Normocapnea: a
bag-valve device versus the Oxylator® FR-300
MPHJ Schors RN1, GJ Noordergraaf
MD1, BPA Kramer1*, PJM van Dun RN1,
T van Egmond MD2
1Dept.
of Anesthesiology *(Lt1 Min. of Defense) and 2Dept.
of Surgery, St. Elisabeth Hospital, Tilburg (NL) |
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INTRODUCTION
Ventilating patients with a bag-valve (BV) device on mask or
endotracheal tube has been demonstrated to be haphazard even
in experienced hands. Severe adverse outcomes have been described.
The Oxylator® FR-300 (a first responder resuscitator) has
been introduced to simplify and improve outcome during emergency
ventilation.
AIM
OF THIS STUDY
This study was designed to evaluate potential improvement
in ventilation with the Oxylator® FR-300, with regard
to establishing and maintaining normocapnea (ETCO2)
compared with the BV device. |
PATIENTS AND METHODS
Firemen were recruited and given three hours of theory and practical
training on manikins. They were told to achieve and maintain
a free airway and normocapnea (AHA guidelines), and distracted.
Patients scheduled for elective general anesthesia were recruited.
After induction of hypnosis (H) a bag-valve followed by the
Oxylator® in manual (Oxy-m) and automatic (Oxy-a) mode were
used to ventilate with mask. These three steps were repeated
after addition of muscle relaxation (HC), first with the mask
and again after placement of the endotracheal tube (ETT).
The fireman ventilating was blinded for the Datex-Ohmeda M-COVX
spirometer monitoring and for the flow (24 L/min or 30 L/min)
of the Oxylator®. The working pressure was 20 cmH2O
in all cases. Per protocol, ventilation was cut off if the inspiration
time was excessive. ETCO2 was kept 
18 mmHg. Time was allowed for return to normocapnea between
steps as needed. |
|
Data are reported
as mean±SD. Statistics were performed with SPSS (v9)
using repeated-measures analysis of variance.
RESULTS
104 patients completed the protocol. The mean age was 49±17
years old (range 18-91). Weight varied from 48 to 132 kg (76±15.1
kg). 47% was male.
ETCO2 as defined by normocapnea (30-45 mmHg) is shown
below. Note that in the Oxy-24 and -30 categories 47 and 57
patients are represented respectively, while all patients were
ventilated with the bag-valve device. There is a strong improvement
in the Oxylator® groups (p<0.01).
ETCO2 data were used only when inspiratory and expiratory
volumes approximated each other. The ETCO2 curve
was visually monitored. |
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DISCUSSION
The Oxylator® FR-300 has been suggested to be a useful resuscitator/ventilator,
improving efficiency. Bag-valve devices are notoriously difficult
to use even in professional hands.1
Little is known about the optimal relation between working pressure
and flow in facilitating a patent airway. As early as the 1970’s
flow reductions have been advocated.2
We observed that, under carefully controlled clinical 'lab'
conditions, using the FR-300, 24 L/min and 30 L/min and both
20 cmH2O, extremes in tidal volumes were avoided. No more than
a tendency towards hyperventilation was noted with the 30 L/min
device. This collaborates earlier work from our clinic.3 Achieving
the desired 2 second inspiration time seems to go well without
attention.
Use of the Oxylator® in manual and automatic mode seems
possible for a long(er) period. In our study 35 minutes was
the longest period of uninterrupted Oxylator® ventilation
in automatic mode and with monitoring.
CONCLUSION
We found that the Oxylator® FR-300 has a high efficacy
and efficiency when used by first responders to achieve
and maintain normocapnea under clinical and controlled
conditions (p<0.01).
Minimal training seems sufficient for safe use by first
responders. A wide weight range of patients can be treated
adequately. |
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