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.