of arterial circulation.
In addition, other technologies are currently in
development currently as well, such as the TandemLife.
19 TandemLife is an alternative extracorporeal
pump that uses the femoral artery for access to the
arterial circulation. This was developed for such
true emergencies such as cardiac arrest, where a
trans-septal approach isn’t feasible.
Each require large bore venous and arterial access,
typically via the femoral vessels, though some have
reported success via the axillary route.
The venous (withdrawal port) generally requires
placement at the right atrial-inferior vena-caval
junction, in order to ensure adequate volume to
avoid collapse of the venous vessel from the suction
action of withdrawal. Typically, a 22–25 F catheter
is required. The arterial catheter is typically smaller,
usually 15–17 F, and can be positioned in the iliac
system for blood infusion.
The hope for such an invasive therapy as extracorporeal life support (ECLS) is that a reversible
cause for the refractory arrest can be identified
and corrected. Emergent cardiac catheterization
and coronary angiography are the mainstays of
this search/approach for remediable conditions.
An acute coronary issue is the easiest to correct of
the reversible conditions, and usually responds well
to primary percutaneous intervention and stenting.
Other critical cardiac conditions that can lead to
refractory cardiac arrest detectable at catheterization include significant cardiomyopathies, aortic
stenosis and myocardial rupture. Finding no coronary issues has been associated with a decrease
in favorable outcomes.
A study in Japan repeatedly shows the importance of simultaneously instituting therapeutic
hypothermia when beginning ECPR. Their best
results are seen when ECPR in begun within 55
arrest, which makes evaluating different therapeutic approaches difficult.
Candidates for ECPR
A major decision point in successfully applying
this new paradigm is determining who should be
included as candidates for this new, aggressive and
Realistically, not all patients will respond well to
extracorporeal CPR (ECPR), so choosing the optimal candidates may greatly influence the success of
such a program, particularly in the early period of
introducing this change in the EMS protocol. Table
2 summarizes clinical features known to negatively
affect outcome from cardiac arrest.
18 Such factors
suggest that the ideal candidate for early transport
from the field with ongoing CPR to an ECPR center should optimally have the following features:
• Younger age;
• Few co-morbid conditions;
• Witnessed v fib cardiac arrest;
• Immediate bystander CPR; and
• Likely cardiac etiology of the arrest.
The specifics regarding how old is too old, or
how long before bystander CPR is begun is too
long, aren’t yet clear, but certainly deserve careful
Providing chest compressions during transport
of refractory cardiac arrest patients is critical to
the success of an ECPR program. Manual chest
compressions in a moving ambulance have been
shown to be both difficult to perform and potentially unsafe for the rescuer.
One report showed that more than 70% of manual
chest compression were too shallow (< 2 inches).
The other published report using a recording manikin in a moving ambulance, found that attempted
manual chest compressions resulted in poor quality CPR and a decrease in CPR fraction. Changing
to mechanical chest compressions improved the
rate, CPR fraction and the depth of compressions.
If mechanical CPR is either not available or not
feasible (e.g., a very large patient won’t fit in the
device), then perhaps a “load and go” strategy may
not be the best option.
Systemic Circulatory Support
Extracorporeal circulation can be provided through
a number of mechanical devices, including extracorporeal membrane oxygenation (ECMO),
percutaneous cardiopulmonary bypass, and
TandemHeart. TandemHeart is an extracorporeal circulatory pump that requires a trans-septal
puncture to access the left atrium for the source
Table 2: Clinical features that
negatively affect favorable
outcomes from cardiac arrest18
No immediate bystander cpr
Non-shockable cardiac arrest rhythm
Prolonged resuscitation effort
( > 30 minutes without ROSC)
Non-cardiac cause for the cardiac arrest
Elderly patients ( > 85 years old)
Significant co-morbid conditions,
particularly end-stage renal disease
Very low pHa level
High lactate levels