.066
MEAN 13.00117 39.74907 16.636 42.778 68.966
STD. DEV. 0.09774 1.68722 4.328 7.496 4.521
COMPRESSION
Pressure +30 cm H20
COMPR 4 13.27219 46.44197 19.195 64.980 63.618
COMPR & 12.88828 40.46686 17.560 66.666 64.715
COMPR 6 12.48792 29.66361 20.840 30.849 36.511
MEAN 12.88280 38.62416 19.195 47.166 64.615
STD. DEV. 0.39216 8.06668 1.646 14.134 16.663
33
TABLE 6: DATA FOR ANIMAL 6
Rat weight: 273 Grama
VC MEF26-76 MEF 25 MEF 50 MEF 75
COMPRESSION
Pressure +40 cm H20
TRIAL 1 7.80664 14.99977 4.260 17.687 38.801
TRIAL 2 7.79604 16.85822 5.073 18.098 65.812
TRIAL 3 7.66893 13.46628 4.525 18.372 22.211
MEAN 7.763S4 15.10776 4.616 18.052 42.275
STD. DEV. 0.08207 1.69905 0.419 0.345 22.007
COMPRESSION
Pressure +30 cm H20
TRIAL 4 8.51175 18.49730 5.896 20.977 48.948
TRIAL 5 7.76216 17.17980 5.896 21.114 42.366
TRIAL 6 8.93679 21.56902 7.815 22.623 44.423
MEAN 8.40023 19.08204 6.536 21.671 45.246
STD. DEV. 0.60013 2.26228 1.108 0.913 3.367
EVACUATION
Pressure -40 cm H20
TRIAL 1 9.74162 21.65082 7.130 29.478 109.130
TRIAL 2 8.89566 18.16076 6.855 23.719 57.311
TRIAL 3 9.13011 16.16644 8.089 26.462 40.447
MEAN 9.25580 18.65934 7.358 26.553 68.963
STD. DEV. 0.43676 2.77597 0.648 2.881 35.793
EVACUATION
Pressure -30 cm H20
TRIAL 4 9.03414 19.01250 6.855 26.599 48.536
TRIALS 9.23706 25.47979 7.130 25.639 54.158
TRIAL 6 9.76219 21.14631 7.962 31.398 62.521
MEAN 9.34446 21.87920 7.312 27.879 55.072
STD. DEV. 0.37572 3.29561 0.671 3.086 7.037
34
TABLE 7: DATA FOB ANIMAL 7
Rat weight: 274 Grams
VC MEF25-76 MEF 25 MEF 50 MEF 75
(ML) (ML/SEC) (MUSEC) (ML/SEC) (ML/SEC
EVACUATION
Pressure -40 cm H20
TRIAL 1 8.70608 18.34524 12.614 18.646 15.630
TRIAL 2 8.78048 20.10522 11.242 20.566 70.474
TRIALS 8.83533 22.41738 13.573 21.800 85.693
MEAN 8.77363 20.28928 12.476 20.337 57.266
STD. DEV. 0.06640 2.04230 1.172 1.589 36.852
EVACUATION
Pressure -30 cm H20
TRIAL 4 8.59676 24.20837 13.710 22.348 32.220
TRIALS 8.76443 21.66041 12.476 30.712 38.627
TRIAL 6 8.68036 21.56045 6.993 31.123 39.624
MEAN 8.67719 22.48308 11.060 28.061 36.790
STD. DEV. 0.07889 1.49535 3.576 4.952 3.996
COMPRESSION
Pressure +40 cm H20
TRIAL 1 8.34448 20.11395 12.476 17.824 62.933
TRIAL 2 7.90573 16.86446 10.694 18.372 10.146
TRIAL 3 7.83032 17.87754 11.517 20.453 9.461
MEAN 8.02684 18.28531 11.562 18.883 27.613
STD. DEV. 0.27765 1.66268 0.892 1.387 30.676
COMPRESSION
Pressure +30 cm H20
TRIAL 4 7.68772 19.43145 10.420 21.937 30.301
TRIALS 8.10728 21.19863 11.654 20.017 44.423
TRIALS 7.66030 19.34766 11.928 21.937 30.026
MEAN 7.81843 19.99256 11.334 21.297 34.917
STD. DEV. 0.25052 1.04531 0.803 1.109 8.234
35
TABLE 8: DATA FOR ANIMAL 8
Rat weight: 265 Grams
VC MEF25-76 MEF 25 MEF 50 MEF 76
(ML) (ML/SEC) (ML/SEC) (ML/SEC) (ML/SEC
EVACUATION
Pressure -40 cm H20
TRIAL 1 10.21465 21.01582 8.089 41.681 76.410
TRIAL 2 9.23157 20.25791 5.073 19.332 50.730
TRIAL 3 9.03963 17.22780 6.993 21.2&1 35.648
MEAN 9.49528 19.50061 6.718 27.421 53.929
STD. DEV. 0.63034 2.00438 1.527 12.386 20.073
EVACUATION
Pressure -30 cm H20
TRIAL 4 9.36732 27.13909 11.106 40.310 44.149
TRIALS 9.03277 25.32716 11.654 40.173 40.858
TRIAL 6 9.18633 29.56421 11.928 44.423 44.834
MEAN 9.19547 27.34348 11.562 41.636 43.280
STD. DEV. 0.16746 2.12591 0.419 2.415 2.126
COMPRESSION
Pressure +40 cm H20
TRIAL 1 8.49530 20.01797 6.170 13.848 55.255
TRIAL 2 7.69046 17.61953 7.130 18.372 43.600
TRIAL 3 7.72063 15.96663 6.307 44.971 47.165
MEAN 7.96880 17.83437 6.536 25.730 48.673
STD. DEV. 0.45621 2.04443 0.519 16.816 5.972
COMPRESSION
Pressure +30 cm H20
TRIAL 4 8.27466 22.96603 8.089 47.166 52.787
TRIALS 8.35682 29.41976 10.146 43.600 51.827
TRIAL 6 8.96873 26.49149 8.089 39.076 53.746
MEAN 8.53003 2628909 8.775 43.280 52.787
STD. DEV. 0.37353 3.29661 1.187 4.054 0.960
36
TABLE 9: DATA FOR ANIMAL 9
Rat weight: 266 Grams
VC MEF26-76 MEF 26 MEF 60 MEF7G
(ML) (ML/SEC) (ML/SEC) (ML/SEC) (ML/SEC
EVACUATION
Pressure -40 cm H20
TRIAL 1 11.60906 29.23858 16.690 29.616 73.363
TRIAL 2 10.16266 24.24780 11.928 25.502 60.182
TRIALS 10.83301 28.43496 14.670 32.632 69.779
MEAN 10.86820 27.30711 14.396 29.260 61.106
STD. DEV. 0.72389 2.67974 2.343 3.579 11.642
EVACUATION
Pressure -30 cm H20
TRIAL 4 10.38330 32.99439 12.339 42.778 74.460
TRIALS 11.16976 34.39486 11.791 48.948 58.967
TRIAL 6 11.12642 33.97374 14.944 42.778 68.664
MEAN 10.89316 33.78766 13.026 44.835 67.320
STD. DEV. 0.44208 0.71864 1.685 3.662 7.820
COMPRESSION
Pressure +40 cm H20
TRIAL 1 9.99390 23.38672 13.026 31.260 51.278
TRIAL 2 10.06971 23.80219 12.066 23.719 71.671
TRIALS 9.63742 20.87490 11.106 24.131 39.213
MEAN 9.89701 22.68760 12.066 26.370 64.021
STD. DEV. 0.22721 1.68360 0.960 4.240 16.362
COMPRESSION
Pressure +30 cm H20
TRIAL 4 10.04463 30.46787 16.316 37.430 63.481
TRIALS 10.18174 30.88389 11.380 33.317 64.706
TRIAL 6 10.19967 31.76062 17.001 28.618 61.278
MEAN 10.14198 31.03079 14.899 33.088 66.486
STD. DEV. 0.08478 0.66877 3.067 4.460 6.294
37
In all animals, the mean value of MEF 75 using the evacuation
maneuver a t -40 cm H&0 was higher than compression a t +40 cm H2O or
+30 cm H2O . Also, in six out of nine animals, the MEF 25, MEF 50, and
MEF 75 are higher during evacuation of -40 cm H2O than compression
at +30 cm H2O and +40 cm H2O .
The compression maneuver with +30 cm H2O produced a higher
mean value of MEF 25, MEF 50, and MEF 75 than compression with
+40 cm H2O in seven different animals.
For all nine animals, a paired comparison of the different
methods with respect to MEF 25, MEF 50, and MEF 75 was done using
a t-Test. The probabilities for each animal are listed in Tables 10-18.
H ie higher the probability value is, the more sim ilar the two methods
are in producing like results. The majority of the probabilities are less
than 0.90, which would m ark a significant likeness in the two methods
being compared.
With respect to MEF 25 only, the evacuation maneuver at -40 cm
H2O matched well with the compression maneuver of +40 cm H2O in
only two animals. H ie results for MEF 50 are identical, which means
there is some sim ilarity between evacuation and compression. This
supports the idea th at the two maneuvers differ greatly. H ie evacuation
maneuver with -30 cm H2 O paired better than the compression
m aneuver of +40 cm H2O . Evacuation with -30 cm H2O provided results
sim ilar to those obtained using evacuation with -40 cm H2O in four
animals.
TABLE 10: PAIRED COMPARISON PROBABILITIES
ANIMAL 1
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 26
COMPRESSION +40 CM H20 0.6366
COMPRESSION +30 CM H20 0.1238
EVACUATION -30 CM H20 0.1006
MEF 60
COMPRESSION +40 CM H20 0.1063
COMPRESSION +30 CM H20 0.0875
EVACUATION -30 CM H20 0.5158
MEF 76
COMPRESSION +40 CM H20 0.3869
COMPRESSION +30 CM H20 0.7285
EVACUATION -30 CM H20 0.3494
TABLE 11: PAIRED COMPARISON PROBABILITIES
ANIMAL 2
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 26
COMPRESSION +40 CM H20 0.0171
COMPRESSION +30 CM H20 0.0729
EVACUATION -30 CM H20 0.4689
MEF 60
COMPRESSION +40 CM H20 0.4846
COMPRESSION +30 CM H20 0.9879
EVACUATION -30 CM H20 0.4746
MEF 76
COMPRESSION +40 CM H20 0.6232
COMPRESSION +30 CM H20 0.7016
EVACUATION -30 CM H20 0.6062
TABLE 12: PAIRED COMPARISON PROBABILITIES
ANIMAL 3
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 26
COMPRESSION +40 CM H20 0.9120
COMPRESSION +30 CM H20 0.5136
EVACUATION -30 CM H20 0.6407
MEF 50
COMPRESSION +40 CM H20 0.9954
COMPRESSION +30 CM H20 0.7288
EVACUATION -30 CM H20 0.9872
MEF 75
COMPRESSION +40 CM H20 0.1916
COMPRESSION +30 CM H20 0.0389
EVACUATION -30 CM H20 0.5696
TABLE 13: PAIRED COMPARISON PROBABILITIES
ANIMAL 4
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 25
COMPRESSION +40 CM H20 0.2078
COMPRESSION +30 CM H20 0.6752
EVACUATION -30 CM H20 0.0163
MEF 60
COMPRESSION +40 CM H20 0.1303
COMPRESSION +30 CM H20 0.9235
EVACUATION -30 CM H20 0.4038
MEF 75
COMPRESSION +40 CM H20 0.0605
COMPRESSION +30 CM H20 0.3627
EVACUATION -30 CM H20 0.7469
TABLE 14: PAIRED COMPARISON PROBABILITIES
ANIMALS
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 25
COMPRESSION +40 CM H20 0.3166
COMPRESSION +30 CM H20 0.3291
EVACUATION -30 CM H20 0.0295
MEF S O
COMPRESSION +40 CM H20 0.1635
COMPRESSION +30 CM H20 0.1588
EVACUATION -30 CM H20 0.0230
MEF 75
COMPRESSION +40 CM H20 0.3300
COMPRESSION +30 CM H20 0.0040
EVACUATION -30 CM H20 0.5330
TABLE 15: PAIRED COMPARISON PROBABILITIES
ANIMAL 6
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 25
COMPRESSION +40 CM H20 0.0340
COMPRESSION +30 CM H20 0.1023
EVACUATION -30 CM H20 0.8082
MEF 50
COMPRESSION +40 CM H20 0.0417
COMPRESSION +30 CM H20 0.1090
EVACUATION -30 CM H20 0.6191
MEF 76
COMPRESSION +40 CM H20 0.3681
COMPRESSION +30 CM H20 0.3389
EVACUATION -30 CM H20 0.6274
TABLE 16: PAIRED COMPARISON PROBABILITIES
ANIMAL 7
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 25
COMPRESSION +40 CM H20 0.2575
COMPRESSION +30 CM H20 0.2866
EVACUATION -30 CM H20 0.6383
MEF 50
COMPRESSION +40 CM H20 0.0679
COMPRESSION +30 CM H20 0.5022
EVACUATION -30 CM H20 0.0624
MEF 75
COMPRESSION +40 CM H20 0.5233
COMPRESSION +30 CM H20 0.3874
EVACUATION -30 CM H20 0.3934
TABLE 17: PAIRED COMPARISON PROBABILITIES
ANIMALS
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 25
COMPRESSION +40 CM H20 0.8907
COMPRESSION +30 CM H20 0.3137
EVACUATION -30 CM H20 0.0424
MEF 50
COMPRESSION +40 CM H20 0.9199
COMPRESSION +30 CM H20 0.1025
EVACUATION -30 CM H20 0.2108
MEF 75
COMPRESSION +40 CM H20 0.6251
COMPRESSION +30 CM H20 0.9317
EVACUATION -30 CM H20 0.4582
TABLE 18: PAIRED COMPARISON PROBABILITIES
ANIMALS
PAIRED t-TEST PROBABILITY
EVACUATION -40 CM H20
MEF 26
COMPRESSION +40 CM H20 0.1995
COMPRESSION +30 CM H20 0.6365
EVACUATION -30 CM H20 0.4427
MEF 50
COMPRESSION +40 CM H20 0.4356
COMPRESSION +30 CM H20 0.4362
EVACUATION-30 CM H20 0.0607
MEF 75
COMPRESSION +40 CM H20 0.6662
COMPRESSION +30 CM H20 0.4202
EVACUATION -30 CM H20 0.1358
43
The evacuation maneuver with -30 cm H20 produced higher MEF
25, MEF 50, and MEF 75 in four animalB th at the compression
maneuver with -1-30 cm H20. So even with a smaller pressure, the
evacuation maneuver still produced better results than the compression
maneuver.
V. Discussion
Evacuation with a pressure of -40 cm H20 provided the best
results with respect to vital capacity and maximal expiratory flow.
Evacuation a t -40 cm H2O produced significantly higher vital capacities
than the compression maneuver at either +40 or +30 cm H2O , but
evacuation at -40 cm H2O did not produce results significantly higher
th an evacuation a t -30 cm H20. The evacuation maneuver at -40 cm
Hj20 also produced significantly higher flowB than the compression
maneuver.
The flow is the most im portant aspect in relation to assisted
cough. A cough can be generated a t a wide range of lung volumes,
therefore, it is im portant to look at a wide range of flows. MEF 50 and
MEF 75 are best suited for providing flows large enough for cough
assist, but this in no way excludes MEF 25 from being used for cough
assist. The m aneuver th at generates the higher MEFs is obviously more
beneficial to utilize with cough assist. For MEF 25, MEF 50, and MEF
75 there are clear differences between compression and evacuation
maneuvers.
44
Although for MEF 25, MEF 50, and MEF 75, there were no
maneuvers th at produced results th at were significantly similar to the
evacuation maneuver with -40 cm H20, some of the probability values
were not very different from 0.90. For example, the MEF 25 for animal
6 has a probability of 0.8082 for evacuation a t -40 cm H20 and
evacuation at -30 cm H2O . This probability value shows th at although
the two maneuvers are not identical, they can be considered somewhat
similar.
The evacuation maneuver with -40 cm H2O provided vital
capacities and maximal expiratory flows th at were greater than the
other maneuvers. However there are areas where evacuation with -40
cm H2O was not the best case. In several trials, for MEF 25 and MEF
50, the compression maneuver of +40 cm H2O provided comparable
results.
Compression with +30 cm H2O is a better maneuver to use with
assisted cough than a compression maneuver with +40 cm H20.
Compression with +30 cm H*j0 consistently provides higher MEF25s,
MEF50&, and MEF75s. In seven out of nine animals, the MEFs
achieved with compression of +30 cm H2O were greater than those from
compression of +40 cm H2O . However, the MEFs achieved with the
compression maneuver of +30 cm H2O are not greater than evacuation of
-40 cm H20.
The fact that there are probability values th at indicate a certain
sim ilarity between evacuation at -40 cm H2O and another maneuver,
may mean th at there is error in the design of the test chamber. It is
45
im portant th a t there is no air leakage from the test chamber itself or the
tubing connecting to the ports. There may have been some leakage at
those points. The tim e it took to complete the trials on each animal did
vary. It may be appropriate to try to keep the testing period fixed.
Another area th at may be an area of improvement deals with the
pump and the air reservoir th at is being used for the test chamber. It
may be necessary to use a larger reservoir to provide a better
instantaneous pressure to the test chamber. If the positive or negative
pressure pump was used without the reservoir, the time delay for the
test chamber to actually reach the desired pressured is too large.
From these experiments, it is possible to see th a t expiratory flows
can be artificially generated by deflating the expanded lungs. In all of
these experiments, the animal was paralyzed and had no ability to add
to the expiration effort. However, with a hum an with a deficient ability
to cough, it may be possible to generate higher flows if the hum an could
generate an effort in conjunction with the maneuver being used for
cough assist.
Trials were not done with the anim al's lungs inflated to a
pressure greater than +30 cm H2O . It was decided th at a larger
pressure may be too overpowering for the animals. With these types of
maneuvers, deflation of the lungs is the process th a t is used to generate
the expiratory flows. It is im portant to inflate the anim al's lungB to as
large a pressure as possible.
This exact experimental set up may have several drawbacks if
used on humans. It may be difficult to develop a chamber th a t all sizes
46
of people can fit in, and due to the health of the patient, being enclosed
in a test chamber may not be beneficial to the patient. More testing
would be necessary to try to develop a maneuver specifically for
humans.
TTie ability of all these m aneuvers to do several repetitions is
convenient for use on humans. Repetitive maneuvers can easily be done
on a single subject. However, the maneuvers tested well from subject to
subject only for certain param eters, which means there is room for
improvement in experimental design.
VI. ConcliiBiona
From these experiments, it is shown that it is possible to create
expiratory flows by deflating the lungB through compression or
evacuation. For the purposes of assisted cough, evacuation is the better
maneuver than compression. More testing will be necessary to
determine if -40 cm H2O is the best pressure to use for evacuation.
Additional testing will also be necessary to determine if it is possible to
inflate the animal's lungs to a pressure greater than +30 cm HgO and
get good results.
Notes
47
1 Jan-Anders Karlsson, Guiseppe Sant'Ambrogio, and John
Widdicombe, "Afferent Neural Pathways in Cough and Reflex
Bronchoconstriction." Journal of Applied Phvaiologv 65 (19S8): 1007.
2 Marc Estenne, and Andr6 De Troyer, "Cough in Tetraplegic
Subjects: An Active Process," Annals of Internal Medicine 112 (1990):
22.
3 Nell A. Kirby, Michel J. Barnerias, and A rthur A. Siebens, "An
Evaluation of Assisted Cough in Quadriparetic Patients," Archives of
Physical Medicine and Rehabilitation 47 (1966): 705.
4 Beat and Tavlor's Physiological Basis of Medical Practice, ed.
John B. West, 11th ed. (Baltimore: Williams and Wilkins, 1985) 1238.
5 Ichiro Kobayashi, Tetsuri Kondo, Hideo Suzuki, Yasuyo Ohta,
and Heyime Yamabayashi, "Expiratory Activity of the Inspiratory
Muscles During Cough," Japanese Journal of Physiology 42 (1992): 906.
6 Handbook of Phvaiologv: Respiration, sec. ed. Wallace O. Fenn
and Herm ann Rahn, vol. 1, (Washington D.C.: American Physiological
Society, 1964) 380.
7 Best and Tavlor's 586-7.
3 Marc Estenne and Andr6 De Troyer, 'The Effects of Tetraplegia
on Chest Wall Statics," American Review of Respiratory Disease 134
(1986): 121.
9 Estenne and De Troyer, Annals of Internal Medicine 22.
48
Andr6 De Troyer, Marc Estenne, and Andr6 Heilpom,
"Mechanism of Active Expiration in Tetraplegic Subjects," The New
England Journal of Medicine 314 (1986): 743.
David E. Leith, "The Development of Cough," American
Review of Respiratory Disease 131 (1985): S39.
12 Leith S39.
13 Leith S39.
1^ Richard S. Irwin, M ark J. Rosen, and Sidney S. Braman,
"Cough. A Comprehensive Review," Archives of Internal Medicine 137
(1977): 1187.
15 Irwin 1187-88.
1® Leith S40.
17 Leith S39.
13 Estenne and De Troyer, The New England Journal of Medicine
744.
19 Respiratory Defense Mechanisms, ed. Joseph D. Brain, Donald
F. Proctor, and Lynne M. Reid, vol. 5, pt. 1 (New York: Marcel Dekker
Inc., 1977) 583.
20 Kirby 707.
21 Matlab. vers. 4.2a, computer software, M ath Works Inc., 1984.
Works Cited
49
Best and Tavlor's Physiological Basis of Medical Practice. Ed. John B.
West, M.D., Ph.D. 11th ed. Baltimore: Williams and Wilkins,
1985.
Bach, John R. "Mechanical Insufflation-ExsufTlation. Comparison of
Peak Expiratory Flows with Manually Assisted and Unassisted
Coughing Techniques." Chest 104 (1993): 1553-62.
De Troyer, Andr6 , and Marc Estenne. "Chest Wall Motion in Paraplegic
Subjects." American Review of Respiratory Disease 141 (1990):
332-36.
De Troyer, An dr Marc Estenne, and Andrd Heilpom. "Mechanism of
Active Expiration in Tetraplegic Subjects." The New England
Journal of Medicine 314 (1986): 740-44.
—, "The Expiratory Muscles in Tetraplegia." Paraplegia 29 (1991): 359-
63.
De Troyer, An dr and Andr6 Heilpom. "Respiratory Mechanics in
Quadriplegia. The Respiratory Function of the Intercostal
Muscles." American Review of Respiratory Disease 122 (1980):
591-600.
Estenne, Marc, and Andr6 De Troyer. "Cough in Tetraplegic Subjects:
An Active Process." Annals of Internal Medicine 112 (1990): 22-
28.
—, "Hie Effects of Tetraplegia on Chest Wall Statics." American Review
of Respiratory Disease 134 (1986): 121-124.
Handbook of Phvaiologv: Respiration. Sec. ed. Wallace O. Fenn and
Hermann Rahn. 2 vols. Washington D.C.: American
Physiological Society, 1964-5.
t t *
50
Irwin, Richard S., Mark J. Rosen, and Sidney S. Braman. "Cough. A
Comprehensive Review." Archives of Internal Medicine 127
(1977): 1186-91.
Karls son, Jan-Anders, Guiseppe Sant'Ambrogio, and John Widdicombe.
"Afferent Neural Pathways in Cough and Reflex
Bronchoconstriction.” Journal of Applied Phvaiologv 65 (1988):
1007-23.
Kirby, Nell A., Michel J. Bam erias, and A rthur A. Siebens. "An
Evaluation of Assisted Cough in Quadriparetic Patients."
Archives of Physical Medicine and Rehabilitation 47 (1966): 705-
10.
Kobayashi, Ichiro, Tetsuri Kondo, Hideo Suzuki, Yasuyo Ohta, and
Hajime Yamabayashi. "Expiratory Activity of the Inspiratory
Muscles During Cough." Japanese Journal of Physiology 42
(1992): 905-16.
Leith, David S. "The Development of Cough." American Review of
Respiratory Disease 131: Suppl. S39-S42.
Matlah. Vers. 4.2a. Computer software. Math Works Inc., 1984.
Respiratory Defense Mechanisms. Ed. Joseph D. Brain, Donald F.
Proctor, and Lynne M. Reid. Vol. 5. Pt. 1, New York: Marcel
Dekker Inc., 1977. 11 vols
Scherer, P.W., and L. Burtz. "Fluid Mechanical Experiments Relevant
to Coughing." Journal of Biomechanics 11 (1978): 183-87.
Staub, Norman C. Basic Respiratory Physiology. New York: Churchill
Livingstone, 1991.
Widdicombe, J.G. "Mechanism of Cough and its Regulation." European
Journal of Respiratory Disease 61 (1980): Suppl. 11-15.
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Asset Metadata
Creator
Young, Marlene Sue
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Core Title
Comparison of evacuation and compression for cough assist
School
Graduate School
Degree
Master of Science
Degree Program
Biomedical Engineering
Degree Conferral Date
1995-05
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), D'Argenio, David B. (
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