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| Internal
study, 1995 |
Studies of the Oxylator® EM-100 Resuscitation System
CPR Medical Devices, Inc.
161 Don Park Road, Markham, Ontario, Canada
Introduction
| Protocol | Methods
| Results | Discussion
| Conclusions
|
Introduction
The EM-100 Oxylator® is a compact, hand-held resuscitator/inhalator
intended for use by emergency response personnel whenever a
patient's ventilatory ability has been compromised. The EM-100
may be used as a resuscitator or, for a patient who is breathing
spontaneously but is in need of supplemental oxygen enrichment,
as an inhalator. It is a stand-alone unit, requires a source
of appropriately-regulated oxygen to function (pressure of 50
psi), and offers the care-giver great flexibility in responding
to the patient's needs.
The Oxylator® contains a valve that delivers compressed
100% oxygen at a maximum flow rate of 40 litres per minute from
a pressure source of 50 psi. The system also permits the adjustment
of it's maximum inspiratory pressures from a value of 25 cmH2O
to 50 cmH2O.
The system has four different operation modes:
| 1. |
Manual mode |
| 2. |
Manual mode with the addition of
a baseline pressure (PEEP) |
| 3. |
Automatic cycling mode with a baseline
pressure (PEEP) |
| 4. |
Inhalation mode which provides oxygen
enriched air |
The third mode, automatic cycling, was used in our investigations.
This mode was used in order to study the efficacy of the EM-100
in delivering adequate ventilation simultaneously with continuous
chest compressions.
The EM-100 Oxylator® system meets all of the standard recommendations
and guidelines for oxygen powered resuscitation devices published
in JAMA 268, 2199-2241, 1992.
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Protocol
Investigation 1:
using the Oxylator® EM-100 resuscitation device (automatic
cycling mode) and a simulated human mannequin.
A modified 'foam-filled' human simulated mannequin (Adam) was
used in these experiments. A cavity was formed inside of the
mannequin by removing some of the underlying foam material.
The cavity was later filled with 2 (2 litres) 'Penlon' anaesthesia
test lungs. Their expansion limit was controlled by covering
the open end cavity with a thick card board.
The mannequin's endotraceal tube was connected to the respirometer
first and then to the Oxylator® EM-100. The mannequin is
equipped with a one way valve that is capable of creating an
airway blockage, if the head of the mannequin is not appropriately
tilted. The Oxylator® was set at the automatic cycling mode,
at a pressure of 50 cmH2O. The EM-100 gives both
a visual an audible indication of such an obstruction by 'clicking'
rapidly.
Investigation 2: using the Oxylator®
EM-100 resuscitation device (automatic cycling mode), a simulated
human mannequin and a Thumper™ (cardiopulmonary resuscitator
system) set at 5:1 ratio (5 compressions to 1 ventilation cycle).
Same as for Investigation 1, but with the addition of the Thumper™.
The Thumper™ is a cardiopulmonary resuscitator system
that is placed on the patient's sternum and compressions occur
at a rate of 80 compressions per minute. Between each 5 continuous
chest compressions, the Thumper™ stops and delivers 1
complete cycle of ventilation. The Thumper™ is also capable
of delivering continuous chest compressions with no interruptions.
The Thumper™ was also set to deliver 80 chest compressions
per minute, at a vertical displacement of the chest, of about
1.5-2 inches. (The contact surface area of the Thumper™
pad, was 3 cm x 2 cm.)
Investigation 3: using
the Oxylator® EM-100 resuscitation device (automatic cycling
mode), a simulated human mannequin and a Thumper™ (cardiopulmonary
resuscitator system) in continuous chest compressions mode.
Same conditions as in Investigation 2, except in this case the
Thumper™ was allowed to deliver continuous chest compressions
at a rate of 80 compressions per minute in conjunction with
the automatic cycling of the Oxylator®.
The three investigations were designed to determine the efficacy
of the Oxylator® EM-100 in delivering adequate oxygenation
in cardiopulmonary resuscitation attempts, in three different
settings:
| 1. |
By itself |
| 2. |
With the Thumper™ set at 5:1
ratio (five chest compressions to one breath) |
| 3. |
With the Thumper™ set at continuous
chest compression mode |
In evaluating the Oxylator's functional characteristics, the
following parameters were measured and recorded:
| 1. |
Rate (breaths per minute) |
| 2. |
Vt tidal volume (litres) |
| 3. |
Vmin minute volume (litres) |
Also, in order to obtain reliable and consistent results, each
one of the three investigations was performed five separate
times, each time using a different Oxylator® EM-100. Equipment
used in these investigations were:
| • |
Five Oxylators® (EM-100 resuscitation
device), serial numbers 019, 080, 228, 246, 251, manufactured
by CPR Medical Devices, Inc., Canada |
| • |
The Thumper™ (cardiopulmonary
resuscitator system), model number 1004, serial number
0118, manufactured by Michigan Instruments, U.S.A. |
| • |
Simulated human mannequin (Adam),
foam-filled and containing 2 (2 litres) 'penlon' anesthesia
test lungs, manufactured by Simulaids Woodstock, U.S.A. |
| • |
Wright respirometer, serial number
H 155, manufactured by Haloscale Infanta, England |
| • |
Stop watch, manufactured by Bulova,
Switzerland |
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Methods
The tidal volumes and the minute volumes generated by the Oxylator®
(EM-100 resuscitation device) and delivered into the 2 (2 litres)
test lungs inside the mannequin, were observed and recorded
with the Wright respirometer; a stop watch was used, in order
to count the respiratory rate (breaths per minute).
Each one of the five EM-100 Oxylators® were allowed to cycle
automatically in the 3 different investigations.
In each case the data was collected and entered into the same
spreadsheet.
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Results
By comparing the results of each investigation, it was noticed
that all of the five Oxylators® (EM-100) were delivering
approximately the same amounts of tidal volumes and minute volumes
into the test lungs.
In the first set of investigations, only the efficacy of the
Oxylator® EM-100 was being tested. The Oxylator® was
capable of delivering tidal volumes between (0.78-0.89 litres)
and minute volumes between (12.2-13.5 litres). Both were within
the acceptable range of what is considered to be adequate ventilation.
In the second set of investigations, the Thumper™ was
activated, in order to simulate a real cardiopulmonary resuscitation
attempt. The standard in such attempts is five 5 chest compressions
followed by a two second pause for ventilation.
The Thumper™ was preset to deliver chest compressions
at a rate of 80 compressions per minute, with a 5:1 ratio (5
compressions to each breath).
At lower inspiratory pressures (25 cmH2O) the Oxylator®
cycled in synchrony with each chest compression cycle, delivering
100% oxygen to the patient during each decompression phase.
At higher inspiratory pressures (45-50 cmH2O), the
Oxylator® cycled asynchronously with the delivered chest
compressions.
Two complete chest compression cycles were needed before the
lung pressure reached the preselected pressure of 50 cmH2O,
which triggered the Oxylator® to switch to the expiratory
phase.
Complete exhalation was observed during two subsequent chest
compression cycles before a new cycle of inspiration started
(see
plotsOxylator®
EM-100 in 'automatic cycling' mode with baseline pressure
set to 50 cmH2O. The three plots show
the Oxylator® EM-100 in 'automatic' mode with the pressure
set between 40 and 42 cmH 2O. The top plot is
without chest compressions. The middle plot is with chest
compressions for two-man cpr according to the JAMA
guidelines (one full inspiration-to-five compressions). The
Oxylator® EM-100 synchronizes automatically with every
chest compression; the '5-to-1' method can be done safely
in 'automatic' mode. The bottom plot is with continuous chest
compressions. The three plots represent the same three actions
as in 25
cmH2O
Oxylator®
EM-100 in 'automatic cycling' mode with baseline pressure
set to 25 cmH2O. The three plots show
the Oxylator® EM-100 in 'automatic'
mode with the pressure set at 25 cmH2O. The top
plot is without chest compressions. The middle plot is with
chest compressions for two-man cpr according to the JAMA
guidelines (one full inspiration-to-five compressions).
The Oxylator® EM-100 synchronizes automatically
with every chest compression. The bottom plot is with continuous
chest compressions. Of note: The pressure setting selected
is never exceeded. The tidal volume is too low to be meaningful.
Our analysis indicates that continuous chest compressions
should not be performed with a pressure setting of 25 cmH2O.
at the higher setting. However, the results are vastly different.
Tidal volume in the continuous chest compression is now adequate
to ventilate a non-breathing patient. To be sure that proper
CO 2 removal occurs, clinical studies (blood gases
etc.) must be done.
). The Oxylator®, was capable of delivering tidal volumes
between (0.65-0.75 litres)and minute volumes between (13.6-15.2
litres) at an approximate rate of 19 breaths per minute.
In the third set of investigation, the Thumper™ was set
to deliver chest compressions continuously. The Oxylator®
was capable of delivering tidal volumes between (0.69-0.77 litres)
and minute volumes between (13.9-15.5 litres) at a rate of approximately
22 breaths per minute.
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Discussion
The following points were observed:
| 1. |
Adequate tidal and minute volumes
were being delivered into the lungs of the mannequin during
continuous chest compressions, approximate of 730 mls
per breath and 14.7 litres per minute. hence stopping
chest compressions for the delivery of a breath may not
be necessary. |
| 2. |
The EM-100 set
at lower inspiratory pressures
Oxylator® EM-100 in 'automatic cycling'
mode with baseline pressure set to 25 cmH2O. The
three plots show the Oxylator® EM-100 in 'automatic'
mode with the pressure set at 25 cmH2O. The top plot is
without chest compressions. The middle plot is with chest compressions
for two-man cpr according to the JAMA guidelines (one full
inspiration-to-five compressions). The Oxylator®
EM-100 synchronizes automatically with every chest compression. The
bottom plot is with continuous chest compressions. Of note: The pressure
setting selected is never exceeded. The tidal volume is too low to
be meaningful. Our analysis indicates that continuous chest compressions
should not be performed with a pressure setting of 25 cmH2O.
(25 cmH2O) was only capable of delivering ventilation
between chest compressions (during the decompression phase),
but when the Oxylator® was set
at higher inspiratory pressures
Oxylator®
EM-100 in 'automatic cycling' mode with baseline pressure
set to 50 cmH2O. The three plots
show the Oxylator® EM-100 in 'automatic' mode with
the pressure set between 40 and 42 cmH 2O.
The top plot is
without chest compressions. The middle plot is with
chest compressions for two-man cpr according to the
JAMA guidelines (one full inspiration-to-five
compressions). The Oxylator® EM-100 synchronizes
automatically with every chest compression; the '5-to-1'
method can be done safely in 'automatic' mode. The bottom
plot is with continuous chest compressions. The three
plots represent the same three actions as in 25
cmH2O
Oxylator®
EM-100 in 'automatic cycling' mode with baseline pressure
set to 25 cmH2O. The three plots
show the Oxylator® EM-100 in
'automatic' mode with the pressure set at 25 cmH2O.
The top plot is without chest compressions. The middle
plot is with chest compressions for two-man cpr according
to the JAMA guidelines (one full inspiration-to-five
compressions). The Oxylator®
EM-100 synchronizes automatically with every chest
compression. The bottom plot is with continuous chest
compressions. Of note: The pressure setting selected
is never exceeded. The tidal volume is too low to
be meaningful. Our analysis indicates that continuous
chest compressions should not be performed with a
pressure setting of 25 cmH2O.
at the higher setting. However, the results are vastly
different. Tidal volume in the continuous chest compression
is now adequate to ventilate a non-breathing patient.
To be sure that proper CO 2 removal occurs,
clinical studies (blood gases etc.) must be done.
(45-50 cmH2O), the system allowed for oxygen delivery
into the lungs during, and between chest compressions. |
| 3. |
When using the Oxylator®, the
preset maximum pressure of 45-50 cmH2O was
not reached during the first chest compression applied,
but was built up over a period of two complete chest compression
cycles. once the pressure reached the preselected value,
the system immediately switched to the passive exhalation
mode, which took the next two chest compressions to complete. |
| 4. |
A new inspiratory phase was initiated
only when exhalation was completed. although continuous
chest compressions were being applied to the mannequin,
exhalation of the lungs was not impaired. |
| 5. |
Unlike pressure cycled resuscitators
that switch immediately to the expiratory mode once a
chest compression is applied, the Oxylator® allows
for ventilation to occur simultaneously during chest compressions.
This is due to the EM-100 ability to be set at higher
pressure limits. |
| 6. |
These results were obtained by using
a Thumper™, which was delivering a specific and
consistent amount of force, on the sternum of the mannequin
(vertical displacement of 1.5-2.0 inches). |
| 7. |
Although the frequency and sequence
of delivery of chest compressions (5:1 or continuous)
varied between the second and third investigations, the
cycling of the EM-100 and the Thumper™ were independent
of each other. The application of compressions during
the expiratory phase assisted in exhalation, thereby reducing
the expiratory time, i.e. allowing the baseline pressure
to be reached sooner, resulting in an increased ventilatory
frequency. |
| 8. |
Minute volumes delivered to the
lungs increased (14.8%) by using the Thumper™ at
a preset ratio of 5:1 and they increased even more, (18.1%),
when the Thumper™ was used to deliver continuous
chest compressions. |
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Conclusions
From the above experiments that were conducted with specific
equipment and under controlled conditions, it was observed that
there was no need to stop chest compressions in order to deliver
adequate ventilation, when using the EM-100.
This system is capable of providing adequate ventilatory volumes
even when the patient has poor lung compliance, which is often
the case during a cardiac arrest. This is possible due to the
Oxylator's patented feature, which allows the user to increase
the maximum inspiratory pressure limit.
The EM-100 Oxylator®, with it's functional characteristics,
was capable of delivering adequate tidal and minute volumes
during continuous chest compressions (average of 730 mls per
breath and 14.7 litres per minute were observed). Delivered
minute volumes were increased when chest compressions were applied
— 14%, on average, when 5:1 ratio was maintained and 18%,
on average, when continuous compressions were applied. This
could potentially increase both blood circulation and ventilation,
and therefore, may improve the outcome of cardiopulmonary resuscitation.
Due to the limitations of these experiments in simulating real-life
situations, future clinical studies are needed to verify and
compare these findings in human subjects.
The use of the Oxylator ® EM-100 could be a revolutionary
step in improving the outcome of cpr.
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