DISCUSSION
ECMO affords us with the ability to treat patients with respiratory
failure refractory to mechanical ventilatory support. However, it is
associated with a number of complications that may require additional
operations and even death.1,2 Therefore, patients who
require prolonged intubation are encouraged to ambulate and this has
been associated with improved outcomes and overall health care
costs.3,4
Cannulation is one of the first steps of ECMO initiation that is
associated with many complications especially in the setting of
percutaneous access of multiple blood vessels.5,6 The
use of subclavian arterial access was first described in 1993 by McGough
and colleagues in for venoarterial support in an infant along with
cannulation of the right internal jugular vein. Shafii et al. in 2012
describes subclavian vein access for placement of the Avalon (Avalon
Laboratories, Rancho Dominguez, CA) bicaval dual-lumen Elite
cannula.7 In their anecdotal experience, they found
that patients were more comfortable and were more easily encouraged to
be mobile. In the current case, there are several advantages to
utilizing a single site subclavian vein cannulation for ECMO support.
Due to her predisposition for poor healing, it was evident that she
would require a prolonged course of ECMO support. This strategy improved
the patient’s mobility to minimize further deconditioning. From a
technical standpoint, the conversion to single site subclavian vein
cannulation can be performed while preserving previously placed ECMO
circuits until while proper placement of the new cannula is achieved to
safely support the patient throughout the procedure. In addition, this
cannulation strategy offers flexibility for future cannulation
conversions as both groin sites as well as the right neck are easily
accessible for the introduction of additional cannulas in both a
controlled and emergent fashion if necessary.
In this manuscript we report some modifications to previous literature
describing the subclavian vein access and CrescentTMcannula use. While our approach echoes that of Shafii and colleagues, we
believe this cannula has important differences to note with the Avalon.
The Avalon has a maximum insertion length of 31 cm and ranges from 13 to
31 Fr allowing for use in the pediatric population. However, all
Crescent Catheter≥ 28 Fr are all 34 cm in length which can be helpful in
larger patients. In addition, because of its design, the Crescent
Catheter has the ability to achieve higher flow rates with a lower
pressure loss according to the manufacturing website compared to the
Avalon, which may provide a distinct theoretical advantage in lower
rates of hemolysis and recirculation. Ultimately additional studies will
have to be performed in order to adjudicate these statements.
There are several clinical aspects to consider with this cannulation
strategy. First, we recommend performing this cannulation conversion
strategy in the operating room with both fluoroscopic and
echocardiographic guidance to ensure proper positioning is achieved for
adequate drainage and infusion. Second, while Shafii et al. reports
easier maintenance by nursing staff, special care is needed to minimize
infection especially in the setting of a tracheostomy which is in close
proximity. Therefore, sterile techniques and close monitoring of the
cannulation site is necessary. Third, in order to minimize the morbidity
of limb ischemia, additional access to the left upper extremity should
be limited. Lastly, it is important to note the length of cannulas used
for this procedure. Given the longer course of the left subclavian
vessels, it is important to obtain adequate length to allow for proper
alignment of the reinfusion port to the tricuspid valve which can be
seen under fluoroscopy.
In conclusion, the use of the CrescentTM Dual-Lumen
Catheter at the left subclavian vein as a single cannulation site for
VV-ECMO support is a safe and viable. This is a safe and viable option
for veno-venous ECMO cannulation. It allows for both adequate drainage
and reinfusion and can be used to maximize mobility in patients who
require prolonged extracorporeal support.