An unusual view for veno-venous extra-corporeal membrane oxygenation cannulas visualization

Excerpt

Echocardiography is currently used to guide and check the correct positioning of veno-venous extra-corporeal membrane oxygenation cannulas, both for cannulation guidance, for daily monitoring and for recirculation assessment. In particular, subcostal and trans-hepatic views easily allow visualizing femoral cannulas and their placement, with respect to the right atrium and supra-hepatic veins. If a jugular cannula is placed, transesophageal echocardiography is usually preferred to visualize both femoral and jugular devices in a mid-esophageal bicaval view; this is normally not accessible with a transthoracic parasternal approach because of the lung interposition impeding the visualization of superior vena cava. However, if lung loss of aeration is complete (Fig. 1), the lung is visualized as a tissue-like pattern and its echo-texture is similar to an abdominal parenchyma, thus providing an ideal condition for ultrasound beam penetration. A transthoracic bicaval view can then be performed with the probe aligned with cranio-caudal axis and placed in right mid-clavicular line. A reliable visualization of both femoral and jugular cannulas (Fig. 1a) can be obtained, with accurate reproduction at the bedside of chest X-ray imaging (Fig. 1b) while avoiding irradiation and allowing dynamic assessment on cannula’s functioning and positioning.

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