STOPPING THE PAUSE
(median 22.8%; IQR 12.6% to 36.5%; range
1.0% to 93.9%). 6
Supraglottic airway devices outperformed
endotracheal intubation when interruptions to chest compressions were studied
using manikins. In these studies, insertion
of supraglottic airway devices interrupted
chest compressions on average for 8. 4 to 20.0
seconds depending upon which device was
being used. 7, 8
Questions still remain whether advanced
airway management in the out-of-hospital setting improves patient survival with
some studies reporting contrasting results. A
nationwide registry in Japan found no survival
benefit from advanced airway management
compared with bag-valve mask ventilation.
And, the Resuscitation Outcome Consortium
(ROC) observed higher survival in patients
who didn’t receive advanced airway management. However, in those patients that
did undergo advanced airway management,
endotracheal intubation provided for a better
outcome than supraglottic airway devices. 9
The second half of the resuscitation symposium
focused on the b-card itself. B-card is a noninvasive ventilation system providing continuous oxygen delivery during CPR. The device
ensures dynamic alveolar ventilation without
the need to interrupt chest compressions.
Connected to an oxygen source delivering
a flow rate of 15 L per minute, the b-card
generates a virtual valve. This valve creates an
initial static pressure in the airways of approximately 4 to 5 cmH2O. This acts as the “heart”
of the device, optimizing the pressure created
during chest compression and decompression
phases of CPR. (See Figure 1.)
Each chest compression has a dual action:
Helping to expel the air contained in the alveoli and simultaneously pumping blood from
the chest cavity into the general circulation.
During the compression phase, the pressure
within the airways is increased to 8 cmH2O.
Animal and clinical studies suggest that prolonged CPR may impair lung function and
promote severe atelectasis. 10, 11
This slight increase in pressure may protect the lower air ways during CPR according
to Vygon. In the decompression phase, the
virtual valve creates a negative intrathoracic
pressure and a pressure of - 1 cmH2O in the
airway, optimizing gas exchange in the alveoli.
At the same time, the negative intrathoracic
pressure improves venous return to the heart.
This increases the blood flow ejected from
the heart during the next chest compression.
So, b-card has been designed to perform the
dual effect of optimizing hemodynamics and
ventilation when chest compressions are being
The b-card is designed with two distinctly different ends. The end that’s open to
the atmosphere has a series of elevated ridges
so that it can’t be easily connected to an airway circuit.
The other end of the b-card can be used
with either a 15 mm or 22 mm airway connector. Because of this design, it can be used
with a facemask, a supraglottic airway device,
or an endotracheal tube, allowing for use by
various levels of providers.
According to Vygon, b-card simplifies the
management of cardiac arrest. As ventilation
is generated by chest compression and decompression, the need for a provider ventilating
the patient has been removed.
However, there’s still the need for a provider
to apply a good mask seal if the b-card is used
with a facemask rather than with a supraglottic
airway device or endotracheal tube. The b-card
is also designed to be used with both manual and mechanical CPR. Historically, most
of the studies have used the Physio-Control
LUCAS chest compression system with the
Boussignac CPR system or the b-card.
An additional benefit of the b-card, as it’s
designed, is minimal risk of gastric inflation
and aspiration since it’s an open system that
uses continuous oxygen insufflation. With
b-card, ventilation is based on negative intrathoracic pressure unlike positive airway pressure that’s used during CPR for ventilation.
The risk of aspiration during CPR is small
but not insignificant and has been reported
to be 0.96%. 12
When the b-card was compared to standard CPR with intermittent positive pressure
Figure 1: Virtual valve created by the b-card