Strategy and tips for cannulation:
We designed a process of in-situ VV-ECMO cannulation based on the layout of our intensive care unit (ICU) where patients with refractory respiratory failure are routinely hospitalized (fig. 1). We utilize a portable fluoroscopy bed which is placed to the side of the ICU bed (fig. 2). After moving the patient from the ICU to the fluoroscopy bed, the medical equipment is positioned around the patient to allow convenient access to the right side of the neck as the cannula insertion site (fig. 3). The procedure is completed under sterile conditions with fluoroscopic guidance. Fluoroscopic guidance represent our preferred imaging method since it may offer the highest level of safety (9,11). However, in the absence of conditions allowing routine use of fluoroscopy at the bedside, the procedure can also be safely performed with transthoracic echocardiogram (TTE) to confirm guidewire and cannula positioning (9, 17-19). Appropriate positioning of the wire can be confirmed with subcostal views, making sure that the guidewire is advanced into the retro-hepatic inferior vena cava (IVC) (9, 18-23). Alternatively, imaging by portable chest X-ray can also be used to spot check guidewire and cannula position (16).
Cannulation best practices using our approach are listed in table 1. We always use real-time ultrasound visualization for the puncture of the IJV. The patient is maintained in slight Trendelenburg position for the entire duration of the procedure to reduce the risk of venous air-embolism. The guidewire is advanced deep into the retrohepatic IVC and its position is confirmed by imaging. We used the standard packaging of the Avalon Elite® venous cannula kit (0.038” x 210 cm change guidewire) in all cases (table 2). After serial dilation of the skin and soft tissue at the cannula insertion site, the IJV is cannulated with 10 Fr through 30 Fr dilators. The cannula is inserted under imaging guidance ensuring no resistance is encountered while the catheter is advanced through the right atrium into the IVC. The cannula is connected to the ECMO circuit with meticulous de-airing and is secured to the skin once final manual manipulation is made to ensure adequate extracorporeal blood flow and desired arterial oxygenation (table 1).