Discussion
In our experience, the procedure of bedside VV-ECMO cannulation was safe and effective. We had only one case of failed IJV single-cannula insertion which required veno-arterial cannulation using the common femoral artery and vein due to anatomic constraints. All procedures were performed in the ICU under fluoroscopic and echocardiographic guidance. Our set-up allowed the efficient utilization of fluoroscopy by using a mobile, x-ray compatible bed (figures 1,2)). We selected the use of a bicaval dual-lumen cannula whenever indicated to facilitate adequate ECMO flow and optimize blood oxygenation by reducing “recirculation” (5,12,24). Although there is a lack of randomized trials comparing the effectiveness of the single dual-lumen versus a double venous cannulation strategy, clinical data and experimental studies show at least comparable flow-parameters and clinical results (24, 25). Nonetheless, the location of the cannula on the side of the neck, as compared to the groin, provides more opportunity for patient mobilization and may offer significant advantages in light of the fact that VV-ECMO support is often required for a considerable length of time.
The benefits of in-situ ECMO cannulation, not only in terms of potentially expediting the timing of initiation of therapy and decreasing the hazard of transporting the patient to the procedural location, appears of crucial importance during the COVID-19 pandemic in the extreme cases of respiratory decompensation and refractory hypoxemia which may benefit from VV-ECMO support. Avoidance of transporting the patient out of the ICU to reach the designated cannulation location reduces the risk of SARS-CoV-2 virus transmission to other patients and healthcare providers while also decreasing the risk of environmental contamination inevitably associated with the transportation process, and possibly decreasing unnecessary personal-protective-equipment (PPE) usage outside of the ICU. The use of fluoroscopic guidance has represented the standard for our protocol, however cannulation can also be safely completed using echocardiographic imaging with TTE or even using portable chest x-ray, which can be both routinely arranged at any healthcare facility. No matter of the imaging technique used, single venous cannulation with bicaval dual-lumen catheter remains a highly demanding procedure with risk of life-threatening complications, so that it should be performed by experienced operators in highly specialized centers (21,23,26).